source: src/ResolvExpr/Unify.cc@ 7329b0a

Last change on this file since 7329b0a was 2908f08, checked in by Andrew Beach <ajbeach@…>, 2 years ago

Most of ResolvExpr was written before the new style standard. Some files updated, focus on headers.
  • Property mode set to 100644
File size: 23.6 KB
Line 
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 "CommonType.hpp" // for commonType
36#include "FindOpenVars.h" // for findOpenVars
37#include "SpecCost.hpp" // for SpecCost
38#include "Tuples/Tuples.h" // for isTtype
39#include "typeops.h" // for flatten, occurs
40
41namespace ast {
42 class SymbolTable;
43}
44
45// #define DEBUG
46
47namespace ResolvExpr {
48
49 bool typesCompatible(
50 const ast::Type * first, const ast::Type * second,
51 const ast::TypeEnvironment & env ) {
52 ast::TypeEnvironment newEnv;
53 ast::OpenVarSet open, closed;
54 ast::AssertionSet need, have;
55
56 ast::ptr<ast::Type> newFirst{ first }, newSecond{ second };
57 env.apply( newFirst );
58 env.apply( newSecond );
59
60 // findOpenVars( newFirst, open, closed, need, have, FirstClosed );
61 findOpenVars( newSecond, open, closed, need, have, newEnv, FirstOpen );
62
63 return unifyExact(newFirst, newSecond, newEnv, need, have, open, noWiden() );
64 }
65
66 bool typesCompatibleIgnoreQualifiers(
67 const ast::Type * first, const ast::Type * second,
68 const ast::TypeEnvironment & env ) {
69 ast::TypeEnvironment newEnv;
70 ast::OpenVarSet open;
71 ast::AssertionSet need, have;
72
73 ast::Type * newFirst = shallowCopy( first );
74 ast::Type * newSecond = shallowCopy( second );
75 if ( auto temp = dynamic_cast<const ast::EnumInstType *>(first) ) {
76 if ( !dynamic_cast< const ast::EnumInstType * >( second ) ) {
77 const ast::EnumDecl * baseEnum = dynamic_cast<const ast::EnumDecl *>(temp->base.get());
78 if ( auto t = baseEnum->base.get() ) {
79 newFirst = ast::shallowCopy( t );
80 }
81 }
82 } else if ( auto temp = dynamic_cast<const ast::EnumInstType *>(second) ) {
83 const ast::EnumDecl * baseEnum = dynamic_cast<const ast::EnumDecl *>(temp->base.get());
84 if ( auto t = baseEnum->base.get() ) {
85 newSecond = ast::shallowCopy( t );
86 }
87 }
88
89 newFirst ->qualifiers = {};
90 newSecond->qualifiers = {};
91 ast::ptr< ast::Type > t1_(newFirst );
92 ast::ptr< ast::Type > t2_(newSecond);
93
94 ast::ptr< ast::Type > subFirst = env.apply(newFirst).node;
95 ast::ptr< ast::Type > subSecond = env.apply(newSecond).node;
96
97 return unifyExact(
98 subFirst,
99 subSecond,
100 newEnv, need, have, open, noWiden() );
101 }
102
103 namespace {
104 /// Replaces ttype variables with their bound types.
105 /// If this isn't done when satifying ttype assertions, then argument lists can have
106 /// different size and structure when they should be compatible.
