Tooling: When applying a set of replacements, do deletions before

insertions. It is unlikely to be the intention to delete parts of newly
inserted code. To do so, changed sorting Replacements at the same offset
to have decreasing length.

llvm-svn: 239809

clang/lib/Tooling/Core/Replacement.cpp

@@ -88,8 +88,13 @@ std::string Replacement::toString() const {
 bool operator<(const Replacement &LHS, const Replacement &RHS) {
   if (LHS.getOffset() != RHS.getOffset())
     return LHS.getOffset() < RHS.getOffset();
+
+  // Apply longer replacements first, specifically so that deletions are
+  // executed before insertions. It is (hopefully) never the intention to
+  // delete parts of newly inserted code.
   if (LHS.getLength() != RHS.getLength())
-    return LHS.getLength() < RHS.getLength();
+    return LHS.getLength() > RHS.getLength();
+
   if (LHS.getFilePath() != RHS.getFilePath())
     return LHS.getFilePath() < RHS.getFilePath();
   return LHS.getReplacementText() < RHS.getReplacementText();

clang/unittests/Tooling/RewriterTest.cpp

@@ -8,9 +8,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "RewriterTestContext.h"
+#include "clang/Tooling/Core/Replacement.h"
 #include "gtest/gtest.h"
 
 namespace clang {
+namespace tooling {
+namespace {
 
 TEST(Rewriter, OverwritesChangedFiles) {
   RewriterTestContext Context;
@@ -34,4 +37,14 @@ TEST(Rewriter, ContinuesOverwritingFilesOnError) {
             Context.getFileContentFromDisk("working.cpp")); 
 }
 
+TEST(Rewriter, AdjacentInsertAndDelete) {
+  Replacements Replaces;
+  Replaces.emplace("<file>", 6, 6, "");
+  Replaces.emplace("<file>", 6, 0, "replaced\n");
+  EXPECT_EQ("line1\nreplaced\nline3\nline4",
+            applyAllReplacements("line1\nline2\nline3\nline4", Replaces));
+}
+
+} // end namespace
+} // end namespace tooling
 } // end namespace clang