Avoid crash if default argument parsed with errors.

If function parameters have default values, and that of the second
parameter is parsed with errors, function declaration would have
a parameter without default value that follows a parameter with
that. Such declaration breaks logic of selecting overloaded
function. As a solution, put opaque object as default value in such case.

This patch fixes PR20055.

Differential Revision: http://reviews.llvm.org/D4378

llvm-svn: 213594

1 files changed, 4 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index a0534ff31f6..c5cd83da59d 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -344,13 +344,16 @@ void Sema::ActOnParamUnparsedDefaultArgument(Decl *param,
 
 /// ActOnParamDefaultArgumentError - Parsing or semantic analysis of
 /// the default argument for the parameter param failed.
-void Sema::ActOnParamDefaultArgumentError(Decl *param) {
+void Sema::ActOnParamDefaultArgumentError(Decl *param,
+                                          SourceLocation EqualLoc) {
   if (!param)
     return;
 
   ParmVarDecl *Param = cast<ParmVarDecl>(param);
   Param->setInvalidDecl();
   UnparsedDefaultArgLocs.erase(Param);
+  Param->setDefaultArg(new(Context)
+                       OpaqueValueExpr(EqualLoc, Param->getType(), VK_RValue));
 }
 
 /// CheckExtraCXXDefaultArguments - Check for any extra default