107 struct TtypeExpander : public ast::WithShortCircuiting, public ast::PureVisitor {
108 ast::TypeEnvironment & tenv;
109
110 TtypeExpander( ast::TypeEnvironment & env ) : tenv( env ) {}
111
112 const ast::Type * postvisit( const ast::TypeInstType * typeInst ) {
113 if ( const ast::EqvClass * clz = tenv.lookup( *typeInst ) ) {
114 // expand ttype parameter into its actual type
115 if ( clz->data.kind == ast::TypeDecl::Ttype && clz->bound ) {
116 return clz->bound;
117 }
118 }
119 return typeInst;
120 }
121 };
122 }
123
124 std::vector< ast::ptr< ast::Type > > flattenList(
125 const std::vector< ast::ptr< ast::Type > > & src, ast::TypeEnvironment & env
126 ) {
127 std::vector< ast::ptr< ast::Type > > dst;
128 dst.reserve( src.size() );
129 for ( const auto & d : src ) {
130 ast::Pass<TtypeExpander> expander{ env };
131 // TtypeExpander pass is impure (may mutate nodes in place)
132 // need to make nodes shared to prevent accidental mutation
133 ast::ptr<ast::Type> dc = d->accept(expander);
134 auto types = flatten( dc );
135 for ( ast::ptr< ast::Type > & t : types ) {
136 // outermost const, volatile, _Atomic qualifiers in parameters should not play
137 // a role in the unification of function types, since they do not determine
138 // whether a function is callable.
139 // NOTE: **must** consider at least mutex qualifier, since functions can be
140 // overloaded on outermost mutex and a mutex function has different
141 // requirements than a non-mutex function
142 remove_qualifiers( t, ast::CV::Const | ast::CV::Volatile | ast::CV::Atomic );
143 dst.emplace_back( t );
144 }
145 }
146 return dst;
147 }
148
149 // Unification of Expressions
150 //
151 // Boolean outcome (obvious): Are they basically spelled the same?
152 // Side effect of binding variables (subtle): if `sizeof(int)` ===_expr `sizeof(T)` then `int` ===_ty `T`
153 //
154 // Context: if `float[VAREXPR1]` ===_ty `float[VAREXPR2]` then `VAREXPR1` ===_expr `VAREXPR2`
155 // where the VAREXPR are meant as notational metavariables representing the fact that unification always
156 // sees distinct ast::VariableExpr objects at these positions
157
158 static bool unify( const ast::Expr * e1, const ast::Expr * e2, ast::TypeEnvironment & env,
159 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
160 WidenMode widen );
161
162 class UnifyExpr final : public ast::WithShortCircuiting {
163 const ast::Expr * e2;
164 ast::TypeEnvironment & tenv;
165 ast::AssertionSet & need;
166 ast::AssertionSet & have;
167 const ast::OpenVarSet & open;
168 WidenMode widen;
169 public:
170 bool result;
171
172 private:
173
174 void tryMatchOnStaticValue( const ast::Expr * e1 ) {
175 Evaluation r1 = eval(e1);
176 Evaluation r2 = eval(e2);
177
178 if ( ! r1.hasKnownValue ) return;
179 if ( ! r2.hasKnownValue ) return;
180
181 if (r1.knownValue != r2.knownValue) return;
182
183 visit_children = false;
184 result = true;
185 }
186
187 public:
188
189 void previsit( const ast::Node * ) { assert(false); }
190
191 void previsit( const ast::Expr * e1 ) {
192 tryMatchOnStaticValue( e1 );
193 visit_children = false;
194 }
195
196 void previsit( const ast::CastExpr * e1 ) {
197 tryMatchOnStaticValue( e1 );
198
199 if (result) {
200 assert (visit_children == false);
201 } else {
202 assert (visit_children == true);
203 visit_children = false;
204
205 auto e2c = dynamic_cast< const ast::CastExpr * >( e2 );
206 if ( ! e2c ) return;
207
208 // inspect casts' target types
209 if ( ! unifyExact(
210 e1->result, e2c->result, tenv, need, have, open, widen ) ) return;
211
