Index: src/InitTweak/FixInit.cpp
===================================================================
--- src/InitTweak/FixInit.cpp	(revision 4dc3b8c90f62876e9e5e2b84283aebb28622582a)
+++ src/InitTweak/FixInit.cpp	(revision 4dc3b8c90f62876e9e5e2b84283aebb28622582a)
@@ -0,0 +1,1385 @@
+#include "FixInit.h"
+
+#include <stddef.h>                    // for NULL
+#include <algorithm>                   // for set_difference, copy_if
+#include <cassert>                     // for assert, strict_dynamic_cast
+#include <iostream>                    // for operator<<, ostream, basic_ost...
+#include <iterator>                    // for insert_iterator, back_inserter
+#include <list>                        // for _List_iterator, list, list<>::...
+#include <map>                         // for _Rb_tree_iterator, _Rb_tree_co...
+#include <memory>                      // for allocator_traits<>::value_type
+#include <set>                         // for set, set<>::value_type
+#include <unordered_map>               // for unordered_map, unordered_map<>...
+#include <unordered_set>               // for unordered_set
+#include <utility>                     // for pair
+
+#include "AST/DeclReplacer.hpp"
+#include "AST/Expr.hpp"
+#include "AST/Inspect.hpp"             // for getFunction, getPointerBase, g...
+#include "AST/Node.hpp"
+#include "AST/Pass.hpp"
+#include "AST/Print.hpp"
+#include "AST/SymbolTable.hpp"
+#include "AST/Type.hpp"
+#include "CodeGen/OperatorTable.h"     // for isConstructor, isCtorDtor, isD...
+#include "Common/SemanticError.h"      // for SemanticError
+#include "Common/ToString.hpp"         // for toCString
+#include "Common/UniqueName.h"         // for UniqueName
+#include "FixGlobalInit.h"             // for fixGlobalInit
+#include "GenInit.h"                   // for genCtorDtor
+#include "GenPoly/GenPoly.h"           // for getFunctionType
+#include "ResolvExpr/Resolver.h"       // for findVoidExpression
+#include "ResolvExpr/Unify.h"          // for typesCompatible
+#include "SymTab/GenImplicitCall.hpp"  // for genImplicitCall
+
+bool ctordtorp = false; // print all debug
+bool ctorp = false; // print ctor debug
+bool cpctorp = false; // print copy ctor debug
+bool dtorp = false; // print dtor debug
+#define PRINT( text ) if ( ctordtorp ) { text }
+#define CP_CTOR_PRINT( text ) if ( ctordtorp || cpctorp ) { text }
+#define DTOR_PRINT( text ) if ( ctordtorp || dtorp ) { text }
+
+namespace InitTweak {
+
+namespace {
+
+// Shallow copy the pointer list for return.
+std::vector<ast::ptr<ast::TypeDecl>> getGenericParams( const ast::Type * t ) {
+	if ( auto inst = dynamic_cast<const ast::StructInstType *>( t ) ) {
+		return inst->base->params;
+	}
+	if ( auto inst = dynamic_cast<const ast::UnionInstType *>( t ) ) {
+		return inst->base->params;
+	}
+	return {};
+}
+
+/// Given type T, generate type of default ctor/dtor, i.e. function type void (*) (T &).
+ast::FunctionDecl * genDefaultFunc(
+		const CodeLocation loc,
+		const std::string fname,
+		const ast::Type * paramType,
+		bool maybePolymorphic = true) {
+	std::vector<ast::ptr<ast::TypeDecl>> typeParams;
+	if ( maybePolymorphic ) typeParams = getGenericParams( paramType );
+	auto dstParam = new ast::ObjectDecl( loc,
+		"_dst",
+		new ast::ReferenceType( paramType ),
+		nullptr,
+		{},
+		ast::Linkage::Cforall
+	);
+	return new ast::FunctionDecl( loc,
+		fname,
+		std::move(typeParams),
+		{},
+		{dstParam},
+		{},
+		new ast::CompoundStmt(loc),
+		{},
+		ast::Linkage::Cforall
+	);
+}
+
+struct SelfAssignChecker {
+	void previsit( const ast::ApplicationExpr * appExpr );
+};
+
+struct StmtExprResult {
+	const ast::StmtExpr * previsit( const ast::StmtExpr * stmtExpr );
+};
+
+/// wrap function application expressions as ImplicitCopyCtorExpr nodes so that it is easy to identify which
+/// function calls need their parameters to be copy constructed
+struct InsertImplicitCalls : public ast::WithShortCircuiting {
+	const ast::Expr * postvisit( const ast::ApplicationExpr * appExpr );
+
+	// only handles each UniqueExpr once
+	// if order of visit does not change, this should be safe
+	void previsit (const ast::UniqueExpr *);
+
+	std::unordered_set<decltype(ast::UniqueExpr::id)> visitedIds;
+};
+
+/// generate temporary ObjectDecls for each argument and return value of each ImplicitCopyCtorExpr,
+/// generate/resolve copy construction expressions for each, and generate/resolve destructors for both
+/// arguments and return value temporaries
+struct ResolveCopyCtors final : public ast::WithGuards, public ast::WithStmtsToAdd<>, public ast::WithSymbolTable, public ast::WithShortCircuiting, public ast::WithVisitorRef<ResolveCopyCtors>, public ast::WithConstTranslationUnit {
+	const ast::Expr * postvisit( const ast::ImplicitCopyCtorExpr * impCpCtorExpr );
+	const ast::StmtExpr * previsit( const ast::StmtExpr * stmtExpr );
+	const ast::UniqueExpr * previsit( const ast::UniqueExpr * unqExpr );
+
+	/// handles distant mutations of environment manually.
+	/// WithConstTypeSubstitution cannot remember where the environment is from
+
+	/// MUST be called at start of overload previsit
+	void previsit( const ast::Expr * expr);
+	/// MUST be called at return of overload postvisit
+	const ast::Expr * postvisit(const ast::Expr * expr);
+
+	/// create and resolve ctor/dtor expression: fname(var, [cpArg])
+	const ast::Expr * makeCtorDtor( const std::string & fname, const ast::ObjectDecl * var, const ast::Expr * cpArg = nullptr );
+	/// true if type does not need to be copy constructed to ensure correctness
+	bool skipCopyConstruct( const ast::Type * type );
+	ast::ptr< ast::Expr > copyConstructArg( const ast::Expr * arg, const ast::ImplicitCopyCtorExpr * impCpCtorExpr, const ast::Type * formal );
+	ast::Expr * destructRet( const ast::ObjectDecl * ret, const ast::Expr * arg );
+private:
+	/// hack to implement WithTypeSubstitution while conforming to mutation safety.
+	ast::TypeSubstitution * env         = nullptr;
+	bool                    envModified = false;
+};
+
+/// collects constructed object decls - used as a base class
+struct ObjDeclCollector : public ast::WithGuards, public ast::WithShortCircuiting {
+	// use ordered data structure to maintain ordering for set_difference and for consistent error messages
+	typedef std::list< const ast::ObjectDecl * > ObjectSet;
+	void previsit( const ast::CompoundStmt *compoundStmt );
+	void previsit( const ast::DeclStmt *stmt );
+
+	// don't go into other functions
+	void previsit( const ast::FunctionDecl * ) { visit_children = false; }
+
+protected:
+	ObjectSet curVars;
+};
+
+// debug
+template<typename ObjectSet>
+struct PrintSet {
+	PrintSet( const ObjectSet & objs ) : objs( objs ) {}
+	const ObjectSet & objs;
+};
+template<typename ObjectSet>
+PrintSet<ObjectSet> printSet( const ObjectSet & objs ) { return PrintSet<ObjectSet>( objs ); }
+template<typename ObjectSet>
+std::ostream & operator<<( std::ostream & out, const PrintSet<ObjectSet> & set) {
+	out << "{ ";
+	for ( auto & obj : set.objs ) {
+		out << obj->name << ", " ;
+	} // for
+	out << " }";
+	return out;
+}
+
+struct LabelFinder final : public ObjDeclCollector {
+	typedef std::map< std::string, ObjectSet > LabelMap;
+	// map of Label -> live variables at that label
+	LabelMap vars;
+
+	typedef ObjDeclCollector Parent;
+	using Parent::previsit;
+	void previsit( const ast::Stmt * stmt );
+
+	void previsit( const ast::CompoundStmt *compoundStmt );
+	void previsit( const ast::DeclStmt *stmt );
+};
+
+/// insert destructor calls at the appropriate places.  must happen before CtorInit nodes are removed
+/// (currently by FixInit)
+struct InsertDtors final : public ObjDeclCollector, public ast::WithStmtsToAdd<> {
+	InsertDtors( ast::Pass<LabelFinder> & finder ) : finder( finder ), labelVars( finder.core.vars ) {}
+
+	typedef ObjDeclCollector Parent;
+	using Parent::previsit;
+
+	void previsit( const ast::FunctionDecl * funcDecl );
+
+	void previsit( const ast::BranchStmt * stmt );
+private:
+	void handleGoto( const ast::BranchStmt * stmt );
+
+	ast::Pass<LabelFinder> & finder;
+	LabelFinder::LabelMap & labelVars;
+};
+
+/// expand each object declaration to use its constructor after it is declared.
+struct FixInit : public ast::WithStmtsToAdd<> {
+	static void fixInitializers( ast::TranslationUnit &translationUnit );
+
+	const ast::DeclWithType * postvisit( const ast::ObjectDecl *objDecl );
+
+	std::list< ast::ptr< ast::Decl > > staticDtorDecls;
+};
+
+/// generate default/copy ctor and dtor calls for user-defined struct ctor/dtors
+/// for any member that is missing a corresponding ctor/dtor call.
+/// error if a member is used before constructed
+struct GenStructMemberCalls final : public ast::WithGuards, public ast::WithShortCircuiting, public ast::WithSymbolTable, public ast::WithVisitorRef<GenStructMemberCalls>, public ast::WithConstTranslationUnit {
+	void previsit( const ast::FunctionDecl * funcDecl );
+	const ast::DeclWithType * postvisit( const ast::FunctionDecl * funcDecl );
+
+	void previsit( const ast::MemberExpr * memberExpr );
+	void previsit( const ast::ApplicationExpr * appExpr );
+
+	/// Note: this post mutate used to be in a separate visitor. If this pass breaks, one place to examine is whether it is
+	/// okay for this part of the recursion to occur alongside the rest.
+	const ast::Expr * postvisit( const ast::UntypedExpr * expr );
+
+	SemanticErrorException errors;
+private:
+	template< typename... Params >
+	void emit( CodeLocation, const Params &... params );
+
+	ast::FunctionDecl * function = nullptr;
+	std::set< const ast::DeclWithType * > unhandled;
+	std::map< const ast::DeclWithType *, CodeLocation > usedUninit;
+	const ast::ObjectDecl * thisParam = nullptr;
+	bool isCtor = false; // true if current function is a constructor
+	const ast::StructDecl * structDecl = nullptr;
+};
+
+/// expands ConstructorExpr nodes into comma expressions, using a temporary for the first argument
+struct FixCtorExprs final : public ast::WithDeclsToAdd<>, public ast::WithSymbolTable, public ast::WithShortCircuiting, public ast::WithConstTranslationUnit {
+	const ast::Expr * postvisit( const ast::ConstructorExpr * ctorExpr );
+};
+
+/// add CompoundStmts around top-level expressions so that temporaries are destroyed in the correct places.
+struct SplitExpressions : public ast::WithShortCircuiting {
+	ast::Stmt * postvisit( const ast::ExprStmt * stmt );
+	void previsit( const ast::TupleAssignExpr * expr );
+};
+
+/// find and return the destructor used in `input`. If `input` is not a simple destructor call, generate a thunk
+/// that wraps the destructor, insert it into `stmtsToAdd` and return the new function declaration
+const ast::DeclWithType * getDtorFunc( const ast::ObjectDecl * objDecl, const ast::Stmt * input, std::list< ast::ptr<ast::Stmt> > & stmtsToAdd ) {
+	const CodeLocation loc = input->location;
+	// unwrap implicit statement wrapper
+	// Statement * dtor = input;
+	assert( input );
+	// std::list< const ast::Expr * > matches;
+	auto matches = collectCtorDtorCalls( input );
+
+	if ( dynamic_cast< const ast::ExprStmt * >( input ) ) {
+		// only one destructor call in the expression
+		if ( matches.size() == 1 ) {
+			auto func = getFunction( matches.front() );
+			assertf( func, "getFunction failed to find function in %s", toString( matches.front() ).c_str() );
+
+			// cleanup argument must be a function, not an object (including function pointer)
+			if ( auto dtorFunc = dynamic_cast< const ast::FunctionDecl * > ( func ) ) {
+				if ( dtorFunc->type->forall.empty() ) {
+					// simple case where the destructor is a monomorphic function call - can simply
+					// use that function as the cleanup function.
+					return func;
+				}
+			}
+		}
+	}
+
+	// otherwise the cleanup is more complicated - need to build a single argument cleanup function that
+	// wraps the more complicated code.
+	static UniqueName dtorNamer( "__cleanup_dtor" );
+	std::string name = dtorNamer.newName();
+	ast::FunctionDecl * dtorFunc = genDefaultFunc( loc, name, objDecl->type->stripReferences(), false );
+	stmtsToAdd.push_back( new ast::DeclStmt(loc, dtorFunc ) );
+
+	// the original code contains uses of objDecl - replace them with the newly generated 'this' parameter.
+	const ast::ObjectDecl * thisParam = getParamThis( dtorFunc );
+	const ast::Expr * replacement = new ast::VariableExpr( loc, thisParam );
+
+	auto base = replacement->result->stripReferences();
+	if ( dynamic_cast< const ast::ArrayType * >( base ) || dynamic_cast< const ast::TupleType * > ( base ) ) {
+		// need to cast away reference for array types, since the destructor is generated without the reference type,
+		// and for tuple types since tuple indexing does not work directly on a reference
+		replacement = new ast::CastExpr( replacement, base );
+	}
+	auto dtor = ast::DeclReplacer::replace( input, ast::DeclReplacer::ExprMap{ std::make_pair( objDecl, replacement ) } );
+	auto mutStmts = dtorFunc->stmts.get_and_mutate();
+	mutStmts->push_back(strict_dynamic_cast<const ast::Stmt *>( dtor ));
+	dtorFunc->stmts = mutStmts;
+
+	return dtorFunc;
+}
+
+void FixInit::fixInitializers( ast::TranslationUnit & translationUnit ) {
+	ast::Pass<FixInit> fixer;
+
+	// can't use mutateAll, because need to insert declarations at top-level
+	// can't use DeclMutator, because sometimes need to insert IfStmt, etc.
+	SemanticErrorException errors;
+	for ( auto i = translationUnit.decls.begin(); i != translationUnit.decls.end(); ++i ) {
+		try {
+			// maybeAccept( *i, fixer ); translationUnit should never contain null
+			*i = (*i)->accept(fixer);
+			translationUnit.decls.splice( i, fixer.core.staticDtorDecls );
+		} catch( SemanticErrorException &e ) {
+			errors.append( e );
+		} // try
+	} // for
+	if ( ! errors.isEmpty() ) {
+		throw errors;
+	} // if
+}
+
+const ast::StmtExpr * StmtExprResult::previsit( const ast::StmtExpr * stmtExpr ) {
+	// we might loose the result expression here so add a pointer to trace back
+	assert( stmtExpr->result );
+	const ast::Type * result = stmtExpr->result;
+	if ( ! result->isVoid() ) {
+		auto mutExpr = mutate(stmtExpr);
+		const ast::CompoundStmt * body = mutExpr->stmts;
+		assert( ! body->kids.empty() );
+		mutExpr->resultExpr = body->kids.back().strict_as<ast::ExprStmt>();
+		return mutExpr;
+	}
+	return stmtExpr;
+}
+
+ast::Stmt * SplitExpressions::postvisit( const ast::ExprStmt * stmt ) {
+	// wrap each top-level ExprStmt in a block so that destructors for argument and return temporaries are destroyed
+	// in the correct places
+	ast::CompoundStmt * ret = new ast::CompoundStmt( stmt->location, { stmt } );
+	return ret;
+}
+
+void SplitExpressions::previsit( const ast::TupleAssignExpr * ) {
+	// don't do this within TupleAssignExpr, since it is already broken up into multiple expressions
+	visit_children = false;
+}
+
+// Relatively simple structural comparison for expressions, needed to determine
+// if two expressions are "the same" (used to determine if self assignment occurs)
+struct StructuralChecker {
+	// Strip all casts and then dynamic_cast.
+	template<typename T>
+	static const T * cast( const ast::Expr * expr ) {
+		// this might be too permissive. It's possible that only particular casts are relevant.
