Clang: Fix dot-arrow-correction for not-yet-parsed unsaved content

The issue was re-producible with e.g.:

    void g()
    {
        // Type 'foo.' as fast as possible in the next line

    }

This led to "foo->" with completion results as if there was no "foo." at
all in that line.

We relied on a correct position for
translationUnit.sourceLocationAtWithoutReparsing(), but the just typed
characters were not yet reparsed. And we do not want to reparse at that
point since takes too long. We already determine the utf8 position for
the dot character, so simply use that instead.

This completes commit 17c1325cc45eb563333d28725a51c04e33cd01f2.

Change-Id: I669888b5c17ee63b2aec7b16c9921f9d79e281f9
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

8 files changed, 117 insertions, 42 deletions

diff --git a/src/tools/clangbackend/ipcsource/codecompleter.cpp b/src/tools/clangbackend/ipcsource/codecompleter.cpp
index 436c668052..4344a22aa9 100644
--- a/src/tools/clangbackend/ipcsource/codecompleter.cpp
+++ b/src/tools/clangbackend/ipcsource/codecompleter.cpp
@@ -68,8 +68,7 @@ CodeCompletions CodeCompleter::complete(uint line, uint column)
                                                 translationUnit.cxUnsavedFiles(),
                                                 translationUnit.unsavedFilesCount());
 
-    if (results.hasNoResultsForDotCompletion() && hasDotAt(line, column - 1))
-        results = completeWithArrowInsteadOfDot(line, column);
+    tryDotArrowCorrectionIfNoResults(results, line, column);
 
     return toCodeCompletions(results);
 }
@@ -93,13 +92,6 @@ ClangCodeCompleteResults CodeCompleter::complete(uint line,
                                 defaultOptions());
 }
 
-bool CodeCompleter::hasDotAt(uint line, uint column) const
-{
-    const UnsavedFile &unsavedFile = translationUnit.unsavedFile();
-
-    return unsavedFile.hasCharacterAt(line, column, '.');
-}
-
 uint CodeCompleter::defaultOptions() const
 {
     uint options = CXCodeComplete_IncludeMacros
@@ -111,12 +103,25 @@ uint CodeCompleter::defaultOptions() const
     return options;
 }
 
-ClangCodeCompleteResults CodeCompleter::completeWithArrowInsteadOfDot(uint line, uint column)
+void CodeCompleter::tryDotArrowCorrectionIfNoResults(ClangCodeCompleteResults &results,
+                                                     uint line,
+                                                     uint column)
 {
-    ClangCodeCompleteResults results;
+    if (results.hasNoResultsForDotCompletion()) {
+        const UnsavedFile &unsavedFile = translationUnit.unsavedFile();
+        bool positionIsOk = false;
+        const uint dotPosition = unsavedFile.toUtf8Position(line, column - 1, &positionIsOk);
+        if (positionIsOk && unsavedFile.hasCharacterAt(dotPosition, '.'))
+            results = completeWithArrowInsteadOfDot(line, column, dotPosition);
+    }
+}
 
-    const SourceLocation location = translationUnit.sourceLocationAtWithoutReparsing(line, column - 1);
-    const bool replaced = translationUnit.unsavedFile().replaceAt(location.offset(),
+ClangCodeCompleteResults CodeCompleter::completeWithArrowInsteadOfDot(uint line,
+                                                                      uint column,
+                                                                      uint dotPosition)
+{
+    ClangCodeCompleteResults results;
+    const bool replaced = translationUnit.unsavedFile().replaceAt(dotPosition,
                                                                   1,
                                                                   Utf8StringLiteral("->"));
 
diff --git a/src/tools/clangbackend/ipcsource/codecompleter.h b/src/tools/clangbackend/ipcsource/codecompleter.h
index 260ac4d581..c785ae5939 100644
--- a/src/tools/clangbackend/ipcsource/codecompleter.h
+++ b/src/tools/clangbackend/ipcsource/codecompleter.h
@@ -46,18 +46,20 @@ public:
 
     CompletionCorrection neededCorrection() const;
 
-public: // for tests
-    bool hasDotAt(uint line, uint column) const;
-
 private:
     uint defaultOptions() const;
 
+    void tryDotArrowCorrectionIfNoResults(ClangCodeCompleteResults &results,
+                                          uint line,
+                                          uint column);
+
     ClangCodeCompleteResults complete(uint line,
                                       uint column,
                                       CXUnsavedFile *unsavedFiles,
                                       unsigned unsavedFileCount);
-
-    ClangCodeCompleteResults completeWithArrowInsteadOfDot(uint line, uint column);
+    ClangCodeCompleteResults completeWithArrowInsteadOfDot(uint line,
+                                                           uint column,
+                                                           uint dotPosition);
 
