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Reapply "[Clang][Sema] Always use latest redeclaration of primary template" (llvm#114569)
This patch reapplies llvm#114258, fixing an infinite recursion bug in `ASTImporter` that occurs when importing the primary template of a class template specialization when the latest redeclaration of that template is a friend declaration in the primary template.
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12 files changed

+222
-67
lines changed

12 files changed

+222
-67
lines changed

‎clang/include/clang/AST/DeclTemplate.h

Lines changed: 5 additions & 47 deletions
Original file line numberDiff line numberDiff line change
@@ -857,16 +857,6 @@ class RedeclarableTemplateDecl : public TemplateDecl,
857857
/// \endcode
858858
bool isMemberSpecialization() const { return Common.getInt(); }
859859

860-
/// Determines whether any redeclaration of this template was
861-
/// a specialization of a member template.
862-
bool hasMemberSpecialization() const {
863-
for (const auto *D : redecls()) {
864-
if (D->isMemberSpecialization())
865-
return true;
866-
}
867-
return false;
868-
}
869-
870860
/// Note that this member template is a specialization.
871861
void setMemberSpecialization() {
872862
assert(!isMemberSpecialization() && "already a member specialization");
@@ -1965,13 +1955,7 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
19651955
/// specialization which was specialized by this.
19661956
llvm::PointerUnion<ClassTemplateDecl *,
19671957
ClassTemplatePartialSpecializationDecl *>
1968-
getSpecializedTemplateOrPartial() const {
1969-
if (const auto *PartialSpec =
1970-
SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization *>())
1971-
return PartialSpec->PartialSpecialization;
1972-
1973-
return SpecializedTemplate.get<ClassTemplateDecl*>();
1974-
}
1958+
getSpecializedTemplateOrPartial() const;
19751959

19761960
/// Retrieve the set of template arguments that should be used
19771961
/// to instantiate members of the class template or class template partial
@@ -2208,17 +2192,6 @@ class ClassTemplatePartialSpecializationDecl
22082192
return InstantiatedFromMember.getInt();
22092193
}
22102194

2211-
/// Determines whether any redeclaration of this this class template partial
2212-
/// specialization was a specialization of a member partial specialization.
2213-
bool hasMemberSpecialization() const {
2214-
for (const auto *D : redecls()) {
2215-
if (cast<ClassTemplatePartialSpecializationDecl>(D)
2216-
->isMemberSpecialization())
2217-
return true;
2218-
}
2219-
return false;
2220-
}
2221-
22222195
/// Note that this member template is a specialization.
22232196
void setMemberSpecialization() { return InstantiatedFromMember.setInt(true); }
22242197

@@ -2740,13 +2713,7 @@ class VarTemplateSpecializationDecl : public VarDecl,
27402713
/// Retrieve the variable template or variable template partial
27412714
/// specialization which was specialized by this.
27422715
llvm::PointerUnion<VarTemplateDecl *, VarTemplatePartialSpecializationDecl *>
2743-
getSpecializedTemplateOrPartial() const {
2744-
if (const auto *PartialSpec =
2745-
SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization *>())
2746-
return PartialSpec->PartialSpecialization;
2747-
2748-
return SpecializedTemplate.get<VarTemplateDecl *>();
2749-
}
2716+
getSpecializedTemplateOrPartial() const;
27502717

27512718
/// Retrieve the set of template arguments that should be used
27522719
/// to instantiate the initializer of the variable template or variable
@@ -2980,18 +2947,6 @@ class VarTemplatePartialSpecializationDecl
29802947
return InstantiatedFromMember.getInt();
29812948
}
29822949

2983-
/// Determines whether any redeclaration of this this variable template
2984-
/// partial specialization was a specialization of a member partial
2985-
/// specialization.
2986-
bool hasMemberSpecialization() const {
2987-
for (const auto *D : redecls()) {
2988-
if (cast<VarTemplatePartialSpecializationDecl>(D)
2989-
->isMemberSpecialization())
2990-
return true;
2991-
}
2992-
return false;
2993-
}
2994-
29952950
/// Note that this member template is a specialization.
29962951
void setMemberSpecialization() { return InstantiatedFromMember.setInt(true); }
29972952