+		while ( auto cast = dynamic_cast< const ast::CastExpr * >( expr ) ) {
+			expr = cast->arg;
+		}
+		return dynamic_cast< const T * >( expr );
+	}
+
+	void previsit( const ast::Expr * ) {
+		// anything else does not qualify
+		result = false;
+	}
+
+	// ignore casts
+	void previsit( const ast::CastExpr * ) {}
+
+	void previsit( const ast::MemberExpr * memExpr ) {
+		if ( auto otherMember = cast< ast::MemberExpr >( other ) ) {
+			if ( otherMember->member == memExpr->member ) {
+				other = otherMember->aggregate;
+				return;
+			}
+		}
+		result = false;
+	}
+
+	void previsit( const ast::VariableExpr * varExpr ) {
+		if ( auto otherVar = cast< ast::VariableExpr >( other ) ) {
+			if ( otherVar->var == varExpr->var ) {
+				return;
+			}
+		}
+		result = false;
+	}
+
+	void previsit( const ast::AddressExpr * ) {
+		if ( auto addrExpr = cast< ast::AddressExpr >( other ) ) {
+			other = addrExpr->arg;
+			return;
+		}
+		result = false;
+	}
+
+	const ast::Expr * other;
+	bool result = true;
+	StructuralChecker( const ast::Expr * other ) : other(other) {}
+};
+
+bool structurallySimilar( const ast::Expr * e1, const ast::Expr * e2 ) {
+	return ast::Pass<StructuralChecker>::read( e1, e2 );
+}
+
+void SelfAssignChecker::previsit( const ast::ApplicationExpr * appExpr ) {
+	auto function = getFunction( appExpr );
+	// Doesn't use isAssignment, because ?+=?, etc. should not count as self-assignment.
+	if ( function->name == "?=?" && appExpr->args.size() == 2
+			// Check for structural similarity (same variable use, ignore casts, etc.
+			// (but does not look too deeply, anything looking like a function is off limits).
+			&& structurallySimilar( appExpr->args.front(), appExpr->args.back() ) ) {
+		SemanticWarning( appExpr->location, Warning::SelfAssignment, toCString( appExpr->args.front() ) );
+	}
+}
+
+const ast::Expr * InsertImplicitCalls::postvisit( const ast::ApplicationExpr * appExpr ) {
+	if ( auto function = appExpr->func.as<ast::VariableExpr>() ) {
+		if ( function->var->linkage.is_builtin ) {
+			// optimization: don't need to copy construct in order to call intrinsic functions
+			return appExpr;
+		} else if ( auto funcDecl = function->var.as<ast::DeclWithType>() ) {
+			auto ftype = dynamic_cast< const ast::FunctionType * >( GenPoly::getFunctionType( funcDecl->get_type() ) );
+			assertf( ftype, "Function call without function type: %s", toString( funcDecl ).c_str() );
+			if ( CodeGen::isConstructor( funcDecl->name ) && ftype->params.size() == 2 ) {
+				auto t1 = getPointerBase( ftype->params.front() );
+				auto t2 = ftype->params.back();
+				assert( t1 );
+
+				if ( ResolvExpr::typesCompatible( t1, t2 ) ) {
+					// optimization: don't need to copy construct in order to call a copy constructor
+					return appExpr;
+				} // if
+			} else if ( CodeGen::isDestructor( funcDecl->name ) ) {
+				// correctness: never copy construct arguments to a destructor
+				return appExpr;
+			} // if
+		} // if
+	} // if
+	CP_CTOR_PRINT( std::cerr << "InsertImplicitCalls: adding a wrapper " << appExpr << std::endl; )
+
+	// wrap each function call so that it is easy to identify nodes that have to be copy constructed
+	ast::ptr<ast::TypeSubstitution> tmp = appExpr->env;
+	auto mutExpr = mutate(appExpr);
+	mutExpr->env = nullptr;
+
+	auto expr = new ast::ImplicitCopyCtorExpr( appExpr->location, mutExpr );
+	// Move the type substitution to the new top-level. The substitution
+	// is needed to obtain the type of temporary variables so that copy
+	// constructor calls can be resolved.
+	expr->env = tmp;
+	return expr;
+}
+
+void ResolveCopyCtors::previsit(const ast::Expr * expr) {
+	if ( nullptr == expr->env ) {
+		return;
+	}
+	GuardValue( env ) = expr->env->clone();
+	GuardValue( envModified ) = false;
+}
+
+const ast::Expr * ResolveCopyCtors::postvisit(const ast::Expr * expr) {
+	// No local environment, skip.
+	if ( nullptr == expr->env ) {
+		return expr;
+	// Environment was modified, mutate and replace.
+	} else if ( envModified ) {
+		auto mutExpr = mutate(expr);
+		mutExpr->env = env;
+		return mutExpr;
+	// Environment was not mutated, delete the shallow copy before guard.
+	} else {
+		delete env;
+		return expr;
+	}
+}
+
+bool ResolveCopyCtors::skipCopyConstruct( const ast::Type * type ) { return ! isConstructable( type ); }
+
+const ast::Expr * ResolveCopyCtors::makeCtorDtor( const std::string & fname, const ast::ObjectDecl * var, const ast::Expr * cpArg ) {
+	assert( var );
+	assert( var->isManaged() );
+	assert( !cpArg || cpArg->isManaged() );
+	// arrays are not copy constructed, so this should always be an ExprStmt
+	ast::ptr< ast::Stmt > stmt = genCtorDtor(var->location, fname, var, cpArg );
+	assertf( stmt, "ResolveCopyCtors: genCtorDtor returned nullptr: %s / %s / %s", fname.c_str(), toString( var ).c_str(), toString( cpArg ).c_str() );
+	auto exprStmt = stmt.strict_as<ast::ImplicitCtorDtorStmt>()->callStmt.strict_as<ast::ExprStmt>();
+	ast::ptr<ast::Expr> untyped = exprStmt->expr; // take ownership of expr
+
+	// resolve copy constructor
+	// should only be one alternative for copy ctor and dtor expressions, since all arguments are fixed
+	// (VariableExpr and already resolved expression)
+	CP_CTOR_PRINT( std::cerr << "ResolvingCtorDtor " << untyped << std::endl; )
+	ast::ptr<ast::Expr> resolved = ResolvExpr::findVoidExpression(untyped, { symtab, transUnit().global } );
+	assert( resolved );
+	if ( resolved->env ) {
+		// Extract useful information and discard new environments. Keeping them causes problems in PolyMutator passes.
+		env->add( *resolved->env );
+		envModified = true;
+		auto mut = mutate(resolved.get());
+		assertf(mut == resolved.get(), "newly resolved expression must be unique");
+		mut->env = nullptr;
+	} // if
+	if ( auto assign = resolved.as<ast::TupleAssignExpr>() ) {
+		// fix newly generated StmtExpr
+		previsit( assign->stmtExpr );
+	}
+	return resolved.release();
+}
+
+ast::ptr<ast::Expr> ResolveCopyCtors::copyConstructArg(
+	const ast::Expr * arg, const ast::ImplicitCopyCtorExpr * impCpCtorExpr, const ast::Type * formal )
+{
+	static UniqueName tempNamer("_tmp_cp");
+	const CodeLocation loc = impCpCtorExpr->location;
+	// CP_CTOR_PRINT( std::cerr << "Type Substitution: " << *env << std::endl; )
+	assert( arg->result );
+	ast::ptr<ast::Type> result = arg->result;
+	if ( skipCopyConstruct( result ) ) return arg; // skip certain non-copyable types
+
+	// type may involve type variables, so apply type substitution to get temporary variable's actual type,
+	// since result type may not be substituted (e.g., if the type does not appear in the parameter list)
+	// Use applyFree so that types bound in function pointers are not substituted, e.g. in forall(dtype T) void (*)(T).
+
+	// xxx - this originally mutates arg->result in place. is it correct?
+	assert( env );
+	result = env->applyFree( result.get() ).node;
+	auto mutResult = result.get_and_mutate();
+	mutResult->set_const(false);
+
+	auto mutArg = mutate(arg);
+	mutArg->result = mutResult;
+
+	ast::ptr<ast::Expr> guard = mutArg;
+
+	ast::ptr<ast::ObjectDecl> tmp = new ast::ObjectDecl(loc, "__tmp", mutResult, nullptr );
+
+	// create and resolve copy constructor
+	CP_CTOR_PRINT( std::cerr << "makeCtorDtor for an argument" << std::endl; )
+	auto cpCtor = makeCtorDtor( "?{}", tmp, mutArg );
+
+	if ( auto appExpr = dynamic_cast< const ast::ApplicationExpr * >( cpCtor ) ) {
+		// if the chosen constructor is intrinsic, the copy is unnecessary, so
+		// don't create the temporary and don't call the copy constructor
+		auto function = appExpr->func.strict_as<ast::VariableExpr>();
+		if ( function->var->linkage == ast::Linkage::Intrinsic ) {
+			// arguments that need to be boxed need a temporary regardless of whether the copy constructor is intrinsic,
+			// so that the object isn't changed inside of the polymorphic function
+			if ( ! GenPoly::needsBoxing( formal, result, impCpCtorExpr->callExpr, env ) ) {
+				// xxx - should arg->result be mutated? see comment above.
+				return guard;
+			}
+		}
+	}
+
+	// set a unique name for the temporary once it's certain the call is necessary
+	auto mut = tmp.get_and_mutate();
+	assertf (mut == tmp, "newly created ObjectDecl must be unique");
+	mut->name = tempNamer.newName();
+
+	// replace argument to function call with temporary
+	stmtsToAddBefore.push_back( new ast::DeclStmt(loc, tmp ) );
+	arg = cpCtor;
+	return destructRet( tmp, arg );
+
+	// impCpCtorExpr->dtors.push_front( makeCtorDtor( "^?{}", tmp ) );
+}
+
+ast::Expr * ResolveCopyCtors::destructRet( const ast::ObjectDecl * ret, const ast::Expr * arg ) {
+	auto global = transUnit().global;
+	// TODO: refactor code for generating cleanup attribute, since it's common and reused in ~3-4 places
+	// check for existing cleanup attribute before adding another(?)
+	// need to add __Destructor for _tmp_cp variables as well
+
+	assertf( global.dtorStruct, "Destructor generation requires __Destructor definition." );
+	assertf( global.dtorStruct->members.size() == 2, "__Destructor definition does not have expected fields." );
+	assertf( global.dtorDestroy, "Destructor generation requires __destroy_Destructor." );
+
+	const CodeLocation & loc = ret->location;
+
+	// generate a __Destructor for ret that calls the destructor
+	auto res = makeCtorDtor( "^?{}", ret );
+	auto dtor = mutate(res);
+
+	// if the chosen destructor is intrinsic, elide the generated dtor handler
+	if ( arg && isIntrinsicCallExpr( dtor ) ) {
+		return new ast::CommaExpr(loc, arg, new ast::VariableExpr(loc, ret ) );
+	}
+
+	if ( ! dtor->env ) dtor->env = maybeClone( env );
+	auto dtorFunc = getDtorFunc( ret, new ast::ExprStmt(loc, dtor ), stmtsToAddBefore );
+
+	auto dtorStructType = new ast::StructInstType( global.dtorStruct );
+
+	// what does this do???
+	dtorStructType->params.push_back( new ast::TypeExpr(loc, new ast::VoidType() ) );
+
+	// cast destructor pointer to void (*)(void *), to silence GCC incompatible pointer warnings
+	auto dtorFtype = new ast::FunctionType();
+	dtorFtype->params.push_back( new ast::PointerType(new ast::VoidType( ) ) );
+	auto dtorType = new ast::PointerType( dtorFtype );
+
+	static UniqueName namer( "_ret_dtor" );
+	auto retDtor = new ast::ObjectDecl(loc, namer.newName(), dtorStructType, new ast::ListInit(loc, { new ast::SingleInit(loc, ast::ConstantExpr::null(loc) ), new ast::SingleInit(loc, new ast::CastExpr( new ast::VariableExpr(loc, dtorFunc ), dtorType ) ) } ) );
+	retDtor->attributes.push_back( new ast::Attribute( "cleanup", { new ast::VariableExpr(loc, global.dtorDestroy ) } ) );
+	stmtsToAddBefore.push_back( new ast::DeclStmt(loc, retDtor ) );
+
+	if ( arg ) {
+		auto member = new ast::MemberExpr(loc, global.dtorStruct->members.front().strict_as<ast::DeclWithType>(), new ast::VariableExpr(loc, retDtor ) );
+		auto object = new ast::CastExpr( new ast::AddressExpr( new ast::VariableExpr(loc, ret ) ), new ast::PointerType(new ast::VoidType() ) );
+		ast::Expr * assign = createBitwiseAssignment( member, object );
+		return new ast::CommaExpr(loc, new ast::CommaExpr(loc, arg, assign ), new ast::VariableExpr(loc, ret ) );
+	}
+	return nullptr;
+	// impCpCtorExpr->get_dtors().push_front( makeCtorDtor( "^?{}", ret ) );
+}
+
+const ast::Expr * ResolveCopyCtors::postvisit( const ast::ImplicitCopyCtorExpr *impCpCtorExpr ) {
+	CP_CTOR_PRINT( std::cerr << "ResolveCopyCtors: " << impCpCtorExpr << std::endl; )
+
+	ast::ApplicationExpr * appExpr = mutate(impCpCtorExpr->callExpr.get());
+	const ast::ObjectDecl * returnDecl = nullptr;
+	const CodeLocation loc = appExpr->location;
+
+	// take each argument and attempt to copy construct it.
+	auto ftype = GenPoly::getFunctionType( appExpr->func->result );
+	assert( ftype );
+	auto & params = ftype->params;
+	auto iter = params.begin();
+	for ( auto & arg : appExpr->args ) {
+		const ast::Type * formal = nullptr;
+		if ( iter != params.end() ) { // does not copy construct C-style variadic arguments
+			// DeclarationWithType * param = *iter++;
+			formal = *iter++;
+		}
+
+		arg = copyConstructArg( arg, impCpCtorExpr, formal );
+	} // for
+
+	// each return value from the call needs to be connected with an ObjectDecl at the call site, which is
+	// initialized with the return value and is destructed later
+	// xxx - handle named return values?
+	const ast::Type * result = appExpr->result;
+	if ( ! result->isVoid() ) {
+		static UniqueName retNamer("_tmp_cp_ret");
+		auto subResult = env->apply( result ).node;
+		auto ret = new ast::ObjectDecl(loc, retNamer.newName(), subResult, nullptr );
+		auto mutType = mutate(ret->type.get());
+		mutType->set_const( false );
+		ret->type = mutType;
+		returnDecl = ret;
+		stmtsToAddBefore.push_back( new ast::DeclStmt(loc, ret ) );
+		CP_CTOR_PRINT( std::cerr << "makeCtorDtor for a return" << std::endl; )
+	} // for
+	CP_CTOR_PRINT( std::cerr << "after Resolving: " << impCpCtorExpr << std::endl; )
+	// ------------------------------------------------------
+
+	CP_CTOR_PRINT( std::cerr << "Coming out the back..." << impCpCtorExpr << std::endl; )
+
+	// detach fields from wrapper node so that it can be deleted without deleting too much
+
+	// xxx - actual env might be somewhere else, need to keep invariant
+
+	// deletion of wrapper should be handled by pass template now
+
+	// impCpCtorExpr->callExpr = nullptr;
+	assert (appExpr->env == nullptr);
+	appExpr->env = impCpCtorExpr->env;
+	// std::swap( impCpCtorExpr->env, appExpr->env );
+	// assert( impCpCtorExpr->env == nullptr );
+	// delete impCpCtorExpr;
+
+	if ( returnDecl ) {
+		ast::Expr * assign = createBitwiseAssignment( new ast::VariableExpr(loc, returnDecl ), appExpr );
+		if ( ! dynamic_cast< const ast::ReferenceType * >( result ) ) {
+			// destructing reference returns is bad because it can cause multiple destructor calls to the same object - the returned object is not a temporary
+			assign = destructRet( returnDecl, assign );
+			assert(assign);
+		} else {
+			assign = new ast::CommaExpr(loc, assign, new ast::VariableExpr(loc, returnDecl ) );
+		}
+		// move env from appExpr to retExpr
+		// std::swap( assign->env, appExpr->env );
+		assign->env = appExpr->env;
+		// actual env is handled by common routine that replaces WithTypeSubstitution
+		return postvisit((const ast::Expr *)assign);
+	} else {
+		return postvisit((const ast::Expr *)appExpr);
+	} // if
+}
+
+const ast::StmtExpr * ResolveCopyCtors::previsit( const ast::StmtExpr * _stmtExpr ) {
+	// function call temporaries should be placed at statement-level, rather than nested inside of a new statement expression,
+	// since temporaries can be shared across sub-expressions, e.g.
