Skip parameter replacements where old text != old name.

tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp

Index: tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
diff --git a/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp b/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
index dddccd1741bb968b0c99fec10af2bda8a3a5ec5a..9679c9ff5d80480c4e56aebd53648424f53ffbbb 100644
--- a/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
+++ b/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
@@ -342,8 +342,21 @@ bool GetNameForDecl(const clang::VarDecl& decl,
   StringRef original_name = decl.getName();
 
   // Nothing to do for unnamed parameters.
-  if (clang::isa<clang::ParmVarDecl>(decl) && original_name.empty())
-    return false;
+  if (clang::isa<clang::ParmVarDecl>(decl)) {
+    if (original_name.empty())
+      return false;
+
+    // Check if |decl| really covers text of |original_name|.  This might not be
+    // true when specializing a templatized class that had an unnamed parameter
+    // in one of method declarations.

[dcheng, 2016/08/25 04:08:51]

Let's file an upstream bug for this with the test case and reference it here: we
end up matching a ParmVarDecl for an unnamed thingie, but somehow it has a name.

[Łukasz Anforowicz, 2016/08/25 23:32:33]

Done: https://llvm.org/bugs/show_bug.cgi?id=29145

+    clang::SourceLocation loc = decl.getLocation();
+    clang::CharSourceRange range = clang::CharSourceRange::getTokenRange(loc);
+    StringRef old_text = clang::Lexer::getSourceText(
+        range, context.getSourceManager(), context.getLangOpts());
+    if (!loc.isMacroID() && old_text != original_name) {

[dcheng, 2016/08/25 04:08:52]

Add a comment why we want to ignore SourceLocations that are in macros.

[Łukasz Anforowicz, 2016/08/25 23:32:33]

I've started using spelling location in the latest patchset - this lets me also
remove isMacroID call.  So - the comment above is no longer applicable.

+      return false;
+    }
+  }
 
   // static class members match against VarDecls. Blink style dictates that
   // these should be prefixed with `s_`, so strip that off. Also check for `m_`