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source: src/ResolvExpr/Unify.cc @ e85a72b8

Last change on this file since e85a72b8 was 8f31be6, checked in by Andrew Beach <ajbeach@…>, 16 months ago
Fixed some warnings, deleted some commented out code.
Property mode set to `100644`
File size: 51.7 KB

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1	//
2	// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
3	//
4	// The contents of this file are covered under the licence agreement in the
5	// file "LICENCE" distributed with Cforall.
6	//
7	// Unify.cc --
8	//
9	// Author : Richard C. Bilson
10	// Created On : Sun May 17 12:27:10 2015
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Fri Dec 13 23:43:05 2019
13	// Update Count : 46
14	//
15
16	#include "Unify.h"
17
18	#include <cassert> // for assertf, assert
19	#include <iterator> // for back_insert_iterator, back_inserter
20	#include <map> // for _Rb_tree_const_iterator, _Rb_tree_i...
21	#include <memory> // for unique_ptr
22	#include <set> // for set
23	#include <string> // for string, operator==, operator!=, bas...
24	#include <utility> // for pair, move
25	#include <vector>
26
27	#include "AST/Copy.hpp"
28	#include "AST/Decl.hpp"
29	#include "AST/Node.hpp"
30	#include "AST/Pass.hpp"
31	#include "AST/Print.hpp"
32	#include "AST/Type.hpp"
33	#include "AST/TypeEnvironment.hpp"
34	#include "Common/Eval.h" // for eval
35	#include "Common/PassVisitor.h" // for PassVisitor
36	#include "CommonType.hpp" // for commonType
37	#include "FindOpenVars.h" // for findOpenVars
38	#include "SpecCost.hpp" // for SpecCost
39	#include "SynTree/LinkageSpec.h" // for C
40	#include "SynTree/Constant.h" // for Constant
41	#include "SynTree/Declaration.h" // for TypeDecl, TypeDecl::Data, Declarati...
42	#include "SynTree/Expression.h" // for TypeExpr, Expression, ConstantExpr
43	#include "SynTree/Mutator.h" // for Mutator
44	#include "SynTree/Type.h" // for Type, TypeInstType, FunctionType
45	#include "SynTree/Visitor.h" // for Visitor
46	#include "Tuples/Tuples.h" // for isTtype
47	#include "TypeEnvironment.h" // for EqvClass, AssertionSet, OpenVarSet
48	#include "typeops.h" // for flatten, occurs
49
50	namespace ast {
51	class SymbolTable;
52	}
53
54	namespace SymTab {
55	class Indexer;
56	} // namespace SymTab
57
58	// #define DEBUG
59
60	namespace ResolvExpr {
61
62	// Template Helpers:
63	template< typename Iterator1, typename Iterator2 >
64	bool unifyList( Iterator1 list1Begin, Iterator1 list1End, Iterator2 list2Begin, Iterator2 list2End, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, OpenVarSet &openVars, const SymTab::Indexer &indexer, std::list< Type* > &commonTypes ) {
65	for ( ; list1Begin != list1End && list2Begin != list2End; ++list1Begin, ++list2Begin ) {
66	Type *commonType = 0;
67	if ( ! unify( list1Begin, list2Begin, env, needAssertions, haveAssertions, openVars, indexer, commonType ) ) {
68	return false;
69	} // if
70	commonTypes.push_back( commonType );
71	} // for
72	return ( list1Begin == list1End && list2Begin == list2End );
73	}
74
75	template< typename Iterator1, typename Iterator2 >
76	bool unifyList( Iterator1 list1Begin, Iterator1 list1End, Iterator2 list2Begin, Iterator2 list2End, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, OpenVarSet &openVars, const SymTab::Indexer &indexer ) {
77	std::list< Type* > commonTypes;
78	if ( unifyList( list1Begin, list1End, list2Begin, list2End, env, needAssertions, haveAssertions, openVars, indexer, commonTypes ) ) {
79	deleteAll( commonTypes );
80	return true;
81	} else {
82	return false;
83	} // if
84	}
85
86	struct Unify_old : public WithShortCircuiting {
87	Unify_old( Type *type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer );
88
89	bool get_result() const { return result; }
90
91	void previsit( BaseSyntaxNode * ) { visit_children = false; }
92
93	void postvisit( VoidType * voidType );
94	void postvisit( BasicType * basicType );
95	void postvisit( PointerType * pointerType );
96	void postvisit( ArrayType * arrayType );
97	void postvisit( ReferenceType * refType );
98	void postvisit( FunctionType * functionType );
99	void postvisit( StructInstType * aggregateUseType );
100	void postvisit( UnionInstType * aggregateUseType );
101	void postvisit( EnumInstType * aggregateUseType );
102	void postvisit( TraitInstType * aggregateUseType );
103	void postvisit( TypeInstType * aggregateUseType );
104	void postvisit( TupleType * tupleType );
105	void postvisit( VarArgsType * varArgsType );
106	void postvisit( ZeroType * zeroType );
107	void postvisit( OneType * oneType );
108
109	private:
110	template< typename RefType > void handleRefType( RefType inst, Type other );
111	template< typename RefType > void handleGenericRefType( RefType inst, Type other );
112
113	bool result;
114	Type *type2; // inherited
115	TypeEnvironment &env;
116	AssertionSet &needAssertions;
117	AssertionSet &haveAssertions;
118	const OpenVarSet &openVars;
119	WidenMode widen;
120	const SymTab::Indexer &indexer;
121	};
122
123	/// Attempts an inexact unification of type1 and type2.
