ClangCodeModel: Fall back to built-in code model when following symbols

In normal interactive mode, users likely want fuzzy look-up, e.g. to a
non-matching overload if no exact match is present.

Fixes: QTCREATORBUG-29814
Change-Id: I55ca32c001e619d374cc015a7dd2f1564ed2a2c9
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdfollowsymbol.cpp

@@ -199,7 +199,6 @@ void ClangdFollowSymbol::emitDone(const Link &link)
         return;
 
     d->done = true;
-    if (link.hasValidTarget())
     d->callback(link);
     emit done();
 }

src/plugins/clangcodemodel/clangmodelmanagersupport.cpp

@@ -53,6 +53,7 @@
 #include <QLabel>
 #include <QLoggingCategory>
 #include <QMenu>
+#include <QPointer>
 #include <QTextBlock>
 #include <QTimer>
 #include <QtDebug>
@@ -299,17 +300,27 @@ ClangModelManagerSupport::~ClangModelManagerSupport()
 
 void ClangModelManagerSupport::followSymbol(const CursorInEditor &data,
                                             const LinkHandler &processLinkCallback,
+                                            FollowSymbolMode mode,
                                             bool resolveTarget, bool inNextSplit)
 {
     if (ClangdClient * const client = clientForFile(data.filePath());
             client && client->isFullyIndexed()) {
+        LinkHandler extendedCallback = [editor = QPointer(data.editorWidget()), data,
+                                        processLinkCallback, mode, resolveTarget, inNextSplit]
+            (const Link &link) {
+            if (link.hasValidTarget() || mode == FollowSymbolMode::Exact || !editor)
+                return processLinkCallback(link);
+            CppModelManager::followSymbol(data, processLinkCallback, resolveTarget, inNextSplit,
+                                          mode, CppModelManager::Backend::Builtin);
+
+        };
         client->followSymbol(data.textDocument(), data.cursor(), data.editorWidget(),
-                             processLinkCallback, resolveTarget, FollowTo::SymbolDef, inNextSplit);
+                             extendedCallback, resolveTarget, FollowTo::SymbolDef, inNextSplit);
         return;
     }
 
     CppModelManager::followSymbol(data, processLinkCallback, resolveTarget, inNextSplit,
-                                  CppModelManager::Backend::Builtin);
+                                  mode, CppModelManager::Backend::Builtin);
 }
 
 void ClangModelManagerSupport::followSymbolToType(const CursorInEditor &data,

src/plugins/clangcodemodel/clangmodelmanagersupport.h

@@ -52,8 +52,9 @@ public:
 
 private:
     void followSymbol(const CppEditor::CursorInEditor &data,
-                      const Utils::LinkHandler &processLinkCallback, bool resolveTarget,
+                      const Utils::LinkHandler &processLinkCallback,
-                      bool inNextSplit) override;
+                      CppEditor::FollowSymbolMode mode,
+                      bool resolveTarget, bool inNextSplit) override;
     void followSymbolToType(const CppEditor::CursorInEditor &data,
                             const Utils::LinkHandler &processLinkCallback,
                             bool inNextSplit) override;

src/plugins/cppeditor/cppbuiltinmodelmanagersupport.cpp

@@ -101,8 +101,13 @@ TextEditor::BaseHoverHandler *BuiltinModelManagerSupport::createHoverHandler()
 
 void BuiltinModelManagerSupport::followSymbol(const CursorInEditor &data,
                                               const Utils::LinkHandler &processLinkCallback,
+                                              FollowSymbolMode mode,
                                               bool resolveTarget, bool inNextSplit)
 {
+    // findMatchingDefinition() has an "strict" parameter, but it doesn't seem worth to
+    // pass the mode down all the way. In practice, we are always fuzzy.
+    Q_UNUSED(mode)
+
     SymbolFinder finder;
     m_followSymbol->findLink(data, processLinkCallback,
             resolveTarget, CppModelManager::snapshot(),

src/plugins/cppeditor/cppbuiltinmodelmanagersupport.h

@@ -29,7 +29,7 @@ public:
 
 private:
     void followSymbol(const CursorInEditor &data, const Utils::LinkHandler &processLinkCallback,
-                      bool resolveTarget, bool inNextSplit) override;
+                      FollowSymbolMode mode, bool resolveTarget, bool inNextSplit) override;
     void followSymbolToType(const CursorInEditor &data,
                             const Utils::LinkHandler &processLinkCallback,
                             bool inNextSplit) override;