+	//   [A, A] f();       // decl
+	//   g([A] x, [A] y);  // decl
+	//   g(f());           // call
+	// f is executed once, so the return temporary is shared across the tuple constructors for x and y.
+	// Explicitly mutating children instead of mutating the inner compound statement forces the temporaries to be added
+	// to the outer context, rather than inside of the statement expression.
+
+	// call the common routine that replaces WithTypeSubstitution
+	previsit((const ast::Expr *) _stmtExpr);
+
+	visit_children = false;
+	const CodeLocation loc = _stmtExpr->location;
+
+	assert( env );
+
+	symtab.enterScope();
+	// visit all statements
+	auto stmtExpr = mutate(_stmtExpr);
+	auto mutStmts = mutate(stmtExpr->stmts.get());
+
+	auto & stmts = mutStmts->kids;
+	for ( auto & stmt : stmts ) {
+		stmt = stmt->accept( *visitor );
+	} // for
+	stmtExpr->stmts = mutStmts;
+	symtab.leaveScope();
+
+	assert( stmtExpr->result );
+	// const ast::Type * result = stmtExpr->result;
+	if ( ! stmtExpr->result->isVoid() ) {
+		static UniqueName retNamer("_tmp_stmtexpr_ret");
+
+		// result = result->clone();
+		auto result = env->apply( stmtExpr->result.get() ).node;
+		if ( ! InitTweak::isConstructable( result ) ) {
+			// delete result;
+			return stmtExpr;
+		}
+		auto mutResult = result.get_and_mutate();
+		mutResult->set_const(false);
+
+		// create variable that will hold the result of the stmt expr
+		auto ret = new ast::ObjectDecl(loc, retNamer.newName(), mutResult, nullptr );
+		stmtsToAddBefore.push_back( new ast::DeclStmt(loc, ret ) );
+
+		assertf(
+			stmtExpr->resultExpr,
+			"Statement-Expression should have a resulting expression at %s:%d",
+			stmtExpr->location.filename.c_str(),
+			stmtExpr->location.first_line
+		);
+
+		const ast::ExprStmt * last = stmtExpr->resultExpr;
+		// xxx - if this is non-unique, need to copy while making resultExpr ref
+		assertf(last->unique(), "attempt to modify weakly shared statement");
+		auto mutLast = mutate(last);
+		// above assertion means in-place mutation is OK
+		try {
+			mutLast->expr = makeCtorDtor( "?{}", ret, mutLast->expr );
+		} catch(...) {
+			std::cerr << "*CFA internal error: ";
+			std::cerr << "can't resolve implicit constructor";
+			std::cerr << " at " << stmtExpr->location.filename;
+			std::cerr << ":" << stmtExpr->location.first_line << std::endl;
+
+			abort();
+		}
+
+		// add destructors after current statement
+		stmtsToAddAfter.push_back( new ast::ExprStmt(loc, makeCtorDtor( "^?{}", ret ) ) );
+
+		// must have a non-empty body, otherwise it wouldn't have a result
+		assert( ! stmts.empty() );
+
+		// if there is a return decl, add a use as the last statement; will not have return decl on non-constructable returns
+		stmts.push_back( new ast::ExprStmt(loc, new ast::VariableExpr(loc, ret ) ) );
+	} // if
+
+	assert( stmtExpr->returnDecls.empty() );
+	assert( stmtExpr->dtors.empty() );
+
+	return stmtExpr;
+}
+
+// to prevent warnings ('_unq0' may be used uninitialized in this function),
+// insert an appropriate zero initializer for UniqueExpr temporaries.
+ast::Init * makeInit( const ast::Type * t, CodeLocation const & loc ) {
+	if ( auto inst = dynamic_cast< const ast::StructInstType * >( t ) ) {
+		// initizer for empty struct must be empty
+		if ( inst->base->members.empty() ) {
+			return new ast::ListInit( loc, {} );
+		}
+	} else if ( auto inst = dynamic_cast< const ast::UnionInstType * >( t ) ) {
+		// initizer for empty union must be empty
+		if ( inst->base->members.empty() ) {
+			return new ast::ListInit( loc, {} );
+		}
+	}
+
+	return new ast::ListInit( loc, {
+		new ast::SingleInit( loc, ast::ConstantExpr::from_int( loc, 0 ) )
+	} );
+}
+
+const ast::UniqueExpr * ResolveCopyCtors::previsit( const ast::UniqueExpr * unqExpr ) {
+	visit_children = false;
+	// xxx - hack to prevent double-handling of unique exprs, otherwise too many temporary variables and destructors are generated
+	static std::unordered_map< int, const ast::UniqueExpr * > unqMap;
+	auto mutExpr = mutate(unqExpr);
+	if ( ! unqMap.count( unqExpr->id ) ) {
+		// resolve expr and find its
+
+		auto impCpCtorExpr = mutExpr->expr.as<ast::ImplicitCopyCtorExpr>();
+		// PassVisitor<ResolveCopyCtors> fixer;
+
+		mutExpr->expr = mutExpr->expr->accept( *visitor );
+		// it should never be necessary to wrap a void-returning expression in a UniqueExpr - if this assumption changes, this needs to be rethought
+		assert( unqExpr->result );
+		if ( impCpCtorExpr ) {
+			auto comma = unqExpr->expr.strict_as<ast::CommaExpr>();
+			auto var = comma->arg2.strict_as<ast::VariableExpr>();
+			// note the variable used as the result from the call
+			mutExpr->var = var;
+		} else {
+			// expr isn't a call expr, so create a new temporary variable to use to hold the value of the unique expression
+			mutExpr->object = new ast::ObjectDecl( mutExpr->location, toString("_unq", mutExpr->id), mutExpr->result, makeInit( mutExpr->result, mutExpr->location ) );
+			mutExpr->var = new ast::VariableExpr( mutExpr->location, mutExpr->object );
+		}
+
+		unqMap[mutExpr->id] = mutExpr;
+	} else {
+		// take data from other UniqueExpr to ensure consistency
+		// delete unqExpr->get_expr();
+		mutExpr->expr = unqMap[mutExpr->id]->expr;
+		// delete unqExpr->result;
+		mutExpr->result = mutExpr->expr->result;
+	}
+	return mutExpr;
+}
+
+const ast::DeclWithType * FixInit::postvisit( const ast::ObjectDecl *_objDecl ) {
+	const CodeLocation loc = _objDecl->location;
+
+	// since this removes the init field from objDecl, it must occur after children are mutated (i.e. postvisit)
+	if ( ast::ptr<ast::ConstructorInit> ctorInit = _objDecl->init.as<ast::ConstructorInit>() ) {
+		auto objDecl = mutate(_objDecl);
+
+		// could this be non-unique?
+		if (objDecl != _objDecl) {
+			std::cerr << "FixInit: non-unique object decl " << objDecl->location << objDecl->name << std::endl;
+		}
+		// a decision should have been made by the resolver, so ctor and init are not both non-NULL
+		assert( ! ctorInit->ctor || ! ctorInit->init );
+		if ( const ast::Stmt * ctor = ctorInit->ctor ) {
+			if ( objDecl->storage.is_static ) {
+				addDataSectionAttribute(objDecl);
+				// originally wanted to take advantage of gcc nested functions, but
+				// we get memory errors with this approach. To remedy this, the static
+				// variable is hoisted when the destructor needs to be called.
+				//
+				// generate:
+				// static T __objName_static_varN;
+				// void __objName_dtor_atexitN() {
+				//   __dtor__...;
+				// }
+				// int f(...) {
+				//   ...
+				//   static bool __objName_uninitialized = true;
+				//   if (__objName_uninitialized) {
+				//     __ctor(__objName);
+				//     __objName_uninitialized = false;
+				//     atexit(__objName_dtor_atexitN);
+				//   }
+				//   ...
+				// }
+
+				static UniqueName dtorCallerNamer( "_dtor_atexit" );
+
+				// static bool __objName_uninitialized = true
+				auto boolType = new ast::BasicType( ast::BasicType::Kind::Bool );
+				auto boolInitExpr = new ast::SingleInit(loc, ast::ConstantExpr::from_int(loc, 1 ) );
+				auto isUninitializedVar = new ast::ObjectDecl(loc, objDecl->mangleName + "_uninitialized", boolType, boolInitExpr, ast::Storage::Static, ast::Linkage::Cforall);
+				isUninitializedVar->fixUniqueId();
+
+				// __objName_uninitialized = false;
+				auto setTrue = new ast::UntypedExpr(loc, new ast::NameExpr(loc, "?=?" ) );
+				setTrue->args.push_back( new ast::VariableExpr(loc, isUninitializedVar ) );
+				setTrue->args.push_back( ast::ConstantExpr::from_int(loc, 0 ) );
+
+				// generate body of if
+				auto initStmts = new ast::CompoundStmt(loc);
+				auto & body = initStmts->kids;
+				body.push_back( ctor );
+				body.push_back( new ast::ExprStmt(loc, setTrue ) );
+
+				// put it all together
+				auto ifStmt = new ast::IfStmt(loc, new ast::VariableExpr(loc, isUninitializedVar ), initStmts, 0 );
+				stmtsToAddAfter.push_back( new ast::DeclStmt(loc, isUninitializedVar ) );
+				stmtsToAddAfter.push_back( ifStmt );
+
+				const ast::Stmt * dtor = ctorInit->dtor;
+
+				// these should be automatically managed once reassigned
+				// objDecl->set_init( nullptr );
+				// ctorInit->set_ctor( nullptr );
+				// ctorInit->set_dtor( nullptr );
+				if ( dtor ) {
+					// if the object has a non-trivial destructor, have to
+					// hoist it and the object into the global space and
+					// call the destructor function with atexit.
+
+					// Statement * dtorStmt = dtor->clone();
+
+					// void __objName_dtor_atexitN(...) {...}
+					ast::FunctionDecl * dtorCaller = new ast::FunctionDecl(loc, objDecl->mangleName + dtorCallerNamer.newName(), {}, {}, {}, {}, new ast::CompoundStmt(loc, {dtor}), ast::Storage::Static, ast::Linkage::C );
+					dtorCaller->fixUniqueId();
+					// dtorCaller->stmts->push_back( dtor );
+
+					// atexit(dtor_atexit);
+					auto callAtexit = new ast::UntypedExpr(loc, new ast::NameExpr(loc, "atexit" ) );
+					callAtexit->args.push_back( new ast::VariableExpr(loc, dtorCaller ) );
+
+					body.push_back( new ast::ExprStmt(loc, callAtexit ) );
+
+					// hoist variable and dtor caller decls to list of decls that will be added into global scope
+					staticDtorDecls.push_back( objDecl );
+					staticDtorDecls.push_back( dtorCaller );
+
+					// need to rename object uniquely since it now appears
+					// at global scope and there could be multiple function-scoped
+					// static variables with the same name in different functions.
+					// Note: it isn't sufficient to modify only the mangleName, because
+					// then subsequent SymbolTable passes can choke on seeing the object's name
+					// if another object has the same name and type. An unfortunate side-effect
+					// of renaming the object is that subsequent NameExprs may fail to resolve,
+					// but there shouldn't be any remaining past this point.
+					static UniqueName staticNamer( "_static_var" );
+					objDecl->name = objDecl->name + staticNamer.newName();
+					objDecl->mangleName = Mangle::mangle( objDecl );
+					objDecl->init = nullptr;
+
+					// xxx - temporary hack: need to return a declaration, but want to hoist the current object out of this scope
+					// create a new object which is never used
+					static UniqueName dummyNamer( "_dummy" );
+					auto dummy = new ast::ObjectDecl(loc, dummyNamer.newName(), new ast::PointerType(new ast::VoidType()), nullptr, ast::Storage::Static, ast::Linkage::Cforall, 0, { new ast::Attribute("unused") } );
+					// delete ctorInit;
+					return dummy;
+				} else {
+					objDecl->init = nullptr;
+					return objDecl;
+				}
+			} else {
+				auto implicit = strict_dynamic_cast< const ast::ImplicitCtorDtorStmt * > ( ctor );
+				auto ctorStmt = implicit->callStmt.as<ast::ExprStmt>();
+				const ast::ApplicationExpr * ctorCall = nullptr;
+				if ( ctorStmt && (ctorCall = isIntrinsicCallExpr( ctorStmt->expr )) && ctorCall->args.size() == 2 ) {
+					// clean up intrinsic copy constructor calls by making them into SingleInits
+					const ast::Expr * ctorArg = ctorCall->args.back();
+					// ctorCall should be gone afterwards
+					auto mutArg = mutate(ctorArg);
+					mutArg->env = ctorCall->env;
+					// std::swap( ctorArg->env, ctorCall->env );
+					objDecl->init = new ast::SingleInit(loc, mutArg );
+
+					// ctorCall->args.pop_back();
+				} else {
+					stmtsToAddAfter.push_back( ctor );
+					objDecl->init = nullptr;
+					// ctorInit->ctor = nullptr;
+				}
+
+				const ast::Stmt * dtor = ctorInit->dtor;
+				if ( dtor ) {
+					auto implicit = strict_dynamic_cast< const ast::ImplicitCtorDtorStmt * >( dtor );
+					const ast::Stmt * dtorStmt = implicit->callStmt;
+
+					// don't need to call intrinsic dtor, because it does nothing, but
+					// non-intrinsic dtors must be called
+					if ( ! isIntrinsicSingleArgCallStmt( dtorStmt ) ) {
+						// set dtor location to the object's location for error messages
+						auto dtorFunc = getDtorFunc( objDecl, dtorStmt, stmtsToAddBefore );
+						objDecl->attributes.push_back( new ast::Attribute( "cleanup", { new ast::VariableExpr(loc, dtorFunc ) } ) );
+						// ctorInit->dtor = nullptr;
+					} // if
+				}
+			} // if
+		} else if ( const ast::Init * init = ctorInit->init ) {
+			objDecl->init = init;
+			// ctorInit->init = nullptr;
+		} else {
+			// no constructor and no initializer, which is okay
+			objDecl->init = nullptr;
+		} // if
+		// delete ctorInit;
+		return objDecl;
+	} // if
+	return _objDecl;
+}
+
+void ObjDeclCollector::previsit( const ast::CompoundStmt * ) {
+	GuardValue( curVars );
+}
+
+void ObjDeclCollector::previsit( const ast::DeclStmt * stmt ) {
+	// keep track of all variables currently in scope
+	if ( auto objDecl = stmt->decl.as<ast::ObjectDecl>() ) {
+		curVars.push_back( objDecl );
+	} // if
+}
+
+void LabelFinder::previsit( const ast::Stmt * stmt ) {
+	// for each label, remember the variables in scope at that label.
+	for ( auto l : stmt->labels ) {
+		vars[l] = curVars;
+	} // for
+}
+
+void LabelFinder::previsit( const ast::CompoundStmt * stmt ) {
+	previsit( (const ast::Stmt *) stmt );
+	Parent::previsit( stmt );
+}
+
+void LabelFinder::previsit( const ast::DeclStmt * stmt ) {
+	previsit( (const ast::Stmt *)stmt );
+	Parent::previsit( stmt );
+}
+
+void InsertDtors::previsit( const ast::FunctionDecl * funcDecl ) {
+	// each function needs to have its own set of labels
+	GuardValue( labelVars );
+	labelVars.clear();
+	// LabelFinder does not recurse into FunctionDecl, so need to visit
+	// its children manually.
+	if (funcDecl->type) funcDecl->type->accept(finder);
+	// maybeAccept( funcDecl->type, finder );
+	if (funcDecl->stmts) funcDecl->stmts->accept(finder) ;
+
+	// all labels for this function have been collected, insert destructors as appropriate via implicit recursion.
+}
+
+// Handle break/continue/goto in the same manner as C++.  Basic idea: any objects that are in scope at the
+// BranchStmt but not at the labelled (target) statement must be destructed.  If there are any objects in scope
+// at the target location but not at the BranchStmt then those objects would be uninitialized so notify the user
+// of the error.  See C++ Reference 6.6 Jump Statements for details.
+void InsertDtors::handleGoto( const ast::BranchStmt * stmt ) {
+	// can't do anything for computed goto
+	if ( stmt->computedTarget ) return;
+
+	assertf( stmt->target.name != "", "BranchStmt missing a label: %s", toString( stmt ).c_str() );
+	// S_L = lvars = set of objects in scope at label definition
+	// S_G = curVars = set of objects in scope at goto statement
+	ObjectSet & lvars = labelVars[ stmt->target ];
+
+	DTOR_PRINT(
+		std::cerr << "at goto label: " << stmt->target.name << std::endl;
+		std::cerr << "S_G = " << printSet( curVars ) << std::endl;
+		std::cerr << "S_L = " << printSet( lvars ) << std::endl;
+	)
+
+
+	// std::set_difference requires that the inputs be sorted.
