[clang] Track function template instantiation from definition #112241
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@llvm/pr-subscribers-clang-modules @llvm/pr-subscribers-clang Author: Matheus Izvekov (mizvekov) ChangesThis fixes instantiation of definition for friend function templates, when the declaration found and the one containing the definition have different template contexts. In these cases, the the function declaration corresponding to the definition is not available; it may not even be instantiated at all. So this patch adds a bit which tracks which function template declaration was instantiated from the member template. It's used to find which primary template serves as a context for the purpose of obtainining the template arguments needed to instantiate the definition. Fixes #55509 Relanding patch, with no changes, after it was reverted due to revert of commit this patch depended on. Full diff: https://github.com/llvm/llvm-project/pull/112241.diff 12 Files Affected:
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 36cf1d8a14db9f..67a12e14a3fb99 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -495,6 +495,7 @@ Bug Fixes to C++ Support
- Fixed an assertion failure in debug mode, and potential crashes in release mode, when
diagnosing a failed cast caused indirectly by a failed implicit conversion to the type of the constructor parameter.
- Fixed an assertion failure by adjusting integral to boolean vector conversions (#GH108326)
+- Clang is now better at keeping track of friend function template instance contexts. (#GH55509)
- Fixed an issue deducing non-type template arguments of reference type. (#GH73460)
- Fixed an issue in constraint evaluation, where type constraints on the lambda expression
containing outer unexpanded parameters were not correctly expanded. (#GH101754)
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 7ff35d73df5997..6afc86710a8137 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -2299,6 +2299,13 @@ class FunctionDecl : public DeclaratorDecl,
FunctionDeclBits.IsLateTemplateParsed = ILT;
}
+ bool isInstantiatedFromMemberTemplate() const {
+ return FunctionDeclBits.IsInstantiatedFromMemberTemplate;
+ }
+ void setInstantiatedFromMemberTemplate(bool Val = true) {
+ FunctionDeclBits.IsInstantiatedFromMemberTemplate = Val;
+ }
+
/// Whether this function is "trivial" in some specialized C++ senses.
/// Can only be true for default constructors, copy constructors,
/// copy assignment operators, and destructors. Not meaningful until
diff --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
index a3447d19909752..f7f4c4cb2957b3 100644
--- a/clang/include/clang/AST/DeclBase.h
+++ b/clang/include/clang/AST/DeclBase.h
@@ -1766,6 +1766,8 @@ class DeclContext {
uint64_t HasImplicitReturnZero : 1;
LLVM_PREFERRED_TYPE(bool)
uint64_t IsLateTemplateParsed : 1;
+ LLVM_PREFERRED_TYPE(bool)
+ uint64_t IsInstantiatedFromMemberTemplate : 1;
/// Kind of contexpr specifier as defined by ConstexprSpecKind.
LLVM_PREFERRED_TYPE(ConstexprSpecKind)
@@ -1816,7 +1818,7 @@ class DeclContext {
};
/// Number of inherited and non-inherited bits in FunctionDeclBitfields.
- enum { NumFunctionDeclBits = NumDeclContextBits + 31 };
+ enum { NumFunctionDeclBits = NumDeclContextBits + 32 };
/// Stores the bits used by CXXConstructorDecl. If modified
/// NumCXXConstructorDeclBits and the accessor
@@ -1827,12 +1829,12 @@ class DeclContext {
LLVM_PREFERRED_TYPE(FunctionDeclBitfields)
uint64_t : NumFunctionDeclBits;
- /// 20 bits to fit in the remaining available space.
+ /// 19 bits to fit in the remaining available space.
/// Note that this makes CXXConstructorDeclBitfields take
/// exactly 64 bits and thus the width of NumCtorInitializers
/// will need to be shrunk if some bit is added to NumDeclContextBitfields,
/// NumFunctionDeclBitfields or CXXConstructorDeclBitfields.
- uint64_t NumCtorInitializers : 17;
+ uint64_t NumCtorInitializers : 16;
LLVM_PREFERRED_TYPE(bool)
uint64_t IsInheritingConstructor : 1;
@@ -1846,7 +1848,7 @@ class DeclContext {
};
/// Number of inherited and non-inherited bits in CXXConstructorDeclBitfields.
- enum { NumCXXConstructorDeclBits = NumFunctionDeclBits + 20 };
+ enum { NumCXXConstructorDeclBits = NumFunctionDeclBits + 19 };
/// Stores the bits used by ObjCMethodDecl.
