[clang] e48d8f9 - [Clang] Correctly initialize placeholder fields from their initializers (#114196)
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Tue Nov 5 20:10:58 PST 2024
Author: cor3ntin
Date: 2024-11-06T05:10:53+01:00
New Revision: e48d8f9fea69095757d3593a567316197ec70450
URL: https://github.com/llvm/llvm-project/commit/e48d8f9fea69095757d3593a567316197ec70450
DIFF: https://github.com/llvm/llvm-project/commit/e48d8f9fea69095757d3593a567316197ec70450.diff
LOG: [Clang] Correctly initialize placeholder fields from their initializers (#114196)
We made the incorrect assumption that names of fields are unique when
creating their default initializers.
We fix that by keeping track of the instantiaation pattern for field
decls that are placeholder vars,
like we already do for unamed fields.
Fixes #114069
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/AST/ASTContext.h
clang/lib/AST/ASTContext.cpp
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
clang/lib/Serialization/ASTReaderDecl.cpp
clang/lib/Serialization/ASTWriterDecl.cpp
clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 5553a0e9130587..88621809bad7e2 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -591,6 +591,7 @@ Bug Fixes to C++ Support
- Clang now correctly ignores previous partial specializations of member templates explicitly specialized for
an implicitly instantiated class template specialization. (#GH51051)
- Fixed an assertion failure caused by invalid enum forward declarations. (#GH112208)
+- Name independent data members were not correctly initialized from default member initializers. (#GH114069)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index 1e8101f60b03fb..dfd5bd8add01a3 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -1041,7 +1041,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
void setInstantiatedFromUsingShadowDecl(UsingShadowDecl *Inst,
UsingShadowDecl *Pattern);
- FieldDecl *getInstantiatedFromUnnamedFieldDecl(FieldDecl *Field);
+ FieldDecl *getInstantiatedFromUnnamedFieldDecl(FieldDecl *Field) const;
void setInstantiatedFromUnnamedFieldDecl(FieldDecl *Inst, FieldDecl *Tmpl);
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 91a7d4bb5a89dd..68ddbc5d09dc59 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1592,14 +1592,17 @@ ASTContext::setInstantiatedFromUsingShadowDecl(UsingShadowDecl *Inst,
InstantiatedFromUsingShadowDecl[Inst] = Pattern;
}
-FieldDecl *ASTContext::getInstantiatedFromUnnamedFieldDecl(FieldDecl *Field) {
+FieldDecl *
+ASTContext::getInstantiatedFromUnnamedFieldDecl(FieldDecl *Field) const {
return InstantiatedFromUnnamedFieldDecl.lookup(Field);
}
void ASTContext::setInstantiatedFromUnnamedFieldDecl(FieldDecl *Inst,
FieldDecl *Tmpl) {
- assert(!Inst->getDeclName() && "Instantiated field decl is not unnamed");
- assert(!Tmpl->getDeclName() && "Template field decl is not unnamed");
+ assert((!Inst->getDeclName() || Inst->isPlaceholderVar(getLangOpts())) &&
+ "Instantiated field decl is not unnamed");
+ assert((!Inst->getDeclName() || Inst->isPlaceholderVar(getLangOpts())) &&
+ "Template field decl is not unnamed");
assert(!InstantiatedFromUnnamedFieldDecl[Inst] &&
"Already noted what unnamed field was instantiated from");
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 7f3cff1054aeed..49fdb5b5ab43da 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5560,6 +5560,24 @@ ExprResult Sema::BuildCXXDefaultArgExpr(SourceLocation CallLoc,
Init, InitializationContext->Context);
}
+static FieldDecl *FindFieldDeclInstantiationPattern(const ASTContext &Ctx,
+ FieldDecl *Field) {
+ if (FieldDecl *Pattern = Ctx.getInstantiatedFromUnnamedFieldDecl(Field))
+ return Pattern;
+ auto *ParentRD = cast<CXXRecordDecl>(Field->getParent());
+ CXXRecordDecl *ClassPattern = ParentRD->getTemplateInstantiationPattern();
+ DeclContext::lookup_result Lookup =
+ ClassPattern->lookup(Field->getDeclName());
+ auto Rng = llvm::make_filter_range(
+ Lookup, [](auto &&L) { return isa<FieldDecl>(*L); });
+ if (Rng.empty())
+ return nullptr;
+ // FIXME: this breaks clang/test/Modules/pr28812.cpp
+ // assert(std::distance(Rng.begin(), Rng.end()) <= 1
+ // && "Duplicated instantiation pattern for field decl");
+ return cast<FieldDecl>(*Rng.begin());
+}
+
ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
assert(Field->hasInClassInitializer());
@@ -5588,15 +5606,8 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
// Maybe we haven't instantiated the in-class initializer. Go check the
// pattern FieldDecl to see if it has one.
