Fixed Use-Nullptr when replacing return(0)

Before fix, the paren expression was being replaced resulting in returnnullptr.
ParenExpr and implicit casts now ignored so we get return(nullptr) instead.

Added new test cases.

Fixes PR15398

Author: Ariel Bernal <ariel.j.bernal@intel.com>
llvm-svn: 176551

clang-tools-extra/cpp11-migrate/UseNullptr/NullptrActions.cpp

@@ -110,8 +110,10 @@ void NullptrFixer::run(const ast_matchers::MatchFinder::MatchResult &Result) {
 
   const CastExpr *Cast = Result.Nodes.getNodeAs<CastExpr>(ImplicitCastNode);
   if (Cast) {
-    SourceLocation StartLoc = Cast->getLocStart();
-    SourceLocation EndLoc = Cast->getLocEnd();
+    const Expr *E = Cast->IgnoreParenImpCasts();
+
+    SourceLocation StartLoc = E->getLocStart();
+    SourceLocation EndLoc = E->getLocEnd();
 
     // If the start/end location is a macro, get the expansion location.
     StartLoc = SM.getFileLoc(StartLoc);

clang-tools-extra/test/cpp11-migrate/UseNullptr/basic.cpp

@@ -204,3 +204,34 @@ void test_function_like_macro2() {
   // CHECK: my_macro(p != nullptr);
 #undef my_macro
 }
+
+// Test parentheses expressions resulting in a nullptr.
+int *test_parentheses_expression1() {
+  return(0);
+  // CHECK: return(nullptr);
+}
+
+int *test_parentheses_expression2() {
+  return(int(0.f));
+  // CHECK: return(nullptr);
+}
+
+int *test_nested_parentheses_expression() {
+  return((((0))));
+  // CHECK: return((((nullptr))));
+}
+
+void *test_parentheses_explicit_cast() {
+  return(static_cast<void*>(0));
+  // CHECK: return(nullptr);
+}
+
+void *test_parentheses_explicit_cast_sequence1() {
+  return(static_cast<void*>(static_cast<int*>((void*)NULL)));
+  // CHECK: return(nullptr);
+}
+
+void *test_parentheses_explicit_cast_sequence2() {
+  return(static_cast<void*>(reinterpret_cast<int*>((float*)int(0.f))));
+  // CHECK: return(nullptr);
+}