C++: add support for resolving typedefs for template arguments

Example:
template <typename T>
struct Base { T t; };
struct Foo { int foo; };
void fun() {
  typedef Foo TypedefedFoo;
  Base<TypedefedFoo> baseFoo;
  baseFoo.t.// no code completion
}

Change-Id: I4822693d3fa1ee2e9b0e4cdd28bb9a8d441fb313
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/libs/cplusplus/ResolveExpression.cpp

@@ -82,13 +82,46 @@ public:
     {
         QSet<Symbol *> visited;
         _binding = binding;
-        // Use a hard limit when trying to resolve typedefs. Typedefs in templates can refer to
+        // Use a hard limit when trying to resolve typedefs.
-        // each other, each time enhancing the template argument and thus making it impossible to
+        // TODO: Now that template arguments are resolved, use an 'alreadyResolved' container to
-        // use an "alreadyResolved" container. FIXME: We might overcome this by resolving the
+        // handle recursive typedefs.
-        // template parameters.
         unsigned maxDepth = 15;
         for (NamedType *namedTy = 0; maxDepth && (namedTy = getNamedType(*type)); --maxDepth) {
-            QList<LookupItem> namedTypeItems = getNamedTypeItems(namedTy->name(), *scope, _binding);
+            NamedType *orgNamedTy = namedTy;
+            const Name *name = namedTy->name();
+            if (const QualifiedNameId *qn = name->asQualifiedNameId()) {
+                const Name *name = qn->name();
+                Scope *templateScope = *scope;
+                if (const TemplateNameId *templateNameId = name->asTemplateNameId()) {
+                    const TemplateNameId *resolvedTemplateNameId =
+                            resolveTemplateParameters(templateNameId, templateScope, binding);
+                    const QualifiedNameId *resolvedQualifiedNamedId =
+                            _context.bindings()->control()->qualifiedNameId(qn->base(),
+                                                                            resolvedTemplateNameId);
+                    namedTy = _context.bindings()->control()->namedType(resolvedQualifiedNamedId);
+                }
+            } else if (const TemplateNameId *templateNameId = name->asTemplateNameId()) {
+                Scope *templateScope = *scope;
+                const TemplateNameId *resolvedTemplateNameId =
+                        resolveTemplateParameters(templateNameId, templateScope, binding);
+                namedTy = _context.bindings()->control()->namedType(resolvedTemplateNameId);
+            }
+
+            if (namedTy != orgNamedTy) {
+                if ((*type)->isPointerType()) {
+                    *type = FullySpecifiedType(_context.bindings()->control()->pointerType(
+                                                   FullySpecifiedType(namedTy)));
+                } else if (ReferenceType *referenceType = (*type)->asReferenceType()) {
+                    *type = FullySpecifiedType(_context.bindings()->control()->referenceType(
+                                                   FullySpecifiedType(namedTy),
+                                                   referenceType->isRvalueReference()));
+                } else {
+                    *type = FullySpecifiedType(namedTy);
+                }
+                name = namedTy->name();
+            }
+
+            QList<LookupItem> namedTypeItems = getNamedTypeItems(name, *scope, _binding);
 
             if (Q_UNLIKELY(debug))
                 qDebug() << "-- we have" << namedTypeItems.size() << "candidates";
@@ -99,6 +132,25 @@ public:
     }
 
 private:
+    const TemplateNameId *resolveTemplateParameters(const TemplateNameId *templateNameId,
+                                                    Scope *templateScope,
+                                                    ClassOrNamespace *binding)
+    {
+        std::vector<FullySpecifiedType> resolvedTemplateArguments;
+        const unsigned templArgumentCount = templateNameId->templateArgumentCount();
+        for (unsigned i = 0; i < templArgumentCount; ++i) {
+            FullySpecifiedType resolvedTemplateArgumentType
+                    = templateNameId->templateArgumentAt(i);
+            resolve(&resolvedTemplateArgumentType, &templateScope, binding);
+            resolvedTemplateArguments.push_back(resolvedTemplateArgumentType);
+        }
+
+        return _context.bindings()->control()->templateNameId(templateNameId->identifier(),
+                                                              templateNameId->isSpecialization(),
+                                                              &resolvedTemplateArguments[0],
+                                                              templArgumentCount);
+    }
+
     NamedType *getNamedType(FullySpecifiedType& type) const
     {
         NamedType *namedTy = type->asNamedType();

src/plugins/cpptools/cppcompletion_test.cpp

@@ -2328,6 +2328,34 @@ void CppToolsPlugin::test_completion_data()
             << QLatin1String("foo")
             << QLatin1String("Foo"));
 
+    QTest::newRow("resolving_template_argument1") << _(
+            "template <typename T>\n"
+            "struct Base { T t; };\n"
+            "struct Foo { int foo; };\n"
+            "void fun() {\n"
+            "   typedef Foo TypedefedFoo;\n"
+            "   Base<TypedefedFoo> baseFoo;\n"
+            "   @\n"
+            "}\n"
+        ) << _("baseFoo.t.") << (QStringList()
+            << QLatin1String("foo")
+            << QLatin1String("Foo"));
+
+    QTest::newRow("resolving_template_argument2") << _(
+            "namespace NS {\n"
+            "template <typename T>\n"
+            "struct Base { T t; };\n"
+            "}\n"
+            "struct Foo { int foo; };\n"
+            "void fun() {\n"
+            "   typedef Foo TypedefedFoo;\n"
+            "   NS::Base<TypedefedFoo> baseFoo;\n"
+            "   @\n"
+            "}\n"
+        ) << _("baseFoo.t.") << (QStringList()
+            << QLatin1String("foo")
+            << QLatin1String("Foo"));
+
     // this is not a valid code(is not compile) but it caused a crash
     QTest::newRow("template_specialization_and_initialization_with_pointer2") << _(
             "template <typename T1, typename T2 = int>\n"