[JIT] Resolve string literal type annotations using `Resolver::resolv…

…eType`

**Summary**
This commit modifies `ScriptTypeParser::parseTypeFromExpr` so that
string literal type annotations are resolved using
`Resolver::resolveType`. At present, they are parsed in
`parseBaseTypeName`, which inadvertently allows any key from
`string_to_type_lut` to be used as a string literal type annotation.

**Test Plan**
Existing unit tests (most notably
`TestClassType.test_self_referential_method` which tests the main
feature, self-referential class type annotations, that make use of
string literal type annotations).

**Fixes**
This commit fixes #47570.

ghstack-source-id: 9e5a2c83f6211084a378df1863e662e2ced936ce
Pull Request resolved: #47731

torch/csrc/jit/frontend/script_type_parser.cpp

@@ -149,9 +149,6 @@ c10::optional<std::string> ScriptTypeParser::parseBaseTypeName(
     case TK_NONE: {
       return "None";
     }
-    case TK_STRINGLITERAL: {
-      return StringLiteral(expr).text();
-    }
     case '.': {
       auto select = Select(expr);
       const std::string& name = select.selector().name();
@@ -190,6 +187,15 @@ TypePtr ScriptTypeParser::parseTypeFromExprImpl(const Expr& expr) const {
     }
     return subscriptToType(*value_name, subscript);
 
+  } else if (expr.kind() == TK_STRINGLITERAL) {
+    auto type_name = StringLiteral(expr).text();
+    if (resolver_) {
+      if (auto typePtr = resolver_->resolveType(type_name, expr.range())) {
+        return typePtr;
+      }
+    }
+
+    throw ErrorReport(expr) << "Unknown type name '" << type_name << "'";
   } else if (auto name = parseBaseTypeName(expr)) {
     auto itr = string_to_type_lut().find(*name);
     if (itr != string_to_type_lut().end()) {