layout computation: eagerly error for unexpected unsized fields

Author: Lukas Markeffsky

compiler/rustc_abi/src/layout.rs

@@ -26,7 +26,7 @@ mod layout;
 #[cfg(test)]
 mod tests;
 
-pub use layout::LayoutCalculator;
+pub use layout::{LayoutCalculator, LayoutCalculatorError};
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
@@ -386,6 +386,14 @@ impl HasDataLayout for TargetDataLayout {
     }
 }
 
+// used by rust-analyzer
+impl HasDataLayout for &TargetDataLayout {
+    #[inline]
+    fn data_layout(&self) -> &TargetDataLayout {
+        (**self).data_layout()
+    }
+}
+
 /// Endianness of the target, which must match cfg(target-endian).
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub enum Endian {

compiler/rustc_abi/src/lib.rs

@@ -319,7 +319,7 @@ pub fn valtree_to_const_value<'tcx>(
                 let branches = valtree.unwrap_branch();
                 // Find the non-ZST field. (There can be aligned ZST!)
                 for (i, &inner_valtree) in branches.iter().enumerate() {
-                    let field = layout.field(&LayoutCx { tcx, param_env }, i);
+                    let field = layout.field(&LayoutCx::new(tcx, param_env), i);
                     if !field.is_zst() {
                         return valtree_to_const_value(tcx, param_env.and(field.ty), inner_valtree);
                     }

compiler/rustc_const_eval/src/const_eval/valtrees.rs

@@ -1,5 +1,7 @@
 use rustc_middle::bug;
-use rustc_middle::ty::layout::{LayoutCx, LayoutError, LayoutOf, TyAndLayout, ValidityRequirement};
+use rustc_middle::ty::layout::{
+    HasTyCtxt, LayoutCx, LayoutError, LayoutOf, TyAndLayout, ValidityRequirement,
+};
 use rustc_middle::ty::{ParamEnvAnd, Ty, TyCtxt};
 use rustc_target::abi::{Abi, FieldsShape, Scalar, Variants};
 
@@ -30,7 +32,7 @@ pub fn check_validity_requirement<'tcx>(
         return Ok(!layout.abi.is_uninhabited());
     }
 
-    let layout_cx = LayoutCx { tcx, param_env: param_env_and_ty.param_env };
+    let layout_cx = LayoutCx::new(tcx, param_env_and_ty.param_env);
     if kind == ValidityRequirement::Uninit || tcx.sess.opts.unstable_opts.strict_init_checks {
         might_permit_raw_init_strict(layout, &layout_cx, kind)
     } else {
@@ -47,7 +49,7 @@ fn might_permit_raw_init_strict<'tcx>(
 ) -> Result<bool, &'tcx LayoutError<'tcx>> {
     let machine = CompileTimeMachine::new(CanAccessMutGlobal::No, CheckAlignment::Error);
 
-    let mut cx = InterpCx::new(cx.tcx, rustc_span::DUMMY_SP, cx.param_env, machine);
+    let mut cx = InterpCx::new(cx.tcx(), rustc_span::DUMMY_SP, cx.param_env, machine);
 
     let allocated = cx
         .allocate(ty, MemoryKind::Machine(crate::const_eval::MemoryKind::Heap))

compiler/rustc_const_eval/src/util/check_validity_requirement.rs

@@ -1,4 +1,3 @@
-use std::borrow::Cow;
 use std::num::NonZero;
 use std::ops::Bound;
 use std::{cmp, fmt};
@@ -287,19 +286,13 @@ impl<'tcx> IntoDiagArg for LayoutError<'tcx> {
 
 #[derive(Clone, Copy)]
 pub struct LayoutCx<'tcx> {
-    pub tcx: TyCtxt<'tcx>,
+    pub calc: LayoutCalculator<TyCtxt<'tcx>>,
     pub param_env: ty::ParamEnv<'tcx>,
 }
 