@@ -3164,6 +3119,9 @@ class VarTemplateDecl : public RedeclarableTemplateDecl {
31643119
return makeSpecIterator(getSpecializations(), true);
31653120
}
31663121

3122+
/// Merge \p Prev with our RedeclarableTemplateDecl::Common.
3123+
void mergePrevDecl(VarTemplateDecl *Prev);
3124+
31673125
// Implement isa/cast/dyncast support
31683126
static bool classof(const Decl *D) { return classofKind(D->getKind()); }
31693127
static bool classofKind(Kind K) { return K == VarTemplate; }

‎clang/lib/AST/ASTImporter.cpp

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6190,7 +6190,8 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
61906190
ExpectedDecl ASTNodeImporter::VisitClassTemplateSpecializationDecl(
61916191
ClassTemplateSpecializationDecl *D) {
61926192
ClassTemplateDecl *ClassTemplate;
6193-
if (Error Err = importInto(ClassTemplate, D->getSpecializedTemplate()))
6193+
if (Error Err = importInto(ClassTemplate,
6194+
D->getSpecializedTemplate()->getCanonicalDecl()))
61946195
return std::move(Err);
61956196

61966197
// Import the context of this declaration.

‎clang/lib/AST/Decl.cpp

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -2708,7 +2708,7 @@ VarDecl *VarDecl::getTemplateInstantiationPattern() const {
27082708
if (isTemplateInstantiation(VDTemplSpec->getTemplateSpecializationKind())) {
27092709
auto From = VDTemplSpec->getInstantiatedFrom();
27102710
if (auto *VTD = From.dyn_cast<VarTemplateDecl *>()) {
2711-
while (!VTD->hasMemberSpecialization()) {
2711+
while (!VTD->isMemberSpecialization()) {
27122712
if (auto *NewVTD = VTD->getInstantiatedFromMemberTemplate())
27132713
VTD = NewVTD;
27142714
else
@@ -2718,7 +2718,7 @@ VarDecl *VarDecl::getTemplateInstantiationPattern() const {
27182718
}
27192719
if (auto *VTPSD =
27202720
From.dyn_cast<VarTemplatePartialSpecializationDecl *>()) {
2721-
while (!VTPSD->hasMemberSpecialization()) {
2721+
while (!VTPSD->isMemberSpecialization()) {
27222722
if (auto *NewVTPSD = VTPSD->getInstantiatedFromMember())
27232723
VTPSD = NewVTPSD;
27242724
else
@@ -2732,7 +2732,7 @@ VarDecl *VarDecl::getTemplateInstantiationPattern() const {
27322732
// If this is the pattern of a variable template, find where it was
27332733
// instantiated from. FIXME: Is this necessary?
27342734
if (VarTemplateDecl *VTD = VD->getDescribedVarTemplate()) {
2735-
while (!VTD->hasMemberSpecialization()) {
2735+
while (!VTD->isMemberSpecialization()) {
27362736
if (auto *NewVTD = VTD->getInstantiatedFromMemberTemplate())
27372737
VTD = NewVTD;
27382738
else
@@ -4153,7 +4153,7 @@ FunctionDecl::getTemplateInstantiationPattern(bool ForDefinition) const {
41534153
if (FunctionTemplateDecl *Primary = getPrimaryTemplate()) {
41544154
// If we hit a point where the user provided a specialization of this
41554155
// template, we're done looking.
4156-
while (!ForDefinition || !Primary->hasMemberSpecialization()) {
4156+
while (!ForDefinition || !Primary->isMemberSpecialization()) {
41574157
if (auto *NewPrimary = Primary->getInstantiatedFromMemberTemplate())
41584158
Primary = NewPrimary;
41594159
else
@@ -4170,7 +4170,7 @@ FunctionTemplateDecl *FunctionDecl::getPrimaryTemplate() const {
41704170
if (FunctionTemplateSpecializationInfo *Info
41714171
= TemplateOrSpecialization
41724172
.dyn_cast<FunctionTemplateSpecializationInfo*>()) {
4173-
return Info->getTemplate();
4173+
return Info->getTemplate()->getMostRecentDecl();
41744174
}
41754175
return nullptr;
41764176
}

