DiffEditor: Fix parsing of mode-only change in patch

If one of the files has mode-only change, the entire patch
fails as a git patch, and is parsed as a text patch.

Because of that, the prefixes (a/, b/) are not stripped and
jumping to a change by double-clicking does not work.

Change-Id: Ib54ce4fa7aad02cb956af1f7de73d3c732ac5a89
Reviewed-by: André Hartmann <aha_1980@gmx.de>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/diffeditor/diffeditorplugin.cpp

@@ -1347,6 +1347,22 @@ void DiffEditor::Internal::DiffEditorPlugin::testReadPatch_data()
     QTest::newRow("Binary files") << patch
                                   << fileDataList8;
 
+    //////////////
+    patch = _("diff --git a/script.sh b/script.sh\n"
+              "old mode 100644\n"
+              "new mode 100755\n"
+              );
+
+    fileData1 = FileData();
+    fileData1.leftFileInfo = DiffFileInfo("script.sh");
+    fileData1.rightFileInfo = DiffFileInfo("script.sh");
+    fileData1.fileOperation = FileData::ChangeMode;
+
+    QList<FileData> fileDataList9;
+    fileDataList9 << fileData1;
+
+    QTest::newRow("Mode change") << patch << fileDataList9;
+
     //////////////
 
     // Subversion New
@@ -1362,10 +1378,10 @@ void DiffEditor::Internal::DiffEditorPlugin::testReadPatch_data()
     chunkData1.leftStartingLineNumber = -1;
     chunkData1.rightStartingLineNumber = 124;
     fileData1.chunks << chunkData1;
-    QList<FileData> fileDataList9;
-    fileDataList9 << fileData1;
+    QList<FileData> fileDataList21;
+    fileDataList21 << fileData1;
     QTest::newRow("Subversion New") << patch
-                                    << fileDataList9;
+                                    << fileDataList21;
 
     //////////////
 
@@ -1382,10 +1398,10 @@ void DiffEditor::Internal::DiffEditorPlugin::testReadPatch_data()
     chunkData1.leftStartingLineNumber = 0;
     chunkData1.rightStartingLineNumber = -1;
     fileData1.chunks << chunkData1;
-    QList<FileData> fileDataList10;
-    fileDataList10 << fileData1;
+    QList<FileData> fileDataList22;
+    fileDataList22 << fileData1;
     QTest::newRow("Subversion Deleted") << patch
-                                        << fileDataList10;
+                                        << fileDataList22;
 
     //////////////
 
@@ -1402,10 +1418,10 @@ void DiffEditor::Internal::DiffEditorPlugin::testReadPatch_data()
     chunkData1.leftStartingLineNumber = 119;
     chunkData1.rightStartingLineNumber = 119;
     fileData1.chunks << chunkData1;
-    QList<FileData> fileDataList11;
-    fileDataList11 << fileData1;
+    QList<FileData> fileDataList23;
+    fileDataList23 << fileData1;
     QTest::newRow("Subversion Normal") << patch
-                                       << fileDataList11;
+                                       << fileDataList23;
 }
 
 void DiffEditor::Internal::DiffEditorPlugin::testReadPatch()

src/plugins/diffeditor/diffutils.cpp

@@ -1025,10 +1025,16 @@ static bool detectIndexAndBinary(QStringRef patch,
     bool hasNewLine;
     *remainingPatch = patch;
 
-    if (remainingPatch->isEmpty() && (fileData->fileOperation == FileData::CopyFile
-                            || fileData->fileOperation == FileData::RenameFile)) {
-        // in case of 100% similarity we don't have more lines in the patch
-        return true;
+    if (remainingPatch->isEmpty()) {
+        switch (fileData->fileOperation) {
+        case FileData::CopyFile:
+        case FileData::RenameFile:
+        case FileData::ChangeMode:
+            // in case of 100% similarity we don't have more lines in the patch
+            return true;
+        default:
+            break;
+        }
     }
 
     QStringRef afterNextLine;
@@ -1151,8 +1157,6 @@ static bool detectFileData(QStringRef patch,
 
         QStringRef afterSecondLine;
         const QStringRef secondLine = readLine(afterDiffGit, &afterSecondLine, &hasNewLine);
-        if (!hasNewLine)
-            return false; // we need to have at least one more line
 
         if (secondLine.startsWith(QStringLiteral("new file mode "))) {
             fileData->fileOperation = FileData::NewFile;
@@ -1165,7 +1169,7 @@ static bool detectFileData(QStringRef patch,
             // new mode
             readLine(afterSecondLine, &afterThirdLine, &hasNewLine);
             if (!hasNewLine)
-                return false; // we need to have at least one more line
+                fileData->fileOperation = FileData::ChangeMode;
 
             // TODO: validate new mode line
             *remainingPatch = afterThirdLine;

src/plugins/diffeditor/diffutils.h

@@ -104,6 +104,7 @@ class DIFFEDITOR_EXPORT FileData {
 public:
     enum FileOperation {
         ChangeFile,
+        ChangeMode,
         NewFile,
         DeleteFile,
         CopyFile,