Type with overloaded method with a generic overload matches type with incompatible method

TypeScript Version: 3.9.0-dev.20200305

Search Terms:
generic type overload

Code

interface I1 {
    f<V extends 'a'>(value: V): void;
    f(value: 'b'): void;
}

interface I2 {
    f(value: 'c'): void;
}

function test(x: I1) {
    function u(y: I2) { }

    u(x);
}

Expected behavior:
Compilation error, u cannot accept x as I1 cannot handle f('c')

Actual behavior:
Compilation succeeds.
Note that all of the following fail, as expected:

interface I1 {
    // f<V extends 'a'>(value: V): void;
    f(value: 'b'): void;
}

interface I2 {
    f(value: 'c'): void;
}

function test(x: I1) {
    function u(y: I2) { }

    u(x);
}

interface I1 {
    f<V extends 'a'>(value: V): void;
    // f(value: 'b'): void;
}

interface I2 {
    f(value: 'c'): void;
}

function test(x: I1) {
    function u(y: I2) { }

    u(x);
}

interface I1 {
    f(value: 'a'): void;
    f(value: 'b'): void;
}

interface I2 {
    f(value: 'c'): void;
}

function test(x: I1) {
    function u(y: I2) { }

    u(x);
}

Playground Link:
https://www.typescriptlang.org/play/?ts=3.9.0-dev.20200305#code/JYOwLgpgTgZghgYwgAgJIEZkG8CwAoZQ5GAHgDVkIAPSEAEwGdkByOZgPgAoA3OAGwCuEAFzIyASlHcA9sDoBufEWI9+Q0cwBGzSchlzFeAL758oSLEQpUAJmxKiMVYJEsEOqbIX4TefDAEQBDBgaRBkSAYwTipRDHF7AkdA4NDwgU4ATzibBKxkXwdCDKpxQyMgA

Related Issues:
Not sure.

Start with the TypeScript 3.9.0-dev.20200305 compiler and the minimal interfaces and call in the issue, using the linked Playground example to reproduce the successful assignment. Confirm that the generic and non-generic overload combination incorrectly accepts I1 as I2, then add a regression test and verify that the call produces the expected compilation error.