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-rw-r--r--clang/include/clang/AST/Decl.h35
-rw-r--r--clang/lib/Sema/SemaDecl.cpp31
-rw-r--r--clang/lib/Sema/SemaTemplateInstantiateDecl.cpp57
-rw-r--r--clang/test/SemaCXX/friend2.cpp28
4 files changed, 100 insertions, 51 deletions
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 1a8f6560e44..5b5ad34b0d4 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -1925,11 +1925,25 @@ public:
SourceRange getSourceRange() const override LLVM_READONLY;
- /// \brief Returns true if the function has a body (definition). The
- /// function body might be in any of the (re-)declarations of this
- /// function. The variant that accepts a FunctionDecl pointer will
- /// set that function declaration to the actual declaration
- /// containing the body (if there is one).
+ // Function definitions.
+ //
+ // A function declaration may be:
+ // - a non defining declaration,
+ // - a definition. A function may be defined because:
+ // - it has a body, or will have it in the case of late parsing.
+ // - it has an uninstantiated body. The body does not exist because the
+ // function is not used yet, but the declaration is considered a
+ // definition and does not allow other definition of this function.
+ // - it does not have a user specified body, but it does not allow
+ // redefinition, because it is deleted/defaulted or is defined through
+ // some other mechanism (alias, ifunc).
+
+ /// Returns true if the function has a body.
+ ///
+ /// The function body might be in any of the (re-)declarations of this
+ /// function. The variant that accepts a FunctionDecl pointer will set that
+ /// function declaration to the actual declaration containing the body (if
+ /// there is one).
bool hasBody(const FunctionDecl *&Definition) const;
bool hasBody() const override {
@@ -1941,9 +1955,11 @@ public:
/// specific codegen.
bool hasTrivialBody() const;
- /// Returns true if the function is defined at all, including a deleted
- /// definition. Except for the behavior when the function is deleted, behaves
- /// like hasBody.
+ /// Returns true if the function has a definition that does not need to be
+ /// instantiated.
+ ///
+ /// The variant that accepts a FunctionDecl pointer will set that function
+ /// declaration to the declaration that is a definition (if there is one).
bool isDefined(const FunctionDecl *&Definition) const;
virtual bool isDefined() const {
@@ -1985,8 +2001,7 @@ public:
IsLateTemplateParsed || WillHaveBody || hasDefiningAttr();
}
- /// Returns whether this specific declaration of the function has a body -
- /// that is, if it is a non-deleted definition.
+ /// Returns whether this specific declaration of the function has a body.
bool doesThisDeclarationHaveABody() const {
return Body || IsLateTemplateParsed;
}
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index a176964fc2f..62fd0207715 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -12283,9 +12283,36 @@ Sema::CheckForFunctionRedefinition(FunctionDecl *FD,
const FunctionDecl *EffectiveDefinition,
SkipBodyInfo *SkipBody) {
const FunctionDecl *Definition = EffectiveDefinition;
+ if (!Definition && !FD->isDefined(Definition) && !FD->isCXXClassMember()) {
+ // If this is a friend function defined in a class template, it does not
+ // have a body until it is used, nevertheless it is a definition, see
+ // [temp.inst]p2:
+ //
+ // ... for the purpose of determining whether an instantiated redeclaration
+ // is valid according to [basic.def.odr] and [class.mem], a declaration that
+ // corresponds to a definition in the template is considered to be a
+ // definition.
+ //
+ // The following code must produce redefinition error:
+ //
+ // template<typename T> struct C20 { friend void func_20() {} };
+ // C20<int> c20i;
+ // void func_20() {}
+ //
+ for (auto I : FD->redecls()) {
+ if (I != FD && !I->isInvalidDecl() &&
+ I->getFriendObjectKind() != Decl::FOK_None) {
+ if (FunctionDecl *Original = I->getInstantiatedFromMemberFunction()) {
+ if (Original->isThisDeclarationADefinition()) {
+ Definition = I;
+ break;
+ }
+ }
+ }
+ }
+ }
if (!Definition)
- if (!FD->isDefined(Definition))
- return;
+ return;
if (canRedefineFunction(Definition, getLangOpts()))
return;
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index d87f9dbbbea..800956dd535 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1806,45 +1806,24 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
// apply to non-template function declarations and definitions also apply
// to these implicit definitions.
if (D->isThisDeclarationADefinition()) {
- // Check for a function body.
