[Sema] Diagnose references to unbound arrays in function definitions

A [*] is only allowed in a declaration for a function, not in its
definition.  We didn't correctly recurse on reference types while
looking for it, causing us to crash in CodeGen instead of rejecting it.

llvm-svn: 234528

clang/lib/Sema/SemaChecking.cpp

@@ -7713,6 +7713,10 @@ static void diagnoseArrayStarInParamType(Sema &S, QualType PType,
     diagnoseArrayStarInParamType(S, PointerTy->getPointeeType(), Loc);
     return;
   }
+  if (const auto *ReferenceTy = dyn_cast<ReferenceType>(PType)) {
+    diagnoseArrayStarInParamType(S, ReferenceTy->getPointeeType(), Loc);
+    return;
+  }
   if (const auto *ParenTy = dyn_cast<ParenType>(PType)) {
     diagnoseArrayStarInParamType(S, ParenTy->getInnerType(), Loc);
     return;

clang/test/SemaCXX/vla.cpp

@@ -17,3 +17,6 @@ namespace PR18581 {
     incomplete c[n]; // expected-error {{incomplete}}
   }
 }
+
+void pr23151(int (&)[*]) { // expected-error {{variable length array must be bound in function definition}}
+}