Don't generate no-op replacements.

No functional changes.

llvm-svn: 173916

2 files changed, 21 insertions, 0 deletions

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 9dfde34e8b5..08ea8e97de5 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -194,6 +194,11 @@ private:
   /// \brief Stores \p Text as the replacement for the whitespace in front of
   /// \p Tok.
   void storeReplacement(const FormatToken &Tok, const std::string Text) {
+    // Don't create a replacement, if it does not change anything.
+    if (StringRef(SourceMgr.getCharacterData(Tok.WhiteSpaceStart),
+                  Tok.WhiteSpaceLength) == Text)
+      return;
+
     Replaces.insert(tooling::Replacement(SourceMgr, Tok.WhiteSpaceStart,
                                          Tok.WhiteSpaceLength, Text));
   }
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 32b2ff7f750..97358982cf6 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -38,6 +38,7 @@ protected:
     tooling::Replacements Replace = reformat(Style, Lex, Context.Sources,
                                              Ranges,
                                              new IgnoringDiagConsumer());
+    ReplacementCount = Replace.size();
     EXPECT_TRUE(applyAllReplacements(Replace, Context.Rewrite));
     DEBUG(llvm::errs() << "\n" << Context.getRewrittenText(ID) << "\n\n");
     return Context.getRewrittenText(ID);
@@ -105,6 +106,8 @@ protected:
     verifyFormat(text);
     verifyFormat(llvm::Twine("void f() { " + text + " }").str());
   }
+
+  int ReplacementCount;
 };
 
 TEST_F(FormatTest, MessUp) {
@@ -148,6 +151,19 @@ TEST_F(FormatTest, ImportantSpaces) {
   verifyFormat("vector< ::Type> v;");
 }
 
+TEST_F(FormatTest, OnlyGeneratesNecessaryReplacements) {
+  EXPECT_EQ("if (a) {\n"
+            "  f();\n"
+            "}", format("if(a){f();}"));
+  EXPECT_EQ(4, ReplacementCount);
+  EXPECT_EQ("if (a) {\n"
+            "  f();\n"
+            "}", format("if (a) {\n"
+                        "  f();\n"
+                        "}"));
+  EXPECT_EQ(0, ReplacementCount);
+}
+
 //===----------------------------------------------------------------------===//
 // Tests for control statements.
 //===----------------------------------------------------------------------===//