[CodeComplete] Fix crash when completing ObjC block parameter with a broken type

Summary:
The fix isn't great, but it's hard to fix properly because the completion
code sensibly uses ParmVarDecl to represent parameters, but the AST-building
code sensibly doesn't synthesize them if the type is broken.
Also this case is apparently really rare, so it's probably not worth bending
over backwards for.

Reviewers: ilya-biryukov

Subscribers: javed.absar, kristof.beyls, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60258

llvm-svn: 357686

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 2412d919ec9..8d953308d81 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -2605,6 +2605,11 @@ static std::string
 FormatFunctionParameter(const PrintingPolicy &Policy, const ParmVarDecl *Param,
                         bool SuppressName = false, bool SuppressBlock = false,
                         Optional<ArrayRef<QualType>> ObjCSubsts = None) {
+  // Params are unavailable in FunctionTypeLoc if the FunctionType is invalid.
+  // It would be better to pass in the param Type, which is usually avaliable.
+  // But this case is rare, so just pretend we fell back to int as elsewhere.
+  if (!Param)
+    return "int";
   bool ObjCMethodParam = isa<ObjCMethodDecl>(Param->getDeclContext());
   if (Param->getType()->isDependentType() ||
       !Param->getType()->isBlockPointerType()) {