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Rollup merge of #124484 - GKFX:offset_of_must_use, r=jieyouxu
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Fix #124478 - offset_of! returns a temporary

This was due to the must_use() call. Adding HIR's `OffsetOf` to the must_use checking within the compiler avoids this issue while maintaining the lint output.

Fixes #124478. `@tgross35`
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@jieyouxu
jieyouxu committed Apr 29, 2024
2 parents 3151ad5 + 2348eb2 commit 0580588
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Showing 15 changed files with 215 additions and 529 deletions.
1 change: 1 addition & 0 deletions compiler/rustc_lint/src/unused.rs
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Expand Up @@ -176,6 +176,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
| hir::BinOpKind::Shr => Some("bitwise operation"),
},
hir::ExprKind::AddrOf(..) => Some("borrow"),
hir::ExprKind::OffsetOf(..) => Some("`offset_of` call"),
hir::ExprKind::Unary(..) => Some("unary operation"),
_ => None,
};
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4 changes: 2 additions & 2 deletions library/core/src/mem/mod.rs
View file
Expand Up @@ -1340,8 +1340,8 @@ impl<T> SizedTypeProperties for T {}
/// assert_eq!(mem::offset_of!(Option<&u8>, Some.0), 0);
/// ```
#[stable(feature = "offset_of", since = "1.77.0")]
#[allow_internal_unstable(builtin_syntax, hint_must_use)]
#[allow_internal_unstable(builtin_syntax)]
pub macro offset_of($Container:ty, $($fields:expr)+ $(,)?) {
// The `{}` is for better error messages
crate::hint::must_use({builtin # offset_of($Container, $($fields)+)})
{builtin # offset_of($Container, $($fields)+)}
}
112 changes: 28 additions & 84 deletions tests/mir-opt/const_prop/offset_of.concrete.GVN.panic-abort.diff
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Expand Up @@ -4,33 +4,26 @@
fn concrete() -> () {
let mut _0: ();
let _1: usize;
let mut _2: usize;
let mut _4: usize;
let mut _6: usize;
let mut _8: usize;
let mut _10: usize;
let mut _12: usize;
let mut _14: usize;
scope 1 {
debug x => _1;
let _3: usize;
let _2: usize;
scope 2 {
debug y => _3;
let _5: usize;
debug y => _2;
let _3: usize;
scope 3 {
debug z0 => _5;
let _7: usize;
debug z0 => _3;
let _4: usize;
scope 4 {
debug z1 => _7;
let _9: usize;
debug z1 => _4;
let _5: usize;
scope 5 {
debug eA0 => _9;
let _11: usize;
debug eA0 => _5;
let _6: usize;
scope 6 {
debug eA1 => _11;
let _13: usize;
debug eA1 => _6;
let _7: usize;
scope 7 {
debug eC => _13;
debug eC => _7;
}
}
}
Expand All @@ -41,82 +34,33 @@

bb0: {
StorageLive(_1);
- _1 = OffsetOf(Alpha, [(0, 0)]);
+ _1 = const 4_usize;
StorageLive(_2);
- _2 = OffsetOf(Alpha, [(0, 0)]);
- _1 = must_use::<usize>(move _2) -> [return: bb1, unwind unreachable];
+ _2 = const 4_usize;
+ _1 = must_use::<usize>(const 4_usize) -> [return: bb1, unwind unreachable];
}

bb1: {
StorageDead(_2);
- _2 = OffsetOf(Alpha, [(0, 1)]);
+ _2 = const 0_usize;
StorageLive(_3);
- _3 = OffsetOf(Alpha, [(0, 2), (0, 0)]);
+ _3 = const 2_usize;
StorageLive(_4);
- _4 = OffsetOf(Alpha, [(0, 1)]);
- _3 = must_use::<usize>(move _4) -> [return: bb2, unwind unreachable];
+ _4 = const 0_usize;
+ _3 = must_use::<usize>(const 0_usize) -> [return: bb2, unwind unreachable];
}