124	/// Returns false if no such unification; if the types can be unified, sets common (unless they unify exactly and have identical type qualifiers)
125	bool unifyInexact( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer, Type *&common );
126	bool unifyExact( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer );
127
128	bool unifyExact(
129	const ast::Type * type1, const ast::Type * type2, ast::TypeEnvironment & env,
130	ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
131	WidenMode widen );
132
133	bool typesCompatible( const Type * first, const Type * second, const SymTab::Indexer & indexer, const TypeEnvironment & env ) {
134	TypeEnvironment newEnv;
135	OpenVarSet openVars, closedVars; // added closedVars
136	AssertionSet needAssertions, haveAssertions;
137	Type * newFirst = first->clone(), * newSecond = second->clone();
138	env.apply( newFirst );
139	env.apply( newSecond );
140
141	// do we need to do this? Seems like we do, types should be able to be compatible if they
142	// have free variables that can unify
143	findOpenVars( newFirst, openVars, closedVars, needAssertions, haveAssertions, false );
144	findOpenVars( newSecond, openVars, closedVars, needAssertions, haveAssertions, true );
145
146	bool result = unifyExact( newFirst, newSecond, newEnv, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
147	delete newFirst;
148	delete newSecond;
149	return result;
150	}
151
152	bool typesCompatible(
153	const ast::Type * first, const ast::Type * second,
154	const ast::TypeEnvironment & env ) {
155	ast::TypeEnvironment newEnv;
156	ast::OpenVarSet open, closed;
157	ast::AssertionSet need, have;
158
159	ast::ptr<ast::Type> newFirst{ first }, newSecond{ second };
160	env.apply( newFirst );
161	env.apply( newSecond );
162
163	// findOpenVars( newFirst, open, closed, need, have, FirstClosed );
164	findOpenVars( newSecond, open, closed, need, have, newEnv, FirstOpen );
165
166	return unifyExact(newFirst, newSecond, newEnv, need, have, open, noWiden() );
167	}
168
169	bool typesCompatibleIgnoreQualifiers( const Type * first, const Type * second, const SymTab::Indexer &indexer, const TypeEnvironment &env ) {
170	TypeEnvironment newEnv;
171	OpenVarSet openVars;
172	AssertionSet needAssertions, haveAssertions;
173	Type newFirst = first->clone(), newSecond = second->clone();
174	env.apply( newFirst );
175	env.apply( newSecond );
176	newFirst->get_qualifiers() = Type::Qualifiers();
177	newSecond->get_qualifiers() = Type::Qualifiers();
178
179	bool result = unifyExact( newFirst, newSecond, newEnv, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
180	delete newFirst;
181	delete newSecond;
182	return result;
183	}
184
185	bool typesCompatibleIgnoreQualifiers(
186	const ast::Type * first, const ast::Type * second,
187	const ast::TypeEnvironment & env ) {
188	ast::TypeEnvironment newEnv;
189	ast::OpenVarSet open;
190	ast::AssertionSet need, have;
191
192	ast::Type * newFirst = shallowCopy( first );
193	ast::Type * newSecond = shallowCopy( second );
194	if ( auto temp = dynamic_cast<const ast::EnumInstType *>(first) ) {
195	if ( !dynamic_cast< const ast::EnumInstType * >( second ) ) {
196	const ast::EnumDecl * baseEnum = dynamic_cast<const ast::EnumDecl *>(temp->base.get());
197	if ( auto t = baseEnum->base.get() ) {
198	newFirst = ast::shallowCopy( t );
199	}
200	}
201	} else if ( auto temp = dynamic_cast<const ast::EnumInstType *>(second) ) {
202	const ast::EnumDecl * baseEnum = dynamic_cast<const ast::EnumDecl *>(temp->base.get());
203	if ( auto t = baseEnum->base.get() ) {
204	newSecond = ast::shallowCopy( t );
205	}
206	}
207
208	newFirst ->qualifiers = {};
209	newSecond->qualifiers = {};
210	ast::ptr< ast::Type > t1_(newFirst );
211	ast::ptr< ast::Type > t2_(newSecond);
212
213	ast::ptr< ast::Type > subFirst = env.apply(newFirst).node;
214	ast::ptr< ast::Type > subSecond = env.apply(newSecond).node;
215
216	return unifyExact(
217	subFirst,
218	subSecond,
219	newEnv, need, have, open, noWiden() );
220	}
221
222	bool unify( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, OpenVarSet &openVars, const SymTab::Indexer &indexer ) {
223	OpenVarSet closedVars;
224	findOpenVars( type1, openVars, closedVars, needAssertions, haveAssertions, false );
225	findOpenVars( type2, openVars, closedVars, needAssertions, haveAssertions, true );
226	Type *commonType = 0;
227	if ( unifyInexact( type1, type2, env, needAssertions, haveAssertions, openVars, WidenMode( true, true ), indexer, commonType ) ) {
228	if ( commonType ) {
229	delete commonType;
230	} // if
231	return true;
232	} else {
233	return false;
234	} // if
235	}
236
237	bool unify( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, OpenVarSet &openVars, const SymTab::Indexer &indexer, Type *&commonType ) {
238	OpenVarSet closedVars;
239	findOpenVars( type1, openVars, closedVars, needAssertions, haveAssertions, false );
240	findOpenVars( type2, openVars, closedVars, needAssertions, haveAssertions, true );
241	return unifyInexact( type1, type2, env, needAssertions, haveAssertions, openVars, WidenMode( true, true ), indexer, commonType );
242	}
243
244	bool unifyExact( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer ) {
245	#ifdef DEBUG
246	TypeEnvironment debugEnv( env );
247	#endif
248	if ( type1->get_qualifiers() != type2->get_qualifiers() ) {
249	return false;
250	}
251
252	bool result;
253	TypeInstType var1 = dynamic_cast< TypeInstType >( type1 );
254	TypeInstType var2 = dynamic_cast< TypeInstType >( type2 );
255	OpenVarSet::const_iterator entry1, entry2;
256	if ( var1 ) {
257	entry1 = openVars.find( var1->get_name() );
258	} // if
259	if ( var2 ) {
260	entry2 = openVars.find( var2->get_name() );
261	} // if
262	bool isopen1 = var1 && ( entry1 != openVars.end() );
263	bool isopen2 = var2 && ( entry2 != openVars.end() );
264
265	if ( isopen1 && isopen2 ) {
266	if ( entry1->second.kind != entry2->second.kind ) {
267	result = false;
268	} else {
269	result = env.bindVarToVar(
270	var1, var2, TypeDecl::Data{ entry1->second, entry2->second }, needAssertions,
271	haveAssertions, openVars, widen, indexer );
272	}
273	} else if ( isopen1 ) {
274	result = env.bindVar( var1, type2, entry1->second, needAssertions, haveAssertions, openVars, widen, indexer );
275	} else if ( isopen2 ) { // TODO: swap widen values in call, since type positions are flipped?
276	result = env.bindVar( var2, type1, entry2->second, needAssertions, haveAssertions, openVars, widen, indexer );
277	} else {
278	PassVisitor<Unify_old> comparator( type2, env, needAssertions, haveAssertions, openVars, widen, indexer );
279	type1->accept( comparator );
280	result = comparator.pass.get_result();
281	} // if
282	#ifdef DEBUG
283	std::cerr << "============ unifyExact" << std::endl;
284	std::cerr << "type1 is ";
285	type1->print( std::cerr );
286	std::cerr << std::endl << "type2 is ";
287	type2->print( std::cerr );
288	std::cerr << std::endl << "openVars are ";
289	printOpenVarSet( openVars, std::cerr, 8 );
290	std::cerr << std::endl << "input env is " << std::endl;
291	debugEnv.print( std::cerr, 8 );
292	std::cerr << std::endl << "result env is " << std::endl;
293	env.print( std::cerr, 8 );
294	std::cerr << "result is " << result << std::endl;
295	#endif
296	return result;
297	}
298
299	bool unifyExact( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, OpenVarSet &openVars, const SymTab::Indexer &indexer ) {
300	return unifyExact( type1, type2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
301	}
302
303	bool unifyInexact( Type type1, Type type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer, Type *&common ) {
304	Type::Qualifiers tq1 = type1->get_qualifiers(), tq2 = type2->get_qualifiers();
305	type1->get_qualifiers() = Type::Qualifiers();
306	type2->get_qualifiers() = Type::Qualifiers();
