https://github.com/mizvekov updated
https://github.com/llvm/llvm-project/pull/112241
>From c1f3c40382b79a3aa3fb422b6f7382a1f7d7c6f5 Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizve...@gmail.com>
Date: Sat, 28 Sep 2024 14:28:58 -0300
Subject: [PATCH] [clang] Track function template instantiation from definition
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
---
clang/docs/ReleaseNotes.rst | 2 +
clang/include/clang/AST/Decl.h | 7 ++
clang/include/clang/AST/DeclBase.h | 10 +-
clang/include/clang/AST/DeclTemplate.h | 9 ++
clang/lib/AST/Decl.cpp | 1 +
clang/lib/Sema/SemaTemplateDeduction.cpp | 17 +--
clang/lib/Sema/SemaTemplateInstantiate.cpp | 9 +-
.../lib/Sema/SemaTemplateInstantiateDecl.cpp | 22 +++-
clang/lib/Serialization/ASTReaderDecl.cpp | 1 +
clang/lib/Serialization/ASTWriterDecl.cpp | 3 +-
clang/test/SemaTemplate/GH55509.cpp | 101 ++++++++++++++++++
11 files changed, 154 insertions(+), 28 deletions(-)
create mode 100644 clang/test/SemaTemplate/GH55509.cpp
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7fafe2807bd3883..7ecf8e61e3aa1a9 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -121,6 +121,8 @@ Bug Fixes to Attribute Support
Bug Fixes to C++ Support
^^^^^^^^^^^^^^^^^^^^^^^^
+- Clang is now better at keeping track of friend function template instance
contexts. (#GH55509)
+
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 9593bab576412a7..362a2741a0cddd1 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -2298,6 +2298,13 @@ 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 2c0c3a8dc2f9d5c..3a13309a6100eed 100644
--- a/clang/include/clang/AST/DeclBase.h
+++ b/clang/include/clang/AST/DeclBase.h
@@ -1777,6 +1777,8 @@ 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)
@@ -1827,7 +1829,7 @@ 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
@@ -1838,12 +1840,12 @@ 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;
@@ -1857,7 +1859,7 @@ 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 9ecff2c898acd5f..0c706036ff70227 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -1011,6 +1011,15 @@ 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/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 0bd4d64b54a0f21..ba77c748815d564 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3069,6 +3069,7 @@ 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 137942f0c30bfe1..6aaf86a6a6ff369 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -4074,22 +4074,7 @@ 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 c45d3ffe2508b2d..b4fa23ddf049d5f 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -479,9 +479,6 @@ MultiLevelTemplateArgumentList
Sema::getTemplateInstantiationArgs(
using namespace TemplateInstArgsHelpers;
const Decl *CurDecl = ND;
- if (!CurDecl)
- CurDecl = Decl::castFromDeclContext(DC);
-
if (Innermost) {
Result.addOuterTemplateArguments(const_cast<NamedDecl *>(ND), *Innermost,
Final);
@@ -495,8 +492,10 @@ MultiLevelTemplateArgumentList
Sema::getTemplateInstantiationArgs(
// has a depth of 0.
if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(CurDecl))
HandleDefaultTempArgIntoTempTempParam(TTP, Result);
- CurDecl = Response::UseNextDecl(CurDecl).NextDecl;
- }
+ CurDecl = DC ? Decl::castFromDeclContext(DC)
+ : Response::UseNextDecl(CurDecl).NextDecl;
+ } else if (!CurDecl)
+ CurDecl = Decl::castFromDeclContext(DC);
while (!CurDecl->isFileContextDecl()) {
Response R;
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 131f5c8ad1a09db..f540431a73445f3 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -12,6 +12,7 @@
#include "TreeTransform.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTLambda.h"
#include "clang/AST/ASTMutationListener.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DependentDiagnostic.h"
@@ -5245,9 +5246,26 @@ void Sema::InstantiateFunctionDefinition(SourceLocation
PointOfInstantiation,
RebuildTypeSourceInfoForDefaultSpecialMembers();
SetDeclDefaulted(Function, PatternDecl->getLocation());
} else {
+ NamedDecl *ND = Function;
+ DeclContext *DC = ND->getLexicalDeclContext();
+ std::optional<ArrayRef<TemplateArgument>> Innermost;
+ if (auto *Primary = Function->getPrimaryTemplate();
+ Primary &&
+ !isGenericLambdaCallOperatorOrStaticInvokerSpecialization(Function) &&
+ Function->getTemplateSpecializationKind() !=
+ TSK_ExplicitSpecialization) {
+ 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();
+ Innermost.emplace(Function->getTemplateSpecializationArgs()->asArray());
+ }
MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
- Function, Function->getLexicalDeclContext(), /*Final=*/false,
- /*Innermost=*/std::nullopt, false, PatternDecl);
+ Function, DC, /*Final=*/false, Innermost, false, PatternDecl);
// 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 8210eb2143acf56..7a15e60d87d83a3 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1064,6 +1064,7 @@ 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 fa2294da95de8db..6a79444bdb98921 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -679,7 +679,7 @@ 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");
@@ -785,6 +785,7 @@ 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 000000000000000..f95833fbed7b192
--- /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
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