Merged Interfaces with incompatible methods and properties should be an error

[weswigham]

TypeScript Version: 2.7.0-dev.201xxxxx

Code

interface Foo {
    bold(): string;
}

interface Foo {
    bold: string;
}

var x: Foo;

const j = x.bold;

Expected behavior:
j is type any, TS issues an error on both declarations of bold because their type doesn't match.

Actual behavior:
No error, j is type string.

Please note, the colors DT package (and one other package) relies on our current buggy behavior here and will need to be fixed.

[DanielRosenwasser]

This is a regression that seems to have started in TypeScript 2.0. TypeScript 1.8 is the last version that reported

error TS2300: Duplicate identifier 'bold'.

[weswigham]

The bisect result says this was an (unintended?) side-effect of #8696. cc @RyanCavanaugh wasn't the restriction only supposed to be relaxed if the declarations had the same types?

[RyanCavanaugh]

Correct, the intended behavior is that this would be an error due to the types not being identical