source: src/ResolvExpr/Unify.cc@ e048ece

Last change on this file since e048ece was 06601401, checked in by JiadaL <j82liang@…>, 20 months ago

Change the common type interpretation of EnumPos
  • Property mode set to 100644
File size: 23.3 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
76 newFirst ->qualifiers = {};
77 newSecond->qualifiers = {};
78 ast::ptr< ast::Type > t1_(newFirst );
79 ast::ptr< ast::Type > t2_(newSecond);
80
81 ast::ptr< ast::Type > subFirst = env.apply(newFirst).node;
82 ast::ptr< ast::Type > subSecond = env.apply(newSecond).node;
83
84 return unifyExact(
85 subFirst,
86 subSecond,
87 newEnv, need, have, open, noWiden() );
88 }
89
90 namespace {
91 /// Replaces ttype variables with their bound types.
92 /// If this isn't done when satifying ttype assertions, then argument lists can have
93 /// different size and structure when they should be compatible.
94 struct TtypeExpander : public ast::WithShortCircuiting, public ast::PureVisitor {
95 ast::TypeEnvironment & tenv;
96
97 TtypeExpander( ast::TypeEnvironment & env ) : tenv( env ) {}
98
99 const ast::Type * postvisit( const ast::TypeInstType * typeInst ) {
100 if ( const ast::EqvClass * clz = tenv.lookup( *typeInst ) ) {
101 // expand ttype parameter into its actual type
102 if ( clz->data.kind == ast::TypeDecl::Ttype && clz->bound ) {
103 return clz->bound;
104 }
105 }
106 return typeInst;
107 }
108 };
109 }
110
111 std::vector< ast::ptr< ast::Type > > flattenList(
112 const std::vector< ast::ptr< ast::Type > > & src, ast::TypeEnvironment & env
113 ) {
114 std::vector< ast::ptr< ast::Type > > dst;
115 dst.reserve( src.size() );
116 for ( const auto & d : src ) {
117 ast::Pass<TtypeExpander> expander{ env };
118 // TtypeExpander pass is impure (may mutate nodes in place)
119 // need to make nodes shared to prevent accidental mutation
120 ast::ptr<ast::Type> dc = d->accept(expander);
121 auto types = flatten( dc );
122 for ( ast::ptr< ast::Type > & t : types ) {
123 // outermost const, volatile, _Atomic qualifiers in parameters should not play
124 // a role in the unification of function types, since they do not determine
125 // whether a function is callable.
126 // NOTE: **must** consider at least mutex qualifier, since functions can be
127 // overloaded on outermost mutex and a mutex function has different
128 // requirements than a non-mutex function
129 remove_qualifiers( t, ast::CV::Const | ast::CV::Volatile | ast::CV::Atomic );
130 dst.emplace_back( t );
131 }
132 }
133 return dst;
134 }
135
136 // Unification of Expressions
137 //
138 // Boolean outcome (obvious): Are they basically spelled the same?
139 // Side effect of binding variables (subtle): if `sizeof(int)` ===_expr `sizeof(T)` then `int` ===_ty `T`
140 //
141 // Context: if `float[VAREXPR1]` ===_ty `float[VAREXPR2]` then `VAREXPR1` ===_expr `VAREXPR2`
142 // where the VAREXPR are meant as notational metavariables representing the fact that unification always
143 // sees distinct ast::VariableExpr objects at these positions
144
145 static bool unify( const ast::Expr * e1, const ast::Expr * e2, ast::TypeEnvironment & env,
146 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
147 WidenMode widen );
148
149 class UnifyExpr final : public ast::WithShortCircuiting {
150 const ast::Expr * e2;
151 ast::TypeEnvironment & tenv;
152 ast::AssertionSet & need;
153 ast::AssertionSet & have;
154 const ast::OpenVarSet & open;
155 WidenMode widen;
156 public:
157 bool result;
158
159 private:
160
161 void tryMatchOnStaticValue( const ast::Expr * e1 ) {
162 Evaluation r1 = eval(e1);
163 Evaluation r2 = eval(e2);
164
165 if ( ! r1.hasKnownValue ) return;
166 if ( ! r2.hasKnownValue ) return;
167
168 if (r1.knownValue != r2.knownValue) return;
169
170 visit_children = false;
171 result = true;