     Utf8String filePath() const;
     static void checkCodeCompleteResult(CXCodeCompleteResults *completeResults);
diff --git a/src/tools/clangbackend/ipcsource/unsavedfile.cpp b/src/tools/clangbackend/ipcsource/unsavedfile.cpp
index a4d6f0fb82..dffbdfd1ff 100644
--- a/src/tools/clangbackend/ipcsource/unsavedfile.cpp
+++ b/src/tools/clangbackend/ipcsource/unsavedfile.cpp
@@ -71,15 +71,24 @@ const char *UnsavedFile::filePath() const
     return cxUnsavedFile.Filename;
 }
 
-bool UnsavedFile::hasCharacterAt(uint line, uint column, char character) const
+uint UnsavedFile::toUtf8Position(uint line, uint column, bool *ok) const
 {
     Utf8PositionFromLineColumn converter(cxUnsavedFile.Contents);
     if (converter.find(line, column)) {
-        const uint utf8Position = converter.position();
-        return hasCharacterAt(utf8Position, character);
+        *ok = true;
+        return converter.position();
     }
 
-    return false;
+    *ok = false;
+    return 0;
+}
+
+bool UnsavedFile::hasCharacterAt(uint line, uint column, char character) const
+{
+    bool positionIsOk = false;
+    const uint utf8Position = toUtf8Position(line, column, &positionIsOk);
+
+    return positionIsOk && hasCharacterAt(utf8Position, character);
 }
 
 bool UnsavedFile::hasCharacterAt(uint position, char character) const
diff --git a/src/tools/clangbackend/ipcsource/unsavedfile.h b/src/tools/clangbackend/ipcsource/unsavedfile.h
index 3433093ae1..dcd4fd026b 100644
--- a/src/tools/clangbackend/ipcsource/unsavedfile.h
+++ b/src/tools/clangbackend/ipcsource/unsavedfile.h
@@ -55,6 +55,7 @@ public:
     const char *filePath() const;
 
     // 1-based line and column
+    uint toUtf8Position(uint line, uint column, bool *ok) const;
     bool hasCharacterAt(uint line, uint column, char character) const;
     bool hasCharacterAt(uint position, char character) const;
     bool replaceAt(uint position, uint length, const Utf8String &replacement);
diff --git a/tests/unit/unittest/codecompletiontest.cpp b/tests/unit/unittest/codecompletiontest.cpp
index a370f93586..c25b03a492 100644
--- a/tests/unit/unittest/codecompletiontest.cpp
+++ b/tests/unit/unittest/codecompletiontest.cpp
@@ -112,6 +112,19 @@ protected:
         readFileContent(QStringLiteral("/complete_withDotArrowCorrectionForPointer.cpp")),
         true
     };
+    ClangBackEnd::FileContainer dotArrowCorrectionForPointerFileContainerBeforeTyping{
+        Utf8StringLiteral(TESTDATA_DIR"/complete_withDotArrowCorrectionForPointer.cpp"),
+        projectPart.projectPartId(),
+        readFileContent(QStringLiteral("/complete_withDotArrowCorrectionForPointer_beforeTyping.cpp")),
+        true
+    };
+    ClangBackEnd::FileContainer dotArrowCorrectionForPointerFileContainerAfterTyping{
+        Utf8StringLiteral(TESTDATA_DIR"/complete_withDotArrowCorrectionForPointer.cpp"),
+        projectPart.projectPartId(),
+        readFileContent(QStringLiteral("/complete_withDotArrowCorrectionForPointer_afterTyping.cpp")),
+        true
+    };
+
     ClangBackEnd::FileContainer dotArrowCorrectionForPointerFileContainerInitial{
         Utf8StringLiteral(TESTDATA_DIR"/complete_withDotArrowCorrectionForPointer.cpp"),
         projectPart.projectPartId(),
@@ -313,33 +326,27 @@ TEST_F(CodeCompleter, ArrowCompletion)
                 ClangBackEnd::CompletionCorrection::NoCorrection);
 }
 
-TEST_F(CodeCompleter, HasDotAt)
+TEST_F(CodeCompleter, DotToArrowCompletionForPointer)
 {
     auto myCompleter = setupCompleter(dotArrowCorrectionForPointerFileContainer);
 
-    ASSERT_TRUE(myCompleter.hasDotAt(5, 8));
-}
-
-TEST_F(CodeCompleter, HasDotAtWithUpdatedUnsavedFile)
-{
-    auto myCompleter = setupCompleter(dotArrowCorrectionForPointerFileContainerInitial);
-    unsavedFiles.createOrUpdate({dotArrowCorrectionForPointerFileContainerUpdated});
-
-    ASSERT_TRUE(myCompleter.hasDotAt(5, 8));
-}
-
-TEST_F(CodeCompleter, HasNoDotAtDueToMissingUnsavedFile)
-{
-    const ClangBackEnd::FileContainer fileContainer = dotArrowCorrectionForPointerFileContainer;
-    translationUnits.create({fileContainer});
-    ClangBackEnd::CodeCompleter myCompleter(translationUnits.translationUnit(fileContainer));
+    const ClangBackEnd::CodeCompletions completions = myCompleter.complete(5, 9);
 