307	bool result;
308	#ifdef DEBUG
309	std::cerr << "unifyInexact type 1 is ";
310	type1->print( std::cerr );
311	std::cerr << " type 2 is ";
312	type2->print( std::cerr );
313	std::cerr << std::endl;
314	#endif
315	if ( ! unifyExact( type1, type2, env, needAssertions, haveAssertions, openVars, widen, indexer ) ) {
316	#ifdef DEBUG
317	std::cerr << "unifyInexact: no exact unification found" << std::endl;
318	#endif
319	if ( ( common = commonType( type1, type2, widen.first, widen.second, indexer, env, openVars ) ) ) {
320	common->tq = tq1.unify( tq2 );
321	#ifdef DEBUG
322	std::cerr << "unifyInexact: common type is ";
323	common->print( std::cerr );
324	std::cerr << std::endl;
325	#endif
326	result = true;
327	} else {
328	#ifdef DEBUG
329	std::cerr << "unifyInexact: no common type found" << std::endl;
330	#endif
331	result = false;
332	} // if
333	} else {
334	if ( tq1 != tq2 ) {
335	if ( ( tq1 > tq2 \|\| widen.first ) && ( tq2 > tq1 \|\| widen.second ) ) {
336	common = type1->clone();
337	common->tq = tq1.unify( tq2 );
338	result = true;
339	} else {
340	result = false;
341	} // if
342	} else {
343	common = type1->clone();
344	common->tq = tq1.unify( tq2 );
345	result = true;
346	} // if
347	} // if
348	type1->get_qualifiers() = tq1;
349	type2->get_qualifiers() = tq2;
350	return result;
351	}
352
353	Unify_old::Unify_old( Type *type2, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, WidenMode widen, const SymTab::Indexer &indexer )
354	: result( false ), type2( type2 ), env( env ), needAssertions( needAssertions ), haveAssertions( haveAssertions ), openVars( openVars ), widen( widen ), indexer( indexer ) {
355	}
356
357	void Unify_old::postvisit( __attribute__((unused)) VoidType *voidType) {
358	result = dynamic_cast< VoidType* >( type2 );
359	}
360
361	void Unify_old::postvisit(BasicType *basicType) {
362	if ( BasicType otherBasic = dynamic_cast< BasicType >( type2 ) ) {
363	result = basicType->get_kind() == otherBasic->get_kind();
364	} // if
365	}
366
367	void markAssertionSet( AssertionSet &assertions, DeclarationWithType *assert ) {
368	AssertionSet::iterator i = assertions.find( assert );
369	if ( i != assertions.end() ) {
370	i->second.isUsed = true;
371	} // if
372	}
373
374	void markAssertions( AssertionSet &assertion1, AssertionSet &assertion2, Type *type ) {
375	for ( std::list< TypeDecl* >::const_iterator tyvar = type->get_forall().begin(); tyvar != type->get_forall().end(); ++tyvar ) {
376	for ( std::list< DeclarationWithType* >::const_iterator assert = (tyvar)->get_assertions().begin(); assert != (tyvar)->get_assertions().end(); ++assert ) {
377	markAssertionSet( assertion1, *assert );
378	markAssertionSet( assertion2, *assert );
379	} // for
380	} // for
381	}
382
383	void Unify_old::postvisit(PointerType *pointerType) {
384	if ( PointerType otherPointer = dynamic_cast< PointerType >( type2 ) ) {
385	result = unifyExact( pointerType->get_base(), otherPointer->get_base(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
386	markAssertions( haveAssertions, needAssertions, pointerType );
387	markAssertions( haveAssertions, needAssertions, otherPointer );
388	} // if
389	}
390
391	void Unify_old::postvisit(ReferenceType *refType) {
392	if ( ReferenceType otherRef = dynamic_cast< ReferenceType >( type2 ) ) {
393	result = unifyExact( refType->get_base(), otherRef->get_base(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
394	markAssertions( haveAssertions, needAssertions, refType );
395	markAssertions( haveAssertions, needAssertions, otherRef );
396	} // if
397	}
398
399	void Unify_old::postvisit(ArrayType *arrayType) {
400	ArrayType otherArray = dynamic_cast< ArrayType >( type2 );
401	// to unify, array types must both be VLA or both not VLA
402	// and must both have a dimension expression or not have a dimension
403	if ( otherArray && arrayType->get_isVarLen() == otherArray->get_isVarLen() ) {
404
405	if ( ! arrayType->get_isVarLen() && ! otherArray->get_isVarLen() &&
406	arrayType->get_dimension() != 0 && otherArray->get_dimension() != 0 ) {
407	ConstantExpr * ce1 = dynamic_cast< ConstantExpr * >( arrayType->get_dimension() );
408	ConstantExpr * ce2 = dynamic_cast< ConstantExpr * >( otherArray->get_dimension() );
409	// see C11 Reference Manual 6.7.6.2.6
410	// two array types with size specifiers that are integer constant expressions are
411	// compatible if both size specifiers have the same constant value
412	if ( ce1 && ce2 ) {
413	Constant * c1 = ce1->get_constant();
414	Constant * c2 = ce2->get_constant();
415
416	if ( c1->get_value() != c2->get_value() ) {
417	// does not unify if the dimension is different
418	return;
419	}
420	}
421	}
422
423	result = unifyExact( arrayType->get_base(), otherArray->get_base(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
424	} // if
425	}
426
427	template< typename Iterator, typename Func >
428	std::unique_ptr<Type> combineTypes( Iterator begin, Iterator end, Func & toType ) {
429	std::list< Type * > types;
430	for ( ; begin != end; ++begin ) {
431	// it's guaranteed that a ttype variable will be bound to a flat tuple, so ensure that this results in a flat tuple
432	flatten( toType( *begin ), back_inserter( types ) );
433	}
434	return std::unique_ptr<Type>( new TupleType( Type::Qualifiers(), types ) );
435	}
436
437	template< typename Iterator1, typename Iterator2 >
438	bool unifyTypeList( Iterator1 list1Begin, Iterator1 list1End, Iterator2 list2Begin, Iterator2 list2End, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, const SymTab::Indexer &indexer ) {
439	auto get_type = [](DeclarationWithType * dwt){ return dwt->get_type(); };
440	for ( ; list1Begin != list1End && list2Begin != list2End; ++list1Begin, ++list2Begin ) {
441	Type * t1 = (*list1Begin)->get_type();
442	Type * t2 = (*list2Begin)->get_type();
443	bool isTtype1 = Tuples::isTtype( t1 );
444	bool isTtype2 = Tuples::isTtype( t2 );
445	// xxx - assumes ttype must be last parameter
446	// xxx - there may be a nice way to refactor this, but be careful because the argument positioning might matter in some cases.
447	if ( isTtype1 && ! isTtype2 ) {
448	// combine all of the things in list2, then unify
449	return unifyExact( t1, combineTypes( list2Begin, list2End, get_type ).get(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
450	} else if ( isTtype2 && ! isTtype1 ) {
451	// combine all of the things in list1, then unify
452	return unifyExact( combineTypes( list1Begin, list1End, get_type ).get(), t2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
453	} else if ( ! unifyExact( t1, t2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer ) ) {
454	return false;
455	} // if
456	} // for
457	// may get to the end of one argument list before the end of the other. This is only okay when the other is a ttype
458	if ( list1Begin != list1End ) {
459	// try unifying empty tuple type with ttype
460	Type * t1 = (*list1Begin)->get_type();
461	if ( Tuples::isTtype( t1 ) ) {
462	return unifyExact( t1, combineTypes( list2Begin, list2End, get_type ).get(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
463	} else return false;
464	} else if ( list2Begin != list2End ) {
465	// try unifying empty tuple type with ttype
466	Type * t2 = (*list2Begin)->get_type();
467	if ( Tuples::isTtype( t2 ) ) {
468	return unifyExact( combineTypes( list1Begin, list1End, get_type ).get(), t2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
469	} else return false;
470	} else {
471	return true;
472	} // if
473	}
474
475	/// Finds ttypes and replaces them with their expansion, if known.
476	/// This needs to be done so that satisfying ttype assertions is easier.
477	/// If this isn't done then argument lists can have wildly different
478	/// size and structure, when they should be compatible.