172 }
173
174 public:
175
176 void previsit( const ast::Node * ) { assert(false); }
177
178 void previsit( const ast::Expr * e1 ) {
179 tryMatchOnStaticValue( e1 );
180 visit_children = false;
181 }
182
183 void previsit( const ast::CastExpr * e1 ) {
184 tryMatchOnStaticValue( e1 );
185
186 if (result) {
187 assert (visit_children == false);
188 } else {
189 assert (visit_children == true);
190 visit_children = false;
191
192 auto e2c = dynamic_cast< const ast::CastExpr * >( e2 );
193 if ( ! e2c ) return;
194
195 // inspect casts' target types
196 if ( ! unifyExact(
197 e1->result, e2c->result, tenv, need, have, open, widen ) ) return;
198
199 // inspect casts' inner expressions
200 result = unify( e1->arg, e2c->arg, tenv, need, have, open, widen );
201 }
202 }
203
204 void previsit( const ast::VariableExpr * e1 ) {
205 tryMatchOnStaticValue( e1 );
206
207 if (result) {
208 assert (visit_children == false);
209 } else {
210 assert (visit_children == true);
211 visit_children = false;
212
213 auto e2v = dynamic_cast< const ast::VariableExpr * >( e2 );
214 if ( ! e2v ) return;
215
216 assert(e1->var);
217 assert(e2v->var);
218
219 // conservative: variable exprs match if their declarations are represented by the same C++ AST object
220 result = (e1->var == e2v->var);
221 }
222 }
223
224 void previsit( const ast::SizeofExpr * e1 ) {
225 tryMatchOnStaticValue( e1 );
226
227 if (result) {
228 assert (visit_children == false);
229 } else {
230 assert (visit_children == true);
231 visit_children = false;
232
233 auto e2so = dynamic_cast< const ast::SizeofExpr * >( e2 );
234 if ( ! e2so ) return;
235
236 assert((e1->type != nullptr) ^ (e1->expr != nullptr));
237 assert((e2so->type != nullptr) ^ (e2so->expr != nullptr));
238 if ( ! (e1->type && e2so->type) ) return;
239
240 // expression unification calls type unification (mutual recursion)
241 result = unifyExact( e1->type, e2so->type, tenv, need, have, open, widen );
242 }
243 }
244
245 UnifyExpr( const ast::Expr * e2, ast::TypeEnvironment & env, ast::AssertionSet & need,
246 ast::AssertionSet & have, const ast::OpenVarSet & open, WidenMode widen )
247 : e2( e2 ), tenv(env), need(need), have(have), open(open), widen(widen), result(false) {}
248 };
249
250 static bool unify( const ast::Expr * e1, const ast::Expr * e2, ast::TypeEnvironment & env,
251 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
252 WidenMode widen ) {
253 assert( e1 && e2 );
254 return ast::Pass<UnifyExpr>::read( e1, e2, env, need, have, open, widen );
255 }
256
257 class Unify final : public ast::WithShortCircuiting {
258 const ast::Type * type2;
259 ast::TypeEnvironment & tenv;
260 ast::AssertionSet & need;
261 ast::AssertionSet & have;
262 const ast::OpenVarSet & open;
263 WidenMode widen;
264 public:
265 static size_t traceId;
266 bool result;
267
268 Unify(
269 const ast::Type * type2, ast::TypeEnvironment & env, ast::AssertionSet & need,
270 ast::AssertionSet & have, const ast::OpenVarSet & open, WidenMode widen )
271 : type2(type2), tenv(env), need(need), have(have), open(open), widen(widen),
272 result(false) {}
273
274 void previsit( const ast::Node * ) { visit_children = false; }
275
276 void postvisit( const ast::VoidType * ) {
277 result = dynamic_cast< const ast::VoidType * >( type2 );
278 }
279
280 void postvisit( const ast::BasicType * basic ) {
281 if ( auto basic2 = dynamic_cast< const ast::BasicType * >( type2 ) ) {
282 result = basic->kind == basic2->kind;
283 }
284 }
285
286 void postvisit( const ast::PointerType * pointer ) {
287 if ( auto pointer2 = dynamic_cast< const ast::PointerType * >( type2 ) ) {
288 result = unifyExact(
289 pointer->base, pointer2->base, tenv, need, have, open,
290 noWiden());
291 }
292 }
293
294 void postvisit( const ast::ArrayType * array ) {
