src/test/ui/repr/repr-no-niche.rs

   1 // run-pass
   2
   3 // This file tests repr(no_niche), which causes an struct/enum to hide
   4 // any niche space that may exist in its internal state from the
   5 // context it appears in.
   6
   7 // Here are the axes this test is seeking to cover:
   8 //
   9 // repr annotation:
  10 // visible: (); cloaked: (no_niche); transparent: (transparent); shadowy: (transparent, no_niche)
  11 //
  12 // enum vs struct
  13 //
  14 // niche-type via type-parameter vs inline declaration
  15
  16 #![feature(decl_macro)]
  17 #![feature(no_niche)]
  18
  19 use std::mem::size_of;
  20 use std::num::{NonZeroU8, NonZeroU16};
  21
  22 mod struct_inline {
  23     use std::num::NonZeroU16 as N16;
  24
  25     #[derive(Debug)] pub struct Visible(N16);
  26
  27     #[repr(no_niche)]
  28     #[derive(Debug)] pub struct Cloaked(N16);
  29
  30     #[repr(transparent)]
  31     #[derive(Debug)] pub struct Transparent(N16);
  32
  33     #[repr(transparent, no_niche)]
  34     #[derive(Debug)] pub struct Shadowy(N16);
  35 }
  36
  37 mod struct_param {
  38     #[derive(Debug)] pub struct Visible<T>(T);
  39
  40     #[repr(no_niche)]
  41     #[derive(Debug)] pub struct Cloaked<T>(T);
  42
  43     #[repr(transparent)]
  44     #[derive(Debug)] pub struct Transparent<T>(T);
  45
  46     #[repr(transparent, no_niche)]
  47     #[derive(Debug)] pub struct Shadowy<T>(T);
  48 }
  49
  50 mod enum_inline {
  51     use crate::two_fifty_six_variant_enum;
  52     use std::num::{NonZeroU8 as N8, NonZeroU16 as N16};
  53
  54     #[derive(Debug)] pub enum Visible1 { _A(N16), }
  55
  56     #[repr(no_niche)]
  57     #[derive(Debug)] pub enum Cloaked1 { _A(N16), }
  58
  59     // (N.B.: transparent enums must be univariant)
  60     #[repr(transparent)]
  61     #[derive(Debug)] pub enum Transparent { _A(N16), }
  62
  63     #[repr(transparent, no_niche)]
  64     #[derive(Debug)] pub enum Shadowy { _A(N16), }
  65
  66     // including multivariant enums for completeness. Payload and
  67     // number of variants (i.e. discriminant size) have been chosen so
  68     // that layout including discriminant is 4 bytes, with no space in
  69     // padding to hide another discrimnant from the surrounding
  70     // context.
  71     //
  72     // (Note that multivariant enums cannot usefully expose a niche in
  73     // general; this test is relying on that.)
  74     two_fifty_six_variant_enum!(Visible2, N8);
  75
  76     #[repr(no_niche)]
  77     two_fifty_six_variant_enum!(Cloaked2, N8);
  78 }
  79
  80 mod enum_param {
  81     use super::two_fifty_six_variant_enum;
  82
  83     #[derive(Debug)] pub enum Visible1<T> { _A(T), }
  84
  85     #[repr(no_niche)]
  86     #[derive(Debug)] pub enum Cloaked1<T> { _A(T), }
  87
  88     // (N.B.: transparent enums must be univariant)
  89     #[repr(transparent)]
  90     #[derive(Debug)] pub enum Transparent<T> { _A(T), }
  91
  92     #[repr(transparent, no_niche)]
  93     #[derive(Debug)] pub enum Shadowy<T> { _A(T), }
  94
  95     // including multivariant enums for completeness. Same notes apply
  96     // here as above (assuming `T` is instantiated with `NonZeroU8`).
