[c++1z] Diagnose non-deducible template parameters in deduction guide templates, per [temp.param]p11.

llvm-svn: 295264

1 files changed, 18 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp b/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
index 011130d0e77..3d256aa6705 100644
--- a/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ b/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -150,3 +150,21 @@ namespace look_into_current_instantiation {
 
   C c = {1, 2};
 }
+
+namespace nondeducible {
+  template<typename A, typename B> struct X {};
+
+  template<typename A> // expected-note {{non-deducible template parameter 'A'}}
+  X() -> X<A, int>; // expected-error {{deduction guide template contains a template parameter that cannot be deduced}}
+
+  template<typename A> // expected-note {{non-deducible template parameter 'A'}}
+  X(typename X<A, int>::type) -> X<A, int>; // expected-error {{deduction guide template contains a template parameter that cannot be deduced}}
+
+  template<typename A = int,
+           typename B> // expected-note {{non-deducible template parameter 'B'}}
+  X(int) -> X<A, B>; // expected-error {{deduction guide template contains a template parameter that cannot be deduced}}
+
+  template<typename A = int,
+           typename ...B>
+  X(float) -> X<A, B...>; // ok
+}