if (isTemplateInstantiation(ParentRD->getTemplateSpecializationKind())) {
- CXXRecordDecl *ClassPattern = ParentRD->getTemplateInstantiationPattern();
- DeclContext::lookup_result Lookup =
- ClassPattern->lookup(Field->getDeclName());
-
- FieldDecl *Pattern = nullptr;
- for (auto *L : Lookup) {
- if ((Pattern = dyn_cast<FieldDecl>(L)))
- break;
- }
+ FieldDecl *Pattern =
+ FindFieldDeclInstantiationPattern(getASTContext(), Field);
assert(Pattern && "We must have set the Pattern!");
if (!Pattern->hasInClassInitializer() ||
InstantiateInClassInitializer(Loc, Field, Pattern,
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index ec3c3ce6057264..1f4b0570708456 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1352,7 +1352,7 @@ Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
if (Invalid)
Field->setInvalidDecl();
- if (!Field->getDeclName()) {
+ if (!Field->getDeclName() || Field->isPlaceholderVar(SemaRef.getLangOpts())) {
// Keep track of where this decl came from.
SemaRef.Context.setInstantiatedFromUnnamedFieldDecl(Field, D);
}
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 20edd53598e5bd..98a2070eda726b 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1547,7 +1547,8 @@ void ASTDeclReader::VisitFieldDecl(FieldDecl *FD) {
else if (Bits & 1)
FD->setBitWidth(Record.readExpr());
- if (!FD->getDeclName()) {
+ if (!FD->getDeclName() ||
+ FD->isPlaceholderVar(Reader.getContext().getLangOpts())) {
if (auto *Tmpl = readDeclAs<FieldDecl>())
Reader.getContext().setInstantiatedFromUnnamedFieldDecl(FD, Tmpl);
}
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index b5fe16bf6e787b..14db0c082c937f 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -1038,7 +1038,7 @@ void ASTDeclWriter::VisitFieldDecl(FieldDecl *D) {
else if (D->BitField)
Record.AddStmt(D->getBitWidth());
- if (!D->getDeclName())
+ if (!D->getDeclName() || D->isPlaceholderVar(Writer.getLangOpts()))
Record.AddDeclRef(Context.getInstantiatedFromUnnamedFieldDecl(D));
if (D->getDeclContext() == D->getLexicalDeclContext() &&
diff --git a/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp b/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
index 29ca3b5ef3df72..8e428c0ef04279 100644
--- a/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
+++ b/clang/test/SemaCXX/cxx2c-placeholder-vars.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang -cc1 -fsyntax-only -verify -std=c++2c -Wunused-parameter -Wunused -Wpre-c++26-compat %s
+// RUN: %clang_cc1 -fsyntax-only -verify -ast-dump -std=c++2c -Wunused-parameter -Wunused -Wpre-c++26-compat %s | FileCheck %s
void static_var() {
static int _; // expected-note {{previous definition is here}} \
@@ -254,3 +254,37 @@ namespace Bases {
}
};
}
+
+namespace GH114069 {
+
+template <class T>
+struct A {
+ T _ = 1;
+ T _ = 2;
+ T : 1;
+ T a = 3;
+ T _ = 4;
+};
+
+void f() {
+ [[maybe_unused]] A<int> a;
+}
+
+// CHECK: NamespaceDecl {{.*}} GH114069
+// CHECK: ClassTemplateSpecializationDecl {{.*}} struct A definition
+// CHECK: CXXConstructorDecl {{.*}} implicit used constexpr A 'void () noexcept'
+// CHECK-NEXT: CXXCtorInitializer Field {{.*}} '_' 'int'
+// CHECK-NEXT: CXXDefaultInitExpr {{.*}} 'int' has rewritten init
+// CHECK-NEXT: IntegerLiteral {{.*}} 'int' 1
+// CHECK-NEXT: CXXCtorInitializer Field {{.*}} '_' 'int'
+// CHECK-NEXT: CXXDefaultInitExpr {{.*}} 'int' has rewritten init
+// CHECK-NEXT: IntegerLiteral {{.*}} 'int' 2
+// CHECK-NEXT: CXXCtorInitializer Field {{.*}} 'a' 'int'
+// CHECK-NEXT: CXXDefaultInitExpr {{.*}} 'int' has rewritten init
+// CHECK-NEXT: IntegerLiteral {{.*}} 'int' 3
+// CHECK-NEXT: CXXCtorInitializer Field {{.*}} '_' 'int'
+// CHECK-NEXT: CXXDefaultInitExpr {{.*}} 'int' has rewritten init
+// CHECK-NEXT: IntegerLiteral {{.*}} 'int' 4
+// CHECK-NEXT: CompoundStmt {{.*}}
+
+}
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