Clang: Fix completion after '{'

Follow-up fix for 8d0391a4f9.

Do not complete after '{' coming not after an identifier.
Take constructor completions only for '{' and function
completions only for '('. Filter constructor completions by
class/struct type.

Task-number: QTCREATORBUG-21004
Change-Id: I7ae2d6bee23cf907648c42b93eb12742942833f6
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/sqlite/utf8string.h

@@ -131,6 +131,16 @@ public:
         return byteArray.indexOf(text);
     }
 
+    int lastIndexOf(const Utf8String &text) const
+    {
+        return byteArray.lastIndexOf(text.byteArray);
+    }
+
+    int lastIndexOf(const char *text) const
+    {
+        return byteArray.lastIndexOf(text);
+    }
+
     int indexOf(char character) const
     {
         return byteArray.indexOf(character);

src/plugins/clangcodemodel/clangcompletionassistprocessor.cpp

@@ -190,8 +190,22 @@ IAssistProposal *ClangCompletionAssistProcessor::perform(const AssistInterface *
 static CodeCompletions filterFunctionSignatures(const CodeCompletions &completions)
 {
     return ::Utils::filtered(completions, [](const CodeCompletion &completion) {
-        return completion.completionKind == CodeCompletion::FunctionOverloadCompletionKind
-                || completion.completionKind == CodeCompletion::ConstructorCompletionKind;
+        return completion.completionKind == CodeCompletion::FunctionOverloadCompletionKind;
+    });
+}
+
+static CodeCompletions filterConstructorSignatures(Utf8String textBefore,
+                                                   const CodeCompletions &completions)
+{
+    const int prevStatementEnd = textBefore.lastIndexOf(";");
+    if (prevStatementEnd != -1)
+        textBefore = textBefore.mid(prevStatementEnd + 1);
+
+    return ::Utils::filtered(completions, [&textBefore](const CodeCompletion &completion) {
+        if (completion.completionKind != CodeCompletion::ConstructorCompletionKind)
+            return false;
+        const Utf8String type = completion.chunks.at(0).text;
+        return textBefore.indexOf(type) != -1;
     });
 }
 
@@ -201,7 +215,18 @@ void ClangCompletionAssistProcessor::handleAvailableCompletions(
     QTC_CHECK(m_completions.isEmpty());
 
     if (m_sentRequestType == FunctionHintCompletion){
-        const CodeCompletions functionSignatures = filterFunctionSignatures(completions);
+        CodeCompletions functionSignatures;
+        if (m_completionOperator == T_LPAREN) {
+            functionSignatures = filterFunctionSignatures(completions);
+        } else {
+            const QTextBlock block = m_interface->textDocument()->findBlock(
+                        m_interface->position());
+            const QString textBefore = block.text().left(
+                        m_interface->position() - block.position());
+
+            functionSignatures = filterConstructorSignatures(textBefore, completions);
+        }
+
         if (!functionSignatures.isEmpty()) {
             setAsyncProposalAvailable(createFunctionHintProposal(functionSignatures));
             return;

src/plugins/cpptools/cppcompletionassistprocessor.cpp

@@ -68,6 +68,22 @@ static bool isDoxygenTagCompletionCharacter(const QChar &character)
         || character == QLatin1Char('@') ;
 }
 
+static bool twoIndentifiersBeforeLBrace(const Tokens &tokens, int tokenIdx)
+{
+    const Token &previousToken = tokens.at(tokenIdx - 1);
+    if (previousToken.kind() != T_IDENTIFIER)
+        return false;
+    for (int index = tokenIdx - 2; index >= 0; index -= 2) {
+        const Token &token = tokens.at(index);
+        if (token.kind() == T_IDENTIFIER)
+            return true;
+
+        if (token.kind() != T_COLON_COLON)
+            return false;
+    }
+    return false;
+}
+
 void CppCompletionAssistProcessor::startOfOperator(QTextDocument *textDocument,
         int positionInDocument,
         unsigned *kind,
@@ -146,6 +162,11 @@ void CppCompletionAssistProcessor::startOfOperator(QTextDocument *textDocument,
                     start = positionInDocument;
                 }
             }
+        } else if (*kind == T_LBRACE) {
+            if (tokenIdx > 0 && !twoIndentifiersBeforeLBrace(tokens, tokenIdx)) {
+                *kind = T_EOF_SYMBOL;
+                start = positionInDocument;
+            }
         }
         // Check for include preprocessor directive
         else if (*kind == T_STRING_LITERAL || *kind == T_ANGLE_STRING_LITERAL || *kind == T_SLASH

tests/unit/unittest/clangcompletioncontextanalyzer-test.cpp

@@ -290,6 +290,13 @@ TEST_F(ClangCompletionContextAnalyzer, WhitespaceBeforeConstructorCallWithBraceI
     ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, 0, positionInText));
 }
 
+TEST_F(ClangCompletionContextAnalyzer, OpenFunctionScopeNotAConstructor)
+{
+    auto analyzer = runAnalyzer("foo() {@");
+
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClang, 0, 0, positionInText));
+}
+
 TEST_F(ClangCompletionContextAnalyzer, AfterOpeningParenthesis)
 {
     auto analyzer = runAnalyzer("(@");