295 auto array2 = dynamic_cast< const ast::ArrayType * >( type2 );
296 if ( ! array2 ) return;
297
298 if ( array->isVarLen != array2->isVarLen ) return;
299 if ( (array->dimension != nullptr) != (array2->dimension != nullptr) ) return;
300
301 if ( array->dimension ) {
302 assert( array2->dimension );
303 // type unification calls expression unification (mutual recursion)
304 if ( ! unify(array->dimension, array2->dimension,
305 tenv, need, have, open, widen) ) return;
306 }
307
308 result = unifyExact(
309 array->base, array2->base, tenv, need, have, open, noWiden());
310 }
311
312 void postvisit( const ast::ReferenceType * ref ) {
313 if ( auto ref2 = dynamic_cast< const ast::ReferenceType * >( type2 ) ) {
314 result = unifyExact(
315 ref->base, ref2->base, tenv, need, have, open, noWiden());
316 }
317 }
318
319 private:
320
321 template< typename Iter >
322 static bool unifyTypeList(
323 Iter crnt1, Iter end1, Iter crnt2, Iter end2, ast::TypeEnvironment & env,
324 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open
325 ) {
326 while ( crnt1 != end1 && crnt2 != end2 ) {
327 const ast::Type * t1 = *crnt1;
328 const ast::Type * t2 = *crnt2;
329 bool isTuple1 = Tuples::isTtype( t1 );
330 bool isTuple2 = Tuples::isTtype( t2 );
331
332 // assumes here that ttype *must* be last parameter
333 if ( isTuple1 && ! isTuple2 ) {
334 // combine remainder of list2, then unify
335 return unifyExact(
336 t1, tupleFromTypes( crnt2, end2 ), env, need, have, open,
337 noWiden() );
338 } else if ( ! isTuple1 && isTuple2 ) {
339 // combine remainder of list1, then unify
340 return unifyExact(
341 tupleFromTypes( crnt1, end1 ), t2, env, need, have, open,
342 noWiden() );
343 }
344
345 if ( ! unifyExact(
346 t1, t2, env, need, have, open, noWiden() )
347 ) return false;
348
349 ++crnt1; ++crnt2;
350 }
351
352 // May get to the end of one argument list before the other. This is only okay if the
353 // other is a ttype
354 if ( crnt1 != end1 ) {
355 // try unifying empty tuple with ttype
356 const ast::Type * t1 = *crnt1;
357 if ( ! Tuples::isTtype( t1 ) ) return false;
358 return unifyExact(
359 t1, tupleFromTypes( crnt2, end2 ), env, need, have, open,
360 noWiden() );
361 } else if ( crnt2 != end2 ) {
362 // try unifying empty tuple with ttype
363 const ast::Type * t2 = *crnt2;
364 if ( ! Tuples::isTtype( t2 ) ) return false;
365 return unifyExact(
366 tupleFromTypes( crnt1, end1 ), t2, env, need, have, open,
367 noWiden() );
368 }
369
370 return true;
371 }
372
373 static bool unifyTypeList(
374 const std::vector< ast::ptr< ast::Type > > & list1,
375 const std::vector< ast::ptr< ast::Type > > & list2,
376 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
377 const ast::OpenVarSet & open
378 ) {
379 return unifyTypeList(
380 list1.begin(), list1.end(), list2.begin(), list2.end(), env, need, have, open);
381 }
382
383 static void markAssertionSet( ast::AssertionSet & assns, const ast::VariableExpr * assn ) {
384 auto i = assns.find( assn );
385 if ( i != assns.end() ) {
386 i->second.isUsed = true;
387 }
388 }
389
390 /// mark all assertions in `type` used in both `assn1` and `assn2`
391 static void markAssertions(
392 ast::AssertionSet & assn1, ast::AssertionSet & assn2,
393 const ast::FunctionType * type
394 ) {
395 for ( auto & assert : type->assertions ) {
396 markAssertionSet( assn1, assert );
397 markAssertionSet( assn2, assert );
398 }
399 }
400
401 public:
402 void postvisit( const ast::FunctionType * func ) {
403 auto func2 = dynamic_cast< const ast::FunctionType * >( type2 );
404 if ( ! func2 ) return;
405
406 if ( func->isVarArgs != func2->isVarArgs ) return;
407
408 // Flatten the parameter lists for both functions so that tuple structure does not
409 // affect unification. Does not actually mutate function parameters.