479	struct TtypeExpander_old : public WithShortCircuiting {
480	TypeEnvironment & tenv;
481	TtypeExpander_old( TypeEnvironment & tenv ) : tenv( tenv ) {}
482	void premutate( TypeInstType * ) { visit_children = false; }
483	Type * postmutate( TypeInstType * typeInst ) {
484	if ( const EqvClass *eqvClass = tenv.lookup( typeInst->get_name() ) ) {
485	// expand ttype parameter into its actual type
486	if ( eqvClass->data.kind == TypeDecl::Ttype && eqvClass->type ) {
487	delete typeInst;
488	return eqvClass->type->clone();
489	}
490	}
491	return typeInst;
492	}
493	};
494
495	/// flattens a list of declarations, so that each tuple type has a single declaration.
496	/// makes use of TtypeExpander to ensure ttypes are flat as well.
497	void flattenList( std::list< DeclarationWithType * > src, std::list< DeclarationWithType * > & dst, TypeEnvironment & env ) {
498	dst.clear();
499	for ( DeclarationWithType * dcl : src ) {
500	PassVisitor<TtypeExpander_old> expander( env );
501	dcl->acceptMutator( expander );
502	std::list< Type * > types;
503	flatten( dcl->get_type(), back_inserter( types ) );
504	for ( Type * t : types ) {
505	// outermost const, volatile, _Atomic qualifiers in parameters should not play a role in the unification of function types, since they do not determine whether a function is callable.
506	// Note: MUST consider at least mutex qualifier, since functions can be overloaded on outermost mutex and a mutex function has different requirements than a non-mutex function.
507	t->get_qualifiers() -= Type::Qualifiers(Type::Const \| Type::Volatile \| Type::Atomic);
508
509	dst.push_back( new ObjectDecl( "", Type::StorageClasses(), LinkageSpec::C, nullptr, t, nullptr ) );
510	}
511	delete dcl;
512	}
513	}
514
515	void Unify_old::postvisit(FunctionType *functionType) {
516	FunctionType otherFunction = dynamic_cast< FunctionType >( type2 );
517	if ( otherFunction && functionType->get_isVarArgs() == otherFunction->get_isVarArgs() ) {
518	// flatten the parameter lists for both functions so that tuple structure
519	// doesn't affect unification. Must be a clone so that the types don't change.
520	std::unique_ptr<FunctionType> flatFunc( functionType->clone() );
521	std::unique_ptr<FunctionType> flatOther( otherFunction->clone() );
522	flattenList( flatFunc->get_parameters(), flatFunc->get_parameters(), env );
523	flattenList( flatOther->get_parameters(), flatOther->get_parameters(), env );
524
525	// sizes don't have to match if ttypes are involved; need to be more precise wrt where the ttype is to prevent errors
526	if (
527	(flatFunc->parameters.size() == flatOther->parameters.size() &&
528	flatFunc->returnVals.size() == flatOther->returnVals.size())
529	\|\| flatFunc->isTtype()
530	\|\| flatOther->isTtype()
531	) {
532	if ( unifyTypeList( flatFunc->parameters.begin(), flatFunc->parameters.end(), flatOther->parameters.begin(), flatOther->parameters.end(), env, needAssertions, haveAssertions, openVars, indexer ) ) {
533	if ( unifyTypeList( flatFunc->returnVals.begin(), flatFunc->returnVals.end(), flatOther->returnVals.begin(), flatOther->returnVals.end(), env, needAssertions, haveAssertions, openVars, indexer ) ) {
534
535	// the original types must be used in mark assertions, since pointer comparisons are used
536	markAssertions( haveAssertions, needAssertions, functionType );
537	markAssertions( haveAssertions, needAssertions, otherFunction );
538
539	result = true;
540	} // if
541	} // if
542	} // if
543	} // if
544	}
545
546	template< typename RefType >
547	void Unify_old::handleRefType( RefType inst, Type other ) {
548	// check that other type is compatible and named the same
549	RefType otherStruct = dynamic_cast< RefType >( other );
550	result = otherStruct && inst->name == otherStruct->name;
551	}
552
553	template< typename RefType >
554	void Unify_old::handleGenericRefType( RefType inst, Type other ) {
555	// Check that other type is compatible and named the same
556	handleRefType( inst, other );
557	if ( ! result ) return;
558	// Check that parameters of types unify, if any
559	std::list< Expression* > params = inst->parameters;
560	std::list< Expression* > otherParams = ((RefType*)other)->parameters;
561
562	std::list< Expression* >::const_iterator it = params.begin(), jt = otherParams.begin();
563	for ( ; it != params.end() && jt != otherParams.end(); ++it, ++jt ) {
564	TypeExpr param = dynamic_cast< TypeExpr >(*it);
565	assertf(param, "Aggregate parameters should be type expressions");
566	TypeExpr otherParam = dynamic_cast< TypeExpr >(*jt);
567	assertf(otherParam, "Aggregate parameters should be type expressions");
568
569	Type* paramTy = param->get_type();
570	Type* otherParamTy = otherParam->get_type();
571
572	bool tupleParam = Tuples::isTtype( paramTy );
573	bool otherTupleParam = Tuples::isTtype( otherParamTy );
574
575	if ( tupleParam && otherTupleParam ) {
576	++it; ++jt; // skip ttype parameters for break
577	} else if ( tupleParam ) {
578	// bundle other parameters into tuple to match
579	std::list< Type * > binderTypes;
580
581	do {
582	binderTypes.push_back( otherParam->get_type()->clone() );
583	++jt;
584
585	if ( jt == otherParams.end() ) break;
586
587	otherParam = dynamic_cast< TypeExpr* >(*jt);
588	assertf(otherParam, "Aggregate parameters should be type expressions");
589	} while (true);
590
591	otherParamTy = new TupleType{ paramTy->get_qualifiers(), binderTypes };
592	++it; // skip ttype parameter for break
593	} else if ( otherTupleParam ) {
594	// bundle parameters into tuple to match other
595	std::list< Type * > binderTypes;
596
597	do {
598	binderTypes.push_back( param->get_type()->clone() );
599	++it;
600
601	if ( it == params.end() ) break;
602
603	param = dynamic_cast< TypeExpr* >(*it);
604	assertf(param, "Aggregate parameters should be type expressions");
605	} while (true);
606
607	paramTy = new TupleType{ otherParamTy->get_qualifiers(), binderTypes };
608	++jt; // skip ttype parameter for break
609	}
610
611	if ( ! unifyExact( paramTy, otherParamTy, env, needAssertions, haveAssertions, openVars, WidenMode(false, false), indexer ) ) {
612	result = false;
613	return;
614	}
615
616	// ttype parameter should be last
617	if ( tupleParam \|\| otherTupleParam ) break;
618	}
619	result = ( it == params.end() && jt == otherParams.end() );
620	}
621
622	void Unify_old::postvisit(StructInstType *structInst) {
623	handleGenericRefType( structInst, type2 );
624	}
625
626	void Unify_old::postvisit(UnionInstType *unionInst) {
627	handleGenericRefType( unionInst, type2 );
628	}
629
630	void Unify_old::postvisit(EnumInstType *enumInst) {
631	handleRefType( enumInst, type2 );
632	}
633
634	void Unify_old::postvisit(TraitInstType *contextInst) {
635	handleRefType( contextInst, type2 );
636	}
637
638	void Unify_old::postvisit(TypeInstType *typeInst) {
639	assert( openVars.find( typeInst->get_name() ) == openVars.end() );
640	TypeInstType otherInst = dynamic_cast< TypeInstType >( type2 );
641	if ( otherInst && typeInst->get_name() == otherInst->get_name() ) {
642	result = true;
643	/// } else {
644	/// NamedTypeDecl *nt = indexer.lookupType( typeInst->get_name() );
645	/// if ( nt ) {
646	/// TypeDecl type = dynamic_cast< TypeDecl >( nt );
647	/// assert( type );
648	/// if ( type->get_base() ) {
649	/// result = unifyExact( type->get_base(), typeInst, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
650	/// }
651	/// }
652	} // if
653	}
654
655	template< typename Iterator1, typename Iterator2 >
656	bool unifyList( Iterator1 list1Begin, Iterator1 list1End, Iterator2 list2Begin, Iterator2 list2End, TypeEnvironment &env, AssertionSet &needAssertions, AssertionSet &haveAssertions, const OpenVarSet &openVars, const SymTab::Indexer &indexer ) {
657	auto get_type = [](Type * t) { return t; };
658	for ( ; list1Begin != list1End && list2Begin != list2End; ++list1Begin, ++list2Begin ) {
659	Type * t1 = *list1Begin;
660	Type * t2 = *list2Begin;
661	bool isTtype1 = Tuples::isTtype( t1 );
662	bool isTtype2 = Tuples::isTtype( t2 );
663	// xxx - assumes ttype must be last parameter
664	// xxx - there may be a nice way to refactor this, but be careful because the argument positioning might matter in some cases.