  97     two_fifty_six_variant_enum!(Visible2<T>);
  98
  99     #[repr(no_niche)]
 100     two_fifty_six_variant_enum!(Cloaked2<T>);
 101 }
 102
 103 fn main() {
 104     // sanity-checks
 105     assert_eq!(size_of::<struct_inline::Visible>(),               2);
 106     assert_eq!(size_of::<struct_inline::Cloaked>(),               2);
 107     assert_eq!(size_of::<struct_inline::Transparent>(),           2);
 108     assert_eq!(size_of::<struct_inline::Shadowy>(),               2);
 109
 110     assert_eq!(size_of::<struct_param::Visible<NonZeroU16>>(), 2);
 111     assert_eq!(size_of::<struct_param::Cloaked<NonZeroU16>>(), 2);
 112     assert_eq!(size_of::<struct_param::Transparent<NonZeroU16>>(), 2);
 113     assert_eq!(size_of::<struct_param::Shadowy<NonZeroU16>>(), 2);
 114
 115     assert_eq!(size_of::<enum_inline::Visible1>(),    2);
 116     assert_eq!(size_of::<enum_inline::Cloaked1>(),    2);
 117     assert_eq!(size_of::<enum_inline::Transparent>(), 2); // transparent enums are univariant
 118     assert_eq!(size_of::<enum_inline::Shadowy>(),     2);
 119     assert_eq!(size_of::<enum_inline::Visible2>(),    4);
 120     assert_eq!(size_of::<enum_inline::Cloaked2>(),    4);
 121
 122     assert_eq!(size_of::<enum_param::Visible1<NonZeroU16>>(),    2);
 123     assert_eq!(size_of::<enum_param::Cloaked1<NonZeroU16>>(),    2);
 124     assert_eq!(size_of::<enum_param::Transparent<NonZeroU16>>(), 2);
 125     assert_eq!(size_of::<enum_param::Shadowy<NonZeroU16>>(),     2);
 126     assert_eq!(size_of::<enum_param::Visible2<NonZeroU8>>(),     4);
 127     assert_eq!(size_of::<enum_param::Cloaked2<NonZeroU8>>(),     4);
 128
 129     // now the actual tests of no_niche: how do inputs above compose
 130     // with `Option` type constructor. The cases with a `_+2` are the
 131     // ones where no_niche fires.
 132     assert_eq!(size_of::<Option<struct_inline::Visible>>(),       2);
 133     assert_eq!(size_of::<Option<struct_inline::Cloaked>>(),       2+2);
 134     assert_eq!(size_of::<Option<struct_inline::Transparent>>(),   2);
 135     assert_eq!(size_of::<Option<struct_inline::Shadowy>>(),       2+2);
 136
 137     assert_eq!(size_of::<Option<struct_param::Visible<NonZeroU16>>>(),     2);
 138     assert_eq!(size_of::<Option<struct_param::Cloaked<NonZeroU16>>>(),     2+2);
 139     assert_eq!(size_of::<Option<struct_param::Transparent<NonZeroU16>>>(), 2);
 140     assert_eq!(size_of::<Option<struct_param::Shadowy<NonZeroU16>>>(),     2+2);
 141
 142     assert_eq!(size_of::<Option<enum_inline::Visible1>>(),    2);
 143     assert_eq!(size_of::<Option<enum_inline::Cloaked1>>(),    2+2);
 144     assert_eq!(size_of::<Option<enum_inline::Transparent>>(), 2);
 145     assert_eq!(size_of::<Option<enum_inline::Shadowy>>(),     2+2);
 146     // cannot use niche of multivariant payload
 147     assert_eq!(size_of::<Option<enum_inline::Visible2>>(),    4+2);
 148     assert_eq!(size_of::<Option<enum_inline::Cloaked2>>(),    4+2);
 149
 150     assert_eq!(size_of::<Option<enum_param::Visible1<NonZeroU16>>>(),    2);
 151     assert_eq!(size_of::<Option<enum_param::Cloaked1<NonZeroU16>>>(),    2+2);