212 // inspect casts' inner expressions
213 result = unify( e1->arg, e2c->arg, tenv, need, have, open, widen );
214 }
215 }
216
217 void previsit( const ast::VariableExpr * e1 ) {
218 tryMatchOnStaticValue( e1 );
219
220 if (result) {
221 assert (visit_children == false);
222 } else {
223 assert (visit_children == true);
224 visit_children = false;
225
226 auto e2v = dynamic_cast< const ast::VariableExpr * >( e2 );
227 if ( ! e2v ) return;
228
229 assert(e1->var);
230 assert(e2v->var);
231
232 // conservative: variable exprs match if their declarations are represented by the same C++ AST object
233 result = (e1->var == e2v->var);
234 }
235 }
236
237 void previsit( const ast::SizeofExpr * e1 ) {
238 tryMatchOnStaticValue( e1 );
239
240 if (result) {
241 assert (visit_children == false);
242 } else {
243 assert (visit_children == true);
244 visit_children = false;
245
246 auto e2so = dynamic_cast< const ast::SizeofExpr * >( e2 );
247 if ( ! e2so ) return;
248
249 assert((e1->type != nullptr) ^ (e1->expr != nullptr));
250 assert((e2so->type != nullptr) ^ (e2so->expr != nullptr));
251 if ( ! (e1->type && e2so->type) ) return;
252
253 // expression unification calls type unification (mutual recursion)
254 result = unifyExact( e1->type, e2so->type, tenv, need, have, open, widen );
255 }
256 }
257
258 UnifyExpr( const ast::Expr * e2, ast::TypeEnvironment & env, ast::AssertionSet & need,
259 ast::AssertionSet & have, const ast::OpenVarSet & open, WidenMode widen )
260 : e2( e2 ), tenv(env), need(need), have(have), open(open), widen(widen), result(false) {}
261 };
262
263 static bool unify( const ast::Expr * e1, const ast::Expr * e2, ast::TypeEnvironment & env,
264 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
265 WidenMode widen ) {
266 assert( e1 && e2 );
267 return ast::Pass<UnifyExpr>::read( e1, e2, env, need, have, open, widen );
268 }
269
270 class Unify final : public ast::WithShortCircuiting {
271 const ast::Type * type2;
272 ast::TypeEnvironment & tenv;
273 ast::AssertionSet & need;
274 ast::AssertionSet & have;
275 const ast::OpenVarSet & open;
276 WidenMode widen;
277 public:
278 static size_t traceId;
279 bool result;
280
281 Unify(
282 const ast::Type * type2, ast::TypeEnvironment & env, ast::AssertionSet & need,
283 ast::AssertionSet & have, const ast::OpenVarSet & open, WidenMode widen )
284 : type2(type2), tenv(env), need(need), have(have), open(open), widen(widen),
285 result(false) {}
286
287 void previsit( const ast::Node * ) { visit_children = false; }
288
289 void postvisit( const ast::VoidType * ) {
290 result = dynamic_cast< const ast::VoidType * >( type2 );
291 }
292
293 void postvisit( const ast::BasicType * basic ) {
294 if ( auto basic2 = dynamic_cast< const ast::BasicType * >( type2 ) ) {
295 result = basic->kind == basic2->kind;
296 }
297 }
298
299 void postvisit( const ast::PointerType * pointer ) {
300 if ( auto pointer2 = dynamic_cast< const ast::PointerType * >( type2 ) ) {
301 result = unifyExact(
302 pointer->base, pointer2->base, tenv, need, have, open,
303 noWiden());
304 }
305 }
306
307 void postvisit( const ast::ArrayType * array ) {
308 auto array2 = dynamic_cast< const ast::ArrayType * >( type2 );
309 if ( ! array2 ) return;
310
311 if ( array->isVarLen != array2->isVarLen ) return;
312 if ( (array->dimension != nullptr) != (array2->dimension != nullptr) ) return;
313
314 if ( array->dimension ) {
315 assert( array2->dimension );
316 // type unification calls expression unification (mutual recursion)
317 if ( ! unify(array->dimension, array2->dimension,