-impl<'tcx> LayoutCalculator for LayoutCx<'tcx> {
-    type TargetDataLayoutRef = &'tcx TargetDataLayout;
-
-    fn delayed_bug(&self, txt: impl Into<Cow<'static, str>>) {
-        self.tcx.dcx().delayed_bug(txt);
-    }
-
-    fn current_data_layout(&self) -> Self::TargetDataLayoutRef {
-        &self.tcx.data_layout
+impl<'tcx> LayoutCx<'tcx> {
+    pub fn new(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
+        Self { calc: LayoutCalculator::new(tcx), param_env }
     }
 }
 
@@ -576,25 +569,25 @@ impl<'tcx> HasParamEnv<'tcx> for LayoutCx<'tcx> {
 
 impl<'tcx> HasDataLayout for LayoutCx<'tcx> {
     fn data_layout(&self) -> &TargetDataLayout {
-        self.tcx.data_layout()
+        self.calc.cx.data_layout()
     }
 }
 
 impl<'tcx> HasTargetSpec for LayoutCx<'tcx> {
     fn target_spec(&self) -> &Target {
-        self.tcx.target_spec()
+        self.calc.cx.target_spec()
     }
 }
 
 impl<'tcx> HasWasmCAbiOpt for LayoutCx<'tcx> {
     fn wasm_c_abi_opt(&self) -> WasmCAbi {
-        self.tcx.wasm_c_abi_opt()
+        self.calc.cx.wasm_c_abi_opt()
     }
 }
 
 impl<'tcx> HasTyCtxt<'tcx> for LayoutCx<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
-        self.tcx.tcx()
+        self.calc.cx
     }
 }
 
@@ -695,7 +688,7 @@ impl<'tcx> LayoutOfHelpers<'tcx> for LayoutCx<'tcx> {
         _: Span,
         _: Ty<'tcx>,
     ) -> &'tcx LayoutError<'tcx> {
-        self.tcx.arena.alloc(err)
+        self.tcx().arena.alloc(err)
     }
 }
 
@@ -1321,7 +1314,7 @@ impl<'tcx> TyCtxt<'tcx> {
     where
         I: Iterator<Item = (VariantIdx, FieldIdx)>,
     {
-        let cx = LayoutCx { tcx: self, param_env };
+        let cx = LayoutCx::new(self, param_env);
         let mut offset = Size::ZERO;
 
         for (variant, field) in indices {

compiler/rustc_middle/src/ty/layout.rs

@@ -128,7 +128,7 @@ fn dump_layout_of(tcx: TyCtxt<'_>, item_def_id: LocalDefId, attr: &Attribute) {
         }
 
         Err(layout_error) => {
-            tcx.dcx().emit_fatal(Spanned { node: layout_error.into_diagnostic(), span });
+            tcx.dcx().emit_err(Spanned { node: layout_error.into_diagnostic(), span });
         }
     }
 }

compiler/rustc_passes/src/layout_test.rs

@@ -63,7 +63,7 @@ pub mod rustc {
     use std::fmt::{self, Write};
 
     use rustc_middle::mir::Mutability;
-    use rustc_middle::ty::layout::{LayoutCx, LayoutError};
+    use rustc_middle::ty::layout::{HasTyCtxt, LayoutCx, LayoutError};
     use rustc_middle::ty::{self, Ty};
     use rustc_target::abi::Layout;
 
@@ -128,7 +128,7 @@ pub mod rustc {
         ty: Ty<'tcx>,
     ) -> Result<Layout<'tcx>, &'tcx LayoutError<'tcx>> {
         use rustc_middle::ty::layout::LayoutOf;
-        let ty = cx.tcx.erase_regions(ty);
+        let ty = cx.tcx().erase_regions(ty);
         cx.layout_of(ty).map(|tl| tl.layout)
     }
 }

compiler/rustc_transmute/src/layout/mod.rs

@@ -212,7 +212,7 @@ pub(crate) mod rustc {
                 return Err(Err::TypeError(e));
             }
 