410 auto params = flattenList( func->params, tenv );
411 auto params2 = flattenList( func2->params, tenv );
412
413 // sizes don't have to match if ttypes are involved; need to be more precise w.r.t.
414 // where the ttype is to prevent errors
415 if (
416 ( params.size() != params2.size() || func->returns.size() != func2->returns.size() )
417 && ! func->isTtype()
418 && ! func2->isTtype()
419 ) return;
420
421 if ( ! unifyTypeList( params, params2, tenv, need, have, open ) ) return;
422 if ( ! unifyTypeList(
423 func->returns, func2->returns, tenv, need, have, open ) ) return;
424
425 markAssertions( have, need, func );
426 markAssertions( have, need, func2 );
427
428 result = true;
429 }
430
431 private:
432 // Returns: other, cast as XInstType
433 // Assigns this->result: whether types are compatible (up to generic parameters)
434 template< typename XInstType >
435 const XInstType * handleRefType( const XInstType * inst, const ast::Type * other ) {
436 // check that the other type is compatible and named the same
437 auto otherInst = dynamic_cast< const XInstType * >( other );
438 if (otherInst && inst->name == otherInst->name)
439 this->result = otherInst;
440 return otherInst;
441 }
442
443 /// Creates a tuple type based on a list of TypeExpr
444 template< typename Iter >
445 static const ast::Type * tupleFromExprs(
446 const ast::TypeExpr * param, Iter & crnt, Iter end, ast::CV::Qualifiers qs
447 ) {
448 std::vector< ast::ptr< ast::Type > > types;
449 do {
450 types.emplace_back( param->type );
451
452 ++crnt;
453 if ( crnt == end ) break;
454 param = strict_dynamic_cast< const ast::TypeExpr * >( crnt->get() );
455 } while(true);
456
457 return new ast::TupleType{ std::move(types), qs };
458 }
459
460 template< typename XInstType >
461 void handleGenericRefType( const XInstType * inst, const ast::Type * other ) {
462 // check that other type is compatible and named the same
463 const XInstType * otherInst = handleRefType( inst, other );
464 if ( ! this->result ) return;
465
466 // check that parameters of types unify, if any
467 const std::vector< ast::ptr< ast::Expr > > & params = inst->params;
468 const std::vector< ast::ptr< ast::Expr > > & params2 = otherInst->params;
469
470 auto it = params.begin();
471 auto jt = params2.begin();
472 for ( ; it != params.end() && jt != params2.end(); ++it, ++jt ) {
473 auto param = strict_dynamic_cast< const ast::TypeExpr * >( it->get() );
474 auto param2 = strict_dynamic_cast< const ast::TypeExpr * >( jt->get() );
475
476 ast::ptr< ast::Type > pty = param->type;
477 ast::ptr< ast::Type > pty2 = param2->type;
478
479 bool isTuple = Tuples::isTtype( pty );
480 bool isTuple2 = Tuples::isTtype( pty2 );
481
482 if ( isTuple && isTuple2 ) {
483 ++it; ++jt; // skip ttype parameters before break
484 } else if ( isTuple ) {
485 // bundle remaining params into tuple
486 pty2 = tupleFromExprs( param2, jt, params2.end(), pty->qualifiers );
487 ++it; // skip ttype parameter for break
488 } else if ( isTuple2 ) {
489 // bundle remaining params into tuple
490 pty = tupleFromExprs( param, it, params.end(), pty2->qualifiers );
491 ++jt; // skip ttype parameter for break
492 }
493
494 if ( ! unifyExact(
495 pty, pty2, tenv, need, have, open, noWiden() ) ) {
496 result = false;
497 return;
498 }
499
500 // ttype parameter should be last
501 if ( isTuple || isTuple2 ) break;
502 }
503 result = it == params.end() && jt == params2.end();
504 }
505
506 public:
507 void postvisit( const ast::StructInstType * aggrType ) {
508 handleGenericRefType( aggrType, type2 );
509 }
510
511 void postvisit( const ast::UnionInstType * aggrType ) {
512 handleGenericRefType( aggrType, type2 );
513 }
514
