CppEditor: Do not underline leading whitespace

... when visualizing the range of a code model warning.
Otherwise, warnings covering multiple lines can get too noisy.

Fixes: QTCREATORBUG-18659
Change-Id: Ieff7729d8069e791027f7bdde5fca13f4c7f7163
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cppeditor/cppeditorplugin.h

@@ -205,6 +205,9 @@ private slots:
     void test_useSelections_data();
     void test_useSelections();
 
+    void test_selectionFiltering_data();
+    void test_selectionFiltering();
+
     // tests for "Include Hierarchy"
     void test_includehierarchy_data();
     void test_includehierarchy();

src/plugins/cppeditor/cppeditorwidget.cpp

@@ -326,7 +326,8 @@ void CppEditorWidget::onCodeWarningsUpdated(unsigned revision,
     if (revision != documentRevision())
         return;
 
-    setExtraSelections(TextEditorWidget::CodeWarningsSelection, selections);
+    setExtraSelections(TextEditorWidget::CodeWarningsSelection,
+                       unselectLeadingWhitespace(selections));
     setRefactorMarkers(refactorMarkers + RefactorMarker::filterOutType(
             this->refactorMarkers(), CppTools::Constants::CPP_CLANG_FIXIT_AVAILABLE_MARKER_ID));
 }
@@ -1163,6 +1164,63 @@ void CppEditorWidget::invokeTextEditorWidgetAssist(TextEditor::AssistKind assist
     invokeAssist(assistKind, provider);
 }
 
+const QList<QTextEdit::ExtraSelection> CppEditorWidget::unselectLeadingWhitespace(
+        const QList<QTextEdit::ExtraSelection> &selections)
+{
+    QList<QTextEdit::ExtraSelection> filtered;
+    for (const QTextEdit::ExtraSelection &sel : selections) {
+        QList<QTextEdit::ExtraSelection> splitSelections;
+        int firstNonWhitespacePos = -1;
+        int lastNonWhitespacePos = -1;
+        bool split = false;
+        const QTextBlock firstBlock = sel.cursor.document()->findBlock(sel.cursor.selectionStart());
+        bool inIndentation = firstBlock.position() == sel.cursor.selectionStart();
+        const auto createSplitSelection = [&] {
+            QTextEdit::ExtraSelection newSelection;
+            newSelection.cursor = QTextCursor(sel.cursor.document());
+            newSelection.cursor.setPosition(firstNonWhitespacePos);
+            newSelection.cursor.setPosition(lastNonWhitespacePos + 1, QTextCursor::KeepAnchor);
+            newSelection.format = sel.format;
+            splitSelections << newSelection;
+        };
+        for (int i = sel.cursor.selectionStart(); i < sel.cursor.selectionEnd(); ++i) {
+            const QChar curChar = sel.cursor.document()->characterAt(i);
+            if (!curChar.isSpace()) {
+                if (firstNonWhitespacePos == -1)
+                    firstNonWhitespacePos = i;
+                lastNonWhitespacePos = i;
+            }
+            if (!inIndentation) {
+                if (curChar == QChar::ParagraphSeparator)
+                    inIndentation = true;
+                continue;
+            }
+            if (curChar == QChar::ParagraphSeparator)
+                continue;
+            if (curChar.isSpace()) {
+                if (firstNonWhitespacePos != -1) {
+                    createSplitSelection();
+                    firstNonWhitespacePos = -1;
+                    lastNonWhitespacePos = -1;
+                }
+                split = true;
+                continue;
+            }
+            inIndentation = false;
+        }
+
+        if (!split) {
+            filtered << sel;
+            continue;
+        }
+
+        if (firstNonWhitespacePos != -1)
+            createSplitSelection();
+        filtered << splitSelections;
+    }
+    return filtered;
+}
+
 } // namespace Internal
 } // namespace CppEditor
 

src/plugins/cppeditor/cppeditorwidget.h

@@ -94,6 +94,9 @@ public:
     void invokeTextEditorWidgetAssist(TextEditor::AssistKind assistKind,
                                       TextEditor::IAssistProvider *provider) override;
 
+    static const QList<QTextEdit::ExtraSelection>
+    unselectLeadingWhitespace(const QList<QTextEdit::ExtraSelection> &selections);
+
 protected:
     bool event(QEvent *e) override;
     void contextMenuEvent(QContextMenuEvent *) override;

src/plugins/cppeditor/cppuseselections_test.cpp

@@ -249,5 +249,70 @@ void CppEditorPlugin::test_useSelections()
     Tests::UseSelectionsTestCase(testDocument, expectedSelections);
 }
 
+void CppEditorPlugin::test_selectionFiltering_data()
+{
+    QTest::addColumn<QString>("source");
+    QTest::addColumn<SelectionList>("original");
+    QTest::addColumn<SelectionList>("filtered");
+
+    QTest::addRow("QTCREATORBUG-18659")
+            << QString("int main()\n"
+                       "{\n"
+                       "    [](const Foo &foo) -> Foo {\n"
+                       "        return foo;\n"
+                       "    };\n"
+                       "}\n")
+            << SelectionList{{3, 4, 53}}
+            << SelectionList{{3, 4, 27}, {4, 8, 11}, {5, 4, 1}};
+    QTest::addRow("indentation-selected-in-first-line")
+            << QString("int main()\n"
+                       "{\n"
+                       "    [](const Foo &foo) -> Foo {\n"
+                       "        return foo;\n"
+                       "    };\n"
+                       "}\n")
+            << SelectionList{{3, 0, 57}}
+            << SelectionList{{3, 4, 27}, {4, 8, 11}, {5, 4, 1}};
+}
+
+void CppEditorPlugin::test_selectionFiltering()
+{
+    QFETCH(QString, source);
+    QFETCH(SelectionList, original);
+    QFETCH(SelectionList, filtered);
+
+    QTextDocument doc;
+    doc.setPlainText(source);
+
+    const auto convertList = [&doc](const SelectionList &in) {
+        QList<QTextEdit::ExtraSelection> out;
+        for (const Selection &selIn : in) {
+            QTextEdit::ExtraSelection selOut;
+            selOut.format.setFontItalic(true);
+            const QTextBlock startBlock = doc.findBlockByLineNumber(selIn.line - 1);
+            const int startPos = startBlock.position() + selIn.column;
+            selOut.cursor = QTextCursor(&doc);
+            selOut.cursor.setPosition(startPos);
+            selOut.cursor.setPosition(startPos + selIn.length, QTextCursor::KeepAnchor);
+            out << selOut;
+        }
+        return out;
+    };
+
+    const QList<QTextEdit::ExtraSelection> expected = convertList(filtered);
+    const QList<QTextEdit::ExtraSelection> actual
+            = CppEditorWidget::unselectLeadingWhitespace(convertList(original));
+
+    QCOMPARE(actual.length(), expected.length());
+    for (int i = 0; i < expected.length(); ++i) {
+        const QTextEdit::ExtraSelection &expectedSelection = expected.at(i);
+        const QTextEdit::ExtraSelection &actualSelection = actual.at(i);
+        QCOMPARE(actualSelection.format, expectedSelection.format);
+        QCOMPARE(actualSelection.cursor.document(), expectedSelection.cursor.document());
+        QCOMPARE(actualSelection.cursor.position(), expectedSelection.cursor.position());
+        QCOMPARE(actualSelection.cursor.anchor(), expectedSelection.cursor.anchor());
+    }
+}
+
 } // namespace Internal
 } // namespace CppEditor