clang-format: [JS] do not clean up duplicated commas.

Summary:
In JavaScript, duplicated commas have semantic meaning.
    x = [a,,b];

The statement above creates an array with three entries, the middle being undefined. Because clang-format should not change semantics, disable this cleanup in JS.

Reviewers: djasper

Subscribers: klimek

Differential Revision: https://reviews.llvm.org/D33641

llvm-svn: 304141

clang/lib/Format/Format.cpp

@@ -1910,6 +1910,9 @@ tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
 tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code,
                               ArrayRef<tooling::Range> Ranges,
                               StringRef FileName) {
+  // cleanups only apply to C++ (they mostly concern ctor commas etc.)
+  if (Style.Language != FormatStyle::LK_Cpp)
+    return tooling::Replacements();
   std::unique_ptr<Environment> Env =
       Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
   Cleaner Clean(*Env, Style);

clang/unittests/Format/CleanupTest.cpp

@@ -36,11 +36,12 @@ protected:
 
   // Returns code after cleanup around \p Offsets.
   std::string cleanupAroundOffsets(llvm::ArrayRef<unsigned> Offsets,
-                                   llvm::StringRef Code) {
+                                   llvm::StringRef Code,
+                                   const FormatStyle &Style = getLLVMStyle()) {
     std::vector<tooling::Range> Ranges;
     for (auto Offset : Offsets)
       Ranges.push_back(tooling::Range(Offset, 0));
-    return cleanup(Code, Ranges);
+    return cleanup(Code, Ranges, Style);
   }
 };
 
@@ -171,6 +172,14 @@ TEST_F(CleanupTest, ListRedundantComma) {
   EXPECT_EQ(Expected, cleanupAroundOffsets({17, 22}, Code));
 }
 
+TEST_F(CleanupTest, NoCleanupsForJavaScript) {
+  std::string Code = "function f() { var x = [a, b, , c]; }";
+  std::string Expected = "function f() { var x = [a, b, , c]; }";
+  const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript);
+
+  EXPECT_EQ(Expected, cleanupAroundOffsets({30}, Code, Style));
+}
+
 TEST_F(CleanupTest, TrailingCommaInParens) {
   std::string Code = "int main() { f(,1,,2,3,f(1,2,),4,,);}";
   std::string Expected = "int main() { f(1,2,3,f(1,2),4);}";