‎clang/lib/AST/DeclCXX.cpp

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2030,7 +2030,7 @@ const CXXRecordDecl *CXXRecordDecl::getTemplateInstantiationPattern() const {
20302030
if (auto *TD = dyn_cast<ClassTemplateSpecializationDecl>(this)) {
20312031
auto From = TD->getInstantiatedFrom();
20322032
if (auto *CTD = From.dyn_cast<ClassTemplateDecl *>()) {
2033-
while (!CTD->hasMemberSpecialization()) {
2033+
while (!CTD->isMemberSpecialization()) {
20342034
if (auto *NewCTD = CTD->getInstantiatedFromMemberTemplate())
20352035
CTD = NewCTD;
20362036
else
@@ -2040,7 +2040,7 @@ const CXXRecordDecl *CXXRecordDecl::getTemplateInstantiationPattern() const {
20402040
}
20412041
if (auto *CTPSD =
20422042
From.dyn_cast<ClassTemplatePartialSpecializationDecl *>()) {
2043-
while (!CTPSD->hasMemberSpecialization()) {
2043+
while (!CTPSD->isMemberSpecialization()) {
20442044
if (auto *NewCTPSD = CTPSD->getInstantiatedFromMemberTemplate())
20452045
CTPSD = NewCTPSD;
20462046
else

‎clang/lib/AST/DeclTemplate.cpp

Lines changed: 54 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -993,7 +993,17 @@ ClassTemplateSpecializationDecl::getSpecializedTemplate() const {
993993
if (const auto *PartialSpec =
994994
SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization*>())
995995
return PartialSpec->PartialSpecialization->getSpecializedTemplate();
996-
return SpecializedTemplate.get<ClassTemplateDecl*>();
996+
return SpecializedTemplate.get<ClassTemplateDecl *>()->getMostRecentDecl();
997+
}
998+
999+
llvm::PointerUnion<ClassTemplateDecl *,
1000+
ClassTemplatePartialSpecializationDecl *>
1001+
ClassTemplateSpecializationDecl::getSpecializedTemplateOrPartial() const {
1002+
if (const auto *PartialSpec =
1003+
SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization *>())
1004+
return PartialSpec->PartialSpecialization->getMostRecentDecl();
1005+
1006+
return SpecializedTemplate.get<ClassTemplateDecl *>()->getMostRecentDecl();
9971007
}
9981008

9991009
SourceRange
@@ -1283,6 +1293,39 @@ VarTemplateDecl::newCommon(ASTContext &C) const {
12831293
return CommonPtr;
12841294
}
12851295

1296+
void VarTemplateDecl::mergePrevDecl(VarTemplateDecl *Prev) {
1297+
// If we haven't created a common pointer yet, then it can just be created
1298+
// with the usual method.
1299+
if (!getCommonPtrInternal())
1300+
return;
1301+
1302+
Common *ThisCommon = static_cast<Common *>(getCommonPtrInternal());
1303+
Common *PrevCommon = nullptr;
1304+
SmallVector<VarTemplateDecl *, 8> PreviousDecls;
1305+
for (; Prev; Prev = Prev->getPreviousDecl()) {
1306+
if (CommonBase *C = Prev->getCommonPtrInternal()) {
1307+
PrevCommon = static_cast<Common *>(C);
1308+
break;
1309+
}
1310+
PreviousDecls.push_back(Prev);
1311+
}
1312+
1313+
// If the previous redecl chain hasn't created a common pointer yet, then just
1314+
// use this common pointer.
1315+
if (!PrevCommon) {
1316+
for (auto *D : PreviousDecls)
1317+
D->setCommonPtr(ThisCommon);
1318+
return;
1319+
}
1320+
1321+
// Ensure we don't leak any important state.
1322+
assert(ThisCommon->Specializations.empty() &&
1323+
ThisCommon->PartialSpecializations.empty() &&
1324+
"Can't merge incompatible declarations!");
1325+
1326+
setCommonPtr(PrevCommon);
1327+
}
1328+
12861329
VarTemplateSpecializationDecl *
12871330
VarTemplateDecl::findSpecialization(ArrayRef<TemplateArgument> Args,
12881331
void *&InsertPos) {
@@ -1405,7 +1448,16 @@ VarTemplateDecl *VarTemplateSpecializationDecl::getSpecializedTemplate() const {
14051448
if (const auto *PartialSpec =
14061449
SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization *>())
14071450
return PartialSpec->PartialSpecialization->getSpecializedTemplate();
1408-
return SpecializedTemplate.get<VarTemplateDecl *>();
1451+
return SpecializedTemplate.get<VarTemplateDecl *>()->getMostRecentDecl();
1452+
}
1453+
1454+
llvm::PointerUnion<VarTemplateDecl *, VarTemplatePartialSpecializationDecl *>
1455+
VarTemplateSpecializationDecl::getSpecializedTemplateOrPartial() const {
1456+
if (const auto *PartialSpec =
1457+
SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization *>())
1458+
return PartialSpec->PartialSpecialization->getMostRecentDecl();
1459+
1460+
return SpecializedTemplate.get<VarTemplateDecl *>()->getMostRecentDecl();
14091461
}
14101462