515 void postvisit( const ast::EnumInstType * aggrType ) {
516 handleRefType( aggrType, type2 );
517 }
518
519 void postvisit( const ast::EnumPosType * posType ) {
520 // Lazy approach for now
521 auto otherPos = dynamic_cast< const ast::EnumPosType *>(type2);
522 if ( otherPos ) {
523 if ( otherPos->instance->base->name == posType->instance->base->name )
524 result = otherPos;
525 }
526 }
527
528 void postvisit( const ast::TraitInstType * aggrType ) {
529 handleRefType( aggrType, type2 );
530 }
531
532 void postvisit( const ast::TypeInstType * typeInst ) {
533 // assert( open.find( *typeInst ) == open.end() );
534 auto otherInst = dynamic_cast< const ast::TypeInstType * >( type2 );
535 if ( otherInst && typeInst->name == otherInst->name ) {
536 this->result = otherInst;
537 }
538 }
539
540 private:
541 /// Creates a tuple type based on a list of Type
542
543 static bool unifyList(
544 const std::vector< ast::ptr< ast::Type > > & list1,
545 const std::vector< ast::ptr< ast::Type > > & list2, ast::TypeEnvironment & env,
546 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open
547 ) {
548 auto crnt1 = list1.begin();
549 auto crnt2 = list2.begin();
550 while ( crnt1 != list1.end() && crnt2 != list2.end() ) {
551 const ast::Type * t1 = *crnt1;
552 const ast::Type * t2 = *crnt2;
553 bool isTuple1 = Tuples::isTtype( t1 );
554 bool isTuple2 = Tuples::isTtype( t2 );
555
556 // assumes ttype must be last parameter
557 if ( isTuple1 && ! isTuple2 ) {
558 // combine entirety of list2, then unify
559 return unifyExact(
560 t1, tupleFromTypes( list2 ), env, need, have, open,
561 noWiden() );
562 } else if ( ! isTuple1 && isTuple2 ) {
563 // combine entirety of list1, then unify
564 return unifyExact(
565 tupleFromTypes( list1 ), t2, env, need, have, open,
566 noWiden() );
567 }
568
569 if ( ! unifyExact(
570 t1, t2, env, need, have, open, noWiden() )
571 ) return false;
572
573 ++crnt1; ++crnt2;
574 }
575
576 if ( crnt1 != list1.end() ) {
577 // try unifying empty tuple type with ttype
578 const ast::Type * t1 = *crnt1;
579 if ( ! Tuples::isTtype( t1 ) ) return false;
580 // xxx - this doesn't generate an empty tuple, contrary to comment; both ported
581 // from Rob's code
582 return unifyExact(
583 t1, tupleFromTypes( list2 ), env, need, have, open,
584 noWiden() );
585 } else if ( crnt2 != list2.end() ) {
586 // try unifying empty tuple with ttype
587 const ast::Type * t2 = *crnt2;
588 if ( ! Tuples::isTtype( t2 ) ) return false;
589 // xxx - this doesn't generate an empty tuple, contrary to comment; both ported
590 // from Rob's code
591 return unifyExact(
592 tupleFromTypes( list1 ), t2, env, need, have, open,
593 noWiden() );
594 }
595
596 return true;
597 }
598
599 public:
600 void postvisit( const ast::TupleType * tuple ) {
601 auto tuple2 = dynamic_cast< const ast::TupleType * >( type2 );
602 if ( ! tuple2 ) return;
603
604 ast::Pass<TtypeExpander> expander{ tenv };
605
606 const ast::Type * flat = tuple->accept( expander );
607 const ast::Type * flat2 = tuple2->accept( expander );
608
609 auto types = flatten( flat );
610 auto types2 = flatten( flat2 );
611
612 result = unifyList( types, types2, tenv, need, have, open );
613 }
614
615 void postvisit( const ast::VarArgsType * ) {
616 result = dynamic_cast< const ast::VarArgsType * >( type2 );
617 }
618
619 void postvisit( const ast::ZeroType * ) {
620 result = dynamic_cast< const ast::ZeroType * >( type2 );
621 }
622
623 void postvisit( const ast::OneType * ) {
624 result = dynamic_cast< const ast::OneType * >( type2 );
625 }
626 };
627
628 // size_t Unify::traceId = Stats::Heap::new_stacktrace_id("Unify");
629
630 bool unify(
631 const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