665	if ( isTtype1 && ! isTtype2 ) {
666	// combine all of the things in list2, then unify
667	return unifyExact( t1, combineTypes( list2Begin, list2End, get_type ).get(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
668	} else if ( isTtype2 && ! isTtype1 ) {
669	// combine all of the things in list1, then unify
670	return unifyExact( combineTypes( list1Begin, list1End, get_type ).get(), t2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
671	} else if ( ! unifyExact( t1, t2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer ) ) {
672	return false;
673	} // if
674
675	} // for
676	if ( list1Begin != list1End ) {
677	// try unifying empty tuple type with ttype
678	Type * t1 = *list1Begin;
679	if ( Tuples::isTtype( t1 ) ) {
680	return unifyExact( t1, combineTypes( list2Begin, list2End, get_type ).get(), env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
681	} else return false;
682	} else if ( list2Begin != list2End ) {
683	// try unifying empty tuple type with ttype
684	Type * t2 = *list2Begin;
685	if ( Tuples::isTtype( t2 ) ) {
686	return unifyExact( combineTypes( list1Begin, list1End, get_type ).get(), t2, env, needAssertions, haveAssertions, openVars, WidenMode( false, false ), indexer );
687	} else return false;
688	} else {
689	return true;
690	} // if
691	}
692
693	void Unify_old::postvisit(TupleType *tupleType) {
694	if ( TupleType otherTuple = dynamic_cast< TupleType >( type2 ) ) {
695	std::unique_ptr<TupleType> flat1( tupleType->clone() );
696	std::unique_ptr<TupleType> flat2( otherTuple->clone() );
697	std::list<Type *> types1, types2;
698
699	PassVisitor<TtypeExpander_old> expander( env );
700	flat1->acceptMutator( expander );
701	flat2->acceptMutator( expander );
702
703	flatten( flat1.get(), back_inserter( types1 ) );
704	flatten( flat2.get(), back_inserter( types2 ) );
705
706	result = unifyList( types1.begin(), types1.end(), types2.begin(), types2.end(), env, needAssertions, haveAssertions, openVars, indexer );
707	} // if
708	}
709
710	void Unify_old::postvisit( __attribute__((unused)) VarArgsType *varArgsType ) {
711	result = dynamic_cast< VarArgsType* >( type2 );
712	}
713
714	void Unify_old::postvisit( __attribute__((unused)) ZeroType *zeroType ) {
715	result = dynamic_cast< ZeroType* >( type2 );
716	}
717
718	void Unify_old::postvisit( __attribute__((unused)) OneType *oneType ) {
719	result = dynamic_cast< OneType* >( type2 );
720	}
721
722	Type * extractResultType( FunctionType * function ) {
723	if ( function->get_returnVals().size() == 0 ) {
724	return new VoidType( Type::Qualifiers() );
725	} else if ( function->get_returnVals().size() == 1 ) {
726	return function->get_returnVals().front()->get_type()->clone();
727	} else {
728	std::list< Type * > types;
729	for ( DeclarationWithType * decl : function->get_returnVals() ) {
730	types.push_back( decl->get_type()->clone() );
731	} // for
732	return new TupleType( Type::Qualifiers(), types );
733	}
734	}
735
736	namespace {
737	/// Replaces ttype variables with their bound types.
738	/// If this isn't done when satifying ttype assertions, then argument lists can have
739	/// different size and structure when they should be compatible.
740	struct TtypeExpander_new : public ast::WithShortCircuiting, public ast::PureVisitor {
741	ast::TypeEnvironment & tenv;
742
743	TtypeExpander_new( ast::TypeEnvironment & env ) : tenv( env ) {}
744
745	const ast::Type * postvisit( const ast::TypeInstType * typeInst ) {
746	if ( const ast::EqvClass * clz = tenv.lookup( *typeInst ) ) {
747	// expand ttype parameter into its actual type
748	if ( clz->data.kind == ast::TypeDecl::Ttype && clz->bound ) {
749	return clz->bound;
750	}
751	}
752	return typeInst;
753	}
754	};
755	}
756
757	std::vector< ast::ptr< ast::Type > > flattenList(
758	const std::vector< ast::ptr< ast::Type > > & src, ast::TypeEnvironment & env
759	) {
760	std::vector< ast::ptr< ast::Type > > dst;
761	dst.reserve( src.size() );
762	for ( const auto & d : src ) {
763	ast::Pass<TtypeExpander_new> expander{ env };
764	// TtypeExpander pass is impure (may mutate nodes in place)
765	// need to make nodes shared to prevent accidental mutation
766	ast::ptr<ast::Type> dc = d->accept(expander);
767	auto types = flatten( dc );
768	for ( ast::ptr< ast::Type > & t : types ) {
769	// outermost const, volatile, _Atomic qualifiers in parameters should not play
770	// a role in the unification of function types, since they do not determine
771	// whether a function is callable.
772	// NOTE: must consider at least mutex qualifier, since functions can be
773	// overloaded on outermost mutex and a mutex function has different
774	// requirements than a non-mutex function
775	remove_qualifiers( t, ast::CV::Const \| ast::CV::Volatile \| ast::CV::Atomic );
776	dst.emplace_back( t );
777	}
778	}
779	return dst;
780	}
781
782	// Unification of Expressions
783	//
784	// Boolean outcome (obvious): Are they basically spelled the same?