14111463
SourceRange VarTemplateSpecializationDecl::getSourceRange() const {

‎clang/lib/Sema/SemaDecl.cpp

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4694,8 +4694,10 @@ void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
46944694

46954695
// Keep a chain of previous declarations.
46964696
New->setPreviousDecl(Old);
4697-
if (NewTemplate)
4697+
if (NewTemplate) {
4698+
NewTemplate->mergePrevDecl(OldTemplate);
46984699
NewTemplate->setPreviousDecl(OldTemplate);
4700+
}
46994701

47004702
// Inherit access appropriately.
47014703
New->setAccess(Old->getAccess());

‎clang/lib/Sema/SemaInit.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9954,7 +9954,7 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
99549954
auto SynthesizeAggrGuide = [&](InitListExpr *ListInit) {
99559955
auto *Pattern = Template;
99569956
while (Pattern->getInstantiatedFromMemberTemplate()) {
9957-
if (Pattern->hasMemberSpecialization())
9957+
if (Pattern->isMemberSpecialization())
99589958
break;
99599959
Pattern = Pattern->getInstantiatedFromMemberTemplate();
99609960
}

‎clang/lib/Sema/SemaTemplateInstantiate.cpp

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -343,7 +343,7 @@ struct TemplateInstantiationArgumentCollecter
343343
// If this function was instantiated from a specialized member that is
344344
// a function template, we're done.
345345
assert(FD->getPrimaryTemplate() && "No function template?");
346-
if (FD->getPrimaryTemplate()->hasMemberSpecialization())
346+
if (FD->getPrimaryTemplate()->isMemberSpecialization())
347347
return Done();
348348

349349
// If this function is a generic lambda specialization, we are done.
@@ -442,11 +442,11 @@ struct TemplateInstantiationArgumentCollecter
442442
Specialized = CTSD->getSpecializedTemplateOrPartial();
443443
if (auto *CTPSD =
444444
Specialized.dyn_cast<ClassTemplatePartialSpecializationDecl *>()) {
445-
if (CTPSD->hasMemberSpecialization())
445+
if (CTPSD->isMemberSpecialization())
446446
return Done();
447447
} else {
448448
auto *CTD = Specialized.get<ClassTemplateDecl *>();
449-
if (CTD->hasMemberSpecialization())
449+
if (CTD->isMemberSpecialization())
450450
return Done();
451451
}
452452
return UseNextDecl(CTSD);
@@ -478,11 +478,11 @@ struct TemplateInstantiationArgumentCollecter
478478
Specialized = VTSD->getSpecializedTemplateOrPartial();
479479
if (auto *VTPSD =
480480
Specialized.dyn_cast<VarTemplatePartialSpecializationDecl *>()) {
481-
if (VTPSD->hasMemberSpecialization())
481+
if (VTPSD->isMemberSpecialization())
482482
return Done();
483483
} else {
484484
auto *VTD = Specialized.get<VarTemplateDecl *>();
485-
if (VTD->hasMemberSpecialization())
485+
if (VTD->isMemberSpecialization())
486486
return Done();
487487
}
488488
return UseNextDecl(VTSD);
@@ -4141,7 +4141,7 @@ getPatternForClassTemplateSpecialization(
41414141
CXXRecordDecl *Pattern = nullptr;
41424142
Specialized = ClassTemplateSpec->getSpecializedTemplateOrPartial();
41434143
if (auto *CTD = Specialized.dyn_cast<ClassTemplateDecl *>()) {
4144-
while (!CTD->hasMemberSpecialization()) {
4144+
while (!CTD->isMemberSpecialization()) {
41454145
if (auto *NewCTD = CTD->getInstantiatedFromMemberTemplate())
41464146
CTD = NewCTD;
41474147
else
@@ -4151,7 +4151,7 @@ getPatternForClassTemplateSpecialization(
41514151
} else if (auto *CTPSD =
41524152
Specialized
41534153
.dyn_cast<ClassTemplatePartialSpecializationDecl *>()) {
4154-
while (!CTPSD->hasMemberSpecialization()) {
4154+
while (!CTPSD->isMemberSpecialization()) {
41554155
if (auto *NewCTPSD = CTPSD->getInstantiatedFromMemberTemplate())
41564156
CTPSD = NewCTPSD;
41574157
else

