PR35045: Convert injected-class-name to its corresponding simple-template-id

during template argument deduction.

We already did this when the injected-class-name was in P, but missed the case
where it was in A. This (probably) can't happen except in implicit deduction
guides.

llvm-svn: 321779

2 files changed, 15 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 3a0f2ff..d09cf99 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -502,6 +502,10 @@ DeduceTemplateArguments(Sema &S,
                         SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
   assert(Arg.isCanonical() && "Argument type must be canonical");
 
+  // Treat an injected-class-name as its underlying template-id.
+  if (auto *Injected = dyn_cast<InjectedClassNameType>(Arg))
+    Arg = Injected->getInjectedSpecializationType();
+
   // Check whether the template argument is a dependent template-id.
   if (const TemplateSpecializationType *SpecArg
         = dyn_cast<TemplateSpecializationType>(Arg)) {
diff --git a/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp b/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
index 9080f67..d21fbf2 100644
--- a/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ b/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -309,6 +309,17 @@ namespace dependent {
   template int New(int);
 }
 
+namespace injected_class_name {
+  template<typename T = void> struct A {
+    A();
+    template<typename U> A(A<U>);
+  };
+  A<int> a;
+  A b = a;
+  using T = decltype(a);
+  using T = decltype(b);
+}
+
 #else
 
 // expected-no-diagnostics