[Sema] Fix an assert when objc_externally_retained was applied to an unprototyped function
rdar://58893199
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index cf3fa38..3a6c2af 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -6561,7 +6561,9 @@
// If D is a function-like declaration (method, block, or function), then we
// make every parameter psuedo-strong.
- for (unsigned I = 0, E = getFunctionOrMethodNumParams(D); I != E; ++I) {
+ unsigned NumParams =
+ hasFunctionProto(D) ? getFunctionOrMethodNumParams(D) : 0;
+ for (unsigned I = 0; I != NumParams; ++I) {
auto *PVD = const_cast<ParmVarDecl *>(getFunctionOrMethodParam(D, I));
QualType Ty = PVD->getType();