+	lvars.sort();
+	curVars.sort();
+
+	ObjectSet diff;
+	// S_L-S_G results in set of objects whose construction is skipped - it's an error if this set is non-empty
+	std::set_difference( lvars.begin(), lvars.end(), curVars.begin(), curVars.end(), std::inserter( diff, diff.begin() ) );
+	DTOR_PRINT(
+		std::cerr << "S_L-S_G = " << printSet( diff ) << std::endl;
+	)
+	if ( ! diff.empty() ) {
+		SemanticError( stmt, std::string("jump to label '") + stmt->target.name + "' crosses initialization of " + (*diff.begin())->name + " " );
+	} // if
+}
+
+void InsertDtors::previsit( const ast::BranchStmt * stmt ) {
+	switch( stmt->kind ) {
+	case ast::BranchStmt::Continue:
+	case ast::BranchStmt::Break:
+		// could optimize the break/continue case, because the S_L-S_G check is unnecessary (this set should
+		// always be empty), but it serves as a small sanity check.
+	case ast::BranchStmt::Goto:
+		handleGoto( stmt );
+		break;
+	default:
+		assert( false );
+	} // switch
+}
+
+bool checkWarnings( const ast::FunctionDecl * funcDecl ) {
+	// only check for warnings if the current function is a user-defined
+	// constructor or destructor
+	if ( ! funcDecl ) return false;
+	if ( ! funcDecl->stmts ) return false;
+	return CodeGen::isCtorDtor( funcDecl->name ) && ! funcDecl->linkage.is_overrideable;
+}
+
+void GenStructMemberCalls::previsit( const ast::FunctionDecl * funcDecl ) {
+	GuardValue( function );
+	GuardValue( unhandled );
+	GuardValue( usedUninit );
+	GuardValue( thisParam );
+	GuardValue( isCtor );
+	GuardValue( structDecl );
+	errors = SemanticErrorException();  // clear previous errors
+
+	// need to start with fresh sets
+	unhandled.clear();
+	usedUninit.clear();
+
+	function = mutate(funcDecl);
+	// could this be non-unique?
+	if (function != funcDecl) {
+		std::cerr << "GenStructMemberCalls: non-unique FunctionDecl " << funcDecl->location << funcDecl->name << std::endl;
+	}
+
+	isCtor = CodeGen::isConstructor( function->name );
+	if ( checkWarnings( function ) ) {
+		// const ast::FunctionType * type = function->type;
+		// assert( ! type->params.empty() );
+		thisParam = function->params.front().strict_as<ast::ObjectDecl>();
+		auto thisType = getPointerBase( thisParam->get_type() );
+		auto structType = dynamic_cast< const ast::StructInstType * >( thisType );
+		if ( structType ) {
+			structDecl = structType->base;
+			for ( auto & member : structDecl->members ) {
+				if ( auto field = member.as<ast::ObjectDecl>() ) {
+					// record all of the struct type's members that need to be constructed or
+					// destructed by the end of the function
+					unhandled.insert( field );
+				}
+			}
+		}
+	}
+}
+
+const ast::DeclWithType * GenStructMemberCalls::postvisit( const ast::FunctionDecl * funcDecl ) {
+	// remove the unhandled objects from usedUninit, because a call is inserted
+	// to handle them - only objects that are later constructed are used uninitialized.
+	std::map< const ast::DeclWithType *, CodeLocation > diff;
+	// need the comparator since usedUninit and unhandled have different types
+	struct comp_t {
+		typedef decltype(usedUninit)::value_type usedUninit_t;
+		typedef decltype(unhandled)::value_type unhandled_t;
+		bool operator()(usedUninit_t x, unhandled_t y) { return x.first < y; }
+		bool operator()(unhandled_t x, usedUninit_t y) { return x < y.first; }
+	} comp;
+	std::set_difference( usedUninit.begin(), usedUninit.end(), unhandled.begin(), unhandled.end(), std::inserter( diff, diff.begin() ), comp );
+	for ( auto p : diff ) {
+		auto member = p.first;
+		auto loc = p.second;
+		// xxx - make error message better by also tracking the location that the object is constructed at?
+		emit( loc, "in ", function->name, ", field ", member->name, " used before being constructed" );
+	}
+
+	const CodeLocation loc = funcDecl->location;
+
+	if ( ! unhandled.empty() ) {
+		auto mutStmts = function->stmts.get_and_mutate();
+		// need to explicitly re-add function parameters to the indexer in order to resolve copy constructors
+		auto guard = makeFuncGuard( [this]() { symtab.enterScope(); }, [this]() { symtab.leaveScope(); } );
+		symtab.addFunction( function );
+		auto global = transUnit().global;
+
+		// need to iterate through members in reverse in order for
+		// ctor/dtor statements to come out in the right order
+		for ( auto & member : reverseIterate( structDecl->members ) ) {
+			auto field = member.as<ast::ObjectDecl>();
+			// skip non-DWT members
+			if ( ! field ) continue;
+			// skip non-constructable members
+			if ( ! tryConstruct( field ) ) continue;
+			// skip handled members
+			if ( ! unhandled.count( field ) ) continue;
+
+			// insert and resolve default/copy constructor call for each field that's unhandled
+			// std::list< const ast::Stmt * > stmt;
+			ast::Expr * arg2 = nullptr;
+			if ( function->name == "?{}" && isCopyFunction( function ) ) {
+				// if copy ctor, need to pass second-param-of-this-function.field
+				// std::list< DeclarationWithType * > & params = function->get_functionType()->get_parameters();
+				assert( function->params.size() == 2 );
+				arg2 = new ast::MemberExpr(funcDecl->location, field, new ast::VariableExpr(funcDecl->location, function->params.back() ) );
+			}
+			InitExpander srcParam( arg2 );
+			// cast away reference type and construct field.
+			ast::Expr * thisExpr = new ast::CastExpr(funcDecl->location, new ast::VariableExpr(funcDecl->location, thisParam ), thisParam->get_type()->stripReferences());
+			ast::Expr * memberDest = new ast::MemberExpr(funcDecl->location, field, thisExpr );
+			ast::ptr<ast::Stmt> callStmt = SymTab::genImplicitCall( srcParam, memberDest, loc, function->name, field, static_cast<SymTab::LoopDirection>(isCtor) );
+
+			if ( callStmt ) {
+				// auto & callStmt = stmt.front();
+
+				try {
+					callStmt = callStmt->accept( *visitor );
+					if ( isCtor ) {
+						mutStmts->push_front( callStmt );
+					} else { // TODO: don't generate destructor function/object for intrinsic calls
+						// destructor statements should be added at the end
+						// function->get_statements()->push_back( callStmt );
+
+						// Optimization: do not need to call intrinsic destructors on members
+						if ( isIntrinsicSingleArgCallStmt( callStmt ) ) continue;
+
+						// __Destructor _dtor0 = { (void *)&b.a1, (void (*)(void *)_destroy_A };
+						std::list< ast::ptr<ast::Stmt> > stmtsToAdd;
+
+						static UniqueName memberDtorNamer = { "__memberDtor" };
+						assertf( global.dtorStruct, "builtin __Destructor not found." );
+						assertf( global.dtorDestroy, "builtin __destroy_Destructor not found." );
+
+						ast::Expr * thisExpr = new ast::CastExpr( new ast::AddressExpr( new ast::VariableExpr(loc, thisParam ) ), new ast::PointerType( new ast::VoidType(), ast::CV::Qualifiers() ) );
+						ast::Expr * dtorExpr = new ast::VariableExpr(loc, getDtorFunc( thisParam, callStmt, stmtsToAdd ) );
+
+						// cast destructor pointer to void (*)(void *), to silence GCC incompatible pointer warnings
+						auto dtorFtype = new ast::FunctionType();
+						dtorFtype->params.emplace_back( new ast::PointerType( new ast::VoidType() ) );
+						auto dtorType = new ast::PointerType( dtorFtype );
+
+						auto destructor = new ast::ObjectDecl(loc, memberDtorNamer.newName(), new ast::StructInstType( global.dtorStruct ), new ast::ListInit(loc, { new ast::SingleInit(loc, thisExpr ), new ast::SingleInit(loc, new ast::CastExpr( dtorExpr, dtorType ) ) } ) );
+						destructor->attributes.push_back( new ast::Attribute( "cleanup", { new ast::VariableExpr( loc, global.dtorDestroy ) } ) );
+						mutStmts->push_front( new ast::DeclStmt(loc, destructor ) );
+						mutStmts->kids.splice( mutStmts->kids.begin(), stmtsToAdd );
+					}
+				} catch ( SemanticErrorException & error ) {
+					emit( funcDecl->location, "in ", function->name , ", field ", field->name, " not explicitly ", isCtor ? "constructed" : "destructed",  " and no ", isCtor ? "default constructor" : "destructor", " found" );
+				}
+			}
+		}
+		function->stmts = mutStmts;
+	}
+	if (! errors.isEmpty()) {
+		throw errors;
+	}
+	// return funcDecl;
+	return function;
+}
+
+/// true if expr is effectively just the 'this' parameter
+bool isThisExpression( const ast::Expr * expr, const ast::DeclWithType * thisParam ) {
+	// TODO: there are more complicated ways to pass 'this' to a constructor, e.g. &*, *&, etc.
+	if ( auto varExpr = dynamic_cast< const ast::VariableExpr * >( expr ) ) {
+		return varExpr->var == thisParam;
+	} else if ( auto castExpr = dynamic_cast< const ast::CastExpr * > ( expr ) ) {
+		return isThisExpression( castExpr->arg, thisParam );
+	}
+	return false;
+}
+
+/// returns a MemberExpr if expr is effectively just member access on the 'this' parameter, else nullptr
+const ast::MemberExpr * isThisMemberExpr( const ast::Expr * expr, const ast::DeclWithType * thisParam ) {
+	if ( auto memberExpr = dynamic_cast< const ast::MemberExpr * >( expr ) ) {
+		if ( isThisExpression( memberExpr->aggregate, thisParam ) ) {
+			return memberExpr;
+		}
+	} else if ( auto castExpr = dynamic_cast< const ast::CastExpr * >( expr ) ) {
+		return isThisMemberExpr( castExpr->arg, thisParam );
+	}
+	return nullptr;
+}
+
+void GenStructMemberCalls::previsit( const ast::ApplicationExpr * appExpr ) {
+	if ( ! checkWarnings( function ) ) {
+		visit_children = false;
+		return;
+	}
+
+	std::string fname = getFunctionName( appExpr );
+	if ( fname == function->name ) {
+		// call to same kind of function
+		const ast::Expr * firstParam = appExpr->args.front();
+
+		if ( isThisExpression( firstParam, thisParam ) ) {
+			// if calling another constructor on thisParam, assume that function handles
+			// all members - if it doesn't a warning will appear in that function.
+			unhandled.clear();
+		} else if ( auto memberExpr = isThisMemberExpr( firstParam, thisParam ) ) {
+			// if first parameter is a member expression on the this parameter,
+			// then remove the member from unhandled set.
+			if ( isThisExpression( memberExpr->aggregate, thisParam ) ) {
+				unhandled.erase( memberExpr->member );
+			}
+		}
+	}
+}
+
+void GenStructMemberCalls::previsit( const ast::MemberExpr * memberExpr ) {
+	if ( ! checkWarnings( function ) || ! isCtor ) {
+		visit_children = false;
+		return;
+	}
+
+	if ( isThisExpression( memberExpr->aggregate, thisParam ) ) {
+		if ( unhandled.count( memberExpr->member ) ) {
+			// emit a warning because a member was used before it was constructed
+			usedUninit.insert( { memberExpr->member, memberExpr->location } );
+		}
+	}
+}
+
+template< typename... Params >
+void GenStructMemberCalls::emit( CodeLocation loc, const Params &... params ) {
+	SemanticErrorException err( loc, toString( params... ) );
+	errors.append( err );
+}
+
+const ast::Expr * GenStructMemberCalls::postvisit( const ast::UntypedExpr * untypedExpr ) {
+	// xxx - functions returning ast::ptr seems wrong...
+	auto res = ResolvExpr::findVoidExpression( untypedExpr, { symtab, transUnit().global } );
+	return res.release();
+}
+
+void InsertImplicitCalls::previsit(const ast::UniqueExpr * unqExpr) {
+	if (visitedIds.count(unqExpr->id)) visit_children = false;
+	else visitedIds.insert(unqExpr->id);
+}
+
+const ast::Expr * FixCtorExprs::postvisit( const ast::ConstructorExpr * ctorExpr ) {
+	const CodeLocation loc = ctorExpr->location;
+	static UniqueName tempNamer( "_tmp_ctor_expr" );
+	// xxx - is the size check necessary?
+	assert( ctorExpr->result && ctorExpr->result->size() == 1 );
+
+	// xxx - this can be TupleAssignExpr now. Need to properly handle this case.
+	// take possession of expr and env
+	ast::ptr<ast::ApplicationExpr> callExpr = ctorExpr->callExpr.strict_as<ast::ApplicationExpr>();
+	ast::ptr<ast::TypeSubstitution> env = ctorExpr->env;
+	// ctorExpr->set_callExpr( nullptr );
+	// ctorExpr->set_env( nullptr );
+
+	// xxx - ideally we would reuse the temporary generated from the copy constructor passes from within firstArg if it exists and not generate a temporary if it's unnecessary.
+	auto tmp = new ast::ObjectDecl(loc, tempNamer.newName(), callExpr->args.front()->result );
+	declsToAddBefore.push_back( tmp );
+
+	// build assignment and replace constructor's first argument with new temporary
+	auto mutCallExpr = callExpr.get_and_mutate();
+	const ast::Expr * firstArg = callExpr->args.front();
+	ast::Expr * assign = new ast::UntypedExpr(loc, new ast::NameExpr(loc, "?=?" ), { new ast::AddressExpr(loc, new ast::VariableExpr(loc, tmp ) ), new ast::AddressExpr( firstArg ) } );
+	firstArg = new ast::VariableExpr(loc, tmp );
+	mutCallExpr->args.front() = firstArg;
+
+	// resolve assignment and dispose of new env
+	auto resolved = ResolvExpr::findVoidExpression( assign, { symtab, transUnit().global } );
+	auto mut = resolved.get_and_mutate();
+	assertf(resolved.get() == mut, "newly resolved expression must be unique");
+	mut->env = nullptr;
+
+	// for constructor expr:
+	//   T x;
+	//   x{};
+	// results in:
+	//   T x;
+	//   T & tmp;
+	//   &tmp = &x, ?{}(tmp), tmp
+	ast::CommaExpr * commaExpr = new ast::CommaExpr(loc, resolved, new ast::CommaExpr(loc, mutCallExpr, new ast::VariableExpr(loc, tmp ) ) );
+	commaExpr->env = env;
+	return commaExpr;
+}
+
+} // namespace
+
+void fix( ast::TranslationUnit & translationUnit, bool inLibrary ) {
+	ast::Pass<SelfAssignChecker>::run( translationUnit );
+
+	// fixes StmtExpr to properly link to their resulting expression
+	ast::Pass<StmtExprResult>::run( translationUnit );
+
+	// fixes ConstructorInit for global variables. should happen before fixInitializers.
+	InitTweak::fixGlobalInit( translationUnit, inLibrary );
+
+	// must happen before ResolveCopyCtors because temporaries have to be inserted into the correct scope
+	ast::Pass<SplitExpressions>::run( translationUnit );
+
+	ast::Pass<InsertImplicitCalls>::run( translationUnit );
+
+	// Needs to happen before ResolveCopyCtors, because argument/return temporaries should not be considered in
+	// error checking branch statements
+	{
+		ast::Pass<LabelFinder> finder;
+		ast::Pass<InsertDtors>::run( translationUnit, finder );
+	}
+
+	ast::Pass<ResolveCopyCtors>::run( translationUnit );
+	FixInit::fixInitializers( translationUnit );
+	ast::Pass<GenStructMemberCalls>::run( translationUnit );
+
+	// Needs to happen after GenStructMemberCalls, since otherwise member constructors exprs
+	// don't have the correct form, and a member can be constructed more than once.
+	ast::Pass<FixCtorExprs>::run( translationUnit );
+}
+
+} // namespace InitTweak
+
+// Local Variables: //
+// tab-width: 4 //
+// mode: c++ //
+// compile-command: "make install" //
+// End: //
Index: src/InitTweak/FixInitNew.cpp
===================================================================
--- src/InitTweak/FixInitNew.cpp	(revision 37273c8cb34ce14d7da1cb9d4d43491327ff6807)
+++ 	(revision )
@@ -1,1385 +1,0 @@
-#include "FixInit.h"
-
-#include <stddef.h>                    // for NULL
-#include <algorithm>                   // for set_difference, copy_if
-#include <cassert>                     // for assert, strict_dynamic_cast
-#include <iostream>                    // for operator<<, ostream, basic_ost...
