1 files changed, 39 insertions, 26 deletions

diff --git a/compiler/rustc_const_eval/src/util/might_permit_raw_init.rs b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
index 4ce107ea6..23fcd22c5 100644
--- a/compiler/rustc_const_eval/src/util/might_permit_raw_init.rs
+++ b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
@@ -1,7 +1,7 @@
-use rustc_middle::ty::layout::{LayoutCx, LayoutOf, TyAndLayout};
-use rustc_middle::ty::{ParamEnv, TyCtxt};
+use rustc_middle::ty::layout::{LayoutCx, LayoutError, LayoutOf, TyAndLayout, ValidityRequirement};
+use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_session::Limit;
-use rustc_target::abi::{Abi, FieldsShape, InitKind, Scalar, Variants};
+use rustc_target::abi::{Abi, FieldsShape, Scalar, Variants};
 
 use crate::const_eval::{CheckAlignment, CompileTimeInterpreter};
 use crate::interpret::{InterpCx, MemoryKind, OpTy};
@@ -18,16 +18,23 @@ use crate::interpret::{InterpCx, MemoryKind, OpTy};
 /// Rust UB as long as there is no risk of miscompilations. The `strict_init_checks` can be set to
 /// do a full check against Rust UB instead (in which case we will also ignore the 0x01-filling and
 /// to the full uninit check).
-pub fn might_permit_raw_init<'tcx>(
+pub fn check_validity_requirement<'tcx>(
     tcx: TyCtxt<'tcx>,
-    ty: TyAndLayout<'tcx>,
-    kind: InitKind,
-) -> bool {
-    if tcx.sess.opts.unstable_opts.strict_init_checks {
-        might_permit_raw_init_strict(ty, tcx, kind)
+    kind: ValidityRequirement,
+    param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
+) -> Result<bool, LayoutError<'tcx>> {
+    let layout = tcx.layout_of(param_env_and_ty)?;
+
+    // There is nothing strict or lax about inhabitedness.
+    if kind == ValidityRequirement::Inhabited {
+        return Ok(!layout.abi.is_uninhabited());
+    }
+
+    if kind == ValidityRequirement::Uninit || tcx.sess.opts.unstable_opts.strict_init_checks {
+        might_permit_raw_init_strict(layout, tcx, kind)
     } else {
-        let layout_cx = LayoutCx { tcx, param_env: ParamEnv::reveal_all() };
-        might_permit_raw_init_lax(ty, &layout_cx, kind)
+        let layout_cx = LayoutCx { tcx, param_env: param_env_and_ty.param_env };
+        might_permit_raw_init_lax(layout, &layout_cx, kind)
     }
 }
 
@@ -36,8 +43,8 @@ pub fn might_permit_raw_init<'tcx>(
 fn might_permit_raw_init_strict<'tcx>(
     ty: TyAndLayout<'tcx>,
     tcx: TyCtxt<'tcx>,
-    kind: InitKind,
-) -> bool {
+    kind: ValidityRequirement,
+) -> Result<bool, LayoutError<'tcx>> {
     let machine = CompileTimeInterpreter::new(
         Limit::new(0),
         /*can_access_statics:*/ false,
@@ -50,7 +57,7 @@ fn might_permit_raw_init_strict<'tcx>(
         .allocate(ty, MemoryKind::Machine(crate::const_eval::MemoryKind::Heap))
         .expect("OOM: failed to allocate for uninit check");
 
-    if kind == InitKind::Zero {
+    if kind == ValidityRequirement::Zero {
         cx.write_bytes_ptr(
             allocated.ptr,
             std::iter::repeat(0_u8).take(ty.layout.size().bytes_usize()),
@@ -64,7 +71,7 @@ fn might_permit_raw_init_strict<'tcx>(
     // This does *not* actually check that references are dereferenceable, but since all types that
     // require dereferenceability also require non-null, we don't actually get any false negatives
     // due to this.
-    cx.validate_operand(&ot).is_ok()
+    Ok(cx.validate_operand(&ot).is_ok())
 }
 
 /// Implements the 'lax' (default) version of the `might_permit_raw_init` checks; see that function for
@@ -72,15 +79,18 @@ fn might_permit_raw_init_strict<'tcx>(
 fn might_permit_raw_init_lax<'tcx>(
     this: TyAndLayout<'tcx>,
     cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
-    init_kind: InitKind,
-) -> bool {
+    init_kind: ValidityRequirement,
+) -> Result<bool, LayoutError<'tcx>> {
     let scalar_allows_raw_init = move |s: Scalar| -> bool {
         match init_kind {
-            InitKind::Zero => {
+            ValidityRequirement::Inhabited => {
+                bug!("ValidityRequirement::Inhabited should have been handled above")
+            }
+            ValidityRequirement::Zero => {
                 // The range must contain 0.
                 s.valid_range(cx).contains(0)
             }
-            InitKind::UninitMitigated0x01Fill => {
+            ValidityRequirement::UninitMitigated0x01Fill => {
                 // The range must include an 0x01-filled buffer.
                 let mut val: u128 = 0x01;
                 for _ in 1..s.size(cx).bytes() {
@@ -89,6 +99,9 @@ fn might_permit_raw_init_lax<'tcx>(
                 }
                 s.valid_range(cx).contains(val)
             }
+            ValidityRequirement::Uninit => {
+                bug!("ValidityRequirement::Uninit should have been handled above")
+            }
         }
     };
 
@@ -102,20 +115,20 @@ fn might_permit_raw_init_lax<'tcx>(
     };
     if !valid {
         // This is definitely not okay.
-        return false;
+        return Ok(false);
     }
 
     // Special magic check for references and boxes (i.e., special pointer types).
     if let Some(pointee) = this.ty.builtin_deref(false) {
-        let pointee = cx.layout_of(pointee.ty).expect("need to be able to compute layouts");
+        let pointee = cx.layout_of(pointee.ty)?;
         // We need to ensure that the LLVM attributes `aligned` and `dereferenceable(size)` are satisfied.
         if pointee.align.abi.bytes() > 1 {
             // 0x01-filling is not aligned.
-            return false;
+            return Ok(false);
         }
         if pointee.size.bytes() > 0 {
             // A 'fake' integer pointer is not sufficiently dereferenceable.
-            return false;
+            return Ok(false);
         }
     }
 
@@ -128,9 +141,9 @@ fn might_permit_raw_init_lax<'tcx>(
         }
         FieldsShape::Arbitrary { offsets, .. } => {
             for idx in 0..offsets.len() {
-                if !might_permit_raw_init_lax(this.field(cx, idx), cx, init_kind) {
+                if !might_permit_raw_init_lax(this.field(cx, idx), cx, init_kind)? {
                     // We found a field that is unhappy with this kind of initialization.
-                    return false;
+                    return Ok(false);
                 }
             }
         }
@@ -147,5 +160,5 @@ fn might_permit_raw_init_lax<'tcx>(
         }
     }
 
-    true
+    Ok(true)
 }