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// compile-flags: -Z print-type-sizes
// build-pass
// ignore-pass
// ^-- needed because `--pass check` does not emit the output needed.
// FIXME: consider using an attribute instead of side-effects.
// This file illustrates how generics are handled: types have to be
// monomorphized, in the MIR of the original function in which they
// occur, to have their size reported.
#![feature(start)]
// In an ad-hoc attempt to avoid the injection of unwinding code
// (which clutters the output of `-Z print-type-sizes` with types from
// `unwind::libunwind`):
//
// * I am not using Default to build values because that seems to
// cause the injection of unwinding code. (Instead I just make `fn new`
// methods.)
//
// * Pair derive Copy to ensure that we don't inject
// unwinding code into generic uses of Pair when T itself is also
// Copy.
//
// (I suspect this reflect some naivety within the rust compiler
// itself; it should be checking for drop glue, i.e., a destructor
// somewhere in the monomorphized types. It should not matter whether
// the type is Copy.)
#[derive(Copy, Clone)]
pub struct Pair<T> {
_car: T,
_cdr: T,
}
impl<T> Pair<T> {
fn new(a: T, d: T) -> Self {
Pair {
_car: a,
_cdr: d,
}
}
}
#[derive(Copy, Clone)]
pub struct SevenBytes([u8; 7]);
pub struct FiftyBytes([u8; 50]);
pub struct ZeroSized;
impl SevenBytes {
fn new() -> Self { SevenBytes([0; 7]) }
}
impl FiftyBytes {
fn new() -> Self { FiftyBytes([0; 50]) }
}
pub fn f1<T:Copy>(x: T) {
let _v: Pair<T> = Pair::new(x, x);
let _v2: Pair<FiftyBytes> =
Pair::new(FiftyBytes::new(), FiftyBytes::new());
}
#[start]
fn start(_: isize, _: *const *const u8) -> isize {
let _b: Pair<u8> = Pair::new(0, 0);
let _s: Pair<SevenBytes> = Pair::new(SevenBytes::new(), SevenBytes::new());
let ref _z: ZeroSized = ZeroSized;
f1::<SevenBytes>(SevenBytes::new());
0
}
|
