Factor out conservative_is_privately_uninhabited

Author: camsteffen

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1564,10 +1564,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 }
             }
             None => {
-                if !self
-                    .tcx()
-                    .conservative_is_privately_uninhabited(self.param_env.and(sig.output()))
-                {
+                if !sig.output().is_privately_uninhabited(self.tcx(), self.param_env) {
                     span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
                 }
             }

compiler/rustc_middle/src/query/mod.rs

@@ -2078,17 +2078,6 @@ rustc_queries! {
         desc { "normalizing opaque types in `{:?}`", key }
     }
 
-    /// Checks whether a type is definitely uninhabited. This is
-    /// conservative: for some types that are uninhabited we return `false`,
-    /// but we only return `true` for types that are definitely uninhabited.
-    /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty`
-    /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
-    /// size, to account for partial initialisation. See #49298 for details.)
-    query conservative_is_privately_uninhabited(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
-        desc { "conservatively checking if `{}` is privately uninhabited", key.value }
-        remap_env_constness
-    }
-
     query limits(key: ()) -> Limits {
         desc { "looking up limits" }
     }

compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs

@@ -41,6 +41,13 @@ impl<'tcx> InhabitedPredicate<'tcx> {
         self.apply_inner(tcx, param_env, &|_| Err(())).ok()
     }
 
+    /// Same as `apply`, but `NotInModule(_)` predicates yield `false`. That is,
+    /// privately uninhabited types are considered always uninhabited.
+    pub fn apply_ignore_module(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> bool {
+        let Ok(result) = self.apply_inner::<!>(tcx, param_env, &|_| Ok(true));
+        result
+    }
+
     fn apply_inner<E>(
         self,
         tcx: TyCtxt<'tcx>,

compiler/rustc_middle/src/ty/inhabitedness/mod.rs

@@ -169,6 +169,15 @@ impl<'tcx> Ty<'tcx> {
     ) -> bool {
         self.inhabited_predicate(tcx).apply(tcx, param_env, module)
     }
+
+    /// Returns true if the type is uninhabited without regard to visibility
+    pub fn is_privately_uninhabited(
+        self,
+        tcx: TyCtxt<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+    ) -> bool {
+        !self.inhabited_predicate(tcx).apply_ignore_module(tcx, param_env)
+    }
 }
 
 /// N.B. this query should only be called through `Ty::inhabited_predicate`

compiler/rustc_mir_build/src/build/matches/simplify.rs

@@ -264,10 +264,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let irrefutable = adt_def.variants().iter_enumerated().all(|(i, v)| {
                     i == variant_index || {
                         self.tcx.features().exhaustive_patterns
-                            && v.inhabited_predicate(self.tcx, adt_def)
+                            && !v
+                                .inhabited_predicate(self.tcx, adt_def)
                                 .subst(self.tcx, substs)
-                                .apply_any_module(self.tcx, self.param_env)
-                                != Some(true)
+                                .apply_ignore_module(self.tcx, self.param_env)
                     }
                 }) && (adt_def.did().is_local()
                     || !adt_def.is_variant_list_non_exhaustive());

compiler/rustc_mir_transform/src/generator.rs

@@ -1015,7 +1015,7 @@ fn insert_panic_block<'tcx>(
 
 fn can_return<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
     // Returning from a function with an uninhabited return type is undefined behavior.
-    if tcx.conservative_is_privately_uninhabited(param_env.and(body.return_ty())) {
+    if body.return_ty().is_privately_uninhabited(tcx, param_env) {
         return false;
     }
 

compiler/rustc_ty_utils/src/layout.rs

@@ -442,8 +442,7 @@ fn layout_of_uncached<'tcx>(
             let element = cx.layout_of(element)?;
             let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow(ty))?;
 
