[clang-format] Do not emit replacements if Java imports are OK

Summary:
Currently clang-format would always emit a replacement for a block of Java imports even if it is correctly formatted:
```
% cat /tmp/Aggregator.java
import X;
% clang-format /tmp/Aggregator.java
import X;
% clang-format -output-replacements-xml /tmp/Aggregator.java
<?xml version='1.0'?>
<replacements xml:space='preserve' incomplete_format='false'>
<replacement offset='0' length='9'>import X;</replacement>
</replacements>
%
```
This change makes clang-format not emit replacements in this case. Note that
there is logic to not emit replacements in this case for C++.

Reviewers: ioeric

Reviewed By: ioeric

Subscribers: jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58436

llvm-svn: 354452

1 files changed, 13 insertions, 7 deletions

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 9575699cf82..9feffeb96cb 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -1853,6 +1853,7 @@ static unsigned findJavaImportGroup(const FormatStyle &Style,
 static void sortJavaImports(const FormatStyle &Style,
                             const SmallVectorImpl<JavaImportDirective> &Imports,
                             ArrayRef<tooling::Range> Ranges, StringRef FileName,
+                            StringRef Code,
                             tooling::Replacements &Replaces) {
   unsigned ImportsBeginOffset = Imports.front().Offset;
   unsigned ImportsEndOffset =
@@ -1868,12 +1869,12 @@ static void sortJavaImports(const FormatStyle &Style,
         findJavaImportGroup(Style, Imports[i].Identifier));
   }
   llvm::sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
-        // Negating IsStatic to push static imports above non-static imports.
-        return std::make_tuple(!Imports[LHSI].IsStatic, JavaImportGroups[LHSI],
-                               Imports[LHSI].Identifier) <
-               std::make_tuple(!Imports[RHSI].IsStatic, JavaImportGroups[RHSI],
-                               Imports[RHSI].Identifier);
-      });
+    // Negating IsStatic to push static imports above non-static imports.
+    return std::make_tuple(!Imports[LHSI].IsStatic, JavaImportGroups[LHSI],
+                           Imports[LHSI].Identifier) <
+           std::make_tuple(!Imports[RHSI].IsStatic, JavaImportGroups[RHSI],
+                           Imports[RHSI].Identifier);
+  });
 
   // Deduplicate imports.
   Indices.erase(std::unique(Indices.begin(), Indices.end(),
@@ -1902,6 +1903,11 @@ static void sortJavaImports(const FormatStyle &Style,
     CurrentImportGroup = JavaImportGroups[Index];
   }
 
+  // If the imports are out of order, we generate a single replacement fixing
+  // the entire block. Otherwise, no replacement is generated.
+  if (result == Code.substr(Imports.front().Offset, ImportsBlockSize))
+    return;
+
   auto Err = Replaces.add(tooling::Replacement(FileName, Imports.front().Offset,
                                                ImportsBlockSize, result));
   // FIXME: better error handling. For now, just skip the replacement for the
@@ -1967,7 +1973,7 @@ tooling::Replacements sortJavaImports(const FormatStyle &Style, StringRef Code,
     SearchFrom = Pos + 1;
   }
   if (!ImportsInBlock.empty())
-    sortJavaImports(Style, ImportsInBlock, Ranges, FileName, Replaces);
+    sortJavaImports(Style, ImportsInBlock, Ranges, FileName, Code, Replaces);
   return Replaces;
 }