 152     assert_eq!(size_of::<Option<enum_param::Transparent<NonZeroU16>>>(), 2);
 153     assert_eq!(size_of::<Option<enum_param::Shadowy<NonZeroU16>>>(),     2+2);
 154     // cannot use niche of multivariant payload
 155     assert_eq!(size_of::<Option<enum_param::Visible2<NonZeroU8>>>(),    4+2);
 156     assert_eq!(size_of::<Option<enum_param::Cloaked2<NonZeroU8>>>(),    4+2);
 157 }
 158
 159 macro two_fifty_six_variant_enum {
 160     ($name:ident<$param:ident>) => {
 161         #[derive(Debug)]
 162         pub enum $name<$param> {
 163             _V00($param, u16), _V01(u16, $param), _V02($param, u16), _V03(u16, $param),
 164             _V04($param, u16), _V05(u16, $param), _V06($param, u16), _V07(u16, $param),
 165             _V08($param, u16), _V09(u16, $param), _V0a($param, u16), _V0b(u16, $param),
 166             _V0c($param, u16), _V0d(u16, $param), _V0e($param, u16), _V0f(u16, $param),
 167
 168             _V10($param, u16), _V11(u16, $param), _V12($param, u16), _V13(u16, $param),
 169             _V14($param, u16), _V15(u16, $param), _V16($param, u16), _V17(u16, $param),
 170             _V18($param, u16), _V19(u16, $param), _V1a($param, u16), _V1b(u16, $param),
 171             _V1c($param, u16), _V1d(u16, $param), _V1e($param, u16), _V1f(u16, $param),
 172
 173             _V20($param, u16), _V21(u16, $param), _V22($param, u16), _V23(u16, $param),
 174             _V24($param, u16), _V25(u16, $param), _V26($param, u16), _V27(u16, $param),
 175             _V28($param, u16), _V29(u16, $param), _V2a($param, u16), _V2b(u16, $param),
 176             _V2c($param, u16), _V2d(u16, $param), _V2e($param, u16), _V2f(u16, $param),
 177
 178             _V30($param, u16), _V31(u16, $param), _V32($param, u16), _V33(u16, $param),
 179             _V34($param, u16), _V35(u16, $param), _V36($param, u16), _V37(u16, $param),
 180             _V38($param, u16), _V39(u16, $param), _V3a($param, u16), _V3b(u16, $param),
 181             _V3c($param, u16), _V3d(u16, $param), _V3e($param, u16), _V3f(u16, $param),
 182
 183             _V40($param, u16), _V41(u16, $param), _V42($param, u16), _V43(u16, $param),
 184             _V44($param, u16), _V45(u16, $param), _V46($param, u16), _V47(u16, $param),
 185             _V48($param, u16), _V49(u16, $param), _V4a($param, u16), _V4b(u16, $param),
 186             _V4c($param, u16), _V4d(u16, $param), _V4e($param, u16), _V4f(u16, $param),
 187
 188             _V50($param, u16), _V51(u16, $param), _V52($param, u16), _V53(u16, $param),
 189             _V54($param, u16), _V55(u16, $param), _V56($param, u16), _V57(u16, $param),
 190             _V58($param, u16), _V59(u16, $param), _V5a($param, u16), _V5b(u16, $param),
 191             _V5c($param, u16), _V5d(u16, $param), _V5e($param, u16), _V5f(u16, $param),
 192
 193             _V60($param, u16), _V61(u16, $param), _V62($param, u16), _V63(u16, $param),
 194             _V64($param, u16), _V65(u16, $param), _V66($param, u16), _V67(u16, $param),
 195             _V68($param, u16), _V69(u16, $param), _V6a($param, u16), _V6b(u16, $param),
 196             _V6c($param, u16), _V6d(u16, $param), _V6e($param, u16), _V6f(u16, $param),
 197