-#include <iterator>                    // for insert_iterator, back_inserter
-#include <list>                        // for _List_iterator, list, list<>::...
-#include <map>                         // for _Rb_tree_iterator, _Rb_tree_co...
-#include <memory>                      // for allocator_traits<>::value_type
-#include <set>                         // for set, set<>::value_type
-#include <unordered_map>               // for unordered_map, unordered_map<>...
-#include <unordered_set>               // for unordered_set
-#include <utility>                     // for pair
-
-#include "AST/DeclReplacer.hpp"
-#include "AST/Expr.hpp"
-#include "AST/Inspect.hpp"             // for getFunction, getPointerBase, g...
-#include "AST/Node.hpp"
-#include "AST/Pass.hpp"
-#include "AST/Print.hpp"
-#include "AST/SymbolTable.hpp"
-#include "AST/Type.hpp"
-#include "CodeGen/OperatorTable.h"     // for isConstructor, isCtorDtor, isD...
-#include "Common/SemanticError.h"      // for SemanticError
-#include "Common/ToString.hpp"         // for toCString
-#include "Common/UniqueName.h"         // for UniqueName
-#include "FixGlobalInit.h"             // for fixGlobalInit
-#include "GenInit.h"                   // for genCtorDtor
-#include "GenPoly/GenPoly.h"           // for getFunctionType
-#include "ResolvExpr/Resolver.h"       // for findVoidExpression
-#include "ResolvExpr/Unify.h"          // for typesCompatible
-#include "SymTab/GenImplicitCall.hpp"  // for genImplicitCall
-
-bool ctordtorp = false; // print all debug
-bool ctorp = false; // print ctor debug
-bool cpctorp = false; // print copy ctor debug
-bool dtorp = false; // print dtor debug
-#define PRINT( text ) if ( ctordtorp ) { text }
-#define CP_CTOR_PRINT( text ) if ( ctordtorp || cpctorp ) { text }
-#define DTOR_PRINT( text ) if ( ctordtorp || dtorp ) { text }
-
-namespace InitTweak {
-
-namespace {
-
-// Shallow copy the pointer list for return.
-std::vector<ast::ptr<ast::TypeDecl>> getGenericParams( const ast::Type * t ) {
-	if ( auto inst = dynamic_cast<const ast::StructInstType *>( t ) ) {
-		return inst->base->params;
-	}
-	if ( auto inst = dynamic_cast<const ast::UnionInstType *>( t ) ) {
-		return inst->base->params;
-	}
-	return {};
-}
-
-/// Given type T, generate type of default ctor/dtor, i.e. function type void (*) (T &).
-ast::FunctionDecl * genDefaultFunc(
-		const CodeLocation loc,
-		const std::string fname,
-		const ast::Type * paramType,
-		bool maybePolymorphic = true) {
-	std::vector<ast::ptr<ast::TypeDecl>> typeParams;
-	if ( maybePolymorphic ) typeParams = getGenericParams( paramType );
-	auto dstParam = new ast::ObjectDecl( loc,
-		"_dst",
-		new ast::ReferenceType( paramType ),
-		nullptr,
-		{},
-		ast::Linkage::Cforall
-	);
-	return new ast::FunctionDecl( loc,
-		fname,
-		std::move(typeParams),
-		{},
-		{dstParam},
-		{},
-		new ast::CompoundStmt(loc),
-		{},
-		ast::Linkage::Cforall
-	);
-}
-
-struct SelfAssignChecker {
-	void previsit( const ast::ApplicationExpr * appExpr );
-};
-
-struct StmtExprResult {
-	const ast::StmtExpr * previsit( const ast::StmtExpr * stmtExpr );
-};
-
-/// wrap function application expressions as ImplicitCopyCtorExpr nodes so that it is easy to identify which
-/// function calls need their parameters to be copy constructed
-struct InsertImplicitCalls : public ast::WithShortCircuiting {
-	const ast::Expr * postvisit( const ast::ApplicationExpr * appExpr );
-
-	// only handles each UniqueExpr once
-	// if order of visit does not change, this should be safe
-	void previsit (const ast::UniqueExpr *);
-
-	std::unordered_set<decltype(ast::UniqueExpr::id)> visitedIds;
-};
-
-/// generate temporary ObjectDecls for each argument and return value of each ImplicitCopyCtorExpr,
-/// generate/resolve copy construction expressions for each, and generate/resolve destructors for both
-/// arguments and return value temporaries
-struct ResolveCopyCtors final : public ast::WithGuards, public ast::WithStmtsToAdd<>, public ast::WithSymbolTable, public ast::WithShortCircuiting, public ast::WithVisitorRef<ResolveCopyCtors>, public ast::WithConstTranslationUnit {
-	const ast::Expr * postvisit( const ast::ImplicitCopyCtorExpr * impCpCtorExpr );
-	const ast::StmtExpr * previsit( const ast::StmtExpr * stmtExpr );
-	const ast::UniqueExpr * previsit( const ast::UniqueExpr * unqExpr );
-
-	/// handles distant mutations of environment manually.
-	/// WithConstTypeSubstitution cannot remember where the environment is from
-
-	/// MUST be called at start of overload previsit
-	void previsit( const ast::Expr * expr);
-	/// MUST be called at return of overload postvisit
-	const ast::Expr * postvisit(const ast::Expr * expr);
-
-	/// create and resolve ctor/dtor expression: fname(var, [cpArg])
-	const ast::Expr * makeCtorDtor( const std::string & fname, const ast::ObjectDecl * var, const ast::Expr * cpArg = nullptr );
-	/// true if type does not need to be copy constructed to ensure correctness
-	bool skipCopyConstruct( const ast::Type * type );
-	ast::ptr< ast::Expr > copyConstructArg( const ast::Expr * arg, const ast::ImplicitCopyCtorExpr * impCpCtorExpr, const ast::Type * formal );
-	ast::Expr * destructRet( const ast::ObjectDecl * ret, const ast::Expr * arg );
-private:
-	/// hack to implement WithTypeSubstitution while conforming to mutation safety.
-	ast::TypeSubstitution * env         = nullptr;
-	bool                    envModified = false;
-};
-
-/// collects constructed object decls - used as a base class
-struct ObjDeclCollector : public ast::WithGuards, public ast::WithShortCircuiting {
-	// use ordered data structure to maintain ordering for set_difference and for consistent error messages
-	typedef std::list< const ast::ObjectDecl * > ObjectSet;
-	void previsit( const ast::CompoundStmt *compoundStmt );
-	void previsit( const ast::DeclStmt *stmt );
-
-	// don't go into other functions
-	void previsit( const ast::FunctionDecl * ) { visit_children = false; }
-
-protected:
-	ObjectSet curVars;
-};
-
-// debug
-template<typename ObjectSet>
-struct PrintSet {
-	PrintSet( const ObjectSet & objs ) : objs( objs ) {}
-	const ObjectSet & objs;
-};
-template<typename ObjectSet>
-PrintSet<ObjectSet> printSet( const ObjectSet & objs ) { return PrintSet<ObjectSet>( objs ); }
-template<typename ObjectSet>
-std::ostream & operator<<( std::ostream & out, const PrintSet<ObjectSet> & set) {
-	out << "{ ";
-	for ( auto & obj : set.objs ) {
-		out << obj->name << ", " ;
-	} // for
-	out << " }";
-	return out;
-}
-
-struct LabelFinder final : public ObjDeclCollector {
-	typedef std::map< std::string, ObjectSet > LabelMap;
-	// map of Label -> live variables at that label
-	LabelMap vars;
-
-	typedef ObjDeclCollector Parent;
-	using Parent::previsit;
-	void previsit( const ast::Stmt * stmt );
-
-	void previsit( const ast::CompoundStmt *compoundStmt );
-	void previsit( const ast::DeclStmt *stmt );
-};
-
-/// insert destructor calls at the appropriate places.  must happen before CtorInit nodes are removed
-/// (currently by FixInit)
-struct InsertDtors final : public ObjDeclCollector, public ast::WithStmtsToAdd<> {
-	InsertDtors( ast::Pass<LabelFinder> & finder ) : finder( finder ), labelVars( finder.core.vars ) {}
-
-	typedef ObjDeclCollector Parent;
-	using Parent::previsit;
-
-	void previsit( const ast::FunctionDecl * funcDecl );
-
-	void previsit( const ast::BranchStmt * stmt );
-private:
-	void handleGoto( const ast::BranchStmt * stmt );
-
-	ast::Pass<LabelFinder> & finder;
-	LabelFinder::LabelMap & labelVars;
-};
-
-/// expand each object declaration to use its constructor after it is declared.
-struct FixInit : public ast::WithStmtsToAdd<> {
-	static void fixInitializers( ast::TranslationUnit &translationUnit );
-
-	const ast::DeclWithType * postvisit( const ast::ObjectDecl *objDecl );
-
-	std::list< ast::ptr< ast::Decl > > staticDtorDecls;
-};
-
-/// generate default/copy ctor and dtor calls for user-defined struct ctor/dtors
-/// for any member that is missing a corresponding ctor/dtor call.
-/// error if a member is used before constructed
-struct GenStructMemberCalls final : public ast::WithGuards, public ast::WithShortCircuiting, public ast::WithSymbolTable, public ast::WithVisitorRef<GenStructMemberCalls>, public ast::WithConstTranslationUnit {
-	void previsit( const ast::FunctionDecl * funcDecl );
-	const ast::DeclWithType * postvisit( const ast::FunctionDecl * funcDecl );
-
-	void previsit( const ast::MemberExpr * memberExpr );
-	void previsit( const ast::ApplicationExpr * appExpr );
-
-	/// Note: this post mutate used to be in a separate visitor. If this pass breaks, one place to examine is whether it is
-	/// okay for this part of the recursion to occur alongside the rest.
-	const ast::Expr * postvisit( const ast::UntypedExpr * expr );
-
-	SemanticErrorException errors;
-private:
-	template< typename... Params >
-	void emit( CodeLocation, const Params &... params );
-
-	ast::FunctionDecl * function = nullptr;
-	std::set< const ast::DeclWithType * > unhandled;
-	std::map< const ast::DeclWithType *, CodeLocation > usedUninit;
-	const ast::ObjectDecl * thisParam = nullptr;
-	bool isCtor = false; // true if current function is a constructor
-	const ast::StructDecl * structDecl = nullptr;
-};
-
-/// expands ConstructorExpr nodes into comma expressions, using a temporary for the first argument
-struct FixCtorExprs final : public ast::WithDeclsToAdd<>, public ast::WithSymbolTable, public ast::WithShortCircuiting, public ast::WithConstTranslationUnit {
-	const ast::Expr * postvisit( const ast::ConstructorExpr * ctorExpr );
-};
-
-/// add CompoundStmts around top-level expressions so that temporaries are destroyed in the correct places.
-struct SplitExpressions : public ast::WithShortCircuiting {
-	ast::Stmt * postvisit( const ast::ExprStmt * stmt );
-	void previsit( const ast::TupleAssignExpr * expr );
-};
-
-/// find and return the destructor used in `input`. If `input` is not a simple destructor call, generate a thunk
-/// that wraps the destructor, insert it into `stmtsToAdd` and return the new function declaration
-const ast::DeclWithType * getDtorFunc( const ast::ObjectDecl * objDecl, const ast::Stmt * input, std::list< ast::ptr<ast::Stmt> > & stmtsToAdd ) {
-	const CodeLocation loc = input->location;
-	// unwrap implicit statement wrapper
-	// Statement * dtor = input;
-	assert( input );
-	// std::list< const ast::Expr * > matches;
-	auto matches = collectCtorDtorCalls( input );
-
-	if ( dynamic_cast< const ast::ExprStmt * >( input ) ) {
-		// only one destructor call in the expression
-		if ( matches.size() == 1 ) {
-			auto func = getFunction( matches.front() );
-			assertf( func, "getFunction failed to find function in %s", toString( matches.front() ).c_str() );
-
-			// cleanup argument must be a function, not an object (including function pointer)
-			if ( auto dtorFunc = dynamic_cast< const ast::FunctionDecl * > ( func ) ) {
-				if ( dtorFunc->type->forall.empty() ) {
-					// simple case where the destructor is a monomorphic function call - can simply
-					// use that function as the cleanup function.
-					return func;
-				}
-			}
-		}
-	}
-
-	// otherwise the cleanup is more complicated - need to build a single argument cleanup function that
-	// wraps the more complicated code.
-	static UniqueName dtorNamer( "__cleanup_dtor" );
-	std::string name = dtorNamer.newName();
-	ast::FunctionDecl * dtorFunc = genDefaultFunc( loc, name, objDecl->type->stripReferences(), false );
-	stmtsToAdd.push_back( new ast::DeclStmt(loc, dtorFunc ) );
-
-	// the original code contains uses of objDecl - replace them with the newly generated 'this' parameter.
-	const ast::ObjectDecl * thisParam = getParamThis( dtorFunc );
-	const ast::Expr * replacement = new ast::VariableExpr( loc, thisParam );
-
-	auto base = replacement->result->stripReferences();
-	if ( dynamic_cast< const ast::ArrayType * >( base ) || dynamic_cast< const ast::TupleType * > ( base ) ) {
-		// need to cast away reference for array types, since the destructor is generated without the reference type,
-		// and for tuple types since tuple indexing does not work directly on a reference
-		replacement = new ast::CastExpr( replacement, base );
-	}
-	auto dtor = ast::DeclReplacer::replace( input, ast::DeclReplacer::ExprMap{ std::make_pair( objDecl, replacement ) } );
-	auto mutStmts = dtorFunc->stmts.get_and_mutate();
-	mutStmts->push_back(strict_dynamic_cast<const ast::Stmt *>( dtor ));
-	dtorFunc->stmts = mutStmts;
-
-	return dtorFunc;
-}
-
-void FixInit::fixInitializers( ast::TranslationUnit & translationUnit ) {
-	ast::Pass<FixInit> fixer;
-
-	// can't use mutateAll, because need to insert declarations at top-level
-	// can't use DeclMutator, because sometimes need to insert IfStmt, etc.
-	SemanticErrorException errors;
-	for ( auto i = translationUnit.decls.begin(); i != translationUnit.decls.end(); ++i ) {
-		try {
-			// maybeAccept( *i, fixer ); translationUnit should never contain null
-			*i = (*i)->accept(fixer);
-			translationUnit.decls.splice( i, fixer.core.staticDtorDecls );
-		} catch( SemanticErrorException &e ) {
-			errors.append( e );
-		} // try
-	} // for
-	if ( ! errors.isEmpty() ) {
-		throw errors;
-	} // if
-}
-
-const ast::StmtExpr * StmtExprResult::previsit( const ast::StmtExpr * stmtExpr ) {
-	// we might loose the result expression here so add a pointer to trace back
-	assert( stmtExpr->result );
-	const ast::Type * result = stmtExpr->result;
-	if ( ! result->isVoid() ) {
-		auto mutExpr = mutate(stmtExpr);
-		const ast::CompoundStmt * body = mutExpr->stmts;
-		assert( ! body->kids.empty() );
-		mutExpr->resultExpr = body->kids.back().strict_as<ast::ExprStmt>();
-		return mutExpr;
-	}
-	return stmtExpr;
-}
-
-ast::Stmt * SplitExpressions::postvisit( const ast::ExprStmt * stmt ) {
-	// wrap each top-level ExprStmt in a block so that destructors for argument and return temporaries are destroyed
-	// in the correct places
-	ast::CompoundStmt * ret = new ast::CompoundStmt( stmt->location, { stmt } );
-	return ret;
-}
-
-void SplitExpressions::previsit( const ast::TupleAssignExpr * ) {
-	// don't do this within TupleAssignExpr, since it is already broken up into multiple expressions
-	visit_children = false;
-}
-
-// Relatively simple structural comparison for expressions, needed to determine
-// if two expressions are "the same" (used to determine if self assignment occurs)
-struct StructuralChecker {
-	// Strip all casts and then dynamic_cast.
-	template<typename T>
-	static const T * cast( const ast::Expr * expr ) {
-		// this might be too permissive. It's possible that only particular casts are relevant.
