Clang: Workaround dot detection for arrow correction

...by explicitly checking for the dot in the source.

Task-number: QTCREATORBUG-15654
Change-Id: I4172e88a7fbb3015ef391daf13ded1f0002aab9c
Reviewed-by: Marco Bubke <marco.bubke@theqtcompany.com>

src/tools/clangbackend/ipcsource/codecompleter.cpp

@@ -68,7 +68,7 @@ CodeCompletions CodeCompleter::complete(uint line, uint column)
                                                 translationUnit.cxUnsavedFiles(),
                                                 translationUnit.unsavedFilesCount());
 
-    if (results.hasNoResultsForDotCompletion())
+    if (results.hasNoResultsForDotCompletion() && hasDotAt(line, column - 1))
         results = completeWithArrowInsteadOfDot(line, column);
 
     return toCodeCompletions(results);
@@ -95,6 +95,14 @@ ClangCodeCompleteResults CodeCompleter::complete(uint line,
                                 options);
 }
 
+bool CodeCompleter::hasDotAt(uint line, uint column) const
+{
+    const UnsavedFile &unsavedFile = translationUnit.unsavedFile();
+    const SourceLocation location = translationUnit.sourceLocationAtWithoutReparsing(line, column);
+
+    return unsavedFile.hasCharacterAt(location.offset(), '.');
+}
+
 ClangCodeCompleteResults CodeCompleter::completeWithArrowInsteadOfDot(uint line, uint column)
 {
     ClangCodeCompleteResults results;

src/tools/clangbackend/ipcsource/codecompleter.h

@@ -46,6 +46,9 @@ public:
 
     CompletionCorrection neededCorrection() const;
 
+public: // for tests
+    bool hasDotAt(uint line, uint column) const;
+
 private:
     ClangCodeCompleteResults complete(uint line,
                                       uint column,

src/tools/clangbackend/ipcsource/unsavedfile.cpp

@@ -65,6 +65,14 @@ const char *UnsavedFile::filePath() const
     return cxUnsavedFile.Filename;
 }
 
+bool UnsavedFile::hasCharacterAt(uint position, char character) const
+{
+    if (position < cxUnsavedFile.Length)
+        return cxUnsavedFile.Contents[position] == character;
+
+    return false;
+}
+
 bool UnsavedFile::replaceAt(uint position, uint length, const Utf8String &replacement)
 {
     if (position < cxUnsavedFile.Length) {

src/tools/clangbackend/ipcsource/unsavedfile.h

@@ -51,6 +51,7 @@ public:
 
     const char *filePath() const;
 
+    bool hasCharacterAt(uint position, char character) const;
     bool replaceAt(uint position, uint length, const Utf8String &replacement);
 
     CXUnsavedFile *data();

tests/unit/unittest/codecompletiontest.cpp

@@ -148,6 +148,12 @@ protected:
         readFileContent(QStringLiteral("/complete_withNoDotArrowCorrectionForOnlyDot.cpp")),
         true
     };
+    ClangBackEnd::FileContainer noDotArrowCorrectionForColonColonFileContainer{
+        Utf8StringLiteral(TESTDATA_DIR"/complete_withNoDotArrowCorrectionForColonColon.cpp"),
+        projectPart.projectPartId(),
+        readFileContent(QStringLiteral("/complete_withNoDotArrowCorrectionForColonColon.cpp")),
+        true
+    };
 };
 
 Utf8String CodeCompleter::readFileContent(const QString &fileName)
@@ -295,6 +301,22 @@ TEST_F(CodeCompleter, ArrowCompletion)
                 ClangBackEnd::CompletionCorrection::NoCorrection);
 }
 
+TEST_F(CodeCompleter, HasDotAt)
+{
+    auto myCompleter = setupCompleter(dotArrowCorrectionForPointerFileContainer);
+
+    ASSERT_TRUE(myCompleter.hasDotAt(5, 8));
+}
+
+TEST_F(CodeCompleter, HasNoDotAtDueToMissingUnsavedFile)
+{
+    const ClangBackEnd::FileContainer fileContainer = dotArrowCorrectionForPointerFileContainer;
+    translationUnits.create({fileContainer});
+    ClangBackEnd::CodeCompleter myCompleter(translationUnits.translationUnit(fileContainer));
+
+    ASSERT_FALSE(myCompleter.hasDotAt(5, 8));
+}
+
 TEST_F(CodeCompleter, DotToArrowCompletionForPointer)
 {
     auto myCompleter = setupCompleter(dotArrowCorrectionForPointerFileContainer);
@@ -374,6 +396,14 @@ TEST_F(CodeCompleter, NoDotArrowCorrectionForOnlyDot)
     ASSERT_THAT(myCompleter.neededCorrection(), ClangBackEnd::CompletionCorrection::NoCorrection);
 }
 
+TEST_F(CodeCompleter, NoDotArrowCorrectionForColonColon)
+{
+    auto myCompleter = setupCompleter(noDotArrowCorrectionForColonColonFileContainer);
+    const ClangBackEnd::CodeCompletions completions = myCompleter.complete(1, 7);
+
+    ASSERT_THAT(myCompleter.neededCorrection(), ClangBackEnd::CompletionCorrection::NoCorrection);
+}
+
 ClangBackEnd::CodeCompleter CodeCompleter::setupCompleter(
         const ClangBackEnd::FileContainer &fileContainer)
 {

tests/unit/unittest/data/complete_withNoDotArrowCorrectionForColonColon.cpp

@@ -0,0 +1 @@
+Blah::

tests/unit/unittest/unsavedfiletest.cpp

@@ -150,4 +150,25 @@ TEST_F(UnsavedFile, Replace)
     ASSERT_THAT(unsavedFile, IsUnsavedFile(filePath, expectedContent, expectedContent.byteSize()));
 }
 
+TEST_F(UnsavedFile, HasNoCharacterForTooBigOffset)
+{
+    ::UnsavedFile unsavedFile(filePath, fileContent);
+
+    ASSERT_FALSE(unsavedFile.hasCharacterAt(100, 'x'));
+}
+
+TEST_F(UnsavedFile, HasNoCharacterForWrongOffset)
+{
+    ::UnsavedFile unsavedFile(filePath, fileContent);
+
+    ASSERT_FALSE(unsavedFile.hasCharacterAt(0, 'x'));
+}
+
+TEST_F(UnsavedFile, HasCharacterForCorrectOffset)
+{
+    ::UnsavedFile unsavedFile(filePath, fileContent);
+
+    ASSERT_TRUE(unsavedFile.hasCharacterAt(0, 'c'));
+}
+
 } // anonymous namespace