 198             _V70($param, u16), _V71(u16, $param), _V72($param, u16), _V73(u16, $param),
 199             _V74($param, u16), _V75(u16, $param), _V76($param, u16), _V77(u16, $param),
 200             _V78($param, u16), _V79(u16, $param), _V7a($param, u16), _V7b(u16, $param),
 201             _V7c($param, u16), _V7d(u16, $param), _V7e($param, u16), _V7f(u16, $param),
 202
 203             _V80($param, u16), _V81(u16, $param), _V82($param, u16), _V83(u16, $param),
 204             _V84($param, u16), _V85(u16, $param), _V86($param, u16), _V87(u16, $param),
 205             _V88($param, u16), _V89(u16, $param), _V8a($param, u16), _V8b(u16, $param),
 206             _V8c($param, u16), _V8d(u16, $param), _V8e($param, u16), _V8f(u16, $param),
 207
 208             _V90($param, u16), _V91(u16, $param), _V92($param, u16), _V93(u16, $param),
 209             _V94($param, u16), _V95(u16, $param), _V96($param, u16), _V97(u16, $param),
 210             _V98($param, u16), _V99(u16, $param), _V9a($param, u16), _V9b(u16, $param),
 211             _V9c($param, u16), _V9d(u16, $param), _V9e($param, u16), _V9f(u16, $param),
 212
 213             _Va0($param, u16), _Va1(u16, $param), _Va2($param, u16), _Va3(u16, $param),
 214             _Va4($param, u16), _Va5(u16, $param), _Va6($param, u16), _Va7(u16, $param),
 215             _Va8($param, u16), _Va9(u16, $param), _Vaa($param, u16), _Vab(u16, $param),
 216             _Vac($param, u16), _Vad(u16, $param), _Vae($param, u16), _Vaf(u16, $param),
 217
 218             _Vb0($param, u16), _Vb1(u16, $param), _Vb2($param, u16), _Vb3(u16, $param),
 219             _Vb4($param, u16), _Vb5(u16, $param), _Vb6($param, u16), _Vb7(u16, $param),
 220             _Vb8($param, u16), _Vb9(u16, $param), _Vba($param, u16), _Vbb(u16, $param),
 221             _Vbc($param, u16), _Vbd(u16, $param), _Vbe($param, u16), _Vbf(u16, $param),
 222
 223             _Vc0($param, u16), _Vc1(u16, $param), _Vc2($param, u16), _Vc3(u16, $param),
 224             _Vc4($param, u16), _Vc5(u16, $param), _Vc6($param, u16), _Vc7(u16, $param),
 225             _Vc8($param, u16), _Vc9(u16, $param), _Vca($param, u16), _Vcb(u16, $param),
 226             _Vcc($param, u16), _Vcd(u16, $param), _Vce($param, u16), _Vcf(u16, $param),
 227
 228             _Vd0($param, u16), _Vd1(u16, $param), _Vd2($param, u16), _Vd3(u16, $param),
 229             _Vd4($param, u16), _Vd5(u16, $param), _Vd6($param, u16), _Vd7(u16, $param),
 230             _Vd8($param, u16), _Vd9(u16, $param), _Vda($param, u16), _Vdb(u16, $param),
 231             _Vdc($param, u16), _Vdd(u16, $param), _Vde($param, u16), _Vdf(u16, $param),
 232
 233             _Ve0($param, u16), _Ve1(u16, $param), _Ve2($param, u16), _Ve3(u16, $param),
 234             _Ve4($param, u16), _Ve5(u16, $param), _Ve6($param, u16), _Ve7(u16, $param),
 235             _Ve8($param, u16), _Ve9(u16, $param), _Vea($param, u16), _Veb(u16, $param),
 236             _Vec($param, u16), _Ved(u16, $param), _Vee($param, u16), _Vef(u16, $param),
 237
 238             _Vf0($param, u16), _Vf1(u16, $param), _Vf2($param, u16), _Vf3(u16, $param),
 239             _Vf4($param, u16), _Vf5(u16, $param), _Vf6($param, u16), _Vf7(u16, $param),
