Fix crash when rewriting call to match placeholder

[amilburn]

Summary

If an argument is a placeholder, rewriteBuiltinFunctionDecl should skip it when trying to rewrite address spaces.

This situation can happen because not all placeholders are rejected by ActOnCallExpr. The supplied test passes it an UnresolvedLookupExpr with overload type.

Fixes PR25961.

[arphaman]

This has already been fixed in r276352. I closed PR25961.

lib/Sema/SemaExpr.cpp

static FunctionDecl *rewriteBuiltinFunctionDecl(Sema *Sema, ASTContext &Context,
 
   bool NeedsNewDecl = false;
   unsigned i = 0;
   SmallVector<QualType, 8> OverloadParams;
 
   for (QualType ParamType : FT->param_types()) {
 
     // Convert array arguments to pointer to simplify type lookup.
-    Expr *Arg = Sema->DefaultFunctionArrayLvalueConversion(ArgExprs[i++]).get();
+    ExprResult R = Sema->DefaultFunctionArrayLvalueConversion(ArgExprs[i++]);
+    if (R.isInvalid())
+      continue;
+    Expr *Arg = R.get();
     QualType ArgType = Arg->getType();
     if (!ParamType->isPointerType() ||
         ParamType.getQualifiers().hasAddressSpace() ||
         !ArgType->isPointerType() ||
         !ArgType->getPointeeType().getQualifiers().hasAddressSpace()) {
       OverloadParams.push_back(ParamType);
       continue;
     }

test/Sema/implicit-function-typo-crash.c

+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// PR25961
+void free(); // expected-note {{'free' declared here}}
+int main() {
+  strcpy(file, 0); // expected-warning {{implicitly declaring library function 'strcpy' with type}} \
+  // expected-note {{include the header <string.h>}} \
+  // expected-error {{use of undeclared identifier 'file'; did you mean 'free'}}
+}