632 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
633 ast::OpenVarSet & open
634 ) {
635 ast::ptr<ast::Type> common;
636 return unify( type1, type2, env, need, have, open, common );
637 }
638
639 bool unify(
640 const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
641 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
642 ast::OpenVarSet & open, ast::ptr<ast::Type> & common
643 ) {
644 ast::OpenVarSet closed;
645 // findOpenVars( type1, open, closed, need, have, FirstClosed );
646 findOpenVars( type2, open, closed, need, have, env, FirstOpen );
647 return unifyInexact(
648 type1, type2, env, need, have, open, WidenMode{ true, true }, common );
649 }
650
651 bool unifyExact(
652 const ast::Type * type1, const ast::Type * type2, ast::TypeEnvironment & env,
653 ast::AssertionSet & need, ast::AssertionSet & have, const ast::OpenVarSet & open,
654 WidenMode widen
655 ) {
656 if ( type1->qualifiers != type2->qualifiers ) return false;
657
658 auto var1 = dynamic_cast< const ast::TypeInstType * >( type1 );
659 auto var2 = dynamic_cast< const ast::TypeInstType * >( type2 );
660 bool isopen1 = var1 && env.lookup(*var1);
661 bool isopen2 = var2 && env.lookup(*var2);
662
663 if ( isopen1 && isopen2 ) {
664 if ( var1->base->kind != var2->base->kind ) return false;
665 return env.bindVarToVar(
666 var1, var2, ast::TypeData{ var1->base->kind, var1->base->sized||var2->base->sized }, need, have,
667 open, widen );
668 } else if ( isopen1 ) {
669 return env.bindVar( var1, type2, ast::TypeData{var1->base}, need, have, open, widen );
670 } else if ( isopen2 ) {
671 return env.bindVar( var2, type1, ast::TypeData{var2->base}, need, have, open, widen );
672 } else {
673 return ast::Pass<Unify>::read(
674 type1, type2, env, need, have, open, widen );
675 }
676 }
677
678 bool unifyInexact(
679 const ast::ptr<ast::Type> & type1, const ast::ptr<ast::Type> & type2,
680 ast::TypeEnvironment & env, ast::AssertionSet & need, ast::AssertionSet & have,
681 const ast::OpenVarSet & open, WidenMode widen,
682 ast::ptr<ast::Type> & common
683 ) {
684 ast::CV::Qualifiers q1 = type1->qualifiers, q2 = type2->qualifiers;
685
686 // force t1 and t2 to be cloned if their qualifiers must be stripped, so that type1 and
687 // type2 are left unchanged; calling convention forces type{1,2}->strong_ref >= 1
688 ast::Type * t1 = shallowCopy(type1.get());
689 ast::Type * t2 = shallowCopy(type2.get());
690 t1->qualifiers = {};
691 t2->qualifiers = {};
692 ast::ptr< ast::Type > t1_(t1);
693 ast::ptr< ast::Type > t2_(t2);
694
695 if ( unifyExact( t1, t2, env, need, have, open, widen ) ) {
696 // if exact unification on unqualified types, try to merge qualifiers
697 if ( q1 == q2 || ( ( q1 > q2 || widen.first ) && ( q2 > q1 || widen.second ) ) ) {
698 t1->qualifiers = q1 | q2;
699 common = t1;
700 return true;
701 } else {
702 return false;
703 }
704
705 } else if (( common = commonType( t1, t2, env, need, have, open, widen ))) {
706 // no exact unification, but common type
707 auto c = shallowCopy(common.get());
708 c->qualifiers = q1 | q2;
709 common = c;
710 return true;
711 } else {
712 return false;
713 }
714 }
715
716 ast::ptr<ast::Type> extractResultType( const ast::FunctionType * func ) {
717 if ( func->returns.empty() ) return new ast::VoidType{};
718 if ( func->returns.size() == 1 ) return func->returns[0];
719
720 std::vector<ast::ptr<ast::Type>> tys;
721 for ( const auto & decl : func->returns ) {
722 tys.emplace_back( decl );
723 }
724 return new ast::TupleType{ std::move(tys) };
725 }
726} // namespace ResolvExpr
727
728// Local Variables: //
729// tab-width: 4 //
730// mode: c++ //
731// compile-command: "make install" //
732// End: //
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