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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/print_type_sizes/packed.rs | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/src/test/ui/print_type_sizes/packed.rs b/src/test/ui/print_type_sizes/packed.rs new file mode 100644 index 000000000..269cc3cc2 --- /dev/null +++ b/src/test/ui/print_type_sizes/packed.rs @@ -0,0 +1,69 @@ +// 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 packing is handled; it should cause +// the elimination of padding that would normally be introduced +// to satisfy alignment desirata. +// +// It avoids using u64/i64 because on some targets that is only 4-byte +// aligned (while on most it is 8-byte aligned) and so the resulting +// padding and overall computed sizes can be quite different. + +#![allow(dead_code)] +#![feature(start)] + +#[derive(Default)] +#[repr(packed)] +struct Packed1 { + a: u8, + b: u8, + g: i32, + c: u8, + h: i16, + d: u8, +} + +#[derive(Default)] +#[repr(packed(2))] +struct Packed2 { + a: u8, + b: u8, + g: i32, + c: u8, + h: i16, + d: u8, +} + +#[derive(Default)] +#[repr(packed(2))] +#[repr(C)] +struct Packed2C { + a: u8, + b: u8, + g: i32, + c: u8, + h: i16, + d: u8, +} + +#[derive(Default)] +struct Padded { + a: u8, + b: u8, + g: i32, + c: u8, + h: i16, + d: u8, +} + +#[start] +fn start(_: isize, _: *const *const u8) -> isize { + let _c: Packed1 = Default::default(); + let _d: Packed2 = Default::default(); + let _e: Packed2C = Default::default(); + let _f: Padded = Default::default(); + 0 +} |