[OpenCL] Improve diagnostic for placement new

Without an explicit declaration for placement new, clang would reject
uses of placement new with "'default new' is not supported in OpenCL
C++".  This may mislead users into thinking that placement new is not
supported, see e.g. PR42060.

Clarify that placement new requires an explicit declaration.

Differential Revision: https://reviews.llvm.org/D63561

llvm-svn: 364423

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index b59f3faa6e6..32b35ba7c32 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -2413,7 +2413,11 @@ bool Sema::FindAllocationFunctions(SourceLocation StartLoc, SourceRange Range,
     }
 
     if (getLangOpts().OpenCLCPlusPlus && R.empty()) {
-      Diag(StartLoc, diag::err_openclcxx_not_supported) << "default new";
+      if (PlaceArgs.empty()) {
+        Diag(StartLoc, diag::err_openclcxx_not_supported) << "default new";
+      } else {
+        Diag(StartLoc, diag::err_openclcxx_placement_new);
+      }
       return true;
     }