-            let target = cx.tcx.data_layout();
+            let target = cx.data_layout();
             let pointer_size = target.pointer_size;
 
             match ty.kind() {
@@ -320,7 +320,7 @@ pub(crate) mod rustc {
 
             // Computes the variant of a given index.
             let layout_of_variant = |index| {
-                let tag = cx.tcx.tag_for_variant((cx.tcx.erase_regions(ty), index));
+                let tag = cx.tcx().tag_for_variant((cx.tcx().erase_regions(ty), index));
                 let variant_def = Def::Variant(def.variant(index));
                 let variant_layout = ty_variant(cx, (ty, layout), index);
                 Self::from_variant(variant_def, tag, (ty, variant_layout), layout.size, cx)
@@ -402,7 +402,7 @@ pub(crate) mod rustc {
             // If a `tag` is provided, place it at the start of the layout.
             if let Some(tag) = tag {
                 size += tag.size();
-                struct_tree = struct_tree.then(Self::from_tag(tag, cx.tcx));
+                struct_tree = struct_tree.then(Self::from_tag(tag, cx.tcx()));
             }
 
             // Append the fields, in memory order, to the layout.
@@ -494,12 +494,12 @@ pub(crate) mod rustc {
                 match layout.variants {
                     Variants::Single { index } => {
                         let field = &def.variant(index).fields[i];
-                        field.ty(cx.tcx, args)
+                        field.ty(cx.tcx(), args)
                     }
                     // Discriminant field for enums (where applicable).
                     Variants::Multiple { tag, .. } => {
                         assert_eq!(i.as_usize(), 0);
-                        ty::layout::PrimitiveExt::to_ty(&tag.primitive(), cx.tcx)
+                        ty::layout::PrimitiveExt::to_ty(&tag.primitive(), cx.tcx())
                     }
                 }
             }
@@ -516,7 +516,7 @@ pub(crate) mod rustc {
         (ty, layout): (Ty<'tcx>, Layout<'tcx>),
         i: VariantIdx,
     ) -> Layout<'tcx> {
-        let ty = cx.tcx.erase_regions(ty);
+        let ty = cx.tcx().erase_regions(ty);
         TyAndLayout { ty, layout }.for_variant(&cx, i).layout
     }
 }

compiler/rustc_transmute/src/layout/tree.rs

@@ -43,7 +43,7 @@ mod rustc {
         pub fn answer(self) -> Answer<<TyCtxt<'tcx> as QueryContext>::Ref> {
             let Self { src, dst, assume, context } = self;
 
-            let layout_cx = LayoutCx { tcx: context, param_env: ParamEnv::reveal_all() };
+            let layout_cx = LayoutCx::new(context, ParamEnv::reveal_all());
 
             // Convert `src` and `dst` from their rustc representations, to `Tree`-based
             // representations.

compiler/rustc_transmute/src/maybe_transmutable/mod.rs

@@ -331,7 +331,7 @@ fn fn_abi_of_fn_ptr<'tcx>(
 ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, &'tcx FnAbiError<'tcx>> {
     let (param_env, (sig, extra_args)) = query.into_parts();
 
-    let cx = LayoutCx { tcx, param_env };
+    let cx = LayoutCx::new(tcx, param_env);
     fn_abi_new_uncached(&cx, sig, extra_args, None, None, false)
 }
 
@@ -347,7 +347,7 @@ fn fn_abi_of_instance<'tcx>(
         instance.def.requires_caller_location(tcx).then(|| tcx.caller_location_ty());
 
     fn_abi_new_uncached(
-        &LayoutCx { tcx, param_env },
+        &LayoutCx::new(tcx, param_env),
         sig,
         extra_args,
         caller_location,
@@ -386,12 +386,14 @@ fn adjust_for_rust_scalar<'tcx>(
         attrs.set(ArgAttribute::NonNull);
     }
 
+    let tcx = cx.tcx();
+
     if let Some(pointee) = layout.pointee_info_at(&cx, offset) {
         let kind = if let Some(kind) = pointee.safe {
             Some(kind)
         } else if let Some(pointee) = drop_target_pointee {
             // The argument to `drop_in_place` is semantically equivalent to a mutable reference.
-            Some(PointerKind::MutableRef { unpin: pointee.is_unpin(cx.tcx, cx.param_env()) })
+            Some(PointerKind::MutableRef { unpin: pointee.is_unpin(tcx, cx.param_env()) })
         } else {
             None
         };
@@ -415,12 +417,12 @@ fn adjust_for_rust_scalar<'tcx>(
             // The aliasing rules for `Box<T>` are still not decided, but currently we emit
             // `noalias` for it. This can be turned off using an unstable flag.
             // See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
-            let noalias_for_box = cx.tcx.sess.opts.unstable_opts.box_noalias;
+            let noalias_for_box = tcx.sess.opts.unstable_opts.box_noalias;
 
             // LLVM prior to version 12 had known miscompiles in the presence of noalias attributes
             // (see #54878), so it was conditionally disabled, but we don't support earlier
             // versions at all anymore. We still support turning it off using -Zmutable-noalias.
-            let noalias_mut_ref = cx.tcx.sess.opts.unstable_opts.mutable_noalias;
+            let noalias_mut_ref = tcx.sess.opts.unstable_opts.mutable_noalias;
 
             // `&T` where `T` contains no `UnsafeCell<U>` is immutable, and can be marked as both
             // `readonly` and `noalias`, as LLVM's definition of `noalias` is based solely on memory
@@ -458,6 +460,7 @@ fn fn_abi_sanity_check<'tcx>(
         spec_abi: SpecAbi,
         arg: &ArgAbi<'tcx, Ty<'tcx>>,
     ) {
+        let tcx = cx.tcx();
         match &arg.mode {
             PassMode::Ignore => {}
             PassMode::Direct(_) => {
@@ -484,7 +487,7 @@ fn fn_abi_sanity_check<'tcx>(
                     // It needs to switch to something else before stabilization can happen.
                     // (See issue: https://github.com/rust-lang/rust/issues/117271)
                     assert!(
-                        matches!(&*cx.tcx.sess.target.arch, "wasm32" | "wasm64")
+                        matches!(&*tcx.sess.target.arch, "wasm32" | "wasm64")
                             || matches!(spec_abi, SpecAbi::PtxKernel | SpecAbi::Unadjusted),
                         "`PassMode::Direct` for aggregates only allowed for \"unadjusted\" and \"ptx-kernel\" functions and on wasm\n\
                           Problematic type: {:#?}",
@@ -516,7 +519,7 @@ fn fn_abi_sanity_check<'tcx>(
                 // With metadata. Must be unsized and not on the stack.
                 assert!(arg.layout.is_unsized() && !on_stack);
                 // Also, must not be `extern` type.
-                let tail = cx.tcx.struct_tail_for_codegen(arg.layout.ty, cx.param_env());
+                let tail = tcx.struct_tail_for_codegen(arg.layout.ty, cx.param_env());
                 if matches!(tail.kind(), ty::Foreign(..)) {
                     // These types do not have metadata, so having `meta_attrs` is bogus.
                     // Conceptually, unsized arguments must be copied around, which requires dynamically
@@ -546,7 +549,8 @@ fn fn_abi_new_uncached<'tcx>(
     // FIXME(eddyb) replace this with something typed, like an `enum`.
     force_thin_self_ptr: bool,
 ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, &'tcx FnAbiError<'tcx>> {
-    let sig = cx.tcx.normalize_erasing_late_bound_regions(cx.param_env, sig);
+    let tcx = cx.tcx();
+    let sig = tcx.normalize_erasing_late_bound_regions(cx.param_env, sig);
 
     let conv = conv_from_spec_abi(cx.tcx(), sig.abi, sig.c_variadic);
 
@@ -576,7 +580,7 @@ fn fn_abi_new_uncached<'tcx>(
     };
 
     let is_drop_in_place =
-        fn_def_id.is_some_and(|def_id| cx.tcx.is_lang_item(def_id, LangItem::DropInPlace));
+        fn_def_id.is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::DropInPlace));
 
     let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, &'tcx FnAbiError<'tcx>> {
         let span = tracing::debug_span!("arg_of");
@@ -588,8 +592,7 @@ fn fn_abi_new_uncached<'tcx>(
             _ => bug!("argument to drop_in_place is not a raw ptr: {:?}", ty),
         });
 
-        let layout =
-            cx.layout_of(ty).map_err(|err| &*cx.tcx.arena.alloc(FnAbiError::Layout(*err)))?;
+        let layout = cx.layout_of(ty).map_err(|err| &*tcx.arena.alloc(FnAbiError::Layout(*err)))?;
         let layout = if force_thin_self_ptr && arg_idx == Some(0) {
             // Don't pass the vtable, it's not an argument of the virtual fn.
             // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
@@ -638,7 +641,7 @@ fn fn_abi_new_uncached<'tcx>(
     fn_abi_adjust_for_abi(cx, &mut fn_abi, sig.abi, fn_def_id)?;
     debug!("fn_abi_new_uncached = {:?}", fn_abi);
     fn_abi_sanity_check(cx, &fn_abi, sig.abi);
-    Ok(cx.tcx.arena.alloc(fn_abi))
+    Ok(tcx.arena.alloc(fn_abi))
 }
 
 #[tracing::instrument(level = "trace", skip(cx))]
@@ -670,17 +673,18 @@ fn fn_abi_adjust_for_abi<'tcx>(
         return Ok(());
     }
 
+    let tcx = cx.tcx();
+
     if abi == SpecAbi::Rust || abi == SpecAbi::RustCall || abi == SpecAbi::RustIntrinsic {
         // Look up the deduced parameter attributes for this function, if we have its def ID and
         // we're optimizing in non-incremental mode. We'll tag its parameters with those attributes
         // as appropriate.
-        let deduced_param_attrs = if cx.tcx.sess.opts.optimize != OptLevel::No
-            && cx.tcx.sess.opts.incremental.is_none()
-        {
-            fn_def_id.map(|fn_def_id| cx.tcx.deduced_param_attrs(fn_def_id)).unwrap_or_default()
-        } else {
-            &[]
-        };
+        let deduced_param_attrs =
+            if tcx.sess.opts.optimize != OptLevel::No && tcx.sess.opts.incremental.is_none() {
+                fn_def_id.map(|fn_def_id| tcx.deduced_param_attrs(fn_def_id)).unwrap_or_default()
+            } else {
+                &[]
+            };
 
         let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>, arg_idx: Option<usize>| {
             if arg.is_ignore() {
@@ -689,7 +693,7 @@ fn fn_abi_adjust_for_abi<'tcx>(
 
             // Avoid returning floats in x87 registers on x86 as loading and storing from x87
             // registers will quiet signalling NaNs.
-            if cx.tcx.sess.target.arch == "x86"
+            if tcx.sess.target.arch == "x86"
                 && arg_idx.is_none()
                 // Intrinsics themselves are not actual "real" functions, so theres no need to
                 // change their ABIs.
@@ -744,7 +748,7 @@ fn fn_abi_adjust_for_abi<'tcx>(
                 // that's how we connect up to LLVM and it's unstable
                 // anyway, we control all calls to it in libstd.
                 Abi::Vector { .. }
-                    if abi != SpecAbi::RustIntrinsic && cx.tcx.sess.target.simd_types_indirect =>
+                    if abi != SpecAbi::RustIntrinsic && tcx.sess.target.simd_types_indirect =>
                 {
                     arg.make_indirect();
                     return;
@@ -793,7 +797,7 @@ fn fn_abi_adjust_for_abi<'tcx>(
     } else {
         fn_abi
             .adjust_for_foreign_abi(cx, abi)
-            .map_err(|err| &*cx.tcx.arena.alloc(FnAbiError::AdjustForForeignAbi(err)))?;
+            .map_err(|err| &*tcx.arena.alloc(FnAbiError::AdjustForForeignAbi(err)))?;
     }
 
     Ok(())