Clang: Treat brace initialization as constructor completion

Try to complete constructor after left brace with fallback
to normal completion.

Task-number: QTCREATORBUG-20957
Change-Id: I6c33790a3ee1e623a3d8abe9a44cfd821b6f3106
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/cplusplus/ExpressionUnderCursor.cpp

@@ -262,7 +262,7 @@ int ExpressionUnderCursor::startOfFunctionCall(const QTextCursor &cursor) const
 
         if (tk.is(T_EOF_SYMBOL)) {
             break;
-        } else if (tk.is(T_LPAREN)) {
+        } else if (tk.is(T_LPAREN) || tk.is(T_LBRACE)) {
             return scanner.startPosition() + tk.utf16charsBegin();
         } else if (tk.is(T_RPAREN)) {
             int matchingBrace = scanner.startOfMatchingBrace(index);

src/plugins/clangcodemodel/clangactivationsequencecontextprocessor.cpp

@@ -83,7 +83,7 @@ void ActivationSequenceContextProcessor::process()
         processComment();
         processInclude();
         processSlashOutsideOfAString();
-        processLeftParen();
+        processLeftParenOrBrace();
         processPreprocessorInclude();
     }
 
@@ -163,9 +163,9 @@ void ActivationSequenceContextProcessor::processSlashOutsideOfAString()
         m_completionKind = CPlusPlus::T_EOF_SYMBOL;
 }
 
-void ActivationSequenceContextProcessor::processLeftParen()
+void ActivationSequenceContextProcessor::processLeftParenOrBrace()
 {
-    if (m_completionKind == CPlusPlus::T_LPAREN) {
+    if (m_completionKind == CPlusPlus::T_LPAREN || m_completionKind == CPlusPlus::T_LBRACE) {
         if (m_tokenIndex > 0) {
             // look at the token at the left of T_LPAREN
             const CPlusPlus::Token &previousToken = m_tokens.at(m_tokenIndex - 1);

src/plugins/clangcodemodel/clangactivationsequencecontextprocessor.h

@@ -67,7 +67,7 @@ protected:
     void processComment();
     void processInclude();
     void processSlashOutsideOfAString();
-    void processLeftParen();
+    void processLeftParenOrBrace();
     void processPreprocessorInclude();
     void resetPositionsForEOFCompletionKind();
 

src/plugins/clangcodemodel/clangactivationsequenceprocessor.cpp

@@ -90,6 +90,7 @@ void ActivationSequenceProcessor::process()
     processDot();
     processComma();
     processLeftParen();
+    processLeftBrace();
     processColonColon();
     processArrow();
     processDotStar();
@@ -125,6 +126,14 @@ void ActivationSequenceProcessor::processLeftParen()
     }
 }
 
+void ActivationSequenceProcessor::processLeftBrace()
+{
+    if (m_char3 == QLatin1Char('{') && m_wantFunctionCall) {
+        m_completionKind = CPlusPlus::T_LBRACE;
+        m_offset = 1;
+    }
+}
+
 void ActivationSequenceProcessor::processColonColon()
 {
     if (m_char2 == QLatin1Char(':') && m_char3 == QLatin1Char(':')) {

src/plugins/clangcodemodel/clangactivationsequenceprocessor.h

@@ -49,6 +49,7 @@ private:
     void processDot();
     void processComma();
     void processLeftParen();
+    void processLeftBrace();
     void processColonColon();
     void processArrow();
     void processDotStar();

src/plugins/clangcodemodel/clangcompletionassistprocessor.cpp

@@ -188,7 +188,8 @@ IAssistProposal *ClangCompletionAssistProcessor::perform(const AssistInterface *
 static CodeCompletions filterFunctionSignatures(const CodeCompletions &completions)
 {
     return ::Utils::filtered(completions, [](const CodeCompletion &completion) {
-        return completion.completionKind == CodeCompletion::FunctionOverloadCompletionKind;
+        return completion.completionKind == CodeCompletion::FunctionOverloadCompletionKind
+                || completion.completionKind == CodeCompletion::ConstructorCompletionKind;
     });
 }
 
@@ -197,19 +198,24 @@ void ClangCompletionAssistProcessor::handleAvailableCompletions(
 {
     QTC_CHECK(m_completions.isEmpty());
 
-    if (m_sentRequestType == NormalCompletion) {
+    if (m_sentRequestType == FunctionHintCompletion){
+        const CodeCompletions functionSignatures = filterFunctionSignatures(completions);
+        if (!functionSignatures.isEmpty()) {
+            setAsyncProposalAvailable(createFunctionHintProposal(functionSignatures));
+            return;
+        }
+        // else: Proceed with a normal completion in case:
+        // 1) it was not a function call, but e.g. a function declaration like "void f("
+        // 2) '{' meant not a constructor call.
+    }
+
+    //m_sentRequestType == NormalCompletion or function signatures were empty
     m_completions = toAssistProposalItems(completions, m_interface.data());
 
     if (m_addSnippets && !m_completions.isEmpty())
         addSnippets();
 
     setAsyncProposalAvailable(createProposal());
-    } else {
-        const CodeCompletions functionSignatures = filterFunctionSignatures(completions);
-        if (!functionSignatures.isEmpty())
-            setAsyncProposalAvailable(createFunctionHintProposal(functionSignatures));
-        // else: Not a function call, but e.g. a function declaration like "void f("
-    }
 }
 
 const TextEditorWidget *ClangCompletionAssistProcessor::textEditorWidget() const

src/plugins/clangcodemodel/clangcompletioncontextanalyzer.cpp

@@ -145,7 +145,7 @@ void ClangCompletionContextAnalyzer::handleCommaInFunctionCall()
 
 void ClangCompletionContextAnalyzer::handleFunctionCall(int afterOperatorPosition)
 {
-    if (m_completionOperator == T_LPAREN) {
+    if (m_completionOperator == T_LPAREN || m_completionOperator == T_LBRACE) {
         ExpressionUnderCursor expressionUnderCursor(m_languageFeatures);
         QTextCursor textCursor(m_interface->textDocument());
         textCursor.setPosition(m_positionEndOfExpression);

tests/unit/unittest/clangcompletioncontextanalyzer-test.cpp

@@ -269,6 +269,27 @@ TEST_F(ClangCompletionContextAnalyzer, WhitespaceAfterFunctionName)
     ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, 0, positionInText));
 }
 
+TEST_F(ClangCompletionContextAnalyzer, ConstructorCallWithBraceInitializer)
+{
+    auto analyzer = runAnalyzer("f{@");
+
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, 0, positionInText));
+}
+
+TEST_F(ClangCompletionContextAnalyzer, ArgumentTwoWithSpaceAtConstructorCallWithBraceInitializer)
+{
+    auto analyzer = runAnalyzer("f{1, @");
+
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, -3, -3, positionInText));
+}
+
+TEST_F(ClangCompletionContextAnalyzer, WhitespaceBeforeConstructorCallWithBraceInitializer)
+{
+    auto analyzer = runAnalyzer("foo {@");
+
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, 0, positionInText));
+}
+
 TEST_F(ClangCompletionContextAnalyzer, AfterOpeningParenthesis)
 {
     auto analyzer = runAnalyzer("(@");