bb2: {
StorageDead(_4);
- _4 = OffsetOf(Alpha, [(0, 2), (0, 1)]);
+ _4 = const 3_usize;
StorageLive(_5);
- _5 = OffsetOf(Epsilon, [(0, 0)]);
+ _5 = const 1_usize;
StorageLive(_6);
- _6 = OffsetOf(Alpha, [(0, 2), (0, 0)]);
- _5 = must_use::<usize>(move _6) -> [return: bb3, unwind unreachable];
- _6 = OffsetOf(Epsilon, [(0, 1)]);
+ _6 = const 2_usize;
+ _5 = must_use::<usize>(const 2_usize) -> [return: bb3, unwind unreachable];
}

bb3: {
StorageDead(_6);
StorageLive(_7);
StorageLive(_8);
- _8 = OffsetOf(Alpha, [(0, 2), (0, 1)]);
- _7 = must_use::<usize>(move _8) -> [return: bb4, unwind unreachable];
+ _8 = const 3_usize;
+ _7 = must_use::<usize>(const 3_usize) -> [return: bb4, unwind unreachable];
}

bb4: {
StorageDead(_8);
StorageLive(_9);
StorageLive(_10);
- _10 = OffsetOf(Epsilon, [(0, 0)]);
- _9 = must_use::<usize>(move _10) -> [return: bb5, unwind unreachable];
+ _10 = const 1_usize;
+ _9 = must_use::<usize>(const 1_usize) -> [return: bb5, unwind unreachable];
}

bb5: {
StorageDead(_10);
StorageLive(_11);
StorageLive(_12);
- _12 = OffsetOf(Epsilon, [(0, 1)]);
- _11 = must_use::<usize>(move _12) -> [return: bb6, unwind unreachable];
+ _12 = const 2_usize;
+ _11 = must_use::<usize>(const 2_usize) -> [return: bb6, unwind unreachable];
}

bb6: {
StorageDead(_12);
StorageLive(_13);
StorageLive(_14);
- _14 = OffsetOf(Epsilon, [(2, 0)]);
- _13 = must_use::<usize>(move _14) -> [return: bb7, unwind unreachable];
+ _14 = const 4_usize;
+ _13 = must_use::<usize>(const 4_usize) -> [return: bb7, unwind unreachable];
}

bb7: {
StorageDead(_14);
- _7 = OffsetOf(Epsilon, [(2, 0)]);
+ _7 = const 4_usize;
_0 = const ();
StorageDead(_13);
StorageDead(_11);
StorageDead(_9);
StorageDead(_7);
StorageDead(_6);
StorageDead(_5);
StorageDead(_4);
StorageDead(_3);
StorageDead(_2);
StorageDead(_1);
return;
}
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112 changes: 28 additions & 84 deletions tests/mir-opt/const_prop/offset_of.concrete.GVN.panic-unwind.diff
View file
Expand Up @@ -4,33 +4,26 @@
fn concrete() -> () {
let mut _0: ();
let _1: usize;
let mut _2: usize;
let mut _4: usize;
let mut _6: usize;
let mut _8: usize;
let mut _10: usize;
let mut _12: usize;
let mut _14: usize;
scope 1 {
debug x => _1;
let _3: usize;
let _2: usize;
scope 2 {
debug y => _3;
let _5: usize;
debug y => _2;
let _3: usize;
scope 3 {
debug z0 => _5;
let _7: usize;
debug z0 => _3;
let _4: usize;
scope 4 {
debug z1 => _7;
let _9: usize;
debug z1 => _4;
let _5: usize;
scope 5 {
debug eA0 => _9;
let _11: usize;
debug eA0 => _5;
let _6: usize;
scope 6 {
debug eA1 => _11;
let _13: usize;
debug eA1 => _6;
let _7: usize;
scope 7 {
debug eC => _13;
debug eC => _7;
}
}
}
Expand All @@ -41,82 +34,33 @@

