[Sema] Fix an assert-on-invalid by avoiding function template specialisation

deduction for invalid functions

The fabricated template parameters cause an assertion because their depth
is invalid.

rdar://34109988

Differential Revision: https://reviews.llvm.org/D37341


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@316778 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDecl.cpp

@@ -8962,10 +8962,10 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
           diag::ext_function_specialization_in_class :
           diag::err_function_specialization_in_class)
           << NewFD->getDeclName();
-      } else if (CheckFunctionTemplateSpecialization(NewFD,
-                                  (HasExplicitTemplateArgs ? &TemplateArgs
-                                                           : nullptr),
-                                                     Previous))
+      } else if (!NewFD->isInvalidDecl() &&
+                 CheckFunctionTemplateSpecialization(
+                     NewFD, (HasExplicitTemplateArgs ? &TemplateArgs : nullptr),
+                     Previous))
         NewFD->setInvalidDecl();
 
       // C++ [dcl.stc]p1:

test/SemaTemplate/deduction-crash.cpp

@@ -144,3 +144,20 @@ namespace var_template_partial_spec_incomplete {
   template<typename T, typename U = void> int n<T *>; // expected-error +{{}} expected-note {{}}
   int k = n<void *>;
 }
+
+namespace deduceFunctionSpecializationForInvalidOutOfLineFunction {
+
+template <typename InputT, typename OutputT>
+struct SourceSelectionRequirement {
+  template<typename T>
+  OutputT evaluateSelectionRequirement(InputT &&Value) {
+  }
+};
+
+template <typename InputT, typename OutputT>
+OutputT SourceSelectionRequirement<InputT, OutputT>::
+evaluateSelectionRequirement<void>(InputT &&Value) { // expected-error {{cannot specialize a member of an unspecialized template}}
+  return Value;
+}
+
+}

test/SemaTemplate/explicit-specialization-member.cpp

@@ -38,24 +38,20 @@ namespace PR18246 {
 
   template<typename T>
   template<int N>
-  void Baz<T>::bar() { // expected-note {{couldn't infer template argument 'N'}}
+  void Baz<T>::bar() {
   }
 
-  // FIXME: We shouldn't try to match this against a prior declaration if
-  // template parameter matching failed.
   template<typename T>
-  void Baz<T>::bar<0>() { // expected-error {{cannot specialize a member of an unspecialized template}} \
-                          // expected-error {{no function template matches}}
+  void Baz<T>::bar<0>() { // expected-error {{cannot specialize a member of an unspecialized template}}
   }
 }
 
 namespace PR19340 {
 template<typename T> struct Helper {
-  template<int N> static void func(const T *m) {} // expected-note {{failed template argument deduction}}
+  template<int N> static void func(const T *m) {}
 };
 
-template<typename T> void Helper<T>::func<2>() {} // expected-error {{cannot specialize a member}} \
-                                                  // expected-error {{no function template matches}}
+template<typename T> void Helper<T>::func<2>() {} // expected-error {{cannot specialize a member}}
 }
 
 namespace SpecLoc {