Fix RawStringLiteral being available to C and C++ versions prior to C++11

Author: robozati

clang-tools-extra/clangd/refactor/tweaks/RawStringLiteral.cpp

@@ -43,6 +43,12 @@ class RawStringLiteral : public Tweak {
 
 REGISTER_TWEAK(RawStringLiteral)
 
+static bool isFeatureAvailable(const Tweak::Selection &Inputs) {
+  // Raw strings are available only for C++11 or later versions, and they are
+  // not available for C.
+  return Inputs.AST->getASTContext().getLangOpts().CPlusPlus11;
+}
+
 static bool isNormalString(const StringLiteral &Str, SourceLocation Cursor,
                           SourceManager &SM) {
   // All chunks must be normal ASCII strings, not u8"..." etc.
@@ -76,7 +82,7 @@ bool RawStringLiteral::prepare(const Selection &Inputs) {
   if (!N)
     return false;
   Str = dyn_cast_or_null<StringLiteral>(N->ASTNode.get<Stmt>());
-  return Str &&
+  return Str && isFeatureAvailable(Inputs) &&
          isNormalString(*Str, Inputs.Cursor, Inputs.AST->getSourceManager()) &&
          needsRaw(Str->getBytes()) && canBeRaw(Str->getBytes());
 }

clang-tools-extra/clangd/unittests/tweaks/RawStringLiteralTests.cpp

@@ -36,6 +36,24 @@ literal)")cpp";
   EXPECT_EQ(apply(Input), Output);
 }
 
+TEST_F(RawStringLiteralTest, TestC) {
+  Context = File;
+  FileName = "TestTU.c";
+  ExtraArgs = {"-xc"}; // raw strings are unavailable in C
+  EXPECT_UNAVAILABLE(R"c(
+    const char* a = "^f^o^o^\^n^";
+  )c");
+}
+
+TEST_F(RawStringLiteralTest, TestCpp98) {
+  Context = File;
+  ExtraArgs = {"-std=c++98"}; // raw strings are unavailable
+                              // in versions prior to C++11
+  EXPECT_UNAVAILABLE(R"cpp(
+    const char* a = "^f^o^o^\^n^";
+  )cpp");
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang