diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs index c5a306fdf1f9a..c1d6856d33c92 100644 --- a/compiler/rustc_middle/src/ty/layout.rs +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -318,7 +318,13 @@ impl<'tcx> SizeSkeleton<'tcx> { Ok(layout) => { return Ok(SizeSkeleton::Known(layout.size)); } - Err(err) => err, + Err(err @ LayoutError::Unknown(_)) => err, + // We can't extract SizeSkeleton info from other layout errors + Err( + e @ LayoutError::Cycle + | e @ LayoutError::SizeOverflow(_) + | e @ LayoutError::NormalizationFailure(..), + ) => return Err(e), }; match *ty.kind() { diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs index 7015778e24b85..fde64cb3ee7d8 100644 --- a/compiler/rustc_ty_utils/src/layout.rs +++ b/compiler/rustc_ty_utils/src/layout.rs @@ -145,17 +145,35 @@ fn layout_of_uncached<'tcx>( return Ok(tcx.mk_layout(LayoutS::scalar(cx, data_ptr))); } - let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env); - let metadata = if let Some(metadata_def_id) = tcx.lang_items().metadata_type() // Projection eagerly bails out when the pointee references errors, // fall back to structurally deducing metadata. && !pointee.references_error() { - let metadata_ty = tcx.normalize_erasing_regions( + let pointee_metadata = tcx.mk_projection(metadata_def_id, [pointee]); + let metadata_ty = match tcx.try_normalize_erasing_regions( param_env, - tcx.mk_projection(metadata_def_id, [pointee]), - ); + pointee_metadata, + ) { + Ok(metadata_ty) => metadata_ty, + Err(mut err) => { + // Usually `::Metadata` can't be normalized because + // its struct tail cannot be normalized either, so try to get a + // more descriptive layout error here, which will lead to less confusing + // diagnostics. + match tcx.try_normalize_erasing_regions( + param_env, + tcx.struct_tail_without_normalization(pointee), + ) { + Ok(_) => {}, + Err(better_err) => { + err = better_err; + } + } + return Err(LayoutError::NormalizationFailure(pointee, err)); + }, + }; + let metadata_layout = cx.layout_of(metadata_ty)?; // If the metadata is a 1-zst, then the pointer is thin. if metadata_layout.is_zst() && metadata_layout.align.abi.bytes() == 1 { @@ -163,10 +181,13 @@ fn layout_of_uncached<'tcx>( } let Abi::Scalar(metadata) = metadata_layout.abi else { - return Err(LayoutError::Unknown(unsized_part)); + return Err(LayoutError::Unknown(pointee)); }; + metadata } else { + let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env); + match unsized_part.kind() { ty::Foreign(..) => { return Ok(tcx.mk_layout(LayoutS::scalar(cx, data_ptr))); @@ -178,7 +199,7 @@ fn layout_of_uncached<'tcx>( vtable } _ => { - return Err(LayoutError::Unknown(unsized_part)); + return Err(LayoutError::Unknown(pointee)); } } }; diff --git a/tests/ui/const-generics/issue-112505-overflow.stderr b/tests/ui/const-generics/issue-112505-overflow.stderr index 0432f2fa8be5d..bd8a4feeff5e7 100644 --- a/tests/ui/const-generics/issue-112505-overflow.stderr +++ b/tests/ui/const-generics/issue-112505-overflow.stderr @@ -4,8 +4,8 @@ error[E0512]: cannot transmute between types of different sizes, or dependently- LL | unsafe { std::mem::transmute(v) } | ^^^^^^^^^^^^^^^^^^^ | - = note: source type: `[[[u32; 8888888]; 9999999]; 777777777]` (values of the type `[[[u32; 8888888]; 9999999]; 777777777]` are too big for the current architecture) - = note: target type: `[[[u32; 9999999]; 777777777]; 239]` (59484438436515561504 bits) + = note: source type: `[[[u32; 8888888]; 9999999]; 777777777]` (values of the type `[[u32; 8888888]; 9999999]` are too big for the current architecture) + = note: target type: `[[[u32; 9999999]; 777777777]; 239]` (values of the type `[[u32; 9999999]; 777777777]` are too big for the current architecture) error: aborting due to previous error diff --git a/tests/ui/const-generics/transmute-fail.stderr b/tests/ui/const-generics/transmute-fail.stderr index 3d1197afd0f79..9e308620a9c2e 100644 --- a/tests/ui/const-generics/transmute-fail.stderr +++ b/tests/ui/const-generics/transmute-fail.stderr @@ -43,8 +43,8 @@ error[E0512]: cannot transmute between types of different sizes, or dependently- LL | std::mem::transmute(v) | ^^^^^^^^^^^^^^^^^^^ | - = note: source type: `[[[u32; 8888888]; 9999999]; 777777777]` (values of the type `[[[u32; 8888888]; 9999999]; 777777777]` are too big for the current architecture) - = note: target type: `[[[u32; 9999999]; 777777777]; 8888888]` (values of the type `[[[u32; 9999999]; 777777777]; 8888888]` are too big for the current architecture) + = note: source type: `[[[u32; 8888888]; 9999999]; 777777777]` (values of the type `[[u32; 8888888]; 9999999]` are too big for the current architecture) + = note: target type: `[[[u32; 9999999]; 777777777]; 8888888]` (values of the type `[[u32; 9999999]; 777777777]` are too big for the current architecture) error: aborting due to 6 previous errors diff --git a/tests/ui/layout/cannot-transmute-unnormalizable-type.rs b/tests/ui/layout/cannot-transmute-unnormalizable-type.rs new file mode 100644 index 0000000000000..d2b6e1d8eba66 --- /dev/null +++ b/tests/ui/layout/cannot-transmute-unnormalizable-type.rs @@ -0,0 +1,22 @@ +trait Trait { + type RefTarget; +} + +impl Trait for () +where + Missing: Trait, + //~^ ERROR cannot find type `Missing` in this scope +{ + type RefTarget = (); +} + +struct Other { + data: <() as Trait>::RefTarget, +} + +fn main() { + unsafe { + std::mem::transmute::, Option<&Other>>(None); + //~^ ERROR cannot transmute between types of different sizes, or dependently-sized types + } +} diff --git a/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr b/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr new file mode 100644 index 0000000000000..dd5119318ff4b --- /dev/null +++ b/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr @@ -0,0 +1,19 @@ +error[E0412]: cannot find type `Missing` in this scope + --> $DIR/cannot-transmute-unnormalizable-type.rs:7:5 + | +LL | Missing: Trait, + | ^^^^^^^ not found in this scope + +error[E0512]: cannot transmute between types of different sizes, or dependently-sized types + --> $DIR/cannot-transmute-unnormalizable-type.rs:19:9 + | +LL | std::mem::transmute::, Option<&Other>>(None); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: source type: `Option<()>` (8 bits) + = note: target type: `Option<&Other>` (unable to determine layout for `Other` because `<() as Trait>::RefTarget` cannot be normalized) + +error: aborting due to 2 previous errors + +Some errors have detailed explanations: E0412, E0512. +For more information about an error, try `rustc --explain E0412`.