318 tenv, need, have, open, widen) ) return;
319 }
320
321 result = unifyExact(
322 array->base, array2->base, tenv, need, have, open, noWiden());
323 }
324
325 void postvisit( const ast::ReferenceType * ref ) {
326 if ( auto ref2 = dynamic_cast< const ast::ReferenceType * >( type2 ) ) {
327 result = unifyExact(
328 ref->base, ref2->base, tenv, need, have, open, noWiden());
329 }
330 }
331
332 private:
333
334 template< typename Iter >
335 static bool unifyTypeList(
336 Iter crnt1, Iter end1, Iter crnt2, Iter end2, ast::TypeEnvironment & env,
337 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open
338 ) {
339 while ( crnt1 != end1 && crnt2 != end2 ) {
340 const ast::Type * t1 = *crnt1;
341 const ast::Type * t2 = *crnt2;
342 bool isTuple1 = Tuples::isTtype( t1 );
343 bool isTuple2 = Tuples::isTtype( t2 );
344
345 // assumes here that ttype *must* be last parameter
346 if ( isTuple1 && ! isTuple2 ) {
347 // combine remainder of list2, then unify
348 return unifyExact(
349 t1, tupleFromTypes( crnt2, end2 ), env, need, have, open,
350 noWiden() );
351 } else if ( ! isTuple1 && isTuple2 ) {
352 // combine remainder of list1, then unify
353 return unifyExact(
354 tupleFromTypes( crnt1, end1 ), t2, env, need, have, open,
355 noWiden() );
356 }
357
358 if ( ! unifyExact(
359 t1, t2, env, need, have, open, noWiden() )
360 ) return false;
361
362 ++crnt1; ++crnt2;
363 }
364
365 // May get to the end of one argument list before the other. This is only okay if the
366 // other is a ttype
367 if ( crnt1 != end1 ) {
368 // try unifying empty tuple with ttype
369 const ast::Type * t1 = *crnt1;
370 if ( ! Tuples::isTtype( t1 ) ) return false;
371 return unifyExact(
372 t1, tupleFromTypes( crnt2, end2 ), env, need, have, open,
373 noWiden() );
374 } else if ( crnt2 != end2 ) {
375 // try unifying empty tuple with ttype
376 const ast::Type * t2 = *crnt2;
377 if ( ! Tuples::isTtype( t2 ) ) return false;
378 return unifyExact(
379 tupleFromTypes( crnt1, end1 ), t2, env, need, have, open,
380 noWiden() );
381 }
382
383 return true;
384 }
385
386 static bool unifyTypeList(
387 const std::vector< ast::ptr< ast::Type > > & list1,
388 const std::vector< ast::ptr< ast::Type > > & list2,
389 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
390 const ast::OpenVarSet & open
391 ) {
392 return unifyTypeList(
393 list1.begin(), list1.end(), list2.begin(), list2.end(), env, need, have, open);
394 }
395
396 static void markAssertionSet( ast::AssertionSet & assns, const ast::VariableExpr * assn ) {
397 auto i = assns.find( assn );
398 if ( i != assns.end() ) {
399 i->second.isUsed = true;
400 }
401 }
402
403 /// mark all assertions in `type` used in both `assn1` and `assn2`
404 static void markAssertions(
405 ast::AssertionSet & assn1, ast::AssertionSet & assn2,
406 const ast::FunctionType * type
407 ) {
408 for ( auto & assert : type->assertions ) {
409 markAssertionSet( assn1, assert );
410 markAssertionSet( assn2, assert );
411 }
412 }
413
414 public:
415 void postvisit( const ast::FunctionType * func ) {
416 auto func2 = dynamic_cast< const ast::FunctionType * >( type2 );
417 if ( ! func2 ) return;
418
419 if ( func->isVarArgs != func2->isVarArgs ) return;
420
421 // Flatten the parameter lists for both functions so that tuple structure does not
422 // affect unification. Does not actually mutate function parameters.
423 auto params = flattenList( func->params, tenv );
424 auto params2 = flattenList( func2->params, tenv );
425
426 // sizes don't have to match if ttypes are involved; need to be more precise w.r.t.
