Mordante created this revision.
Mordante added reviewers: sepavloff, rsmith.
Mordante added a project: clang.
This fixes https://bugs.llvm.org/show_bug.cgi?id=28500
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D65694
Files:
clang/lib/Sema/SemaTemplateInstantiate.cpp
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
clang/test/SemaTemplate/default-arguments-cxx0x.cpp
Index: clang/test/SemaTemplate/default-arguments-cxx0x.cpp
===================================================================
--- clang/test/SemaTemplate/default-arguments-cxx0x.cpp
+++ clang/test/SemaTemplate/default-arguments-cxx0x.cpp
@@ -114,3 +114,34 @@
S<int> _a{};
};
}
+
+// https://bugs.llvm.org/show_bug.cgi?id=28500
+// Failure to resolve the decltype part during instantiation caused an
+// assertion failure
+namespace PR28500 {
+namespace original {
+template <class T>
+void bar(T t = [](decltype(t) i) { return 0; }(0)) {}
+void foo() {
+ bar<int>();
+}
+} // namespace original
+
+namespace cast {
+template <class T>
+void bar(T t = decltype(t)(0)) {}
+void foo() {
+ bar<int>();
+ bar<double>();
+}
+} // namespace cast
+
+namespace value {
+template <class T>
+void bar(T t = decltype(t)()) {}
+void foo() {
+ bar<int>();
+ bar<double>();
+}
+} // namespace value
+} // namespace PR28500
Index: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -5287,29 +5287,33 @@
// }
//
// In this case instantiation of the type of 'g1' requires definition of
- // 'x1', which is defined later. Error recovery may produce an enum used
- // before definition. In these cases we need to instantiate relevant
- // declarations here.
+ // 'x1', which is defined later.
+ //
+ // Error recovery may produce an enum used before definition.
+ //
+ // Default arguments with a decltype referencing arguments:
+ //
+ // template <class T> void bar(T t = decltype(t)()) {}
+ //
+ // Else we must have a label decl that hasn't been found yet.
+ //
+ // In these cases we need to instantiate relevant declarations here.
bool NeedInstantiate = false;
if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D))
NeedInstantiate = RD->isLocalClass();
else
- NeedInstantiate = isa<EnumDecl>(D);
+ NeedInstantiate =
+ isa<EnumDecl>(D) || isa<LabelDecl>(D) || isa<ParmVarDecl>(D);
if (NeedInstantiate) {
Decl *Inst = SubstDecl(D, CurContext, TemplateArgs);
+ assert(Inst && "Failed to instantiate");
CurrentInstantiationScope->InstantiatedLocal(D, Inst);
- return cast<TypeDecl>(Inst);
+ return cast<NamedDecl>(Inst);
}
- // If we didn't find the decl, then we must have a label decl that hasn't
- // been found yet. Lazily instantiate it and return it now.
- assert(isa<LabelDecl>(D));
-
- Decl *Inst = SubstDecl(D, CurContext, TemplateArgs);
- assert(Inst && "Failed to instantiate label??");
+ assert(0 && "Failed to instantiate");
- CurrentInstantiationScope->InstantiatedLocal(D, Inst);
- return cast<LabelDecl>(Inst);
+ return nullptr;
}
if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2974,6 +2974,11 @@
if (isa<EnumDecl>(D))
return nullptr;
+ // Default arguments with a decltype referencing arguments prior to definition
+ // may require instantiation.
+ if (isa<ParmVarDecl>(D))
+ return nullptr;
+
// If we didn't find the decl, then we either have a sema bug, or we have a
// forward reference to a label declaration. Return null to indicate that
// we have an uninstantiated label.
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