erik.pilkington updated this revision to Diff 168939.
erik.pilkington added a comment.
Merge the common pointers rather than trying to use the previous one. Thanks!
https://reviews.llvm.org/D53046
Files:
clang/include/clang/AST/DeclTemplate.h
clang/lib/AST/DeclTemplate.cpp
clang/lib/Sema/SemaDecl.cpp
clang/test/SemaCXX/friend-template-redecl.cpp
Index: clang/test/SemaCXX/friend-template-redecl.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/friend-template-redecl.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -std=c++17 -verify -emit-llvm-only %s
+
+// expected-no-diagnostics
+
+template <class T> void bar(const T &t) { foo(t); }
+
+template <class>
+struct HasFriend {
+ template <class T>
+ friend void foo(const HasFriend<T> &m) noexcept(false);
+};
+
+template <class T>
+void foo(const HasFriend<T> &m) noexcept(false) {}
+
+void f() {
+ HasFriend<int> x;
+ foo(x);
+ bar(x);
+}
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -10022,11 +10022,17 @@
if (FunctionTemplateDecl *OldTemplateDecl =
dyn_cast<FunctionTemplateDecl>(OldDecl)) {
auto *OldFD = OldTemplateDecl->getTemplatedDecl();
- NewFD->setPreviousDeclaration(OldFD);
- adjustDeclContextForDeclaratorDecl(NewFD, OldFD);
FunctionTemplateDecl *NewTemplateDecl
= NewFD->getDescribedFunctionTemplate();
assert(NewTemplateDecl && "Template/non-template mismatch");
+
+ // The call to MergeFunctionDecl above may have created some state in
+ // NewTemplateDecl that needs to be merged with OldTemplateDecl before we
+ // can add it as a redeclaration.
+ NewTemplateDecl->mergePrevDecl(OldTemplateDecl);
+
+ NewFD->setPreviousDeclaration(OldFD);
+ adjustDeclContextForDeclaratorDecl(NewFD, OldFD);
if (NewFD->isCXXClassMember()) {
NewFD->setAccess(OldTemplateDecl->getAccess());
NewTemplateDecl->setAccess(OldTemplateDecl->getAccess());
Index: clang/lib/AST/DeclTemplate.cpp
===================================================================
--- clang/lib/AST/DeclTemplate.cpp
+++ clang/lib/AST/DeclTemplate.cpp
@@ -300,6 +300,42 @@
return llvm::makeArrayRef(CommonPtr->InjectedArgs, Params->size());
}
+void FunctionTemplateDecl::mergePrevDecl(FunctionTemplateDecl *Prev) {
+ using Base = RedeclarableTemplateDecl;
+
+ // If we haven't created a common pointer yet, then it can just be created
+ // with the usual method.
+ if (!Base::Common)
+ return;
+
+ Common *ThisCommon = static_cast<Common *>(Base::Common);
+ Common *PrevCommon = nullptr;
+ SmallVector<FunctionTemplateDecl *, 8> PreviousDecls;
+ for (; Prev; Prev = Prev->getPreviousDecl()) {
+ if (Prev->Base::Common) {
+ PrevCommon = static_cast<Common *>(Prev->Base::Common);
+ break;
+ }
+ PreviousDecls.push_back(Prev);
+ }
+
+ // If the previous redecl chain hasn't created a common pointer yet, then just
+ // use this common pointer.
+ if (!PrevCommon) {
+ for (auto *D : PreviousDecls)
+ D->Base::Common = ThisCommon;
+ return;
+ }
+
+ // Ensure we don't leak any important state.
+ assert(ThisCommon->Specializations.size() == 0 &&
+ !ThisCommon->InstantiatedFromMember.getPointer() &&
+ !ThisCommon->InstantiatedFromMember.getInt() &&
+ "Can't merge incompatible declarations!");
+
+ Base::Common = PrevCommon;
+}
+
//===----------------------------------------------------------------------===//
// ClassTemplateDecl Implementation
//===----------------------------------------------------------------------===//
Index: clang/include/clang/AST/DeclTemplate.h
===================================================================
--- clang/include/clang/AST/DeclTemplate.h
+++ clang/include/clang/AST/DeclTemplate.h
@@ -1093,6 +1093,9 @@
/// template.
ArrayRef<TemplateArgument> getInjectedTemplateArgs();
+ /// Merge our RedeclarableTemplateDecl::Common with \param Prev.
+ void mergePrevDecl(FunctionTemplateDecl *Prev);
+
/// Create a function template node.
static FunctionTemplateDecl *Create(ASTContext &C, DeclContext *DC,
SourceLocation L,
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