/// If modified NumObjCMethodDeclBits and the accessor
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index 141f58c4600af0..203bcf7574019a 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -1018,6 +1018,15 @@ class FunctionTemplateDecl : public RedeclarableTemplateDecl {
return getTemplatedDecl()->isThisDeclarationADefinition();
}
+ bool isCompatibleWithDefinition() const {
+ return getTemplatedDecl()->isInstantiatedFromMemberTemplate() ||
+ isThisDeclarationADefinition();
+ }
+ void setInstantiatedFromMemberTemplate(FunctionTemplateDecl *D) {
+ getTemplatedDecl()->setInstantiatedFromMemberTemplate();
+ RedeclarableTemplateDecl::setInstantiatedFromMemberTemplate(D);
+ }
+
/// Return the specialization with the provided arguments if it exists,
/// otherwise return the insertion point.
FunctionDecl *findSpecialization(ArrayRef<TemplateArgument> Args,
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 0faa5aed4eec3b..02bce060665702 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -13019,6 +13019,12 @@ class Sema final : public SemaBase {
std::optional<ArrayRef<TemplateArgument>> Innermost = std::nullopt,
bool RelativeToPrimary = false, bool ForConstraintInstantiation = false);
+ void getTemplateInstantiationArgs(
+ MultiLevelTemplateArgumentList &Result, const NamedDecl *D,
+ const DeclContext *DC = nullptr, bool Final = false,
+ std::optional<ArrayRef<TemplateArgument>> Innermost = std::nullopt,
+ bool RelativeToPrimary = false, bool ForConstraintInstantiation = false);
+
/// RAII object to handle the state changes required to synthesize
/// a function body.
class SynthesizedFunctionScope {
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index f083ffff87a8ec..e5d8072be88457 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3066,6 +3066,7 @@ FunctionDecl::FunctionDecl(Kind DK, ASTContext &C, DeclContext *DC,
FunctionDeclBits.IsIneligibleOrNotSelected = false;
FunctionDeclBits.HasImplicitReturnZero = false;
FunctionDeclBits.IsLateTemplateParsed = false;
+ FunctionDeclBits.IsInstantiatedFromMemberTemplate = false;
FunctionDeclBits.ConstexprKind = static_cast<uint64_t>(ConstexprKind);
FunctionDeclBits.BodyContainsImmediateEscalatingExpression = false;
FunctionDeclBits.InstantiationIsPending = false;
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 7cfb8d687c796a..14549e4e846ba2 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -3928,22 +3928,7 @@ TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
if (FunctionTemplate->getFriendObjectKind())
Owner = FunctionTemplate->getLexicalDeclContext();
FunctionDecl *FD = FunctionTemplate->getTemplatedDecl();
- // additional check for inline friend,
- // ```
- // template <class F1> int foo(F1 X);
- // template <int A1> struct A {
- // template <class F1> friend int foo(F1 X) { return A1; }
- // };
- // template struct A<1>;
- // int a = foo(1.0);
- // ```
- const FunctionDecl *FDFriend;
- if (FD->getFriendObjectKind() == Decl::FriendObjectKind::FOK_None &&
- FD->isDefined(FDFriend, /*CheckForPendingFriendDefinition*/ true) &&
- FDFriend->getFriendObjectKind() != Decl::FriendObjectKind::FOK_None) {
- FD = const_cast<FunctionDecl *>(FDFriend);
- Owner = FD->getLexicalDeclContext();
- }
+
MultiLevelTemplateArgumentList SubstArgs(
FunctionTemplate, CanonicalDeducedArgumentList->asArray(),
/*Final=*/false);
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 8c7f694c09042e..125c9bf1664dd0 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -512,13 +512,13 @@ struct TemplateInstantiationArgumentCollecter
} // namespace
-MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
- const NamedDecl *ND, const DeclContext *DC, bool Final,
+void Sema::getTemplateInstantiationArgs(
+ MultiLevelTemplateArgumentList &Result, const NamedDecl *ND,
+ const DeclContext *DC, bool Final,
std::optional<ArrayRef<TemplateArgument>> Innermost, bool RelativeToPrimary,
bool ForConstraintInstantiation) {
assert((ND || DC) && "Can't find arguments for a decl if one isn't provided");
// Accumulate the set of template argument lists in this structure.