 240             _Vf8($param, u16), _Vf9(u16, $param), _Vfa($param, u16), _Vfb(u16, $param),
 241             _Vfc($param, u16), _Vfd(u16, $param), _Vfe($param, u16), _Vff(u16, $param),
 242         }
 243     },
 244
 245     ($name:ident, $param:ty) => {
 246         #[derive(Debug)]
 247         pub enum $name {
 248             _V00($param, u16), _V01(u16, $param), _V02($param, u16), _V03(u16, $param),
 249             _V04($param, u16), _V05(u16, $param), _V06($param, u16), _V07(u16, $param),
 250             _V08($param, u16), _V09(u16, $param), _V0a($param, u16), _V0b(u16, $param),
 251             _V0c($param, u16), _V0d(u16, $param), _V0e($param, u16), _V0f(u16, $param),
 252
 253             _V10($param, u16), _V11(u16, $param), _V12($param, u16), _V13(u16, $param),
 254             _V14($param, u16), _V15(u16, $param), _V16($param, u16), _V17(u16, $param),
 255             _V18($param, u16), _V19(u16, $param), _V1a($param, u16), _V1b(u16, $param),
 256             _V1c($param, u16), _V1d(u16, $param), _V1e($param, u16), _V1f(u16, $param),
 257
 258             _V20($param, u16), _V21(u16, $param), _V22($param, u16), _V23(u16, $param),
 259             _V24($param, u16), _V25(u16, $param), _V26($param, u16), _V27(u16, $param),
 260             _V28($param, u16), _V29(u16, $param), _V2a($param, u16), _V2b(u16, $param),
 261             _V2c($param, u16), _V2d(u16, $param), _V2e($param, u16), _V2f(u16, $param),
 262
 263             _V30($param, u16), _V31(u16, $param), _V32($param, u16), _V33(u16, $param),
 264             _V34($param, u16), _V35(u16, $param), _V36($param, u16), _V37(u16, $param),
 265             _V38($param, u16), _V39(u16, $param), _V3a($param, u16), _V3b(u16, $param),
 266             _V3c($param, u16), _V3d(u16, $param), _V3e($param, u16), _V3f(u16, $param),
 267
 268             _V40($param, u16), _V41(u16, $param), _V42($param, u16), _V43(u16, $param),
 269             _V44($param, u16), _V45(u16, $param), _V46($param, u16), _V47(u16, $param),
 270             _V48($param, u16), _V49(u16, $param), _V4a($param, u16), _V4b(u16, $param),
 271             _V4c($param, u16), _V4d(u16, $param), _V4e($param, u16), _V4f(u16, $param),
 272
 273             _V50($param, u16), _V51(u16, $param), _V52($param, u16), _V53(u16, $param),
 274             _V54($param, u16), _V55(u16, $param), _V56($param, u16), _V57(u16, $param),
 275             _V58($param, u16), _V59(u16, $param), _V5a($param, u16), _V5b(u16, $param),
 276             _V5c($param, u16), _V5d(u16, $param), _V5e($param, u16), _V5f(u16, $param),
 277
 278             _V60($param, u16), _V61(u16, $param), _V62($param, u16), _V63(u16, $param),
 279             _V64($param, u16), _V65(u16, $param), _V66($param, u16), _V67(u16, $param),
 280             _V68($param, u16), _V69(u16, $param), _V6a($param, u16), _V6b(u16, $param),
 281             _V6c($param, u16), _V6d(u16, $param), _V6e($param, u16), _V6f(u16, $param),
 282
 283             _V70($param, u16), _V71(u16, $param), _V72($param, u16), _V73(u16, $param),
 284             _V74($param, u16), _V75(u16, $param), _V76($param, u16), _V77(u16, $param),
 285             _V78($param, u16), _V79(u16, $param), _V7a($param, u16), _V7b(u16, $param),
