C++: use pointer in template specialization and initialization

Fix code completion for using pointer in template specialization and
initialization.
Example:
template <typename T>
struct S {};

template <typename T>
struct S<T*> { T* t; };

struct Foo { int foo; };

int main()
{
  S<Foo*> s;
  s.t-> //no code completion
  return 0;
}

Task-number: QTCREATORBUG-12638
Change-Id: Idcd461806a22f08b76236f2db6346f157b12f5d3
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/libs/cplusplus/LookupContext.cpp

@@ -1084,6 +1084,10 @@ ClassOrNamespace *ClassOrNamespace::nestedType(const Name *name, ClassOrNamespac
 
             Subst subst(_control.data());
             if (_factory->expandTemplates()) {
+                const TemplateNameId *templSpecId
+                        = templateSpecialization->name()->asTemplateNameId();
+                const unsigned templSpecArgumentCount = templSpecId ?
+                            templSpecId->templateArgumentCount() : 0;
                 Clone cloner(_control.data());
                 for (unsigned i = 0; i < argumentCountOfSpecialization; ++i) {
                     const TypenameArgument *tParam
@@ -1098,6 +1102,12 @@ ClassOrNamespace *ClassOrNamespace::nestedType(const Name *name, ClassOrNamespac
                                 templId->templateArgumentAt(i):
                                 cloner.type(tParam->type(), &subst);
 
+                    if (i < templSpecArgumentCount
+                            && templSpecId->templateArgumentAt(i)->isPointerType()) {
+                        if (PointerType *pointerType = ty->asPointerType())
+                            ty = pointerType->elementType();
+                    }
+
                     subst.bind(cloner.name(name, &subst), ty);
                 }
 

src/plugins/cpptools/cppcompletion_test.cpp

@@ -2295,6 +2295,35 @@ void CppToolsPlugin::test_completion_data()
         ) << _("derived.t.") << (QStringList()
             << QLatin1String("foo")
             << QLatin1String("Foo"));
+
+    QTest::newRow("template_specialization_and_initialization_with_pointer1") << _(
+            "template <typename T>\n"
+            "struct S {};\n"
+            "template <typename T>\n"
+            "struct S<T*> { T *t; };\n"
+            "struct Foo { int foo; };\n"
+            "void fun() {\n"
+            "   S<Foo*> s;\n"
+            "   @\n"
+            "}\n"
+        ) << _("s.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"
+            "struct S {};\n"
+            "template <typename T1, typename T2>\n"
+            "struct S<T1*> { T1 *t; };\n"
+            "struct Foo { int foo; };\n"
+            "void fun() {\n"
+            "   S<Foo*> s;\n"
+            "   @\n"
+            "}\n"
+        ) << _("s.t->") << (QStringList()
+            << QLatin1String("foo")
+            << QLatin1String("Foo"));
 }
 
 void CppToolsPlugin::test_completion_member_access_operator()