- MultiLevelTemplateArgumentList Result;
const Decl *CurDecl = ND;
if (!CurDecl)
@@ -529,6 +529,17 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
do {
CurDecl = Collecter.Visit(const_cast<Decl *>(CurDecl));
} while (CurDecl);
+}
+
+MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
+ const NamedDecl *ND, const DeclContext *DC, bool Final,
+ std::optional<ArrayRef<TemplateArgument>> Innermost, bool RelativeToPrimary,
+ bool ForConstraintInstantiation) {
+ assert((ND || DC) && "Can't find arguments for a decl if one isn't provided");
+ // Accumulate the set of template argument lists in this structure.
+ MultiLevelTemplateArgumentList Result;
+ getTemplateInstantiationArgs(Result, ND, DC, Final, Innermost,
+ RelativeToPrimary, ForConstraintInstantiation);
return Result;
}
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 3e948232057afe..58512ab154e597 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -5227,8 +5227,26 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
RebuildTypeSourceInfoForDefaultSpecialMembers();
SetDeclDefaulted(Function, PatternDecl->getLocation());
} else {
- MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
- Function, Function->getLexicalDeclContext());
+ DeclContext *DC = Function;
+ MultiLevelTemplateArgumentList TemplateArgs;
+ if (auto *Primary = Function->getPrimaryTemplate();
+ Primary &&
+ !isGenericLambdaCallOperatorOrStaticInvokerSpecialization(Function)) {
+ auto It = llvm::find_if(Primary->redecls(),
+ [](const RedeclarableTemplateDecl *RTD) {
+ return cast<FunctionTemplateDecl>(RTD)
+ ->isCompatibleWithDefinition();
+ });
+ assert(It != Primary->redecls().end() &&
+ "Should't get here without a definition");
+ DC = (*It)->getLexicalDeclContext();
+ if (Function->getTemplateSpecializationKind() !=
+ TSK_ExplicitSpecialization)
+ TemplateArgs.addOuterTemplateArguments(
+ Function, Function->getTemplateSpecializationArgs()->asArray(),
+ /*Final=*/false);
+ }
+ getTemplateInstantiationArgs(TemplateArgs, /*D=*/nullptr, DC);
// Substitute into the qualifier; we can get a substitution failure here
// through evil use of alias templates.
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 1ccc810f415eb4..a44df84a8bcef2 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1087,6 +1087,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
FD->setHasImplicitReturnZero(FunctionDeclBits.getNextBit());
FD->setIsMultiVersion(FunctionDeclBits.getNextBit());
FD->setLateTemplateParsed(FunctionDeclBits.getNextBit());
+ FD->setInstantiatedFromMemberTemplate(FunctionDeclBits.getNextBit());
FD->setFriendConstraintRefersToEnclosingTemplate(
FunctionDeclBits.getNextBit());
FD->setUsesSEHTry(FunctionDeclBits.getNextBit());
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index f21cbd11b6ab89..dec93317dc7b37 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -626,7 +626,7 @@ void ASTDeclWriter::VisitDeclaratorDecl(DeclaratorDecl *D) {
}
void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
- static_assert(DeclContext::NumFunctionDeclBits == 44,
+ static_assert(DeclContext::NumFunctionDeclBits == 45,
"You need to update the serializer after you change the "
"FunctionDeclBits");
@@ -732,6 +732,7 @@ void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
FunctionDeclBits.addBit(D->hasImplicitReturnZero());
FunctionDeclBits.addBit(D->isMultiVersion());
FunctionDeclBits.addBit(D->isLateTemplateParsed());
+ FunctionDeclBits.addBit(D->isInstantiatedFromMemberTemplate());
FunctionDeclBits.addBit(D->FriendConstraintRefersToEnclosingTemplate());
FunctionDeclBits.addBit(D->usesSEHTry());
Record.push_back(FunctionDeclBits);
diff --git a/clang/test/SemaTemplate/GH55509.cpp b/clang/test/SemaTemplate/GH55509.cpp
new file mode 100644
index 00000000000000..f95833fbed7b19
--- /dev/null
+++ b/clang/test/SemaTemplate/GH55509.cpp
@@ -0,0 +1,101 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++26 %s
+
+namespace t1 {
+ template<int N> struct A {
+ template<class C> friend auto cica(const A<N-1>&, C) {
+ return N;
+ }
+ };
+
+ template<> struct A<0> {
+ template<class C> friend auto cica(const A<0>&, C);
+ // expected-note@-1 {{declared here}}
+ };
+
+ void test() {
+ cica(A<0>{}, 0);
+ // expected-error@-1 {{function 'cica<int>' with deduced return type cannot be used before it is defined}}
+
+ (void)A<1>{};
+ cica(A<0>{}, 0);