- const FunctionDecl *Definition = nullptr;
- if (Function->isDefined(Definition) &&
- Definition->getTemplateSpecializationKind() == TSK_Undeclared) {
- SemaRef.Diag(Function->getLocation(), diag::err_redefinition)
- << Function->getDeclName();
- SemaRef.Diag(Definition->getLocation(), diag::note_previous_definition);
- }
- // Check for redefinitions due to other instantiations of this or
- // a similar friend function.
- else for (auto R : Function->redecls()) {
- if (R == Function)
- continue;
-
- // If some prior declaration of this function has been used, we need
- // to instantiate its definition.
- if (!QueuedInstantiation && R->isUsed(false)) {
- if (MemberSpecializationInfo *MSInfo =
- Function->getMemberSpecializationInfo()) {
- if (MSInfo->getPointOfInstantiation().isInvalid()) {
- SourceLocation Loc = R->getLocation(); // FIXME
- MSInfo->setPointOfInstantiation(Loc);
- SemaRef.PendingLocalImplicitInstantiations.push_back(
- std::make_pair(Function, Loc));
- QueuedInstantiation = true;
- }
- }
- }
-
- // If some prior declaration of this function was a friend with an
- // uninstantiated definition, reject it.
- if (R->getFriendObjectKind()) {
- if (const FunctionDecl *RPattern =
- R->getTemplateInstantiationPattern()) {
- if (RPattern->isDefined(RPattern)) {
- SemaRef.Diag(Function->getLocation(), diag::err_redefinition)
- << Function->getDeclName();
- SemaRef.Diag(R->getLocation(), diag::note_previous_definition);
- break;
+ SemaRef.CheckForFunctionRedefinition(Function);
+ if (!Function->isInvalidDecl()) {
+ for (auto R : Function->redecls()) {
+ if (R == Function)
+ continue;
+
+ // If some prior declaration of this function has been used, we need
+ // to instantiate its definition.
+ if (!QueuedInstantiation && R->isUsed(false)) {
+ if (MemberSpecializationInfo *MSInfo =
+ Function->getMemberSpecializationInfo()) {
+ if (MSInfo->getPointOfInstantiation().isInvalid()) {
+ SourceLocation Loc = R->getLocation(); // FIXME
+ MSInfo->setPointOfInstantiation(Loc);
+ SemaRef.PendingLocalImplicitInstantiations.push_back(
+ std::make_pair(Function, Loc));
+ QueuedInstantiation = true;
+ }
}
}
}
diff --git a/clang/test/SemaCXX/friend2.cpp b/clang/test/SemaCXX/friend2.cpp
index d1d4b628ba2..8eacdeb19c6 100644
--- a/clang/test/SemaCXX/friend2.cpp
+++ b/clang/test/SemaCXX/friend2.cpp
@@ -101,6 +101,34 @@ template<typename T> class C12 {
friend void func_12(int x = 0); // expected-error{{friend declaration specifying a default argument must be the only declaration}}
};
+// Friend function with uninstantiated body is still a definition.
+
+template<typename T> struct C20 {
+ friend void func_20() {} // expected-note{{previous definition is here}}
+};
+C20<int> c20i;
+void func_20() {} // expected-error{{redefinition of 'func_20'}}
+
+template<typename T> struct C21a {
+ friend void func_21() {} // expected-note{{previous definition is here}}
+};
+template<typename T> struct C21b {
+ friend void func_21() {} // expected-error{{redefinition of 'func_21'}}
+};
+C21a<int> c21ai;
+C21b<int> c21bi; // expected-note{{in instantiation of template class 'C21b<int>' requested here}}
+
+template<typename T> struct C22a {
+ friend void func_22() {} // expected-note{{previous definition is here}}
+};
+template<typename T> struct C22b {
+ friend void func_22();
+};
+C22a<int> c22ai;
+C22b<int> c22bi;
+void func_22() {} // expected-error{{redefinition of 'func_22'}}
+
+
namespace pr22307 {
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