diff options
| -rw-r--r-- | compiler/rustc_mir_transform/src/check_enums.rs | 15 | ||||
| -rw-r--r-- | tests/ui/mir/validate/ice-zst-as-discr-145786.rs | 14 | ||||
| -rw-r--r-- | tests/ui/mir/validate/ice-zst-as-discr-145786.stderr | 12 |
3 files changed, 41 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/check_enums.rs b/compiler/rustc_mir_transform/src/check_enums.rs index 33a87cb9873..12447dc7cbb 100644 --- a/compiler/rustc_mir_transform/src/check_enums.rs +++ b/compiler/rustc_mir_transform/src/check_enums.rs @@ -48,6 +48,21 @@ impl<'tcx> crate::MirPass<'tcx> for CheckEnums { let new_block = split_block(basic_blocks, location); match check { + EnumCheckType::Direct { op_size, .. } + | EnumCheckType::WithNiche { op_size, .. } + if op_size.bytes() == 0 => + { + // It is never valid to use a ZST as a discriminant for an inhabited enum, but that will + // have been caught by the type checker. Do nothing but ensure that a bug has been signaled. + tcx.dcx().span_delayed_bug( + source_info.span, + "cannot build enum discriminant from zero-sized type", + ); + basic_blocks[block].terminator = Some(Terminator { + source_info, + kind: TerminatorKind::Goto { target: new_block }, + }); + } EnumCheckType::Direct { source_op, discr, op_size, valid_discrs } => { insert_direct_enum_check( tcx, diff --git a/tests/ui/mir/validate/ice-zst-as-discr-145786.rs b/tests/ui/mir/validate/ice-zst-as-discr-145786.rs new file mode 100644 index 00000000000..616736bcf12 --- /dev/null +++ b/tests/ui/mir/validate/ice-zst-as-discr-145786.rs @@ -0,0 +1,14 @@ +// Do not attempt to take the discriminant as the source +// converted to a `u128`, that won't work for ZST. +// +//@ compile-flags: -Zvalidate-mir + +enum A { + B, + C, +} + +fn main() { + let _: A = unsafe { std::mem::transmute(()) }; + //~^ ERROR cannot transmute between types of different sizes, or dependently-sized types +} diff --git a/tests/ui/mir/validate/ice-zst-as-discr-145786.stderr b/tests/ui/mir/validate/ice-zst-as-discr-145786.stderr new file mode 100644 index 00000000000..b0bca1eb39c --- /dev/null +++ b/tests/ui/mir/validate/ice-zst-as-discr-145786.stderr @@ -0,0 +1,12 @@ +error[E0512]: cannot transmute between types of different sizes, or dependently-sized types + --> $DIR/ice-zst-as-discr-145786.rs:12:25 + | +LL | let _: A = unsafe { std::mem::transmute(()) }; + | ^^^^^^^^^^^^^^^^^^^ + | + = note: source type: `()` (0 bits) + = note: target type: `A` (8 bits) + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0512`. |