`this` in function declarations inside object literals should be typed

[sandersn]

let o = {
  f: function () { this./**/ }
}

Expected: Intellisense shows 'f' in the list
Actual: Intellisense shows nothing because this: any.

Note that this similar code already works:

let o = {
  f() { this./**/ }
}

[sandersn]

#8389 reverts this fix for now.

[mhegazy]

Just to clarify, both patterns will result in a this of type any.

We have tried different ways of addressing this issue, and the current behavior (this in an object literal is of type any) seems to be the most reasonable.

Classes present stronger assumptions about how the functions will be called. object literals on the other hand can be used as a property bag often with no assumptions about the relationship of the methods and properties on them. we have seen common JS patterns where methods are added, removed, or called with a different this target at runtime (see #8133 for an example).

the recommendation is to specify an explicit this type in methods:

interface FooBar {
    foo(): void;
    bar(): void;
}

let o = {
    foo: function (this: FooBar) { this /* FooBar */ },
    bar(this: FooBar) { this /* FooBar */ }
}

[FranklinWhale]

Moved to #12785