src/plugins/cppeditor/cppeditorwidget.cpp

@@ -625,7 +625,7 @@ void CppEditorWidget::renameUsages(const QString &replacement, QTextCursor curso
     };
     CppModelManager::followSymbol(
                 CursorInEditor{cursor, textDocument()->filePath(), this, textDocument()},
-                continuation, true, false);
+        continuation, true, false, FollowSymbolMode::Exact);
 }
 
 void CppEditorWidget::renameUsages(const Utils::FilePath &filePath, const QString &replacement,
@@ -986,7 +986,8 @@ void CppEditorWidget::findLinkAt(const QTextCursor &cursor,
     CppModelManager::followSymbol(CursorInEditor{cursor, filePath, this, textDocument()},
                                   callbackWrapper,
                                   resolveTarget,
-                                  inNextSplit);
+                                  inNextSplit,
+                                  FollowSymbolMode::Fuzzy);
 }
 
 void CppEditorWidget::findTypeAt(const QTextCursor &cursor,

src/plugins/cppeditor/cppmodelmanager.cpp

@@ -2065,9 +2065,10 @@ TextEditor::BaseHoverHandler *CppModelManager::createHoverHandler()
 
 void CppModelManager::followSymbol(const CursorInEditor &data,
                                    const LinkHandler &processLinkCallback,
-                                   bool resolveTarget, bool inNextSplit, Backend backend)
+                                   bool resolveTarget, bool inNextSplit,
+                                   FollowSymbolMode mode, Backend backend)
 {
-    modelManagerSupport(backend)->followSymbol(data, processLinkCallback,
+    modelManagerSupport(backend)->followSymbol(data, processLinkCallback, mode,
                                                resolveTarget, inNextSplit);
 }
 

src/plugins/cppeditor/cppmodelmanager.h

@@ -5,6 +5,7 @@
 
 #include "cppeditor_global.h"
 
+#include "cpptoolsreuse.h"
 #include "cursorineditor.h"
 #include "projectinfo.h"
 #include "projectpart.h"
@@ -174,7 +175,8 @@ public:
     enum class Backend { Builtin, Best };
     static void followSymbol(const CursorInEditor &data,
                              const Utils::LinkHandler &processLinkCallback,
-                             bool resolveTarget, bool inNextSplit, Backend backend = Backend::Best);
+                             bool resolveTarget, bool inNextSplit,
+                             FollowSymbolMode mode, Backend backend = Backend::Best);
     static void followSymbolToType(const CursorInEditor &data,
                                    const Utils::LinkHandler &processLinkCallback, bool inNextSplit,
                                    Backend backend = Backend::Best);

src/plugins/cppeditor/cppmodelmanagersupport.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include "cppeditor_global.h"
+#include "cpptoolsreuse.h"
 #include "cursorineditor.h"
 
 #include <utils/link.h>
@@ -12,7 +13,6 @@
 #include <QString>
 
 #include <functional>
-#include <memory>
 
 namespace Core { class SearchResult; }
 namespace TextEditor {
@@ -41,6 +41,7 @@ public:
 
     virtual void followSymbol(const CursorInEditor &data,
                               const Utils::LinkHandler &processLinkCallback,
+                              FollowSymbolMode mode,
                               bool resolveTarget, bool inNextSplit) = 0;
     virtual void followSymbolToType(const CursorInEditor &data,
                                    const Utils::LinkHandler &processLinkCallback,

src/plugins/cppeditor/cppquickfixes.cpp

@@ -3017,6 +3017,7 @@ void AddDeclarationForUndeclaredIdentifier::match(const CppQuickFixInterface &in
             collectOperations(interface, result);
     };
     CppModelManager::followSymbol(cursorInEditor, followSymbolFallback, false, false,
+                                  FollowSymbolMode::Exact,
                                   CppModelManager::Backend::Builtin);
 }
 
@@ -9649,7 +9650,8 @@ private:
             (const Link &link) {
             moveComments(link, symbolLoc, comments);
         };
-        CppModelManager::followSymbol(cursorInEditor, callback, true, false);
+        CppModelManager::followSymbol(cursorInEditor, callback, true, false,
+                                      FollowSymbolMode::Exact);
     }
 
     static void moveComments(const Link &targetLoc, const Link &symbolLoc,

src/plugins/cppeditor/cpptoolsreuse.h

@@ -33,6 +33,8 @@ class CppRefactoringFile;
 class ProjectInfo;
 class CppCompletionAssistProcessor;
 
+enum class FollowSymbolMode { Exact, Fuzzy };
+
 void CPPEDITOR_EXPORT moveCursorToEndOfIdentifier(QTextCursor *tc);
 void CPPEDITOR_EXPORT moveCursorToStartOfIdentifier(QTextCursor *tc);