-		while ( auto cast = dynamic_cast< const ast::CastExpr * >( expr ) ) {
-			expr = cast->arg;
-		}
-		return dynamic_cast< const T * >( expr );
-	}
-
-	void previsit( const ast::Expr * ) {
-		// anything else does not qualify
-		result = false;
-	}
-
-	// ignore casts
-	void previsit( const ast::CastExpr * ) {}
-
-	void previsit( const ast::MemberExpr * memExpr ) {
-		if ( auto otherMember = cast< ast::MemberExpr >( other ) ) {
-			if ( otherMember->member == memExpr->member ) {
-				other = otherMember->aggregate;
-				return;
-			}
-		}
-		result = false;
-	}
-
-	void previsit( const ast::VariableExpr * varExpr ) {
-		if ( auto otherVar = cast< ast::VariableExpr >( other ) ) {
-			if ( otherVar->var == varExpr->var ) {
-				return;
-			}
-		}
-		result = false;
-	}
-
-	void previsit( const ast::AddressExpr * ) {
-		if ( auto addrExpr = cast< ast::AddressExpr >( other ) ) {
-			other = addrExpr->arg;
-			return;
-		}
-		result = false;
-	}
-
-	const ast::Expr * other;
-	bool result = true;
-	StructuralChecker( const ast::Expr * other ) : other(other) {}
-};
-
-bool structurallySimilar( const ast::Expr * e1, const ast::Expr * e2 ) {
-	return ast::Pass<StructuralChecker>::read( e1, e2 );
-}
-
-void SelfAssignChecker::previsit( const ast::ApplicationExpr * appExpr ) {
-	auto function = getFunction( appExpr );
-	// Doesn't use isAssignment, because ?+=?, etc. should not count as self-assignment.
-	if ( function->name == "?=?" && appExpr->args.size() == 2
-			// Check for structural similarity (same variable use, ignore casts, etc.
-			// (but does not look too deeply, anything looking like a function is off limits).
-			&& structurallySimilar( appExpr->args.front(), appExpr->args.back() ) ) {
-		SemanticWarning( appExpr->location, Warning::SelfAssignment, toCString( appExpr->args.front() ) );
-	}
-}
-
-const ast::Expr * InsertImplicitCalls::postvisit( const ast::ApplicationExpr * appExpr ) {
-	if ( auto function = appExpr->func.as<ast::VariableExpr>() ) {
-		if ( function->var->linkage.is_builtin ) {
-			// optimization: don't need to copy construct in order to call intrinsic functions
-			return appExpr;
-		} else if ( auto funcDecl = function->var.as<ast::DeclWithType>() ) {
-			auto ftype = dynamic_cast< const ast::FunctionType * >( GenPoly::getFunctionType( funcDecl->get_type() ) );
-			assertf( ftype, "Function call without function type: %s", toString( funcDecl ).c_str() );
-			if ( CodeGen::isConstructor( funcDecl->name ) && ftype->params.size() == 2 ) {
-				auto t1 = getPointerBase( ftype->params.front() );
-				auto t2 = ftype->params.back();
-				assert( t1 );
-
-				if ( ResolvExpr::typesCompatible( t1, t2 ) ) {
-					// optimization: don't need to copy construct in order to call a copy constructor
-					return appExpr;
-				} // if
-			} else if ( CodeGen::isDestructor( funcDecl->name ) ) {
-				// correctness: never copy construct arguments to a destructor
-				return appExpr;
-			} // if
-		} // if
-	} // if
-	CP_CTOR_PRINT( std::cerr << "InsertImplicitCalls: adding a wrapper " << appExpr << std::endl; )
-
-	// wrap each function call so that it is easy to identify nodes that have to be copy constructed
-	ast::ptr<ast::TypeSubstitution> tmp = appExpr->env;
-	auto mutExpr = mutate(appExpr);
-	mutExpr->env = nullptr;
-
-	auto expr = new ast::ImplicitCopyCtorExpr( appExpr->location, mutExpr );
-	// Move the type substitution to the new top-level. The substitution
-	// is needed to obtain the type of temporary variables so that copy
-	// constructor calls can be resolved.
-	expr->env = tmp;
-	return expr;
-}
-
-void ResolveCopyCtors::previsit(const ast::Expr * expr) {
-	if ( nullptr == expr->env ) {
-		return;
-	}
-	GuardValue( env ) = expr->env->clone();
-	GuardValue( envModified ) = false;
-}
-
-const ast::Expr * ResolveCopyCtors::postvisit(const ast::Expr * expr) {
-	// No local environment, skip.
-	if ( nullptr == expr->env ) {
-		return expr;
-	// Environment was modified, mutate and replace.
-	} else if ( envModified ) {
-		auto mutExpr = mutate(expr);
-		mutExpr->env = env;
-		return mutExpr;
-	// Environment was not mutated, delete the shallow copy before guard.
-	} else {
-		delete env;
-		return expr;
-	}
-}
-
-bool ResolveCopyCtors::skipCopyConstruct( const ast::Type * type ) { return ! isConstructable( type ); }
-
-const ast::Expr * ResolveCopyCtors::makeCtorDtor( const std::string & fname, const ast::ObjectDecl * var, const ast::Expr * cpArg ) {
-	assert( var );
-	assert( var->isManaged() );
-	assert( !cpArg || cpArg->isManaged() );
-	// arrays are not copy constructed, so this should always be an ExprStmt
-	ast::ptr< ast::Stmt > stmt = genCtorDtor(var->location, fname, var, cpArg );
-	assertf( stmt, "ResolveCopyCtors: genCtorDtor returned nullptr: %s / %s / %s", fname.c_str(), toString( var ).c_str(), toString( cpArg ).c_str() );
-	auto exprStmt = stmt.strict_as<ast::ImplicitCtorDtorStmt>()->callStmt.strict_as<ast::ExprStmt>();
-	ast::ptr<ast::Expr> untyped = exprStmt->expr; // take ownership of expr
-
-	// resolve copy constructor
-	// should only be one alternative for copy ctor and dtor expressions, since all arguments are fixed
-	// (VariableExpr and already resolved expression)
-	CP_CTOR_PRINT( std::cerr << "ResolvingCtorDtor " << untyped << std::endl; )
-	ast::ptr<ast::Expr> resolved = ResolvExpr::findVoidExpression(untyped, { symtab, transUnit().global } );
-	assert( resolved );
-	if ( resolved->env ) {
-		// Extract useful information and discard new environments. Keeping them causes problems in PolyMutator passes.
-		env->add( *resolved->env );
-		envModified = true;
-		auto mut = mutate(resolved.get());
-		assertf(mut == resolved.get(), "newly resolved expression must be unique");
-		mut->env = nullptr;
-	} // if
-	if ( auto assign = resolved.as<ast::TupleAssignExpr>() ) {
-		// fix newly generated StmtExpr
-		previsit( assign->stmtExpr );
-	}
-	return resolved.release();
-}
-
-ast::ptr<ast::Expr> ResolveCopyCtors::copyConstructArg(
-	const ast::Expr * arg, const ast::ImplicitCopyCtorExpr * impCpCtorExpr, const ast::Type * formal )
-{
-	static UniqueName tempNamer("_tmp_cp");
-	const CodeLocation loc = impCpCtorExpr->location;
-	// CP_CTOR_PRINT( std::cerr << "Type Substitution: " << *env << std::endl; )
-	assert( arg->result );
-	ast::ptr<ast::Type> result = arg->result;
-	if ( skipCopyConstruct( result ) ) return arg; // skip certain non-copyable types
-
-	// type may involve type variables, so apply type substitution to get temporary variable's actual type,
-	// since result type may not be substituted (e.g., if the type does not appear in the parameter list)
-	// Use applyFree so that types bound in function pointers are not substituted, e.g. in forall(dtype T) void (*)(T).
-
-	// xxx - this originally mutates arg->result in place. is it correct?
-	assert( env );
-	result = env->applyFree( result.get() ).node;
-	auto mutResult = result.get_and_mutate();
-	mutResult->set_const(false);
-
-	auto mutArg = mutate(arg);
-	mutArg->result = mutResult;
-
-	ast::ptr<ast::Expr> guard = mutArg;
-
-	ast::ptr<ast::ObjectDecl> tmp = new ast::ObjectDecl(loc, "__tmp", mutResult, nullptr );
-
-	// create and resolve copy constructor
-	CP_CTOR_PRINT( std::cerr << "makeCtorDtor for an argument" << std::endl; )
-	auto cpCtor = makeCtorDtor( "?{}", tmp, mutArg );
-
-	if ( auto appExpr = dynamic_cast< const ast::ApplicationExpr * >( cpCtor ) ) {
-		// if the chosen constructor is intrinsic, the copy is unnecessary, so
-		// don't create the temporary and don't call the copy constructor
-		auto function = appExpr->func.strict_as<ast::VariableExpr>();
-		if ( function->var->linkage == ast::Linkage::Intrinsic ) {
-			// arguments that need to be boxed need a temporary regardless of whether the copy constructor is intrinsic,
-			// so that the object isn't changed inside of the polymorphic function
-			if ( ! GenPoly::needsBoxing( formal, result, impCpCtorExpr->callExpr, env ) ) {
-				// xxx - should arg->result be mutated? see comment above.
-				return guard;
-			}
-		}
-	}
-
-	// set a unique name for the temporary once it's certain the call is necessary
-	auto mut = tmp.get_and_mutate();
-	assertf (mut == tmp, "newly created ObjectDecl must be unique");
-	mut->name = tempNamer.newName();
-
-	// replace argument to function call with temporary
-	stmtsToAddBefore.push_back( new ast::DeclStmt(loc, tmp ) );
-	arg = cpCtor;
-	return destructRet( tmp, arg );
-
-	// impCpCtorExpr->dtors.push_front( makeCtorDtor( "^?{}", tmp ) );
-}
-
-ast::Expr * ResolveCopyCtors::destructRet( const ast::ObjectDecl * ret, const ast::Expr * arg ) {
-	auto global = transUnit().global;
-	// TODO: refactor code for generating cleanup attribute, since it's common and reused in ~3-4 places
-	// check for existing cleanup attribute before adding another(?)
-	// need to add __Destructor for _tmp_cp variables as well
-
-	assertf( global.dtorStruct, "Destructor generation requires __Destructor definition." );
-	assertf( global.dtorStruct->members.size() == 2, "__Destructor definition does not have expected fields." );
-	assertf( global.dtorDestroy, "Destructor generation requires __destroy_Destructor." );
-
-	const CodeLocation & loc = ret->location;
-
-	// generate a __Destructor for ret that calls the destructor
-	auto res = makeCtorDtor( "^?{}", ret );
-	auto dtor = mutate(res);
-
-	// if the chosen destructor is intrinsic, elide the generated dtor handler
-	if ( arg && isIntrinsicCallExpr( dtor ) ) {
-		return new ast::CommaExpr(loc, arg, new ast::VariableExpr(loc, ret ) );
-	}
-
-	if ( ! dtor->env ) dtor->env = maybeClone( env );
-	auto dtorFunc = getDtorFunc( ret, new ast::ExprStmt(loc, dtor ), stmtsToAddBefore );
-
-	auto dtorStructType = new ast::StructInstType( global.dtorStruct );
-
-	// what does this do???
-	dtorStructType->params.push_back( new ast::TypeExpr(loc, new ast::VoidType() ) );
-
-	// cast destructor pointer to void (*)(void *), to silence GCC incompatible pointer warnings
-	auto dtorFtype = new ast::FunctionType();
-	dtorFtype->params.push_back( new ast::PointerType(new ast::VoidType( ) ) );
-	auto dtorType = new ast::PointerType( dtorFtype );
-
-	static UniqueName namer( "_ret_dtor" );
-	auto retDtor = new ast::ObjectDecl(loc, namer.newName(), dtorStructType, new ast::ListInit(loc, { new ast::SingleInit(loc, ast::ConstantExpr::null(loc) ), new ast::SingleInit(loc, new ast::CastExpr( new ast::VariableExpr(loc, dtorFunc ), dtorType ) ) } ) );
-	retDtor->attributes.push_back( new ast::Attribute( "cleanup", { new ast::VariableExpr(loc, global.dtorDestroy ) } ) );
-	stmtsToAddBefore.push_back( new ast::DeclStmt(loc, retDtor ) );
-
-	if ( arg ) {
-		auto member = new ast::MemberExpr(loc, global.dtorStruct->members.front().strict_as<ast::DeclWithType>(), new ast::VariableExpr(loc, retDtor ) );
-		auto object = new ast::CastExpr( new ast::AddressExpr( new ast::VariableExpr(loc, ret ) ), new ast::PointerType(new ast::VoidType() ) );
-		ast::Expr * assign = createBitwiseAssignment( member, object );
-		return new ast::CommaExpr(loc, new ast::CommaExpr(loc, arg, assign ), new ast::VariableExpr(loc, ret ) );
-	}
-	return nullptr;
-	// impCpCtorExpr->get_dtors().push_front( makeCtorDtor( "^?{}", ret ) );
-}
-
-const ast::Expr * ResolveCopyCtors::postvisit( const ast::ImplicitCopyCtorExpr *impCpCtorExpr ) {
-	CP_CTOR_PRINT( std::cerr << "ResolveCopyCtors: " << impCpCtorExpr << std::endl; )
-
-	ast::ApplicationExpr * appExpr = mutate(impCpCtorExpr->callExpr.get());
-	const ast::ObjectDecl * returnDecl = nullptr;
-	const CodeLocation loc = appExpr->location;
-
-	// take each argument and attempt to copy construct it.
-	auto ftype = GenPoly::getFunctionType( appExpr->func->result );
-	assert( ftype );
-	auto & params = ftype->params;
-	auto iter = params.begin();
-	for ( auto & arg : appExpr->args ) {
-		const ast::Type * formal = nullptr;
-		if ( iter != params.end() ) { // does not copy construct C-style variadic arguments
-			// DeclarationWithType * param = *iter++;
-			formal = *iter++;
-		}
-
-		arg = copyConstructArg( arg, impCpCtorExpr, formal );
-	} // for
-
-	// each return value from the call needs to be connected with an ObjectDecl at the call site, which is
-	// initialized with the return value and is destructed later
-	// xxx - handle named return values?
-	const ast::Type * result = appExpr->result;
-	if ( ! result->isVoid() ) {
-		static UniqueName retNamer("_tmp_cp_ret");
-		auto subResult = env->apply( result ).node;
-		auto ret = new ast::ObjectDecl(loc, retNamer.newName(), subResult, nullptr );
-		auto mutType = mutate(ret->type.get());
-		mutType->set_const( false );
-		ret->type = mutType;
-		returnDecl = ret;
-		stmtsToAddBefore.push_back( new ast::DeclStmt(loc, ret ) );
-		CP_CTOR_PRINT( std::cerr << "makeCtorDtor for a return" << std::endl; )
-	} // for
-	CP_CTOR_PRINT( std::cerr << "after Resolving: " << impCpCtorExpr << std::endl; )
-	// ------------------------------------------------------
-
-	CP_CTOR_PRINT( std::cerr << "Coming out the back..." << impCpCtorExpr << std::endl; )
-
-	// detach fields from wrapper node so that it can be deleted without deleting too much
-
-	// xxx - actual env might be somewhere else, need to keep invariant
-
-	// deletion of wrapper should be handled by pass template now
-
-	// impCpCtorExpr->callExpr = nullptr;
-	assert (appExpr->env == nullptr);
-	appExpr->env = impCpCtorExpr->env;
-	// std::swap( impCpCtorExpr->env, appExpr->env );
-	// assert( impCpCtorExpr->env == nullptr );
-	// delete impCpCtorExpr;
-
-	if ( returnDecl ) {
-		ast::Expr * assign = createBitwiseAssignment( new ast::VariableExpr(loc, returnDecl ), appExpr );
-		if ( ! dynamic_cast< const ast::ReferenceType * >( result ) ) {
-			// destructing reference returns is bad because it can cause multiple destructor calls to the same object - the returned object is not a temporary
-			assign = destructRet( returnDecl, assign );
-			assert(assign);
-		} else {
-			assign = new ast::CommaExpr(loc, assign, new ast::VariableExpr(loc, returnDecl ) );
-		}
-		// move env from appExpr to retExpr
-		// std::swap( assign->env, appExpr->env );
-		assign->env = appExpr->env;
-		// actual env is handled by common routine that replaces WithTypeSubstitution
-		return postvisit((const ast::Expr *)assign);
-	} else {
-		return postvisit((const ast::Expr *)appExpr);
-	} // if
-}
-
-const ast::StmtExpr * ResolveCopyCtors::previsit( const ast::StmtExpr * _stmtExpr ) {
-	// function call temporaries should be placed at statement-level, rather than nested inside of a new statement expression,
-	// since temporaries can be shared across sub-expressions, e.g.
-	//   [A, A] f();       // decl
-	//   g([A] x, [A] y);  // decl
-	//   g(f());           // call
-	// f is executed once, so the return temporary is shared across the tuple constructors for x and y.
-	// Explicitly mutating children instead of mutating the inner compound statement forces the temporaries to be added
-	// to the outer context, rather than inside of the statement expression.
