CppEditor: Fix looking up containing function for search result

- Move look-up to CplusPlus::FindUsages, where we are guaranteed that
  we actually have the document source.
- Use the same straightforward algorithm as with clangd.
- Undo the changes to CppDocument::functionAt(), which broke
  the autotest.
Amends 6f7e7980d2b604c79507f9165098f783db8ab2e3.

Change-Id: I008d05ba41a3b63b71e3131d7021e0d4e7d0641f
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

1 files changed, 9 insertions, 81 deletions

diff --git a/src/libs/cplusplus/CppDocument.cpp b/src/libs/cplusplus/CppDocument.cpp
index 60144b2320..90660f2b55 100644
--- a/src/libs/cplusplus/CppDocument.cpp
+++ b/src/libs/cplusplus/CppDocument.cpp
@@ -96,86 +96,6 @@ protected:
     }
 };
 
-class ContainingFunctionAt: protected SymbolVisitor
-{
-    TranslationUnit *translationUnit;
-    Symbol *root;
-    int line;
-    int column;
-    Symbol *functionSymbol;
-    bool foundFunction;
-    bool foundBlock;
-
-    bool scopeContains(Scope* scope, int line, int column){
-        if (!scope)
-            return false;
-
-        int scopeStartLine{-1}, scopeStartColumn{-1}, scopeEndLine{-1}, scopeEndColumn{-1};
-        translationUnit->getPosition(scope->startOffset(), &scopeStartLine, &scopeStartColumn);
-        translationUnit->getPosition(scope->endOffset(), &scopeEndLine, &scopeEndColumn);
-
-        if (line < scopeStartLine || line > scopeEndLine)
-            return false;
-
-        if (line > scopeStartLine && line < scopeEndLine)
-            return true;
-
-        if (scopeStartLine == line && column >= scopeStartColumn)
-            return true;
-
-        if (scopeEndLine == line && column <= scopeEndColumn)
-            return true;
-
-        return false;
-    }
-
-public:
-    ContainingFunctionAt(TranslationUnit *unit, Symbol *root)
-        : translationUnit(unit), root(root), line(0), column(0), functionSymbol(nullptr)
-        , foundFunction(false), foundBlock(false) {}
-
-    Symbol *operator()(int line, int column)
-    {
-        this->line = line;
-        this->column = column;
-        this->functionSymbol = nullptr;
-        accept(root);
-
-        return foundBlock ? functionSymbol : nullptr;
-    }
-
-protected:
-    bool preVisit(Symbol *s) final
-    {
-        if (foundBlock)
-            return false;
-
-        if (foundFunction) {
-            auto block = s->asBlock();
-            if (!block)
-                return true;
-
-            if (scopeContains(block->asScope(), line, column)) {
-                foundBlock = true;
-                return false;
-            }
-            return true;
-        }
-
-        auto asFunction = s->asFunction();
-        if (asFunction) {
-            if (s->line() < line || (s->line() == line && s->column() <= column)) {
-                foundFunction = scopeContains(s->asScope(), line, column);
-                if (foundFunction)
-                    functionSymbol = asFunction;
-            }
-        }
-
-        return true;
-    }
-};
-
-
 class FindScopeAt: protected SymbolVisitor
 {
     TranslationUnit *_unit;
@@ -592,12 +512,20 @@ QString Document::functionAt(int line, int column, int *lineOpeningDeclaratorPar
     if (line < 1 || column < 1)
         return QString();
 
-    Symbol *symbol = ContainingFunctionAt{translationUnit(), globalNamespace()}(line, column);
+    Symbol *symbol = lastVisibleSymbolAt(line, column);
     if (!symbol)
         return QString();
 
+    // Find the enclosing function scope (which might be several levels up, or we might be standing
+    // on it)
     Scope *scope = symbol->asScope();
     if (!scope)
+        scope = symbol->enclosingScope();
+
+    while (scope && !scope->isFunction() )
+        scope = scope->enclosingScope();
+
+    if (!scope)
         return QString();
 
     // We found the function scope