-            let abi = if count != 0 && tcx.conservative_is_privately_uninhabited(param_env.and(ty))
-            {
+            let abi = if count != 0 && ty.is_privately_uninhabited(tcx, param_env) {
                 Abi::Uninhabited
             } else {
                 Abi::Aggregate { sized: true }

compiler/rustc_ty_utils/src/layout_sanity_check.rs

@@ -12,7 +12,7 @@ pub(super) fn sanity_check_layout<'tcx>(
     layout: &TyAndLayout<'tcx>,
 ) {
     // Type-level uninhabitedness should always imply ABI uninhabitedness.
-    if cx.tcx.conservative_is_privately_uninhabited(cx.param_env.and(layout.ty)) {
+    if layout.ty.is_privately_uninhabited(cx.tcx, cx.param_env) {
         assert!(layout.abi.is_uninhabited());
     }
 

compiler/rustc_ty_utils/src/ty.rs

@@ -416,62 +416,6 @@ fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync {
     node.fn_sig().map_or(hir::IsAsync::NotAsync, |sig| sig.header.asyncness)
 }
 
-/// Don't call this directly: use ``tcx.conservative_is_privately_uninhabited`` instead.
-pub fn conservative_is_privately_uninhabited_raw<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    param_env_and: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
-) -> bool {
-    let (param_env, ty) = param_env_and.into_parts();
-    match ty.kind() {
-        ty::Never => {
-            debug!("ty::Never =>");
-            true
-        }
-        ty::Adt(def, _) if def.is_union() => {
-            debug!("ty::Adt(def, _) if def.is_union() =>");
-            // For now, `union`s are never considered uninhabited.
-            false
-        }
-        ty::Adt(def, substs) => {
-            debug!("ty::Adt(def, _) if def.is_not_union() =>");
-            // Any ADT is uninhabited if either:
-            // (a) It has no variants (i.e. an empty `enum`);
-            // (b) Each of its variants (a single one in the case of a `struct`) has at least
-            //     one uninhabited field.
-            def.variants().iter().all(|var| {
-                var.fields.iter().any(|field| {
-                    let ty = tcx.bound_type_of(field.did).subst(tcx, substs);
-                    tcx.conservative_is_privately_uninhabited(param_env.and(ty))
-                })
-            })
-        }
-        ty::Tuple(fields) => {
-            debug!("ty::Tuple(..) =>");
-            fields.iter().any(|ty| tcx.conservative_is_privately_uninhabited(param_env.and(ty)))
-        }
-        ty::Array(ty, len) => {
-            debug!("ty::Array(ty, len) =>");
-            match len.try_eval_usize(tcx, param_env) {
-                Some(0) | None => false,
-                // If the array is definitely non-empty, it's uninhabited if
-                // the type of its elements is uninhabited.
-                Some(1..) => tcx.conservative_is_privately_uninhabited(param_env.and(*ty)),
-            }
-        }
-        ty::Ref(..) => {
-            debug!("ty::Ref(..) =>");
-            // References to uninitialised memory is valid for any type, including
-            // uninhabited types, in unsafe code, so we treat all references as
-            // inhabited.
-            false
-        }
-        _ => {
-            debug!("_ =>");
-            false
-        }
-    }
-}
-
 pub fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         asyncness,
@@ -481,7 +425,6 @@ pub fn provide(providers: &mut ty::query::Providers) {
         instance_def_size_estimate,
         issue33140_self_ty,
         impl_defaultness,
-        conservative_is_privately_uninhabited: conservative_is_privately_uninhabited_raw,
         ..*providers
     };
 }

src/test/ui/const-generics/conservative_is_privately_uninhabited_uses_correct_param_env-1.rs renamed to src/test/ui/const-generics/inhabited-assoc-ty-ice-1.rs

@@ -2,7 +2,7 @@
 #![feature(generic_const_exprs)]
 #![allow(incomplete_features)]
 
-// This tests that the `conservative_is_privately_uninhabited` fn doesn't cause
+// This tests that the inhabited check doesn't cause
 // ICEs by trying to evaluate `T::ASSOC` with an incorrect `ParamEnv`.
 
 trait Foo {