-
-	// call the common routine that replaces WithTypeSubstitution
-	previsit((const ast::Expr *) _stmtExpr);
-
-	visit_children = false;
-	const CodeLocation loc = _stmtExpr->location;
-
-	assert( env );
-
-	symtab.enterScope();
-	// visit all statements
-	auto stmtExpr = mutate(_stmtExpr);
-	auto mutStmts = mutate(stmtExpr->stmts.get());
-
-	auto & stmts = mutStmts->kids;
-	for ( auto & stmt : stmts ) {
-		stmt = stmt->accept( *visitor );
-	} // for
-	stmtExpr->stmts = mutStmts;
-	symtab.leaveScope();
-
-	assert( stmtExpr->result );
-	// const ast::Type * result = stmtExpr->result;
-	if ( ! stmtExpr->result->isVoid() ) {
-		static UniqueName retNamer("_tmp_stmtexpr_ret");
-
-		// result = result->clone();
-		auto result = env->apply( stmtExpr->result.get() ).node;
-		if ( ! InitTweak::isConstructable( result ) ) {
-			// delete result;
-			return stmtExpr;
-		}
-		auto mutResult = result.get_and_mutate();
-		mutResult->set_const(false);
-
-		// create variable that will hold the result of the stmt expr
-		auto ret = new ast::ObjectDecl(loc, retNamer.newName(), mutResult, nullptr );
-		stmtsToAddBefore.push_back( new ast::DeclStmt(loc, ret ) );
-
-		assertf(
-			stmtExpr->resultExpr,
-			"Statement-Expression should have a resulting expression at %s:%d",
-			stmtExpr->location.filename.c_str(),
-			stmtExpr->location.first_line
-		);
-
-		const ast::ExprStmt * last = stmtExpr->resultExpr;
-		// xxx - if this is non-unique, need to copy while making resultExpr ref
-		assertf(last->unique(), "attempt to modify weakly shared statement");
-		auto mutLast = mutate(last);
-		// above assertion means in-place mutation is OK
-		try {
-			mutLast->expr = makeCtorDtor( "?{}", ret, mutLast->expr );
-		} catch(...) {
-			std::cerr << "*CFA internal error: ";
-			std::cerr << "can't resolve implicit constructor";
-			std::cerr << " at " << stmtExpr->location.filename;
-			std::cerr << ":" << stmtExpr->location.first_line << std::endl;
-
-			abort();
-		}
-
-		// add destructors after current statement
-		stmtsToAddAfter.push_back( new ast::ExprStmt(loc, makeCtorDtor( "^?{}", ret ) ) );
-
-		// must have a non-empty body, otherwise it wouldn't have a result
-		assert( ! stmts.empty() );
-
-		// if there is a return decl, add a use as the last statement; will not have return decl on non-constructable returns
-		stmts.push_back( new ast::ExprStmt(loc, new ast::VariableExpr(loc, ret ) ) );
-	} // if
-
-	assert( stmtExpr->returnDecls.empty() );
-	assert( stmtExpr->dtors.empty() );
-
-	return stmtExpr;
-}
-
-// to prevent warnings ('_unq0' may be used uninitialized in this function),
-// insert an appropriate zero initializer for UniqueExpr temporaries.
-ast::Init * makeInit( const ast::Type * t, CodeLocation const & loc ) {
-	if ( auto inst = dynamic_cast< const ast::StructInstType * >( t ) ) {
-		// initizer for empty struct must be empty
-		if ( inst->base->members.empty() ) {
-			return new ast::ListInit( loc, {} );
-		}
-	} else if ( auto inst = dynamic_cast< const ast::UnionInstType * >( t ) ) {
-		// initizer for empty union must be empty
-		if ( inst->base->members.empty() ) {
-			return new ast::ListInit( loc, {} );
-		}
-	}
-
-	return new ast::ListInit( loc, {
-		new ast::SingleInit( loc, ast::ConstantExpr::from_int( loc, 0 ) )
-	} );
-}
-
-const ast::UniqueExpr * ResolveCopyCtors::previsit( const ast::UniqueExpr * unqExpr ) {
-	visit_children = false;
-	// xxx - hack to prevent double-handling of unique exprs, otherwise too many temporary variables and destructors are generated
-	static std::unordered_map< int, const ast::UniqueExpr * > unqMap;
-	auto mutExpr = mutate(unqExpr);
-	if ( ! unqMap.count( unqExpr->id ) ) {
-		// resolve expr and find its
-
-		auto impCpCtorExpr = mutExpr->expr.as<ast::ImplicitCopyCtorExpr>();
-		// PassVisitor<ResolveCopyCtors> fixer;
-
-		mutExpr->expr = mutExpr->expr->accept( *visitor );
-		// it should never be necessary to wrap a void-returning expression in a UniqueExpr - if this assumption changes, this needs to be rethought
-		assert( unqExpr->result );
-		if ( impCpCtorExpr ) {
-			auto comma = unqExpr->expr.strict_as<ast::CommaExpr>();
-			auto var = comma->arg2.strict_as<ast::VariableExpr>();
-			// note the variable used as the result from the call
-			mutExpr->var = var;
-		} else {
-			// expr isn't a call expr, so create a new temporary variable to use to hold the value of the unique expression
-			mutExpr->object = new ast::ObjectDecl( mutExpr->location, toString("_unq", mutExpr->id), mutExpr->result, makeInit( mutExpr->result, mutExpr->location ) );
-			mutExpr->var = new ast::VariableExpr( mutExpr->location, mutExpr->object );
-		}
-
-		unqMap[mutExpr->id] = mutExpr;
-	} else {
-		// take data from other UniqueExpr to ensure consistency
-		// delete unqExpr->get_expr();
-		mutExpr->expr = unqMap[mutExpr->id]->expr;
-		// delete unqExpr->result;
-		mutExpr->result = mutExpr->expr->result;
-	}
-	return mutExpr;
-}
-
-const ast::DeclWithType * FixInit::postvisit( const ast::ObjectDecl *_objDecl ) {
-	const CodeLocation loc = _objDecl->location;
-
-	// since this removes the init field from objDecl, it must occur after children are mutated (i.e. postvisit)
-	if ( ast::ptr<ast::ConstructorInit> ctorInit = _objDecl->init.as<ast::ConstructorInit>() ) {
-		auto objDecl = mutate(_objDecl);
-
-		// could this be non-unique?
-		if (objDecl != _objDecl) {
-			std::cerr << "FixInit: non-unique object decl " << objDecl->location << objDecl->name << std::endl;
-		}
-		// a decision should have been made by the resolver, so ctor and init are not both non-NULL
-		assert( ! ctorInit->ctor || ! ctorInit->init );
-		if ( const ast::Stmt * ctor = ctorInit->ctor ) {
-			if ( objDecl->storage.is_static ) {
-				addDataSectionAttribute(objDecl);
-				// originally wanted to take advantage of gcc nested functions, but
-				// we get memory errors with this approach. To remedy this, the static
-				// variable is hoisted when the destructor needs to be called.
-				//
-				// generate:
-				// static T __objName_static_varN;
-				// void __objName_dtor_atexitN() {
-				//   __dtor__...;
-				// }
-				// int f(...) {
-				//   ...
-				//   static bool __objName_uninitialized = true;
-				//   if (__objName_uninitialized) {
-				//     __ctor(__objName);
-				//     __objName_uninitialized = false;
-				//     atexit(__objName_dtor_atexitN);
-				//   }
-				//   ...
-				// }
-
-				static UniqueName dtorCallerNamer( "_dtor_atexit" );
-
-				// static bool __objName_uninitialized = true
-				auto boolType = new ast::BasicType( ast::BasicType::Kind::Bool );
-				auto boolInitExpr = new ast::SingleInit(loc, ast::ConstantExpr::from_int(loc, 1 ) );
-				auto isUninitializedVar = new ast::ObjectDecl(loc, objDecl->mangleName + "_uninitialized", boolType, boolInitExpr, ast::Storage::Static, ast::Linkage::Cforall);
-				isUninitializedVar->fixUniqueId();
-
-				// __objName_uninitialized = false;
-				auto setTrue = new ast::UntypedExpr(loc, new ast::NameExpr(loc, "?=?" ) );
-				setTrue->args.push_back( new ast::VariableExpr(loc, isUninitializedVar ) );
-				setTrue->args.push_back( ast::ConstantExpr::from_int(loc, 0 ) );
-
-				// generate body of if
-				auto initStmts = new ast::CompoundStmt(loc);
-				auto & body = initStmts->kids;
-				body.push_back( ctor );
-				body.push_back( new ast::ExprStmt(loc, setTrue ) );
-
-				// put it all together
-				auto ifStmt = new ast::IfStmt(loc, new ast::VariableExpr(loc, isUninitializedVar ), initStmts, 0 );
-				stmtsToAddAfter.push_back( new ast::DeclStmt(loc, isUninitializedVar ) );
-				stmtsToAddAfter.push_back( ifStmt );
-
-				const ast::Stmt * dtor = ctorInit->dtor;
-
-				// these should be automatically managed once reassigned
-				// objDecl->set_init( nullptr );
-				// ctorInit->set_ctor( nullptr );
-				// ctorInit->set_dtor( nullptr );
-				if ( dtor ) {
-					// if the object has a non-trivial destructor, have to
-					// hoist it and the object into the global space and
-					// call the destructor function with atexit.
-
-					// Statement * dtorStmt = dtor->clone();
-
-					// void __objName_dtor_atexitN(...) {...}
-					ast::FunctionDecl * dtorCaller = new ast::FunctionDecl(loc, objDecl->mangleName + dtorCallerNamer.newName(), {}, {}, {}, {}, new ast::CompoundStmt(loc, {dtor}), ast::Storage::Static, ast::Linkage::C );
-					dtorCaller->fixUniqueId();
-					// dtorCaller->stmts->push_back( dtor );
-
-					// atexit(dtor_atexit);
-					auto callAtexit = new ast::UntypedExpr(loc, new ast::NameExpr(loc, "atexit" ) );
-					callAtexit->args.push_back( new ast::VariableExpr(loc, dtorCaller ) );
-
-					body.push_back( new ast::ExprStmt(loc, callAtexit ) );
-
-					// hoist variable and dtor caller decls to list of decls that will be added into global scope
-					staticDtorDecls.push_back( objDecl );
-					staticDtorDecls.push_back( dtorCaller );
-
-					// need to rename object uniquely since it now appears
-					// at global scope and there could be multiple function-scoped
-					// static variables with the same name in different functions.
-					// Note: it isn't sufficient to modify only the mangleName, because
-					// then subsequent SymbolTable passes can choke on seeing the object's name
-					// if another object has the same name and type. An unfortunate side-effect
-					// of renaming the object is that subsequent NameExprs may fail to resolve,
-					// but there shouldn't be any remaining past this point.
-					static UniqueName staticNamer( "_static_var" );
-					objDecl->name = objDecl->name + staticNamer.newName();
-					objDecl->mangleName = Mangle::mangle( objDecl );
-					objDecl->init = nullptr;
-
-					// xxx - temporary hack: need to return a declaration, but want to hoist the current object out of this scope
-					// create a new object which is never used
-					static UniqueName dummyNamer( "_dummy" );
-					auto dummy = new ast::ObjectDecl(loc, dummyNamer.newName(), new ast::PointerType(new ast::VoidType()), nullptr, ast::Storage::Static, ast::Linkage::Cforall, 0, { new ast::Attribute("unused") } );
-					// delete ctorInit;
-					return dummy;
-				} else {
-					objDecl->init = nullptr;
-					return objDecl;
-				}
-			} else {
-				auto implicit = strict_dynamic_cast< const ast::ImplicitCtorDtorStmt * > ( ctor );
-				auto ctorStmt = implicit->callStmt.as<ast::ExprStmt>();
-				const ast::ApplicationExpr * ctorCall = nullptr;
-				if ( ctorStmt && (ctorCall = isIntrinsicCallExpr( ctorStmt->expr )) && ctorCall->args.size() == 2 ) {
-					// clean up intrinsic copy constructor calls by making them into SingleInits
-					const ast::Expr * ctorArg = ctorCall->args.back();
-					// ctorCall should be gone afterwards
-					auto mutArg = mutate(ctorArg);
-					mutArg->env = ctorCall->env;
-					// std::swap( ctorArg->env, ctorCall->env );
-					objDecl->init = new ast::SingleInit(loc, mutArg );
-
-					// ctorCall->args.pop_back();
-				} else {
-					stmtsToAddAfter.push_back( ctor );
-					objDecl->init = nullptr;
-					// ctorInit->ctor = nullptr;
-				}
-
-				const ast::Stmt * dtor = ctorInit->dtor;
-				if ( dtor ) {
-					auto implicit = strict_dynamic_cast< const ast::ImplicitCtorDtorStmt * >( dtor );
-					const ast::Stmt * dtorStmt = implicit->callStmt;
-
-					// don't need to call intrinsic dtor, because it does nothing, but
-					// non-intrinsic dtors must be called
-					if ( ! isIntrinsicSingleArgCallStmt( dtorStmt ) ) {
-						// set dtor location to the object's location for error messages
-						auto dtorFunc = getDtorFunc( objDecl, dtorStmt, stmtsToAddBefore );
-						objDecl->attributes.push_back( new ast::Attribute( "cleanup", { new ast::VariableExpr(loc, dtorFunc ) } ) );
-						// ctorInit->dtor = nullptr;
-					} // if
-				}
-			} // if
-		} else if ( const ast::Init * init = ctorInit->init ) {
-			objDecl->init = init;
-			// ctorInit->init = nullptr;
-		} else {
-			// no constructor and no initializer, which is okay
-			objDecl->init = nullptr;
-		} // if
-		// delete ctorInit;
-		return objDecl;
-	} // if
-	return _objDecl;
-}
-
-void ObjDeclCollector::previsit( const ast::CompoundStmt * ) {
-	GuardValue( curVars );
-}
-
-void ObjDeclCollector::previsit( const ast::DeclStmt * stmt ) {
-	// keep track of all variables currently in scope
-	if ( auto objDecl = stmt->decl.as<ast::ObjectDecl>() ) {
-		curVars.push_back( objDecl );
-	} // if
-}
-
-void LabelFinder::previsit( const ast::Stmt * stmt ) {
-	// for each label, remember the variables in scope at that label.
-	for ( auto l : stmt->labels ) {
-		vars[l] = curVars;
-	} // for
-}
-
-void LabelFinder::previsit( const ast::CompoundStmt * stmt ) {
-	previsit( (const ast::Stmt *) stmt );
-	Parent::previsit( stmt );
-}
-
-void LabelFinder::previsit( const ast::DeclStmt * stmt ) {
-	previsit( (const ast::Stmt *)stmt );
-	Parent::previsit( stmt );
-}
-
-void InsertDtors::previsit( const ast::FunctionDecl * funcDecl ) {
-	// each function needs to have its own set of labels
-	GuardValue( labelVars );
-	labelVars.clear();
-	// LabelFinder does not recurse into FunctionDecl, so need to visit
-	// its children manually.
-	if (funcDecl->type) funcDecl->type->accept(finder);
-	// maybeAccept( funcDecl->type, finder );
-	if (funcDecl->stmts) funcDecl->stmts->accept(finder) ;
-
-	// all labels for this function have been collected, insert destructors as appropriate via implicit recursion.
-}
-
-// Handle break/continue/goto in the same manner as C++.  Basic idea: any objects that are in scope at the
-// BranchStmt but not at the labelled (target) statement must be destructed.  If there are any objects in scope
-// at the target location but not at the BranchStmt then those objects would be uninitialized so notify the user
-// of the error.  See C++ Reference 6.6 Jump Statements for details.
-void InsertDtors::handleGoto( const ast::BranchStmt * stmt ) {
-	// can't do anything for computed goto
-	if ( stmt->computedTarget ) return;
-
-	assertf( stmt->target.name != "", "BranchStmt missing a label: %s", toString( stmt ).c_str() );
-	// S_L = lvars = set of objects in scope at label definition
-	// S_G = curVars = set of objects in scope at goto statement
-	ObjectSet & lvars = labelVars[ stmt->target ];
-
-	DTOR_PRINT(
-		std::cerr << "at goto label: " << stmt->target.name << std::endl;
-		std::cerr << "S_G = " << printSet( curVars ) << std::endl;
-		std::cerr << "S_L = " << printSet( lvars ) << std::endl;
-	)
-
-
-	// std::set_difference requires that the inputs be sorted.