‎clang/test/AST/ast-dump-decl.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -530,7 +530,7 @@ namespace testCanonicalTemplate {
530530
// CHECK-NEXT: | `-ClassTemplateDecl 0x{{.+}} parent 0x{{.+}} <col:5, col:40> col:40 friend_undeclared TestClassTemplate{{$}}
531531
// CHECK-NEXT: | |-TemplateTypeParmDecl 0x{{.+}} <col:14, col:23> col:23 typename depth 1 index 0 T2{{$}}
532532
// CHECK-NEXT: | `-CXXRecordDecl 0x{{.+}} parent 0x{{.+}} <col:34, col:40> col:40 class TestClassTemplate{{$}}
533-
// CHECK-NEXT: `-ClassTemplateSpecializationDecl 0x{{.+}} <line:[[@LINE-19]]:3, line:[[@LINE-17]]:3> line:[[@LINE-19]]:31 class TestClassTemplate definition implicit_instantiation{{$}}
533+
// CHECK-NEXT: `-ClassTemplateSpecializationDecl 0x{{.+}} <col:5, col:40> line:[[@LINE-19]]:31 class TestClassTemplate definition implicit_instantiation{{$}}
534534
// CHECK-NEXT: |-DefinitionData pass_in_registers empty aggregate standard_layout trivially_copyable pod trivial literal has_constexpr_non_copy_move_ctor can_const_default_init{{$}}
535535
// CHECK-NEXT: | |-DefaultConstructor exists trivial constexpr defaulted_is_constexpr{{$}}
536536
// CHECK-NEXT: | |-CopyConstructor simple trivial has_const_param implicit_has_const_param{{$}}

‎clang/test/ASTMerge/class-template-spec/Inputs/class-template-spec.cpp

Lines changed: 47 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,47 @@
1+
namespace N0 {
2+
template<typename T>
3+
struct A {
4+
template<typename U>
5+
friend struct A;
6+
};
7+
8+
template struct A<long>;
9+
} // namespace N0
10+
11+
namespace N1 {
12+
template<typename T>
13+
struct A;
14+
15+
template<typename T>
16+
struct A {
17+
template<typename U>
18+
friend struct A;
19+
};
20+
21+
template struct A<long>;
22+
} // namespace N1
23+
24+
namespace N2 {
25+
template<typename T>
26+
struct A {
27+
template<typename U>
28+
friend struct A;
29+
};
30+
31+
template<typename T>
32+
struct A;
33+
34+
template struct A<long>;
35+
} // namespace N2
36+
37+
namespace N3 {
38+
struct A {
39+
template<typename T>
40+
friend struct B;
41+
};
42+
43+
template<typename T>
44+
struct B { };
45+
46+
template struct B<long>;
47+
} // namespace N3

‎clang/test/ASTMerge/class-template-spec/test.cpp

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
1+
// RUN: %clang_cc1 -emit-pch -o %t.1.ast %S/Inputs/class-template-spec.cpp
2+
// RUN: %clang_cc1 -ast-merge %t.1.ast -fsyntax-only -verify %s
3+
// expected-no-diagnostics
4+
5+
template struct N0::A<short>;
6+
template struct N1::A<short>;
7+
template struct N2::A<short>;
8+
template struct N3::B<short>;

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