427 // where the ttype is to prevent errors
428 if (
429 ( params.size() != params2.size() || func->returns.size() != func2->returns.size() )
430 && ! func->isTtype()
431 && ! func2->isTtype()
432 ) return;
433
434 if ( ! unifyTypeList( params, params2, tenv, need, have, open ) ) return;
435 if ( ! unifyTypeList(
436 func->returns, func2->returns, tenv, need, have, open ) ) return;
437
438 markAssertions( have, need, func );
439 markAssertions( have, need, func2 );
440
441 result = true;
442 }
443
444 private:
445 // Returns: other, cast as XInstType
446 // Assigns this->result: whether types are compatible (up to generic parameters)
447 template< typename XInstType >
448 const XInstType * handleRefType( const XInstType * inst, const ast::Type * other ) {
449 // check that the other type is compatible and named the same
450 auto otherInst = dynamic_cast< const XInstType * >( other );
451 if (otherInst && inst->name == otherInst->name)
452 this->result = otherInst;
453 return otherInst;
454 }
455
456 /// Creates a tuple type based on a list of TypeExpr
457 template< typename Iter >
458 static const ast::Type * tupleFromExprs(
459 const ast::TypeExpr * param, Iter & crnt, Iter end, ast::CV::Qualifiers qs
460 ) {
461 std::vector< ast::ptr< ast::Type > > types;
462 do {
463 types.emplace_back( param->type );
464
465 ++crnt;
466 if ( crnt == end ) break;
467 param = strict_dynamic_cast< const ast::TypeExpr * >( crnt->get() );
468 } while(true);
469
470 return new ast::TupleType{ std::move(types), qs };
471 }
472
473 template< typename XInstType >
474 void handleGenericRefType( const XInstType * inst, const ast::Type * other ) {
475 // check that other type is compatible and named the same
476 const XInstType * otherInst = handleRefType( inst, other );
477 if ( ! this->result ) return;
478
479 // check that parameters of types unify, if any
480 const std::vector< ast::ptr< ast::Expr > > & params = inst->params;
481 const std::vector< ast::ptr< ast::Expr > > & params2 = otherInst->params;
482
483 auto it = params.begin();
484 auto jt = params2.begin();
485 for ( ; it != params.end() && jt != params2.end(); ++it, ++jt ) {
486 auto param = strict_dynamic_cast< const ast::TypeExpr * >( it->get() );
487 auto param2 = strict_dynamic_cast< const ast::TypeExpr * >( jt->get() );
488
489 ast::ptr< ast::Type > pty = param->type;
490 ast::ptr< ast::Type > pty2 = param2->type;
491
492 bool isTuple = Tuples::isTtype( pty );
493 bool isTuple2 = Tuples::isTtype( pty2 );
494
495 if ( isTuple && isTuple2 ) {
496 ++it; ++jt; // skip ttype parameters before break
497 } else if ( isTuple ) {
498 // bundle remaining params into tuple
499 pty2 = tupleFromExprs( param2, jt, params2.end(), pty->qualifiers );
500 ++it; // skip ttype parameter for break
501 } else if ( isTuple2 ) {
502 // bundle remaining params into tuple
503 pty = tupleFromExprs( param, it, params.end(), pty2->qualifiers );
504 ++jt; // skip ttype parameter for break
505 }
506
507 if ( ! unifyExact(
508 pty, pty2, tenv, need, have, open, noWiden() ) ) {
509 result = false;
510 return;
511 }
512
513 // ttype parameter should be last
514 if ( isTuple || isTuple2 ) break;
515 }
516 result = it == params.end() && jt == params2.end();
517 }
518
519 public:
520 void postvisit( const ast::StructInstType * aggrType ) {
521 handleGenericRefType( aggrType, type2 );
522 }
523
524 void postvisit( const ast::UnionInstType * aggrType ) {
525 handleGenericRefType( aggrType, type2 );
526 }
527
528 void postvisit( const ast::EnumInstType * aggrType ) {
