Tag all the fields of a mutable item `mutable`

[ijklam]

Currently, the semantic token of fields in a mutable item (e.g. var variable, mutable pointer) is property, but as the field can be change, it should have a mutable modifier in its semantic token, same as var variables. Though the mutable modifier takes no effect for now, unless we implement https://codeberg.org/ziglang/vscode-zig/issues/492.

For example:

fn f() void {
  var a: struct {
    x: u32,
  } = .{ .x = 1 };
  const b = &a;

  _ = a.x; // `x` here should be taggeg `mutable`
  _ = b.*.x; // `x` here should be taggeg `mutable`
}

Moreover, methods that accepts self: *@This() can also tagged as mutable, to indicate that it may change the fields of self in the method body.

[xdBronch]

Moreover, methods that accepts self: *@this() can also tagged as mutable, to indicate that it may change the fields of self in the method body.

i did this originally in #2244 but it was rejected, i think it could be nice but its probably less reasonable in a language like zig that doesnt have any specific concept of a self

[ijklam]

i did this originally in #2244 but it was rejected, i think it could be nice but its probably less reasonable in a language like zig that doesnt have any specific concept of a self

Or maybe we can mark all the functions that receives mutable pointer(s) to be mutable, not just for methods in self.

[Techatrix]

Marking function/methods that take in non const pointer parameters as mutable is rejected for now even if constrained to the first parameter. This doesn't mix well with the current usage of this token modifier which has much stronger guarantees. But in the long term, there might be room to add this after #2106 with a different token modifier.

Whether tracking mutability through field accesses is accepted depends on the exact semantic being proposed here, it's impact on "common" code with popular themes and editors, and how it interacts with the current usage of mutable regarding user preference and customizability. None of which has been taken into consideration here.