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sx/examples/0808-memory-xx-value-routes-through-context-allocator.sx

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// Phase 1.1 — the compiler-internal heap-copy that backs `xx <rvalue>`
// protocol erasure must dispatch through `context.allocator`, not call
// libc malloc directly. So when a `push Context.{ allocator = tracer }`
// block is active, a `xx StructLiteral.{}` inside it MUST be allocated
// by the tracker.
//
// Note: `xx` only heap-copies for RVALUES (struct literals, call results).
// `xx <lvalue>` (an identifier, field access, index, or deref) borrows
// the operand's storage, so it never allocates and never reaches this
// path. See specs.md §3 — Protocol value ownership and lifetime.
#import "modules/std.sx";
#import "modules/std/mem.sx"; // `Allocator` is non-transitive: name it, import it.
Tracer :: struct {
count: s64;
init :: () -> *Tracer {
t : *Tracer = xx libc_malloc(size_of(Tracer));
t.count = 0;
t
}
}
impl Allocator for Tracer {
alloc_bytes :: (self: *Tracer, size: s64) -> *void {
self.count += 1;
return libc_malloc(size);
}
dealloc_bytes :: (self: *Tracer, ptr: *void) {
libc_free(ptr);
}
}
ByValue :: struct { x: s64; y: s64; }
main :: () -> s32 {
tracer := Tracer.init();
push Context.{ allocator = xx tracer, data = null } {
// Struct-literal operand: rvalue → heap-copy through context.allocator.
ignore : Allocator = xx ByValue.{ x = 1, y = 2 };
_ = ignore;
}
print("Tracer.count = {}\n", tracer.count);
0
}