785	// Side effect of binding variables (subtle): if `sizeof(int)` ===_expr `sizeof(T)` then `int` ===_ty `T`
786	//
787	// Context: if `float[VAREXPR1]` ===_ty `float[VAREXPR2]` then `VAREXPR1` ===_expr `VAREXPR2`
788	// where the VAREXPR are meant as notational metavariables representing the fact that unification always
789	// sees distinct ast::VariableExpr objects at these positions
790
791	static bool unify( const ast::Expr * e1, const ast::Expr * e2, ast::TypeEnvironment & env,
792	ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
793	WidenMode widen );
794
795	class UnifyExpr final : public ast::WithShortCircuiting {
796	const ast::Expr * e2;
797	ast::TypeEnvironment & tenv;
798	ast::AssertionSet & need;
799	ast::AssertionSet & have;
800	const ast::OpenVarSet & open;
801	WidenMode widen;
802	public:
803	bool result;
804
805	private:
806
807	void tryMatchOnStaticValue( const ast::Expr * e1 ) {
808	Evaluation r1 = eval(e1);
809	Evaluation r2 = eval(e2);
810
811	if ( ! r1.hasKnownValue ) return;
812	if ( ! r2.hasKnownValue ) return;
813
814	if (r1.knownValue != r2.knownValue) return;
815
816	visit_children = false;
817	result = true;
818	}
819
820	public:
821
822	void previsit( const ast::Node * ) { assert(false); }
823
824	void previsit( const ast::Expr * e1 ) {
825	tryMatchOnStaticValue( e1 );
826	visit_children = false;
827	}
828
829	void previsit( const ast::CastExpr * e1 ) {
830	tryMatchOnStaticValue( e1 );
831
832	if (result) {
833	assert (visit_children == false);
834	} else {
835	assert (visit_children == true);
836	visit_children = false;
837
838	auto e2c = dynamic_cast< const ast::CastExpr * >( e2 );
839	if ( ! e2c ) return;
840
841	// inspect casts' target types
842	if ( ! unifyExact(
843	e1->result, e2c->result, tenv, need, have, open, widen ) ) return;
844
845	// inspect casts' inner expressions
846	result = unify( e1->arg, e2c->arg, tenv, need, have, open, widen );
847	}
848	}
849
850	void previsit( const ast::VariableExpr * e1 ) {
851	tryMatchOnStaticValue( e1 );
852
853	if (result) {
854	assert (visit_children == false);
855	} else {
856	assert (visit_children == true);
857	visit_children = false;
858
859	auto e2v = dynamic_cast< const ast::VariableExpr * >( e2 );
860	if ( ! e2v ) return;
861
862	assert(e1->var);
863	assert(e2v->var);
864
865	// conservative: variable exprs match if their declarations are represented by the same C++ AST object
866	result = (e1->var == e2v->var);
867	}
868	}
869
870	void previsit( const ast::SizeofExpr * e1 ) {
871	tryMatchOnStaticValue( e1 );
872
873	if (result) {
874	assert (visit_children == false);
875	} else {
876	assert (visit_children == true);
877	visit_children = false;
878
879	auto e2so = dynamic_cast< const ast::SizeofExpr * >( e2 );
880	if ( ! e2so ) return;
881
882	assert((e1->type != nullptr) ^ (e1->expr != nullptr));
883	assert((e2so->type != nullptr) ^ (e2so->expr != nullptr));
884	if ( ! (e1->type && e2so->type) ) return;
885
886	// expression unification calls type unification (mutual recursion)
887	result = unifyExact( e1->type, e2so->type, tenv, need, have, open, widen );
888	}
889	}
890
891	UnifyExpr( const ast::Expr * e2, ast::TypeEnvironment & env, ast::AssertionSet & need,
892	ast::AssertionSet & have, const ast::OpenVarSet & open, WidenMode widen )
893	: e2( e2 ), tenv(env), need(need), have(have), open(open), widen(widen), result(false) {}
894	};
895
896	static bool unify( const ast::Expr * e1, const ast::Expr * e2, ast::TypeEnvironment & env,
897	ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
898	WidenMode widen ) {
899	assert( e1 && e2 );
900	return ast::Pass<UnifyExpr>::read( e1, e2, env, need, have, open, widen );
901	}
902
903	class Unify_new final : public ast::WithShortCircuiting {
904	const ast::Type * type2;
905	ast::TypeEnvironment & tenv;
906	ast::AssertionSet & need;
907	ast::AssertionSet & have;
908	const ast::OpenVarSet & open;
909	WidenMode widen;
910	public:
911	static size_t traceId;
912	bool result;
913
914	Unify_new(
915	const ast::Type * type2, ast::TypeEnvironment & env, ast::AssertionSet & need,
916	ast::AssertionSet & have, const ast::OpenVarSet & open, WidenMode widen )
917	: type2(type2), tenv(env), need(need), have(have), open(open), widen(widen),
918	result(false) {}
919
920	void previsit( const ast::Node * ) { visit_children = false; }
921
922	void postvisit( const ast::VoidType * ) {
923	result = dynamic_cast< const ast::VoidType * >( type2 );
924	}
925
926	void postvisit( const ast::BasicType * basic ) {
927	if ( auto basic2 = dynamic_cast< const ast::BasicType * >( type2 ) ) {
928	result = basic->kind == basic2->kind;
929	}
930	}
931
932	void postvisit( const ast::PointerType * pointer ) {
933	if ( auto pointer2 = dynamic_cast< const ast::PointerType * >( type2 ) ) {
934	result = unifyExact(
935	pointer->base, pointer2->base, tenv, need, have, open,
936	noWiden());
937	}
938	}
939
940	void postvisit( const ast::ArrayType * array ) {
941	auto array2 = dynamic_cast< const ast::ArrayType * >( type2 );
942	if ( ! array2 ) return;
943
944	if ( array->isVarLen != array2->isVarLen ) return;
945	if ( (array->dimension != nullptr) != (array2->dimension != nullptr) ) return;
946
947	if ( array->dimension ) {
948	assert( array2->dimension );
949	// type unification calls expression unification (mutual recursion)
950	if ( ! unify(array->dimension, array2->dimension,
951	tenv, need, have, open, widen) ) return;
952	}
953
954	result = unifyExact(
955	array->base, array2->base, tenv, need, have, open, noWiden());
956	}
957
958	void postvisit( const ast::ReferenceType * ref ) {
959	if ( auto ref2 = dynamic_cast< const ast::ReferenceType * >( type2 ) ) {
960	result = unifyExact(
961	ref->base, ref2->base, tenv, need, have, open, noWiden());
962	}
963	}
964
965	private:
966
967	template< typename Iter >
968	static bool unifyTypeList(
969	Iter crnt1, Iter end1, Iter crnt2, Iter end2, ast::TypeEnvironment & env,
970	ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open
971	) {
972	while ( crnt1 != end1 && crnt2 != end2 ) {
973	const ast::Type * t1 = *crnt1;
974	const ast::Type * t2 = *crnt2;
975	bool isTuple1 = Tuples::isTtype( t1 );
976	bool isTuple2 = Tuples::isTtype( t2 );
977
978	// assumes here that ttype must be last parameter
979	if ( isTuple1 && ! isTuple2 ) {
980	// combine remainder of list2, then unify
981	return unifyExact(
982	t1, tupleFromTypes( crnt2, end2 ), env, need, have, open,
983	noWiden() );
984	} else if ( ! isTuple1 && isTuple2 ) {
985	// combine remainder of list1, then unify
986	return unifyExact(
987	tupleFromTypes( crnt1, end1 ), t2, env, need, have, open,
988	noWiden() );
989	}
990
991	if ( ! unifyExact(
992	t1, t2, env, need, have, open, noWiden() )
993	) return false;
994
995	++crnt1; ++crnt2;
996	}
997
998	// May get to the end of one argument list before the other. This is only okay if the
999	// other is a ttype
1000	if ( crnt1 != end1 ) {
1001	// try unifying empty tuple with ttype
1002	const ast::Type * t1 = *crnt1;
1003	if ( ! Tuples::isTtype( t1 ) ) return false;
1004	return unifyExact(
1005	t1, tupleFromTypes( crnt2, end2 ), env, need, have, open,
1006	noWiden() );
1007	} else if ( crnt2 != end2 ) {
1008	// try unifying empty tuple with ttype
1009	const ast::Type * t2 = *crnt2;
1010	if ( ! Tuples::isTtype( t2 ) ) return false;
1011	return unifyExact(
1012	tupleFromTypes( crnt1, end1 ), t2, env, need, have, open,
1013	noWiden() );
1014	}
1015
1016	return true;
1017	}
1018
1019	static bool unifyTypeList(
1020	const std::vector< ast::ptr< ast::Type > > & list1,
1021	const std::vector< ast::ptr< ast::Type > > & list2,
1022	ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
1023	const ast::OpenVarSet & open
1024	) {
1025	return unifyTypeList(
1026	list1.begin(), list1.end(), list2.begin(), list2.end(), env, need, have, open);
1027	}
1028
1029	static void markAssertionSet( ast::AssertionSet & assns, const ast::VariableExpr * assn ) {
1030	auto i = assns.find( assn );
1031	if ( i != assns.end() ) {
1032	i->second.isUsed = true;
1033	}
1034	}
1035
1036	/// mark all assertions in `type` used in both `assn1` and `assn2`
1037	static void markAssertions(
1038	ast::AssertionSet & assn1, ast::AssertionSet & assn2,
1039	const ast::FunctionType * type
1040	) {
1041	for ( auto & assert : type->assertions ) {
1042	markAssertionSet( assn1, assert );
1043	markAssertionSet( assn2, assert );
1044	}
1045	}
1046
1047	public:
1048	void postvisit( const ast::FunctionType * func ) {
1049	auto func2 = dynamic_cast< const ast::FunctionType * >( type2 );
1050	if ( ! func2 ) return;
1051
1052	if ( func->isVarArgs != func2->isVarArgs ) return;
1053
1054	// Flatten the parameter lists for both functions so that tuple structure does not
1055	// affect unification. Does not actually mutate function parameters.
