TextEditor: Introduce shortcut for forcing a function hint proposal

... and support it in the ClangCodeModel.
This allows users to get function signature(s) displayed regardless of
where exactly the cursor is on the function call.

Fixes: QTCREATORBUG-19394
Change-Id: I033e8774db93680bfc3ee52610b817e0ef8ccc76
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangcompletionassistinterface.cpp

@@ -30,8 +30,7 @@
 namespace ClangCodeModel {
 namespace Internal {
 
-ClangCompletionAssistInterface::ClangCompletionAssistInterface(
-        BackendCommunicator &communicator,
+ClangCompletionAssistInterface::ClangCompletionAssistInterface(BackendCommunicator &communicator, CompletionType type,
         const TextEditor::TextEditorWidget *textEditorWidget,
         int position,
         const QString &fileName,
@@ -40,6 +39,7 @@ ClangCompletionAssistInterface::ClangCompletionAssistInterface(
         const CPlusPlus::LanguageFeatures &features)
     : AssistInterface(textEditorWidget->document(), position, fileName, reason)
     , m_communicator(communicator)
+    , m_type(type)
     , m_headerPaths(headerPaths)
     , m_languageFeatures(features)
     , m_textEditorWidget(textEditorWidget)

src/plugins/clangcodemodel/clangcompletionassistinterface.h

@@ -33,10 +33,13 @@
 namespace ClangCodeModel {
 namespace Internal {
 
+enum class CompletionType { FunctionHint, Other };
+
 class ClangCompletionAssistInterface: public TextEditor::AssistInterface
 {
 public:
     ClangCompletionAssistInterface(BackendCommunicator &communicator,
+                                   CompletionType type,
                                    const TextEditor::TextEditorWidget *textEditorWidget,
                                    int position,
                                    const QString &fileName,
@@ -45,6 +48,7 @@ public:
                                    const CPlusPlus::LanguageFeatures &features);
 
     BackendCommunicator &communicator() const;
+    CompletionType type() const { return m_type; }
     bool objcEnabled() const;
     const ProjectExplorer::HeaderPaths &headerPaths() const;
     CPlusPlus::LanguageFeatures languageFeatures() const;
@@ -54,6 +58,7 @@ public:
 
 private:
     BackendCommunicator &m_communicator;
+    const CompletionType m_type;
     QStringList m_options;
     ProjectExplorer::HeaderPaths m_headerPaths;
     CPlusPlus::LanguageFeatures m_languageFeatures;

src/plugins/clangcodemodel/clangcompletionassistprocessor.cpp

@@ -347,6 +347,7 @@ IAssistProposal *ClangCompletionAssistProcessor::startCompletionHelper()
                                               analyzer.functionNameStart());
         break;
     }
+    case ClangCompletionContextAnalyzer::CompleteNone:
     default:
         break;
     }

src/plugins/clangcodemodel/clangcompletionassistprovider.cpp

@@ -43,8 +43,9 @@
 namespace ClangCodeModel {
 namespace Internal {
 
-ClangCompletionAssistProvider::ClangCompletionAssistProvider(BackendCommunicator &communicator)
-    : m_communicator(communicator)
+ClangCompletionAssistProvider::ClangCompletionAssistProvider(BackendCommunicator &communicator,
+                                                             CompletionType type)
+    : m_communicator(communicator), m_type(type)
 {
 }
 
@@ -68,6 +69,7 @@ TextEditor::AssistInterface *ClangCompletionAssistProvider::createAssistInterfac
     const CppTools::ProjectPart::Ptr projectPart = projectPartForFileBasedOnProcessor(filePath);
     if (projectPart) {
         return new ClangCompletionAssistInterface(m_communicator,
+                                                  m_type,
                                                   textEditorWidget,
                                                   position,
                                                   filePath,

src/plugins/clangcodemodel/clangcompletionassistprovider.h

@@ -26,6 +26,7 @@
 #pragma once
 
 #include "clangbackendcommunicator.h"
+#include "clangcompletionassistinterface.h"
 
 #include <cpptools/cppcompletionassistprovider.h>
 
@@ -39,7 +40,7 @@ class ClangCompletionAssistProvider : public CppTools::CppCompletionAssistProvid
     Q_OBJECT
 
 public:
-    ClangCompletionAssistProvider(BackendCommunicator &communicator);
+    ClangCompletionAssistProvider(BackendCommunicator &communicator, CompletionType type);
 
