zig fmt: canonicalize nested cast builtin order

[Justus2308]

Closes #24106

Searches for surrounding tokens tagged with .builtin when a .builtin_... node whose main token ends in "Cast" is encountered and picks which one to render first according to the field order in CastKind. In case of a redundant casting operation (e.g. @ptrCast(@volatileCast(@ptrCast(...)))) no reordering is done for the entire nested chain.

The canonical ordering is the one proposed by mlugg:

@ptrCast(@alignCast(@addrSpaceCast(@constCast(@volatileCast(something)))))

It can be changed by simply rearranging the fields of CastKind (and adjusting the rendering order in translate_c.removeCVQualifiers for @constCast()/@volatileCast() and related tests).

The first commit is the actual implementation,the second commit is the new ordering applied to affected source files.

[Vexu]

Wouldn't it be easier to just include Cast int the enum field names?

[Justus2308]

Yeah I guess so I probably thought that that checking for 'Cast' first would filter out builtins that don't match more quickly when I wrote this but looking at the list of exsiting builtins again I don't even think that is true

[Justus2308]

Yeah I guess so I probably thought that that checking for 'Cast' first would filter out builtins that don't match more quickly when I wrote this but looking at the list of exsiting builtins again I don't even think that is true

[Justus2308]

Suggested change

	const CastKind = enum {
	ptr,
	@"align",
	addrSpace,
	@"const",
	@"volatile",
	};
	const kind = blk: {
	const slice = tree.tokenSlice(builtin_token);
	if (!mem.endsWith(u8, slice, "Cast")) break :canonicalize;
	const end = slice.len - "Cast".len;
	break :blk meta.stringToEnum(CastKind, slice[1..end]) orelse break :canonicalize;
	};
	const CastKind = enum {
	ptrCast,
	alignCast,
	addrSpaceCast,
	constCast,
	volatileCast,
	};
	const kind = kind: {
	const slice = tree.tokenSlice(builtin_token);
	break :kind meta.stringToEnum(CastKind, slice[1..slice.len]) orelse break :canonicalize;
	};

[Justus2308]

Suggested change

	if (!mem.endsWith(u8, slice, "Cast")) break;
	const end = slice.len - "Cast".len;
	const prev_kind = meta.stringToEnum(CastKind, slice[1..end]) orelse break;
	const prev_kind = meta.stringToEnum(CastKind, slice[1..slice.len]) orelse break;

[Justus2308]

Suggested change

	if (!mem.endsWith(u8, slice, "Cast")) break;
	const end = slice.len - "Cast".len;
	const next_kind = meta.stringToEnum(CastKind, slice[1..end]) orelse break;
	const next_kind = meta.stringToEnum(CastKind, slice[1..slice.len]) orelse break;