bb0: {
StorageLive(_1);
- _1 = OffsetOf(Alpha, [(0, 0)]);
+ _1 = const 4_usize;
StorageLive(_2);
- _2 = OffsetOf(Alpha, [(0, 0)]);
- _1 = must_use::<usize>(move _2) -> [return: bb1, unwind continue];
+ _2 = const 4_usize;
+ _1 = must_use::<usize>(const 4_usize) -> [return: bb1, unwind continue];
}

bb1: {
StorageDead(_2);
- _2 = OffsetOf(Alpha, [(0, 1)]);
+ _2 = const 0_usize;
StorageLive(_3);
- _3 = OffsetOf(Alpha, [(0, 2), (0, 0)]);
+ _3 = const 2_usize;
StorageLive(_4);
- _4 = OffsetOf(Alpha, [(0, 1)]);
- _3 = must_use::<usize>(move _4) -> [return: bb2, unwind continue];
+ _4 = const 0_usize;
+ _3 = must_use::<usize>(const 0_usize) -> [return: bb2, unwind continue];
}

bb2: {
StorageDead(_4);
- _4 = OffsetOf(Alpha, [(0, 2), (0, 1)]);
+ _4 = const 3_usize;
StorageLive(_5);
- _5 = OffsetOf(Epsilon, [(0, 0)]);
+ _5 = const 1_usize;
StorageLive(_6);
- _6 = OffsetOf(Alpha, [(0, 2), (0, 0)]);
- _5 = must_use::<usize>(move _6) -> [return: bb3, unwind continue];
- _6 = OffsetOf(Epsilon, [(0, 1)]);
+ _6 = const 2_usize;
+ _5 = must_use::<usize>(const 2_usize) -> [return: bb3, unwind continue];
}

bb3: {
StorageDead(_6);
StorageLive(_7);
StorageLive(_8);
- _8 = OffsetOf(Alpha, [(0, 2), (0, 1)]);
- _7 = must_use::<usize>(move _8) -> [return: bb4, unwind continue];
+ _8 = const 3_usize;
+ _7 = must_use::<usize>(const 3_usize) -> [return: bb4, unwind continue];
}

bb4: {
StorageDead(_8);
StorageLive(_9);
StorageLive(_10);
- _10 = OffsetOf(Epsilon, [(0, 0)]);
- _9 = must_use::<usize>(move _10) -> [return: bb5, unwind continue];
+ _10 = const 1_usize;
+ _9 = must_use::<usize>(const 1_usize) -> [return: bb5, unwind continue];
}

bb5: {
StorageDead(_10);
StorageLive(_11);
StorageLive(_12);
- _12 = OffsetOf(Epsilon, [(0, 1)]);
- _11 = must_use::<usize>(move _12) -> [return: bb6, unwind continue];
+ _12 = const 2_usize;
+ _11 = must_use::<usize>(const 2_usize) -> [return: bb6, unwind continue];
}

bb6: {
StorageDead(_12);
StorageLive(_13);
StorageLive(_14);
- _14 = OffsetOf(Epsilon, [(2, 0)]);
- _13 = must_use::<usize>(move _14) -> [return: bb7, unwind continue];
+ _14 = const 4_usize;
+ _13 = must_use::<usize>(const 4_usize) -> [return: bb7, unwind continue];
}

bb7: {
StorageDead(_14);
- _7 = OffsetOf(Epsilon, [(2, 0)]);
+ _7 = const 4_usize;
_0 = const ();
StorageDead(_13);
StorageDead(_11);
StorageDead(_9);
StorageDead(_7);
StorageDead(_6);
StorageDead(_5);
StorageDead(_4);
StorageDead(_3);
StorageDead(_2);
StorageDead(_1);
return;
}
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