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feat: pointee($P: Type) -> Type comptime reflection builtin

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Project a pointer type to its target: `pointee(*X)` -> `X`. The one reflection
primitive missing for the `race` result synthesis (`*Task(A)` -> `A` via
`field_type(pointee(*Task(A)), 0)`) — reflection could read aggregate fields but
was blind to a pointer's target type.

Mirrors the `field_type` builtin: declared `#builtin` in std/core.sx, resolved as
a lower-time type-call fold in resolveTypeCallWithBindings (src/ir/lower/generic.zig)
so it composes in any type-arg slot. `.pointer` -> pointee, `.many_pointer` ->
element; a non-pointer arg is a loud diagnostic + `.unresolved` sentinel (no silent
fallback). Adversarially reviewed (SHIP). Locked by
examples/comptime/0647-comptime-pointee-reflection.sx. Suite green (819/0).

PLAN-RACE step 1 of 6.
This commit is contained in:
agra
2026-06-26 12:47:02 +03:00
parent dea96bd66a
commit f1d298764f
6 changed files with 57 additions and 0 deletions
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21
src/ir/lower/generic.zig
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@@ -1424,6 +1424,27 @@ pub fn resolveTypeCallWithBindings(self: *Lowering, cl: *const ast.Call) TypeId
};
return self.fieldTypeOf(t, idx, cl.callee.span);
}
// pointee($P) -> Type — comptime reflection: the target type of a pointer
// (`pointee(*X)` -> `X`). Folds at lower time like `field_type` so it
// composes inside any type-arg slot. A non-pointer arg is a loud error.
if (std.mem.eql(u8, callee_name, "pointee")) {
if (cl.args.len != 1) {
if (self.diagnostics) |d|
d.addFmt(.err, cl.callee.span, "pointee takes one type: pointee($P)", .{});
return .unresolved;
}
const t = self.resolveTypeArg(cl.args[0]);
if (t == .unresolved) return .unresolved;
return switch (self.module.types.get(t)) {
.pointer => |p| p.pointee,
.many_pointer => |p| p.element,
else => blk: {
if (self.diagnostics) |d|
d.addFmt(.err, cl.callee.span, "pointee: '{s}' is not a pointer type", .{self.formatTypeName(t)});
break :blk .unresolved;
},
};
}
// Built-in: Vector(N, T)
if (std.mem.eql(u8, callee_name, "Vector") and cl.args.len == 2) {
const length = self.resolveVectorLane(cl.args[0]) orelse return .unresolved;