r319584 - [c++17] When deducing the type of a non-type template parameter from the type

[Richard Smith via cfe-commits]

Author: rsmith
Date: Fri Dec  1 13:24:36 2017
New Revision: 319584

URL: http://llvm.org/viewvc/llvm-project?rev=319584&view=rev
Log:
[c++17] When deducing the type of a non-type template parameter from the type
of its argument, perform function-to-pointer and array-to-pointer decay on the
parameter type first.

Otherwise deduction will fail, as the type of the argument will be decayed.

Modified:
    cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
    cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp

Modified: cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp?rev=319584&r1=319583&r2=319584&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp Fri Dec  1 13:24:36 2017
@@ -354,8 +354,9 @@ static Sema::TemplateDeductionResult Ded
     // expanded NTTP should be a pack expansion type?
     return Sema::TDK_Success;
 
-  // Get the type of the parameter for deduction.
-  QualType ParamType = NTTP->getType();
+  // Get the type of the parameter for deduction. If it's a (dependent) array
+  // or function type, we will not have decayed it yet, so do that now.
+  QualType ParamType = S.Context.getAdjustedParameterType(NTTP->getType());
   if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
     ParamType = Expansion->getPattern();
 

Modified: cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp?rev=319584&r1=319583&r2=319584&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp (original)
+++ cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp Fri Dec  1 13:24:36 2017
@@ -238,6 +238,10 @@ namespace Auto {
     constexpr char s[] = "test";
     template<const auto* p> struct S { };
     S<s> p;
+
+    template<typename R, typename P, R F(P)> struct A {};
+    template<typename R, typename P, R F(P)> void x(A<R, P, F> a);
+    void g(int) { x(A<void, int, &g>()); }
   }
 
   namespace DecltypeAuto {