529 handleRefType( aggrType, type2 );
530 }
531
532 void postvisit( const ast::TraitInstType * aggrType ) {
533 handleRefType( aggrType, type2 );
534 }
535
536 void postvisit( const ast::TypeInstType * typeInst ) {
537 // assert( open.find( *typeInst ) == open.end() );
538 auto otherInst = dynamic_cast< const ast::TypeInstType * >( type2 );
539 if ( otherInst && typeInst->name == otherInst->name ) {
540 this->result = otherInst;
541 }
542 }
543
544 private:
545 /// Creates a tuple type based on a list of Type
546
547 static bool unifyList(
548 const std::vector< ast::ptr< ast::Type > > & list1,
549 const std::vector< ast::ptr< ast::Type > > & list2, ast::TypeEnvironment & env,
550 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open
551 ) {
552 auto crnt1 = list1.begin();
553 auto crnt2 = list2.begin();
554 while ( crnt1 != list1.end() && crnt2 != list2.end() ) {
555 const ast::Type * t1 = *crnt1;
556 const ast::Type * t2 = *crnt2;
557 bool isTuple1 = Tuples::isTtype( t1 );
558 bool isTuple2 = Tuples::isTtype( t2 );
559
560 // assumes ttype must be last parameter
561 if ( isTuple1 && ! isTuple2 ) {
562 // combine entirety of list2, then unify
563 return unifyExact(
564 t1, tupleFromTypes( list2 ), env, need, have, open,
565 noWiden() );
566 } else if ( ! isTuple1 && isTuple2 ) {
567 // combine entirety of list1, then unify
568 return unifyExact(
569 tupleFromTypes( list1 ), t2, env, need, have, open,
570 noWiden() );
571 }
572
573 if ( ! unifyExact(
574 t1, t2, env, need, have, open, noWiden() )
575 ) return false;
576
577 ++crnt1; ++crnt2;
578 }
579
580 if ( crnt1 != list1.end() ) {
581 // try unifying empty tuple type with ttype
582 const ast::Type * t1 = *crnt1;
583 if ( ! Tuples::isTtype( t1 ) ) return false;
584 // xxx - this doesn't generate an empty tuple, contrary to comment; both ported
585 // from Rob's code
586 return unifyExact(
587 t1, tupleFromTypes( list2 ), env, need, have, open,
588 noWiden() );
589 } else if ( crnt2 != list2.end() ) {
590 // try unifying empty tuple with ttype
591 const ast::Type * t2 = *crnt2;
592 if ( ! Tuples::isTtype( t2 ) ) return false;
593 // xxx - this doesn't generate an empty tuple, contrary to comment; both ported
594 // from Rob's code
595 return unifyExact(
596 tupleFromTypes( list1 ), t2, env, need, have, open,
597 noWiden() );
598 }
599
600 return true;
601 }
602
603 public:
604 void postvisit( const ast::TupleType * tuple ) {
605 auto tuple2 = dynamic_cast< const ast::TupleType * >( type2 );
606 if ( ! tuple2 ) return;
607
608 ast::Pass<TtypeExpander> expander{ tenv };
609
610 const ast::Type * flat = tuple->accept( expander );
611 const ast::Type * flat2 = tuple2->accept( expander );
612
613 auto types = flatten( flat );
614 auto types2 = flatten( flat2 );
615
616 result = unifyList( types, types2, tenv, need, have, open );
617 }
618
619 void postvisit( const ast::VarArgsType * ) {
620 result = dynamic_cast< const ast::VarArgsType * >( type2 );
621 }
622
623 void postvisit( const ast::ZeroType * ) {
624 result = dynamic_cast< const ast::ZeroType * >( type2 );
625 }
626
627 void postvisit( const ast::OneType * ) {
628 result = dynamic_cast< const ast::OneType * >( type2 );
629 }
630 };
631
632 // size_t Unify::traceId = Stats::Heap::new_stacktrace_id("Unify");
633
634 bool unify(
635 const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
636 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
637 ast::OpenVarSet & open
638 ) {
639 ast::ptr<ast::Type> common;