     IAssistProvider::RunType runType() const override;
 
@@ -53,6 +54,7 @@ public:
 
 private:
     BackendCommunicator &m_communicator;
+    CompletionType m_type;
 };
 
 } // namespace Internal

src/plugins/clangcodemodel/clangcompletioncontextanalyzer.cpp

@@ -84,7 +84,8 @@ void ClangCompletionContextAnalyzer::analyze()
     m_positionEndOfExpression = activationSequenceContextProcessor.operatorStartPosition();
     m_positionForProposal = activationSequenceContextProcessor.startOfNamePosition();
 
-    const bool actionIsSet = handleNonFunctionCall(afterOperatorPosition);
+    const bool actionIsSet = m_interface->type() != CompletionType::FunctionHint
+            && handleNonFunctionCall(afterOperatorPosition);
     if (!actionIsSet) {
         handleCommaInFunctionCall();
         handleFunctionCall(afterOperatorPosition);
@@ -150,6 +151,19 @@ void ClangCompletionContextAnalyzer::handleCommaInFunctionCall()
 
 void ClangCompletionContextAnalyzer::handleFunctionCall(int afterOperatorPosition)
 {
+    if (m_interface->type() == CompletionType::FunctionHint) {
+        const int functionNameStart = startOfFunctionCall(afterOperatorPosition);
+        if (functionNameStart >= 0) {
+            m_addSnippets = functionNameStart == afterOperatorPosition;
+            setActionAndClangPosition(PassThroughToLibClangAfterLeftParen,
+                                      m_positionForProposal,
+                                      functionNameStart);
+        } else {
+            m_completionAction = CompleteNone;
+        }
+        return;
+    }
+
     if (m_completionOperator == T_LPAREN || m_completionOperator == T_LBRACE) {
         ExpressionUnderCursor expressionUnderCursor(m_languageFeatures);
         QTextCursor textCursor(m_interface->textDocument());

src/plugins/clangcodemodel/clangcompletioncontextanalyzer.h

@@ -51,7 +51,8 @@ public:
         CompleteIncludePath,
         CompletePreprocessorDirective,
         CompleteSignal,
-        CompleteSlot
+        CompleteSlot,
+        CompleteNone
     };
     CompletionAction completionAction() const { return m_completionAction; }
     unsigned completionOperator() const { return m_completionOperator; }

src/plugins/clangcodemodel/clangmodelmanagersupport.cpp

@@ -69,7 +69,8 @@ static CppTools::CppModelManager *cppModelManager()
 }
 
 ClangModelManagerSupport::ClangModelManagerSupport()
-    : m_completionAssistProvider(m_communicator)
+    : m_completionAssistProvider(m_communicator, CompletionType::Other)
+    , m_functionHintAssistProvider(m_communicator, CompletionType::FunctionHint)
     , m_followSymbol(new ClangFollowSymbol)
     , m_refactoringEngine(new RefactoringEngine)
 {
@@ -119,6 +120,11 @@ CppTools::CppCompletionAssistProvider *ClangModelManagerSupport::completionAssis
     return &m_completionAssistProvider;
 }
 
+CppTools::CppCompletionAssistProvider *ClangModelManagerSupport::functionHintAssistProvider()
+{
+    return &m_functionHintAssistProvider;
+}
+
 TextEditor::BaseHoverHandler *ClangModelManagerSupport::createHoverHandler()
 {
     return new Internal::ClangHoverHandler;

src/plugins/clangcodemodel/clangmodelmanagersupport.h

@@ -63,6 +63,7 @@ public:
     ~ClangModelManagerSupport() override;
 
     CppTools::CppCompletionAssistProvider *completionAssistProvider() override;
+    CppTools::CppCompletionAssistProvider *functionHintAssistProvider() override;
     TextEditor::BaseHoverHandler *createHoverHandler() override;
     CppTools::BaseEditorDocumentProcessor *createEditorDocumentProcessor(
                 TextEditor::TextDocument *baseTextDocument) override;
@@ -121,6 +122,7 @@ private:
     UiHeaderOnDiskManager m_uiHeaderOnDiskManager;
     BackendCommunicator m_communicator;
     ClangCompletionAssistProvider m_completionAssistProvider;
+    ClangCompletionAssistProvider m_functionHintAssistProvider;
     std::unique_ptr<CppTools::FollowSymbolInterface> m_followSymbol;
     std::unique_ptr<CppTools::RefactoringEngineInterface> m_refactoringEngine;