Implement C++ core issue 974, which permits default arguments for

lambda expressions. Because these issue was pulled back from Ready
status at the Kona meeting, we still emit an ExtWarn when using
default arguments for lambda expressions.

llvm-svn: 150519

1 files changed, 15 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 84063e5fd0f..624dc5d1e6f 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -585,11 +585,25 @@ void Sema::CheckCXXDefaultArguments(FunctionDecl *FD) {
   unsigned NumParams = FD->getNumParams();
   unsigned p;
 
+  bool IsLambda = FD->getOverloadedOperator() == OO_Call &&
+                  isa<CXXMethodDecl>(FD) &&
+                  cast<CXXMethodDecl>(FD)->getParent()->isLambda();
+              
   // Find first parameter with a default argument
   for (p = 0; p < NumParams; ++p) {
     ParmVarDecl *Param = FD->getParamDecl(p);
-    if (Param->hasDefaultArg())
+    if (Param->hasDefaultArg()) {
+      // C++11 [expr.prim.lambda]p5:
+      //   [...] Default arguments (8.3.6) shall not be specified in the 
+      //   parameter-declaration-clause of a lambda-declarator.
+      //
+      // FIXME: Core issue 974 strikes this sentence, we only provide an
+      // extension warning.
+      if (IsLambda)
+        Diag(Param->getLocation(), diag::ext_lambda_default_arguments)
+          << Param->getDefaultArgRange();
       break;
+    }
   }
 
   // C++ [dcl.fct.default]p4: