Feat: Enable type attributes

vhdl_lang/src/analysis/expression.rs

@@ -1453,6 +1453,24 @@ mod test {
         );
     }
 
+    #[test]
+    fn type_attributes_cannot_be_used_as_an_expression() {
+        let test = TestSetup::new();
+        test.declarative_part("variable x : integer;");
+        let code = test.snippet("x'subtype");
+
+        let mut diagnostics = Vec::new();
+        assert_eq!(test.expr_type(&code, &mut diagnostics), None);
+
+        check_diagnostics(
+            diagnostics,
+            vec![Diagnostic::error(
+                code.s1("x'subtype"),
+                "integer type 'INTEGER' cannot be used in an expression",
+            )],
+        );
+    }
+
     #[test]
     fn binary_expression_missing_names() {
         let test = TestSetup::new();

vhdl_lang/src/analysis/formal_region.rs

@@ -266,6 +266,8 @@ impl<'a> std::ops::Deref for GpkgInterfaceEnt<'a> {
             GpkgInterfaceEnt::Type(typ) => typ.deref(),
             GpkgInterfaceEnt::Constant(obj) => obj.deref(),
             GpkgInterfaceEnt::Subprogram(subp) => subp.deref(),
+            // `ent` is of type `&&AnyEnt`. `deref()` returns `&AnyEnt` which is what we want
+            #[allow(suspicious_double_ref_op)]
             GpkgInterfaceEnt::Package(ent) => ent.deref(),
         }
     }