CppEditor: Another name minimalization fix

... involving using declarations.
See also aae3ce15aa.

Fixes: QTCREATORBUG-28386
Change-Id: I4171dce7b4e34b41c4a894e3bb34b3f62f82ac0f
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/cplusplus/LookupContext.cpp

@@ -229,11 +229,11 @@ static bool isInlineNamespace(ClassOrNamespace *con, const Name *name)
 const Name *LookupContext::minimalName(Symbol *symbol, ClassOrNamespace *target, Control *control)
 {
     const Name *n = nullptr;
+    std::optional<QList<const Name *>> minimal;
     QList<const Name *> names = LookupContext::fullyQualifiedName(symbol);
-    ClassOrNamespace *current = target;
 
     const auto getNameFromItems = [symbol, target, control](const QList<LookupItem> &items,
-            const QList<const Name *> &names) -> const Name * {
+            const QList<const Name *> &names) -> std::optional<QList<const Name *>> {
         for (const LookupItem &item : items) {
             if (!symbol->asUsingDeclaration() && !symbolIdentical(item.declaration(), symbol))
                 continue;
@@ -246,24 +246,30 @@ const Name *LookupContext::minimalName(Symbol *symbol, ClassOrNamespace *target,
                     minimal.removeAt(i);
             }
 
-            return control->toName(minimal);
+            return minimal;
         }
-
+        return {};
-        return nullptr;
     };
 
+    do {
+        ClassOrNamespace *current = target;
+        n = nullptr;
+
         for (int i = names.size() - 1; i >= 0; --i) {
             if (! n)
                 n = names.at(i);
             else
                 n = control->qualifiedNameId(names.at(i), n);
 
-        // once we're qualified enough to get the same symbol, break
             if (target) {
-            const Name * const minimal = getNameFromItems(target->lookup(n), names.mid(i));
+                const auto candidate = getNameFromItems(target->lookup(n), names.mid(i));
-            if (minimal)
+                if (candidate && (!minimal || minimal->size() > candidate->size())) {
-                return minimal;
+                    minimal = candidate;
+                    if (minimal && minimal->size() == 1)
+                        return control->toName(*minimal);
                 }
+            }
+
             if (current) {
                 const ClassOrNamespace * const nested = current->getNested(names.last());
                 if (nested) {
@@ -271,16 +277,23 @@ const Name *LookupContext::minimalName(Symbol *symbol, ClassOrNamespace *target,
                             = names.mid(0, names.size() - i - 1) << names.last();
                     const QList<ClassOrNamespace *> usings = nested->usings();
                     for (ClassOrNamespace * const u : usings) {
-                    const Name * const minimal = getNameFromItems(u->lookup(symbol->name()),
+                        const auto candidate = getNameFromItems(u->lookup(symbol->name()), nameList);
-                                                                  nameList);
+                        if (candidate && (!minimal || minimal->size() > candidate->size())) {
-                    if (minimal)
+                            minimal = candidate;
-                        return minimal;
+                            if (minimal && minimal->size() == 1)
+                                return control->toName(*minimal);
+                        }
                     }
                 }
                 current = current->getNested(names.at(names.size() - i - 1));
             }
         }
+        if (target)
+            target = target->parent();
+    } while (target);
 
+    if (minimal)
+        return control->toName(*minimal);
     return n;
 }
 

src/plugins/cppeditor/cppquickfix_test.cpp

@@ -4555,6 +4555,39 @@ D::D()
 )";
     testDocuments << CppTestDocument::create("file.cpp", original, expected);
     QuickFixOperationTest(testDocuments, &factory);
+
+    testDocuments.clear();
+    original = R"(
+namespace ns1 { template<typename T> class span {}; }
+
+namespace ns {
+using ns1::span;
+class foo
+{
+    void @bar(ns::span<int>);
+};
+}
+)";
+    expected = R"(
+namespace ns1 { template<typename T> class span {}; }
+
+namespace ns {
+using ns1::span;
+class foo
+{
+    void bar(ns::span<int>);
+};
+
+void foo::bar(ns::span<int>)
+{
+
+}
+
+}
+)";
+    // TODO: Unneeded namespace gets inserted in RewriteName::visit(const QualifiedNameId *)
+    testDocuments << CppTestDocument::create("file.cpp", original, expected);
+    QuickFixOperationTest(testDocuments, &factory);
 }
 
 /// Find right implementation file. (QTCREATORBUG-10728)