640 return unify( type1, type2, env, need, have, open, common );
641 }
642
643 bool unify(
644 const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
645 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
646 ast::OpenVarSet & open, ast::ptr<ast::Type> & common
647 ) {
648 ast::OpenVarSet closed;
649 // findOpenVars( type1, open, closed, need, have, FirstClosed );
650 findOpenVars( type2, open, closed, need, have, env, FirstOpen );
651 return unifyInexact(
652 type1, type2, env, need, have, open, WidenMode{ true, true }, common );
653 }
654
655 bool unifyExact(
656 const ast::Type * type1, const ast::Type * type2, ast::TypeEnvironment & env,
657 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
658 WidenMode widen
659 ) {
660 if ( type1->qualifiers != type2->qualifiers ) return false;
661
662 auto var1 = dynamic_cast< const ast::TypeInstType * >( type1 );
663 auto var2 = dynamic_cast< const ast::TypeInstType * >( type2 );
664 bool isopen1 = var1 && env.lookup(*var1);
665 bool isopen2 = var2 && env.lookup(*var2);
666
667 if ( isopen1 && isopen2 ) {
668 if ( var1->base->kind != var2->base->kind ) return false;
669 return env.bindVarToVar(
670 var1, var2, ast::TypeData{ var1->base->kind, var1->base->sized||var2->base->sized }, need, have,
671 open, widen );
672 } else if ( isopen1 ) {
673 return env.bindVar( var1, type2, ast::TypeData{var1->base}, need, have, open, widen );
674 } else if ( isopen2 ) {
675 return env.bindVar( var2, type1, ast::TypeData{var2->base}, need, have, open, widen );
676 } else {
677 return ast::Pass<Unify>::read(
678 type1, type2, env, need, have, open, widen );
679 }
680 }
681
682 bool unifyInexact(
683 const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
684 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
685 const ast::OpenVarSet & open, WidenMode widen,
686 ast::ptr<ast::Type> & common
687 ) {
688 ast::CV::Qualifiers q1 = type1->qualifiers, q2 = type2->qualifiers;
689
690 // force t1 and t2 to be cloned if their qualifiers must be stripped, so that type1 and
691 // type2 are left unchanged; calling convention forces type{1,2}->strong_ref >= 1
692 ast::Type * t1 = shallowCopy(type1.get());
693 ast::Type * t2 = shallowCopy(type2.get());
694 t1->qualifiers = {};
695 t2->qualifiers = {};
696 ast::ptr< ast::Type > t1_(t1);
697 ast::ptr< ast::Type > t2_(t2);
698
699 if ( unifyExact( t1, t2, env, need, have, open, widen ) ) {
700 // if exact unification on unqualified types, try to merge qualifiers
701 if ( q1 == q2 || ( ( q1 > q2 || widen.first ) && ( q2 > q1 || widen.second ) ) ) {
702 t1->qualifiers = q1 | q2;
703 common = t1;
704 return true;
705 } else {
706 return false;
707 }
708
709 } else if (( common = commonType( t1, t2, env, need, have, open, widen ))) {
710 // no exact unification, but common type
711 auto c = shallowCopy(common.get());
712 c->qualifiers = q1 | q2;
713 common = c;
714 return true;
715 } else {
716 return false;
717 }
718 }
719
720 ast::ptr<ast::Type> extractResultType( const ast::FunctionType * func ) {
721 if ( func->returns.empty() ) return new ast::VoidType{};
722 if ( func->returns.size() == 1 ) return func->returns[0];
723
724 std::vector<ast::ptr<ast::Type>> tys;
725 for ( const auto & decl : func->returns ) {
726 tys.emplace_back( decl );
727 }
728 return new ast::TupleType{ std::move(tys) };
729 }
730} // namespace ResolvExpr
731
732// Local Variables: //
733// tab-width: 4 //
734// mode: c++ //
735// compile-command: "make install" //
736// End: //
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