-	lvars.sort();
-	curVars.sort();
-
-	ObjectSet diff;
-	// S_L-S_G results in set of objects whose construction is skipped - it's an error if this set is non-empty
-	std::set_difference( lvars.begin(), lvars.end(), curVars.begin(), curVars.end(), std::inserter( diff, diff.begin() ) );
-	DTOR_PRINT(
-		std::cerr << "S_L-S_G = " << printSet( diff ) << std::endl;
-	)
-	if ( ! diff.empty() ) {
-		SemanticError( stmt, std::string("jump to label '") + stmt->target.name + "' crosses initialization of " + (*diff.begin())->name + " " );
-	} // if
-}
-
-void InsertDtors::previsit( const ast::BranchStmt * stmt ) {
-	switch( stmt->kind ) {
-	case ast::BranchStmt::Continue:
-	case ast::BranchStmt::Break:
-		// could optimize the break/continue case, because the S_L-S_G check is unnecessary (this set should
-		// always be empty), but it serves as a small sanity check.
-	case ast::BranchStmt::Goto:
-		handleGoto( stmt );
-		break;
-	default:
-		assert( false );
-	} // switch
-}
-
-bool checkWarnings( const ast::FunctionDecl * funcDecl ) {
-	// only check for warnings if the current function is a user-defined
-	// constructor or destructor
-	if ( ! funcDecl ) return false;
-	if ( ! funcDecl->stmts ) return false;
-	return CodeGen::isCtorDtor( funcDecl->name ) && ! funcDecl->linkage.is_overrideable;
-}
-
-void GenStructMemberCalls::previsit( const ast::FunctionDecl * funcDecl ) {
-	GuardValue( function );
-	GuardValue( unhandled );
-	GuardValue( usedUninit );
-	GuardValue( thisParam );
-	GuardValue( isCtor );
-	GuardValue( structDecl );
-	errors = SemanticErrorException();  // clear previous errors
-
-	// need to start with fresh sets
-	unhandled.clear();
-	usedUninit.clear();
-
-	function = mutate(funcDecl);
-	// could this be non-unique?
-	if (function != funcDecl) {
-		std::cerr << "GenStructMemberCalls: non-unique FunctionDecl " << funcDecl->location << funcDecl->name << std::endl;
-	}
-
-	isCtor = CodeGen::isConstructor( function->name );
-	if ( checkWarnings( function ) ) {
-		// const ast::FunctionType * type = function->type;
-		// assert( ! type->params.empty() );
-		thisParam = function->params.front().strict_as<ast::ObjectDecl>();
-		auto thisType = getPointerBase( thisParam->get_type() );
-		auto structType = dynamic_cast< const ast::StructInstType * >( thisType );
-		if ( structType ) {
-			structDecl = structType->base;
-			for ( auto & member : structDecl->members ) {
-				if ( auto field = member.as<ast::ObjectDecl>() ) {
-					// record all of the struct type's members that need to be constructed or
-					// destructed by the end of the function
-					unhandled.insert( field );
-				}
-			}
-		}
-	}
-}
-
-const ast::DeclWithType * GenStructMemberCalls::postvisit( const ast::FunctionDecl * funcDecl ) {
-	// remove the unhandled objects from usedUninit, because a call is inserted
-	// to handle them - only objects that are later constructed are used uninitialized.
-	std::map< const ast::DeclWithType *, CodeLocation > diff;
-	// need the comparator since usedUninit and unhandled have different types
-	struct comp_t {
-		typedef decltype(usedUninit)::value_type usedUninit_t;
-		typedef decltype(unhandled)::value_type unhandled_t;
-		bool operator()(usedUninit_t x, unhandled_t y) { return x.first < y; }
-		bool operator()(unhandled_t x, usedUninit_t y) { return x < y.first; }
-	} comp;
-	std::set_difference( usedUninit.begin(), usedUninit.end(), unhandled.begin(), unhandled.end(), std::inserter( diff, diff.begin() ), comp );
-	for ( auto p : diff ) {
-		auto member = p.first;
-		auto loc = p.second;
-		// xxx - make error message better by also tracking the location that the object is constructed at?
-		emit( loc, "in ", function->name, ", field ", member->name, " used before being constructed" );
-	}
-
-	const CodeLocation loc = funcDecl->location;
-
-	if ( ! unhandled.empty() ) {
-		auto mutStmts = function->stmts.get_and_mutate();
-		// need to explicitly re-add function parameters to the indexer in order to resolve copy constructors
-		auto guard = makeFuncGuard( [this]() { symtab.enterScope(); }, [this]() { symtab.leaveScope(); } );
-		symtab.addFunction( function );
-		auto global = transUnit().global;
-
-		// need to iterate through members in reverse in order for
-		// ctor/dtor statements to come out in the right order
-		for ( auto & member : reverseIterate( structDecl->members ) ) {
-			auto field = member.as<ast::ObjectDecl>();
-			// skip non-DWT members
-			if ( ! field ) continue;
-			// skip non-constructable members
-			if ( ! tryConstruct( field ) ) continue;
-			// skip handled members
-			if ( ! unhandled.count( field ) ) continue;
-
-			// insert and resolve default/copy constructor call for each field that's unhandled
-			// std::list< const ast::Stmt * > stmt;
-			ast::Expr * arg2 = nullptr;
-			if ( function->name == "?{}" && isCopyFunction( function ) ) {
-				// if copy ctor, need to pass second-param-of-this-function.field
-				// std::list< DeclarationWithType * > & params = function->get_functionType()->get_parameters();
-				assert( function->params.size() == 2 );
-				arg2 = new ast::MemberExpr(funcDecl->location, field, new ast::VariableExpr(funcDecl->location, function->params.back() ) );
-			}
-			InitExpander srcParam( arg2 );
-			// cast away reference type and construct field.
-			ast::Expr * thisExpr = new ast::CastExpr(funcDecl->location, new ast::VariableExpr(funcDecl->location, thisParam ), thisParam->get_type()->stripReferences());
-			ast::Expr * memberDest = new ast::MemberExpr(funcDecl->location, field, thisExpr );
-			ast::ptr<ast::Stmt> callStmt = SymTab::genImplicitCall( srcParam, memberDest, loc, function->name, field, static_cast<SymTab::LoopDirection>(isCtor) );
-
-			if ( callStmt ) {
-				// auto & callStmt = stmt.front();
-
-				try {
-					callStmt = callStmt->accept( *visitor );
-					if ( isCtor ) {
-						mutStmts->push_front( callStmt );
-					} else { // TODO: don't generate destructor function/object for intrinsic calls
-						// destructor statements should be added at the end
-						// function->get_statements()->push_back( callStmt );
-
-						// Optimization: do not need to call intrinsic destructors on members
-						if ( isIntrinsicSingleArgCallStmt( callStmt ) ) continue;
-
-						// __Destructor _dtor0 = { (void *)&b.a1, (void (*)(void *)_destroy_A };
-						std::list< ast::ptr<ast::Stmt> > stmtsToAdd;
-
-						static UniqueName memberDtorNamer = { "__memberDtor" };
-						assertf( global.dtorStruct, "builtin __Destructor not found." );
-						assertf( global.dtorDestroy, "builtin __destroy_Destructor not found." );
-
-						ast::Expr * thisExpr = new ast::CastExpr( new ast::AddressExpr( new ast::VariableExpr(loc, thisParam ) ), new ast::PointerType( new ast::VoidType(), ast::CV::Qualifiers() ) );
-						ast::Expr * dtorExpr = new ast::VariableExpr(loc, getDtorFunc( thisParam, callStmt, stmtsToAdd ) );
-
-						// cast destructor pointer to void (*)(void *), to silence GCC incompatible pointer warnings
-						auto dtorFtype = new ast::FunctionType();
-						dtorFtype->params.emplace_back( new ast::PointerType( new ast::VoidType() ) );
-						auto dtorType = new ast::PointerType( dtorFtype );
-
-						auto destructor = new ast::ObjectDecl(loc, memberDtorNamer.newName(), new ast::StructInstType( global.dtorStruct ), new ast::ListInit(loc, { new ast::SingleInit(loc, thisExpr ), new ast::SingleInit(loc, new ast::CastExpr( dtorExpr, dtorType ) ) } ) );
-						destructor->attributes.push_back( new ast::Attribute( "cleanup", { new ast::VariableExpr( loc, global.dtorDestroy ) } ) );
-						mutStmts->push_front( new ast::DeclStmt(loc, destructor ) );
-						mutStmts->kids.splice( mutStmts->kids.begin(), stmtsToAdd );
-					}
-				} catch ( SemanticErrorException & error ) {
-					emit( funcDecl->location, "in ", function->name , ", field ", field->name, " not explicitly ", isCtor ? "constructed" : "destructed",  " and no ", isCtor ? "default constructor" : "destructor", " found" );
-				}
-			}
-		}
-		function->stmts = mutStmts;
-	}
-	if (! errors.isEmpty()) {
-		throw errors;
-	}
-	// return funcDecl;
-	return function;
-}
-
-/// true if expr is effectively just the 'this' parameter
-bool isThisExpression( const ast::Expr * expr, const ast::DeclWithType * thisParam ) {
-	// TODO: there are more complicated ways to pass 'this' to a constructor, e.g. &*, *&, etc.
-	if ( auto varExpr = dynamic_cast< const ast::VariableExpr * >( expr ) ) {
-		return varExpr->var == thisParam;
-	} else if ( auto castExpr = dynamic_cast< const ast::CastExpr * > ( expr ) ) {
-		return isThisExpression( castExpr->arg, thisParam );
-	}
-	return false;
-}
-
-/// returns a MemberExpr if expr is effectively just member access on the 'this' parameter, else nullptr
-const ast::MemberExpr * isThisMemberExpr( const ast::Expr * expr, const ast::DeclWithType * thisParam ) {
-	if ( auto memberExpr = dynamic_cast< const ast::MemberExpr * >( expr ) ) {
-		if ( isThisExpression( memberExpr->aggregate, thisParam ) ) {
-			return memberExpr;
-		}
-	} else if ( auto castExpr = dynamic_cast< const ast::CastExpr * >( expr ) ) {
-		return isThisMemberExpr( castExpr->arg, thisParam );
-	}
-	return nullptr;
-}
-
-void GenStructMemberCalls::previsit( const ast::ApplicationExpr * appExpr ) {
-	if ( ! checkWarnings( function ) ) {
-		visit_children = false;
-		return;
-	}
-
-	std::string fname = getFunctionName( appExpr );
-	if ( fname == function->name ) {
-		// call to same kind of function
-		const ast::Expr * firstParam = appExpr->args.front();
-
-		if ( isThisExpression( firstParam, thisParam ) ) {
-			// if calling another constructor on thisParam, assume that function handles
-			// all members - if it doesn't a warning will appear in that function.
-			unhandled.clear();
-		} else if ( auto memberExpr = isThisMemberExpr( firstParam, thisParam ) ) {
-			// if first parameter is a member expression on the this parameter,
-			// then remove the member from unhandled set.
-			if ( isThisExpression( memberExpr->aggregate, thisParam ) ) {
-				unhandled.erase( memberExpr->member );
-			}
-		}
-	}
-}
-
-void GenStructMemberCalls::previsit( const ast::MemberExpr * memberExpr ) {
-	if ( ! checkWarnings( function ) || ! isCtor ) {
-		visit_children = false;
-		return;
-	}
-
-	if ( isThisExpression( memberExpr->aggregate, thisParam ) ) {
-		if ( unhandled.count( memberExpr->member ) ) {
-			// emit a warning because a member was used before it was constructed
-			usedUninit.insert( { memberExpr->member, memberExpr->location } );
-		}
-	}
-}
-
-template< typename... Params >
-void GenStructMemberCalls::emit( CodeLocation loc, const Params &... params ) {
-	SemanticErrorException err( loc, toString( params... ) );
-	errors.append( err );
-}
-
-const ast::Expr * GenStructMemberCalls::postvisit( const ast::UntypedExpr * untypedExpr ) {
-	// xxx - functions returning ast::ptr seems wrong...
-	auto res = ResolvExpr::findVoidExpression( untypedExpr, { symtab, transUnit().global } );
-	return res.release();
-}
-
-void InsertImplicitCalls::previsit(const ast::UniqueExpr * unqExpr) {
-	if (visitedIds.count(unqExpr->id)) visit_children = false;
-	else visitedIds.insert(unqExpr->id);
-}
-
-const ast::Expr * FixCtorExprs::postvisit( const ast::ConstructorExpr * ctorExpr ) {
-	const CodeLocation loc = ctorExpr->location;
-	static UniqueName tempNamer( "_tmp_ctor_expr" );
-	// xxx - is the size check necessary?
-	assert( ctorExpr->result && ctorExpr->result->size() == 1 );
-
-	// xxx - this can be TupleAssignExpr now. Need to properly handle this case.
-	// take possession of expr and env
-	ast::ptr<ast::ApplicationExpr> callExpr = ctorExpr->callExpr.strict_as<ast::ApplicationExpr>();
-	ast::ptr<ast::TypeSubstitution> env = ctorExpr->env;
-	// ctorExpr->set_callExpr( nullptr );
-	// ctorExpr->set_env( nullptr );
-
-	// xxx - ideally we would reuse the temporary generated from the copy constructor passes from within firstArg if it exists and not generate a temporary if it's unnecessary.
-	auto tmp = new ast::ObjectDecl(loc, tempNamer.newName(), callExpr->args.front()->result );
-	declsToAddBefore.push_back( tmp );
-
-	// build assignment and replace constructor's first argument with new temporary
-	auto mutCallExpr = callExpr.get_and_mutate();
-	const ast::Expr * firstArg = callExpr->args.front();
-	ast::Expr * assign = new ast::UntypedExpr(loc, new ast::NameExpr(loc, "?=?" ), { new ast::AddressExpr(loc, new ast::VariableExpr(loc, tmp ) ), new ast::AddressExpr( firstArg ) } );
-	firstArg = new ast::VariableExpr(loc, tmp );
-	mutCallExpr->args.front() = firstArg;
-
-	// resolve assignment and dispose of new env
-	auto resolved = ResolvExpr::findVoidExpression( assign, { symtab, transUnit().global } );
-	auto mut = resolved.get_and_mutate();
-	assertf(resolved.get() == mut, "newly resolved expression must be unique");
-	mut->env = nullptr;
-
-	// for constructor expr:
-	//   T x;
-	//   x{};
-	// results in:
-	//   T x;
-	//   T & tmp;
-	//   &tmp = &x, ?{}(tmp), tmp
-	ast::CommaExpr * commaExpr = new ast::CommaExpr(loc, resolved, new ast::CommaExpr(loc, mutCallExpr, new ast::VariableExpr(loc, tmp ) ) );
-	commaExpr->env = env;
-	return commaExpr;
-}
-
-} // namespace
-
-void fix( ast::TranslationUnit & translationUnit, bool inLibrary ) {
-	ast::Pass<SelfAssignChecker>::run( translationUnit );
-
-	// fixes StmtExpr to properly link to their resulting expression
-	ast::Pass<StmtExprResult>::run( translationUnit );
-
-	// fixes ConstructorInit for global variables. should happen before fixInitializers.
-	InitTweak::fixGlobalInit( translationUnit, inLibrary );
-
-	// must happen before ResolveCopyCtors because temporaries have to be inserted into the correct scope
-	ast::Pass<SplitExpressions>::run( translationUnit );
-
-	ast::Pass<InsertImplicitCalls>::run( translationUnit );
-
-	// Needs to happen before ResolveCopyCtors, because argument/return temporaries should not be considered in
-	// error checking branch statements
-	{
-		ast::Pass<LabelFinder> finder;
-		ast::Pass<InsertDtors>::run( translationUnit, finder );
-	}
-
-	ast::Pass<ResolveCopyCtors>::run( translationUnit );
-	FixInit::fixInitializers( translationUnit );
-	ast::Pass<GenStructMemberCalls>::run( translationUnit );
-
-	// Needs to happen after GenStructMemberCalls, since otherwise member constructors exprs
-	// don't have the correct form, and a member can be constructed more than once.
-	ast::Pass<FixCtorExprs>::run( translationUnit );
-}
-
-} // namespace InitTweak
-
-// Local Variables: //
-// tab-width: 4 //
-// mode: c++ //
-// compile-command: "make install" //
-// End: //
Index: src/InitTweak/module.mk
===================================================================
--- src/InitTweak/module.mk	(revision 37273c8cb34ce14d7da1cb9d4d43491327ff6807)
+++ src/InitTweak/module.mk	(revision 4dc3b8c90f62876e9e5e2b84283aebb28622582a)
@@ -24,6 +24,6 @@
 	InitTweak/FixGlobalInit.cc \
 	InitTweak/FixGlobalInit.h \
-	InitTweak/FixInit.h \
-	InitTweak/FixInitNew.cpp
+	InitTweak/FixInit.cpp \
+	InitTweak/FixInit.h
 
 SRCDEMANGLE += $(SRC_INITTWEAK)