Fix a constexpr FIXME: When implicitly instantiating the primary template for an
explicit specialization of a function template, mark the instantiation as
constexpr if the specialization is, rather than requiring them to match.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151001 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 17bdd69..2c98d0a 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -5677,8 +5677,13 @@
   // Note: do not overwrite location info if previous template
   // specialization kind was explicit.
   TemplateSpecializationKind TSK = SpecInfo->getTemplateSpecializationKind();
-  if (TSK == TSK_Undeclared || TSK == TSK_ImplicitInstantiation)
+  if (TSK == TSK_Undeclared || TSK == TSK_ImplicitInstantiation) {
     Specialization->setLocation(FD->getLocation());
+    // C++11 [dcl.constexpr]p1: An explicit specialization of a constexpr
+    // function can differ from the template declaration with respect to
+    // the constexpr specifier.
+    Specialization->setConstexpr(FD->isConstexpr());
+  }
 
   // FIXME: Check if the prior specialization has a point of instantiation.
   // If so, we have run afoul of .