1056	auto params = flattenList( func->params, tenv );
1057	auto params2 = flattenList( func2->params, tenv );
1058
1059	// sizes don't have to match if ttypes are involved; need to be more precise w.r.t.
1060	// where the ttype is to prevent errors
1061	if (
1062	( params.size() != params2.size() \|\| func->returns.size() != func2->returns.size() )
1063	&& ! func->isTtype()
1064	&& ! func2->isTtype()
1065	) return;
1066
1067	if ( ! unifyTypeList( params, params2, tenv, need, have, open ) ) return;
1068	if ( ! unifyTypeList(
1069	func->returns, func2->returns, tenv, need, have, open ) ) return;
1070
1071	markAssertions( have, need, func );
1072	markAssertions( have, need, func2 );
1073
1074	result = true;
1075	}
1076
1077	private:
1078	// Returns: other, cast as XInstType
1079	// Assigns this->result: whether types are compatible (up to generic parameters)
1080	template< typename XInstType >
1081	const XInstType * handleRefType( const XInstType * inst, const ast::Type * other ) {
1082	// check that the other type is compatible and named the same
1083	auto otherInst = dynamic_cast< const XInstType * >( other );
1084	if (otherInst && inst->name == otherInst->name)
1085	this->result = otherInst;
1086	return otherInst;
1087	}
1088
1089	/// Creates a tuple type based on a list of TypeExpr
1090	template< typename Iter >
1091	static const ast::Type * tupleFromExprs(
1092	const ast::TypeExpr * param, Iter & crnt, Iter end, ast::CV::Qualifiers qs
1093	) {
1094	std::vector< ast::ptr< ast::Type > > types;
1095	do {
1096	types.emplace_back( param->type );
1097
1098	++crnt;
1099	if ( crnt == end ) break;
1100	param = strict_dynamic_cast< const ast::TypeExpr * >( crnt->get() );
1101	} while(true);
1102
1103	return new ast::TupleType{ std::move(types), qs };
1104	}
1105
1106	template< typename XInstType >
1107	void handleGenericRefType( const XInstType * inst, const ast::Type * other ) {
1108	// check that other type is compatible and named the same
1109	const XInstType * otherInst = handleRefType( inst, other );
1110	if ( ! this->result ) return;
1111
1112	// check that parameters of types unify, if any
1113	const std::vector< ast::ptr< ast::Expr > > & params = inst->params;
1114	const std::vector< ast::ptr< ast::Expr > > & params2 = otherInst->params;
1115
1116	auto it = params.begin();
1117	auto jt = params2.begin();
1118	for ( ; it != params.end() && jt != params2.end(); ++it, ++jt ) {
1119	auto param = strict_dynamic_cast< const ast::TypeExpr * >( it->get() );
1120	auto param2 = strict_dynamic_cast< const ast::TypeExpr * >( jt->get() );
1121
1122	ast::ptr< ast::Type > pty = param->type;
1123	ast::ptr< ast::Type > pty2 = param2->type;
1124
1125	bool isTuple = Tuples::isTtype( pty );
1126	bool isTuple2 = Tuples::isTtype( pty2 );
1127
1128	if ( isTuple && isTuple2 ) {
1129	++it; ++jt; // skip ttype parameters before break
1130	} else if ( isTuple ) {
1131	// bundle remaining params into tuple
1132	pty2 = tupleFromExprs( param2, jt, params2.end(), pty->qualifiers );
1133	++it; // skip ttype parameter for break
1134	} else if ( isTuple2 ) {
1135	// bundle remaining params into tuple
1136	pty = tupleFromExprs( param, it, params.end(), pty2->qualifiers );
1137	++jt; // skip ttype parameter for break
1138	}
1139
1140	if ( ! unifyExact(
1141	pty, pty2, tenv, need, have, open, noWiden() ) ) {
1142	result = false;
1143	return;
1144	}
1145
1146	// ttype parameter should be last
1147	if ( isTuple \|\| isTuple2 ) break;
1148	}
1149	result = it == params.end() && jt == params2.end();
1150	}
1151
1152	public:
1153	void postvisit( const ast::StructInstType * aggrType ) {
1154	handleGenericRefType( aggrType, type2 );
1155	}
1156
1157	void postvisit( const ast::UnionInstType * aggrType ) {
1158	handleGenericRefType( aggrType, type2 );
1159	}
1160
1161	void postvisit( const ast::EnumInstType * aggrType ) {
1162	handleRefType( aggrType, type2 );
1163	}
1164
1165	void postvisit( const ast::TraitInstType * aggrType ) {
1166	handleRefType( aggrType, type2 );
1167	}
1168
1169	void postvisit( const ast::TypeInstType * typeInst ) {
1170	// assert( open.find( *typeInst ) == open.end() );
1171	auto otherInst = dynamic_cast< const ast::TypeInstType * >( type2 );
1172	if (otherInst && typeInst->name == otherInst->name)
1173	this->result = otherInst;
1174	// return otherInst;
1175	}
1176
1177	private:
1178	/// Creates a tuple type based on a list of Type
1179
1180	static bool unifyList(
1181	const std::vector< ast::ptr< ast::Type > > & list1,
1182	const std::vector< ast::ptr< ast::Type > > & list2, ast::TypeEnvironment & env,
1183	ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open
1184	) {
1185	auto crnt1 = list1.begin();
1186	auto crnt2 = list2.begin();
1187	while ( crnt1 != list1.end() && crnt2 != list2.end() ) {
1188	const ast::Type * t1 = *crnt1;
1189	const ast::Type * t2 = *crnt2;
1190	bool isTuple1 = Tuples::isTtype( t1 );
1191	bool isTuple2 = Tuples::isTtype( t2 );
1192
1193	// assumes ttype must be last parameter
1194	if ( isTuple1 && ! isTuple2 ) {
1195	// combine entirety of list2, then unify
1196	return unifyExact(
1197	t1, tupleFromTypes( list2 ), env, need, have, open,
1198	noWiden() );
1199	} else if ( ! isTuple1 && isTuple2 ) {
1200	// combine entirety of list1, then unify
1201	return unifyExact(
1202	tupleFromTypes( list1 ), t2, env, need, have, open,
1203	noWiden() );
1204	}
1205
1206	if ( ! unifyExact(
1207	t1, t2, env, need, have, open, noWiden() )
1208	) return false;
1209
1210	++crnt1; ++crnt2;
1211	}
1212
1213	if ( crnt1 != list1.end() ) {
1214	// try unifying empty tuple type with ttype
1215	const ast::Type * t1 = *crnt1;
1216	if ( ! Tuples::isTtype( t1 ) ) return false;