 286             _V7c($param, u16), _V7d(u16, $param), _V7e($param, u16), _V7f(u16, $param),
 287
 288             _V80($param, u16), _V81(u16, $param), _V82($param, u16), _V83(u16, $param),
 289             _V84($param, u16), _V85(u16, $param), _V86($param, u16), _V87(u16, $param),
 290             _V88($param, u16), _V89(u16, $param), _V8a($param, u16), _V8b(u16, $param),
 291             _V8c($param, u16), _V8d(u16, $param), _V8e($param, u16), _V8f(u16, $param),
 292
 293             _V90($param, u16), _V91(u16, $param), _V92($param, u16), _V93(u16, $param),
 294             _V94($param, u16), _V95(u16, $param), _V96($param, u16), _V97(u16, $param),
 295             _V98($param, u16), _V99(u16, $param), _V9a($param, u16), _V9b(u16, $param),
 296             _V9c($param, u16), _V9d(u16, $param), _V9e($param, u16), _V9f(u16, $param),
 297
 298             _Va0($param, u16), _Va1(u16, $param), _Va2($param, u16), _Va3(u16, $param),
 299             _Va4($param, u16), _Va5(u16, $param), _Va6($param, u16), _Va7(u16, $param),
 300             _Va8($param, u16), _Va9(u16, $param), _Vaa($param, u16), _Vab(u16, $param),
 301             _Vac($param, u16), _Vad(u16, $param), _Vae($param, u16), _Vaf(u16, $param),
 302
 303             _Vb0($param, u16), _Vb1(u16, $param), _Vb2($param, u16), _Vb3(u16, $param),
 304             _Vb4($param, u16), _Vb5(u16, $param), _Vb6($param, u16), _Vb7(u16, $param),
 305             _Vb8($param, u16), _Vb9(u16, $param), _Vba($param, u16), _Vbb(u16, $param),
 306             _Vbc($param, u16), _Vbd(u16, $param), _Vbe($param, u16), _Vbf(u16, $param),
 307
 308             _Vc0($param, u16), _Vc1(u16, $param), _Vc2($param, u16), _Vc3(u16, $param),
 309             _Vc4($param, u16), _Vc5(u16, $param), _Vc6($param, u16), _Vc7(u16, $param),
 310             _Vc8($param, u16), _Vc9(u16, $param), _Vca($param, u16), _Vcb(u16, $param),
 311             _Vcc($param, u16), _Vcd(u16, $param), _Vce($param, u16), _Vcf(u16, $param),
 312
 313             _Vd0($param, u16), _Vd1(u16, $param), _Vd2($param, u16), _Vd3(u16, $param),
 314             _Vd4($param, u16), _Vd5(u16, $param), _Vd6($param, u16), _Vd7(u16, $param),
 315             _Vd8($param, u16), _Vd9(u16, $param), _Vda($param, u16), _Vdb(u16, $param),
 316             _Vdc($param, u16), _Vdd(u16, $param), _Vde($param, u16), _Vdf(u16, $param),
 317
 318             _Ve0($param, u16), _Ve1(u16, $param), _Ve2($param, u16), _Ve3(u16, $param),
 319             _Ve4($param, u16), _Ve5(u16, $param), _Ve6($param, u16), _Ve7(u16, $param),
 320             _Ve8($param, u16), _Ve9(u16, $param), _Vea($param, u16), _Veb(u16, $param),
 321             _Vec($param, u16), _Ved(u16, $param), _Vee($param, u16), _Vef(u16, $param),
 322
 323             _Vf0($param, u16), _Vf1(u16, $param), _Vf2($param, u16), _Vf3(u16, $param),
 324             _Vf4($param, u16), _Vf5(u16, $param), _Vf6($param, u16), _Vf7(u16, $param),
 325             _Vf8($param, u16), _Vf9(u16, $param), _Vfa($param, u16), _Vfb(u16, $param),
 326             _Vfc($param, u16), _Vfd(u16, $param), _Vfe($param, u16), _Vff(u16, $param),
 327         }
 328     }
 329 }