+ }
+} // namespace t1
+namespace t2 {
+ template<int N> struct A {
+ template<class C> friend auto cica(const A<N-1>&, C) {
+ return N;
+ }
+ };
+
+ template<> struct A<0> {
+ template<class C> friend auto cica(const A<0>&, C);
+ };
+
+ template <int N, class = decltype(cica(A<N>{}, nullptr))>
+ void MakeCica();
+ // expected-note@-1 {{candidate function}}
+
+ template <int N> void MakeCica(A<N+1> = {});
+ // expected-note@-1 {{candidate function}}
+
+ void test() {
+ MakeCica<0>();
+
+ MakeCica<0>();
+ // expected-error@-1 {{call to 'MakeCica' is ambiguous}}
+ }
+} // namespace t2
+namespace t3 {
+ template<int N> struct A {
+ template<class C> friend auto cica(const A<N-1>&, C) {
+ return N-1;
+ }
+ };
+
+ template<> struct A<0> {
+ template<class C> friend auto cica(const A<0>&, C);
+ };
+
+ template <int N, class AT, class = decltype(cica(AT{}, nullptr))>
+ static constexpr bool MakeCica(int);
+
+ template <int N, class AT>
+ static constexpr bool MakeCica(short, A<N+1> = {});
+
+ template <int N, class AT = A<N>, class Val = decltype(MakeCica<N, AT>(0))>
+ static constexpr bool has_cica = Val{};
+
+ constexpr bool cica2 = has_cica<0> || has_cica<0>;
+} // namespace t3
+namespace t4 {
+ template<int N> struct A {
+ template<class C> friend auto cica(const A<N-1>&, C);
+ };
+
+ template<> struct A<0> {
+ template<class C> friend auto cica(const A<0>&, C) {
+ C a;
+ }
+ };
+
+ template struct A<1>;
+
+ void test() {
+ cica(A<0>{}, 0);
+ }
+} // namespace t4
+namespace regression1 {
+ template <class> class A;
+
+ template <class T> [[gnu::abi_tag("TAG")]] void foo(A<T>);
+
+ template <class> struct A {
+ friend void foo <>(A);
+ };
+
+ template struct A<int>;
+
+ template <class T> [[gnu::abi_tag("TAG")]] void foo(A<T>) {}
+
+ template void foo<int>(A<int>);
+} // namespace regression1
|
cor3ntin
approved these changes
Oct 14, 2024
|
@mizvekov did you just forget to merge? |
This fixes instantiation of definition for friend function templates, when the declaration found and the one containing the definition have different template contexts. In these cases, the the function declaration corresponding to the definition is not available; it may not even be instantiated at all. So this patch adds a bit which tracks which function template declaration was instantiated from the member template. It's used to find which primary template serves as a context for the purpose of obtainining the template arguments needed to instantiate the definition. Fixes #55509
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This change breaks compiling Qt. To reproduce on e.g. Linux, clone https://github.com/qt/qtbase, check out the tag Please revert (and don't backport this) until this is sorted out. |
mstorsjo
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Jan 30, 2025
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I pushed a revert for this myself now after running tests, to see that it didn't tie in to any other recent change. |
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Jan 30, 2025
… definition (#112241)" This reverts commit 07a0e2b. This change broke compiling Qt; see llvm/llvm-project#112241 for details.
|
Thanks for the report, this is the reduced reproducer: template <typename> struct QWindowSystemHelper {
template <typename EventType> static void handleEvent() {
QWindowSystemHelper<int>::handleEvent<EventType>();
}
};
template <>
template <typename EventType>
void QWindowSystemHelper<int>::handleEvent() {
static_assert(__is_same(EventType, long));
}
template void QWindowSystemHelper<void>::handleEvent<long>(); |
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This fixes instantiation of definition for friend function templates, when the declaration found and the one containing the definition have different template contexts.
In these cases, the the function declaration corresponding to the definition is not available; it may not even be instantiated at all.
So this patch adds a bit which tracks which function template declaration was instantiated from the member template. It's used to find which primary template serves as a context for the purpose of obtainining the template arguments needed to instantiate the definition.
Fixes #55509
Relanding patch, with no changes, after it was reverted due to revert of commit this patch depended on.