From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Sat, 14 Dec 2013 03:18:05 +0000 (+0000)
Subject: PR18246: When performing template argument deduction to decide which template
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b300e5bbaa71a937629ab0f6034d434f75363bd6;p=clang

PR18246: When performing template argument deduction to decide which template
is specialized by an explicit specialization, start from the first declaration
in case we've got a member of a class template (redeclarations might not number
the template parameters the same way).

Our recover here is still far from ideal.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197305 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index b134f6ea51..e4fa380c3d 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -6521,9 +6521,9 @@ bool Sema::CheckFunctionTemplateSpecialization(
       // FIXME: It is somewhat wasteful to build
       TemplateDeductionInfo Info(FailedCandidates.getLocation());
       FunctionDecl *Specialization = 0;
-      if (TemplateDeductionResult TDK
-            = DeduceTemplateArguments(FunTmpl, ExplicitTemplateArgs, FT,
-                                      Specialization, Info)) {
+      if (TemplateDeductionResult TDK = DeduceTemplateArguments(
+              cast<FunctionTemplateDecl>(FunTmpl->getFirstDecl()),
+              ExplicitTemplateArgs, FT, Specialization, Info)) {
         // Template argument deduction failed; record why it failed, so
         // that we can provide nifty diagnostics.
         FailedCandidates.addCandidate()
diff --git a/test/SemaTemplate/explicit-specialization-member.cpp b/test/SemaTemplate/explicit-specialization-member.cpp
index 9ddbc04953..07d7389446 100644
--- a/test/SemaTemplate/explicit-specialization-member.cpp
+++ b/test/SemaTemplate/explicit-specialization-member.cpp
@@ -28,3 +28,22 @@ namespace PR12331 {
   };
   template<> struct S<int>::U { static const int n = sizeof(int); }; // expected-error {{explicit specialization of 'U' after instantiation}}
 }
+
+namespace PR18246 {
+  template<typename T>
+  class Baz {
+  public:
+    template<int N> void bar();
+  };
+
+  template<typename T>
+  template<int N>
+  void Baz<T>::bar() {
+  }
+
+  // FIXME: Don't suggest the 'template<>' correction here, because this cannot
+  // be an explicit specialization.
+  template<typename T>
+  void Baz<T>::bar<0>() { // expected-error {{requires 'template<>'}}
+  }
+}