[flow] declare function does not recognize bounded polymorphic types

[rattrayalex]

In the course of #444 , I noticed that

    it("declared function type parameter bounds", () => {
      verifyAndAssertMessages(
        unpad(`
          import type Foo from 'foo';
          declare function foo<T: Foo>(a: T): T;
          foo(1);
        `),
        { "no-unused-vars": 1, "no-undef": 1 },
        []
      );
    });

results in

[
   {
      "ruleId":"no-unused-vars",
      "severity":1,
      "message":"'Foo' is defined but never used.",
      "line":1,
      "column":13,
      "nodeType":"Identifier",
      "source":"import type Foo from 'foo';"
   }
]

and

    it("declared class type parameter bounds", () => {
      verifyAndAssertMessages(
        unpad(`
          import type Foo from 'foo';
          declare class C<T: Foo> {
            x: T
          };
          new C();
        `),
        { "no-unused-vars": 1, "no-undef": 1 },
        []
      );
    });

results in

[
   {
      "ruleId":"no-unused-vars",
      "severity":1,
      "message":"'Foo' is defined but never used.",
      "line":1,
      "column":13,
      "nodeType":"Identifier",
      "source":"import type Foo from 'foo';"
   },
   {
      "ruleId":"no-unused-vars",
      "severity":1,
      "message":"'T' is defined but never used.",
      "line":2,
      "column":17,
      "nodeType":"Identifier",
      "source":"declare class C<T: Foo> {"
   }
]

I don't use Flow much, so I'm not encountering this in the wild, but trying the above at https://flowtype.org/try/ appears to indicate that the code is semantically correct.

[zertosh]

@rattrayalex #459 now fixes this, but I need to split up that PR

[rattrayalex]

Nice!

[pronebird]

I have a similar case:

declare class ClipboardData {
  setData(type: string, data: string): void;
  getData(type: string): string;
}

declare class ClipboardEvent extends Event {
  clipboardData: ClipboardData;
}

Output:

'ClipboardData' is defined but never used.

[kaicataldo]

Thank you for the issue. Now that @babel/eslint-parser has been released, we are making this repository read-only. If this is a change you would still like to advocate for, please reopen this in the babel/babel monorepo.