-    ASSERT_FALSE(myCompleter.hasDotAt(5, 8));
+    ASSERT_THAT(completions,
+                Contains(IsCodeCompletion(Utf8StringLiteral("member"),
+                                          CodeCompletion::VariableCompletionKind)));
+    ASSERT_THAT(myCompleter.neededCorrection(),
+                ClangBackEnd::CompletionCorrection::DotToArrowCorrection);
 }
 
-TEST_F(CodeCompleter, DotToArrowCompletionForPointer)
+TEST_F(CodeCompleter, DotToArrowCompletionForPointerInOutdatedTranslationUnit)
 {
-    auto myCompleter = setupCompleter(dotArrowCorrectionForPointerFileContainer);
+    auto fileContainerBeforeTyping = dotArrowCorrectionForPointerFileContainerBeforeTyping;
+    auto myCompleter = setupCompleter(fileContainerBeforeTyping);
+    auto translationUnit = translationUnits.translationUnit(fileContainerBeforeTyping.filePath(),
+                                                            fileContainerBeforeTyping.projectPartId());
+    translationUnit.cxTranslationUnit(); // Parse
+    unsavedFiles.createOrUpdate({dotArrowCorrectionForPointerFileContainerAfterTyping});
 
     const ClangBackEnd::CodeCompletions completions = myCompleter.complete(5, 9);
 
diff --git a/tests/unit/unittest/data/complete_withDotArrowCorrectionForPointer_afterTyping.cpp b/tests/unit/unittest/data/complete_withDotArrowCorrectionForPointer_afterTyping.cpp
new file mode 100644
index 0000000000..9f8d3645b2
--- /dev/null
+++ b/tests/unit/unittest/data/complete_withDotArrowCorrectionForPointer_afterTyping.cpp
@@ -0,0 +1,6 @@
+struct Foo { int member; };
+
+void g(Foo *foo)
+{
+    foo.
+}
diff --git a/tests/unit/unittest/data/complete_withDotArrowCorrectionForPointer_beforeTyping.cpp b/tests/unit/unittest/data/complete_withDotArrowCorrectionForPointer_beforeTyping.cpp
new file mode 100644
index 0000000000..0472cfacaa
--- /dev/null
+++ b/tests/unit/unittest/data/complete_withDotArrowCorrectionForPointer_beforeTyping.cpp
@@ -0,0 +1,6 @@
+struct Foo { int member; };
+
+void g(Foo *foo)
+{
+
+}
diff --git a/tests/unit/unittest/unsavedfiletest.cpp b/tests/unit/unittest/unsavedfiletest.cpp
index 3f0ae6d90b..463c29be8b 100644
--- a/tests/unit/unittest/unsavedfiletest.cpp
+++ b/tests/unit/unittest/unsavedfiletest.cpp
@@ -34,6 +34,7 @@
 using ClangBackEnd::UnsavedFile;
 using ClangBackEnd::UnsavedFiles;
 
+using ::testing::Eq;
 using ::testing::PrintToString;
 
 namespace {
@@ -150,6 +151,44 @@ TEST_F(UnsavedFile, Replace)
     ASSERT_THAT(unsavedFile, IsUnsavedFile(filePath, expectedContent, expectedContent.byteSize()));
 }
 
+TEST_F(UnsavedFile, ToUtf8PositionForValidLineColumn)
+{
+    ::UnsavedFile unsavedFile(filePath, fileContent);
+    bool ok = false;
+
+    const uint position = unsavedFile.toUtf8Position(1, 1, &ok);
+
+    ASSERT_TRUE(ok);
+    ASSERT_THAT(position, Eq(0));
+}
+
+TEST_F(UnsavedFile, ToUtf8PositionForInValidLineColumn)
+{
+    ::UnsavedFile unsavedFile(filePath, fileContent);
+    bool ok = false;
+
+    unsavedFile.toUtf8Position(2, 1, &ok);
+
+    ASSERT_FALSE(ok);
+}
+
+TEST_F(UnsavedFile, ToUtf8PositionForDefaultConstructedUnsavedFile)
+{
+    ::UnsavedFile unsavedFile;
+    bool ok = false;
+
+    unsavedFile.toUtf8Position(1, 1, &ok);
+
+    ASSERT_FALSE(ok);
+}
+
+TEST_F(UnsavedFile, HasNoCharacterForDefaultConstructedUnsavedFile)
+{
+    ::UnsavedFile unsavedFile;
+
+    ASSERT_FALSE(unsavedFile.hasCharacterAt(0, 'x'));
+}
+
 TEST_F(UnsavedFile, HasNoCharacterForTooBigOffset)
 {
     ::UnsavedFile unsavedFile(filePath, fileContent);