1217	// xxx - this doesn't generate an empty tuple, contrary to comment; both ported
1218	// from Rob's code
1219	return unifyExact(
1220	t1, tupleFromTypes( list2 ), env, need, have, open,
1221	noWiden() );
1222	} else if ( crnt2 != list2.end() ) {
1223	// try unifying empty tuple with ttype
1224	const ast::Type * t2 = *crnt2;
1225	if ( ! Tuples::isTtype( t2 ) ) return false;
1226	// xxx - this doesn't generate an empty tuple, contrary to comment; both ported
1227	// from Rob's code
1228	return unifyExact(
1229	tupleFromTypes( list1 ), t2, env, need, have, open,
1230	noWiden() );
1231	}
1232
1233	return true;
1234	}
1235
1236	public:
1237	void postvisit( const ast::TupleType * tuple ) {
1238	auto tuple2 = dynamic_cast< const ast::TupleType * >( type2 );
1239	if ( ! tuple2 ) return;
1240
1241	ast::Pass<TtypeExpander_new> expander{ tenv };
1242
1243	const ast::Type * flat = tuple->accept( expander );
1244	const ast::Type * flat2 = tuple2->accept( expander );
1245
1246	auto types = flatten( flat );
1247	auto types2 = flatten( flat2 );
1248
1249	result = unifyList( types, types2, tenv, need, have, open );
1250	}
1251
1252	void postvisit( const ast::VarArgsType * ) {
1253	result = dynamic_cast< const ast::VarArgsType * >( type2 );
1254	}
1255
1256	void postvisit( const ast::ZeroType * ) {
1257	result = dynamic_cast< const ast::ZeroType * >( type2 );
1258	}
1259
1260	void postvisit( const ast::OneType * ) {
1261	result = dynamic_cast< const ast::OneType * >( type2 );
1262	}
1263
1264	private:
1265	template< typename RefType > void handleRefType( RefType inst, Type other );
1266	template< typename RefType > void handleGenericRefType( RefType inst, Type other );
1267	};
1268
1269	// size_t Unify_new::traceId = Stats::Heap::new_stacktrace_id("Unify_new");
1270	bool unify(
1271	const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
1272	ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
1273	ast::OpenVarSet & open
1274	) {
1275	ast::ptr<ast::Type> common;
1276	return unify( type1, type2, env, need, have, open, common );
1277	}
1278
1279	bool unify(
1280	const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
1281	ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
1282	ast::OpenVarSet & open, ast::ptr<ast::Type> & common
1283	) {
1284	ast::OpenVarSet closed;
1285	// findOpenVars( type1, open, closed, need, have, FirstClosed );
1286	findOpenVars( type2, open, closed, need, have, env, FirstOpen );
1287	return unifyInexact(
1288	type1, type2, env, need, have, open, WidenMode{ true, true }, common );
1289	}
1290
1291	bool unifyExact(
1292	const ast::Type * type1, const ast::Type * type2, ast::TypeEnvironment & env,
1293	ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
1294	WidenMode widen
1295	) {
1296	if ( type1->qualifiers != type2->qualifiers ) return false;
1297
1298	auto var1 = dynamic_cast< const ast::TypeInstType * >( type1 );
1299	auto var2 = dynamic_cast< const ast::TypeInstType * >( type2 );
1300	bool isopen1 = var1 && env.lookup(*var1);
1301	bool isopen2 = var2 && env.lookup(*var2);
1302
1303	if ( isopen1 && isopen2 ) {
1304	if ( var1->base->kind != var2->base->kind ) return false;
1305	return env.bindVarToVar(
1306	var1, var2, ast::TypeData{ var1->base->kind, var1->base->sized\|\|var2->base->sized }, need, have,
1307	open, widen );
1308	} else if ( isopen1 ) {
1309	return env.bindVar( var1, type2, ast::TypeData{var1->base}, need, have, open, widen );
1310	} else if ( isopen2 ) {
1311	return env.bindVar( var2, type1, ast::TypeData{var2->base}, need, have, open, widen );
1312	} else {
1313	return ast::Pass<Unify_new>::read(
1314	type1, type2, env, need, have, open, widen );
1315	}
1316	}
1317
1318	bool unifyInexact(
1319	const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
1320	ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
1321	const ast::OpenVarSet & open, WidenMode widen,
1322	ast::ptr<ast::Type> & common
1323	) {
1324	ast::CV::Qualifiers q1 = type1->qualifiers, q2 = type2->qualifiers;
1325
1326	// force t1 and t2 to be cloned if their qualifiers must be stripped, so that type1 and
1327	// type2 are left unchanged; calling convention forces type{1,2}->strong_ref >= 1
1328	ast::Type * t1 = shallowCopy(type1.get());
1329	ast::Type * t2 = shallowCopy(type2.get());
1330	t1->qualifiers = {};
1331	t2->qualifiers = {};
1332	ast::ptr< ast::Type > t1_(t1);
1333	ast::ptr< ast::Type > t2_(t2);
1334
1335	if ( unifyExact( t1, t2, env, need, have, open, widen ) ) {
1336	// if exact unification on unqualified types, try to merge qualifiers
1337	if ( q1 == q2 \|\| ( ( q1 > q2 \|\| widen.first ) && ( q2 > q1 \|\| widen.second ) ) ) {
1338	t1->qualifiers = q1 \| q2;
1339	common = t1;
1340	return true;
1341	} else {
1342	return false;
1343	}
1344
1345	} else if (( common = commonType( t1, t2, env, need, have, open, widen ))) {
1346	// no exact unification, but common type
1347	auto c = shallowCopy(common.get());
1348	c->qualifiers = q1 \| q2;
1349	common = c;
1350	return true;
1351	} else {
1352	return false;
1353	}
1354	}
1355
1356	ast::ptr<ast::Type> extractResultType( const ast::FunctionType * func ) {
1357	if ( func->returns.empty() ) return new ast::VoidType{};
1358	if ( func->returns.size() == 1 ) return func->returns[0];
1359
1360	std::vector<ast::ptr<ast::Type>> tys;
1361	for ( const auto & decl : func->returns ) {
1362	tys.emplace_back( decl );
1363	}
1364	return new ast::TupleType{ std::move(tys) };
1365	}
1366	} // namespace ResolvExpr
1367
1368	// Local Variables: //
1369	// tab-width: 4 //
1370	// mode: c++ //
1371	// compile-command: "make install" //
1372	// End: //

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