P0426: Make the library implementation of constexpr char_traits a little easier

by providing a memchr builtin that returns char* instead of void*.

Also add a __has_feature flag to indicate the presence of constexpr forms of
the relevant <string> functions.

llvm-svn: 292555

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 2ede1d46b3d..b3d02f1f51c 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1189,6 +1189,10 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
     return RValue::get(Dest.getPointer());
   }
 
+  case Builtin::BI__builtin_char_memchr:
+    BuiltinID = Builtin::BI__builtin_memchr;
+    break;
+
   case Builtin::BI__builtin___memcpy_chk: {
     // fold __builtin_memcpy_chk(x, y, cst1, cst2) to memcpy iff cst1<=cst2.
     llvm::APSInt Size, DstSize;