Auto merge of #115762 - oli-obk:early_const_prop_lint2, r=<try>

Avoid revealing in layout_of

r? `@compiler-errors`

I feel like `layout_of` is doing too many things at once, and I don't really know why. It could allow us to if callers could decide whether to reveal opaque types.

Author: bors

compiler/rustc_middle/src/ty/layout.rs

@@ -324,6 +324,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
         param_env: ty::ParamEnv<'tcx>,
     ) -> Result<SizeSkeleton<'tcx>, &'tcx LayoutError<'tcx>> {
         debug_assert!(!ty.has_non_region_infer());
+        let param_env = param_env.with_reveal_all_normalized(tcx);
 
         // First try computing a static layout.
         let err = match tcx.layout_of(param_env.and(ty)) {

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -176,7 +176,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     ) -> ConstPropagator<'mir, 'tcx> {
         let def_id = body.source.def_id();
         let args = &GenericArgs::identity_for_item(tcx, def_id);
-        let param_env = tcx.param_env_reveal_all_normalized(def_id);
+        let param_env = tcx.param_env(def_id);
 
         let can_const_prop = CanConstProp::check(tcx, param_env, body);
         let mut ecx = InterpCx::new(

compiler/rustc_passes/src/layout_test.rs

@@ -66,7 +66,7 @@ pub fn ensure_wf<'tcx>(
 }
 
 fn dump_layout_of(tcx: TyCtxt<'_>, item_def_id: LocalDefId, attr: &Attribute) {
-    let param_env = tcx.param_env(item_def_id);
+    let param_env = tcx.param_env_reveal_all_normalized(item_def_id);
     let ty = tcx.type_of(item_def_id).instantiate_identity();
     let span = tcx.def_span(item_def_id.to_def_id());
     if !ensure_wf(tcx, param_env, ty, item_def_id, span) {

compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs

@@ -1106,7 +1106,10 @@ pub fn typeid_for_instance<'tcx>(
     options: TypeIdOptions,
 ) -> String {
     let fn_abi = tcx
-        .fn_abi_of_instance(tcx.param_env(instance.def_id()).and((*instance, ty::List::empty())))
+        .fn_abi_of_instance(
+            tcx.param_env_reveal_all_normalized(instance.def_id())
+                .and((*instance, ty::List::empty())),
+        )
         .unwrap_or_else(|instance| {
             bug!("typeid_for_instance: couldn't get fn_abi of instance {:?}", instance)
         });

compiler/rustc_ty_utils/src/layout.rs

@@ -4,6 +4,7 @@ use rustc_index::bit_set::BitSet;
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::mir::{GeneratorLayout, GeneratorSavedLocal};
 use rustc_middle::query::Providers;
+use rustc_middle::traits::Reveal;
 use rustc_middle::ty::layout::{
     IntegerExt, LayoutCx, LayoutError, LayoutOf, TyAndLayout, MAX_SIMD_LANES,
 };
@@ -36,7 +37,6 @@ fn layout_of<'tcx>(
     let (param_env, ty) = query.into_parts();
     debug!(?ty);
 
-    let param_env = param_env.with_reveal_all_normalized(tcx);
     let unnormalized_ty = ty;
 
     // FIXME: We might want to have two different versions of `layout_of`:
@@ -52,7 +52,19 @@ fn layout_of<'tcx>(
         }
     };
 
-    if ty != unnormalized_ty {
+    if ty == unnormalized_ty {
+        // see comment in eval_to_allocation_raw_provider for what we're doing here
+        if param_env.reveal() == Reveal::All {
+            let mut query = query;
+            query.param_env = param_env.with_user_facing();
+            match tcx.layout_of(query) {
+                // try again with reveal all as requested
+                Err(LayoutError::Unknown(_) | LayoutError::NormalizationFailure(_, _)) => {}
+                // deduplicate calls
+                other => return other,
+            }
+        }
+    } else {
         // Ensure this layout is also cached for the normalized type.
         return tcx.layout_of(param_env.and(ty));
     }

src/tools/clippy/clippy_lints/src/large_futures.rs

@@ -69,7 +69,7 @@ impl<'tcx> LateLintPass<'tcx> for LargeFuture {
                 && let ty = cx.typeck_results().expr_ty(expr)
                 && let Some(future_trait_def_id) = cx.tcx.lang_items().future_trait()
                 && implements_trait(cx, ty, future_trait_def_id, &[])
-                && let Ok(layout) = cx.tcx.layout_of(cx.param_env.and(ty))
+                && let Ok(layout) = cx.tcx.layout_of(cx.param_env.with_reveal_all_normalized(cx.tcx).and(ty))
                 && let size = layout.layout.size()
                 && size >= Size::from_bytes(self.future_size_threshold)
             {

tests/ui/associated-consts/issue-24949-assoc-const-static-recursion-impl.stderr

@@ -4,11 +4,6 @@ error[E0391]: cycle detected when elaborating drops for `<impl at $DIR/issue-249
 LL |     const BAR: u32 = IMPL_REF_BAR;
    |                      ^^^^^^^^^^^^
    |
-note: ...which requires const-evaluating + checking `IMPL_REF_BAR`...
-  --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:7:1
-   |
-LL | const IMPL_REF_BAR: u32 = GlobalImplRef::BAR;
-   | ^^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires const-evaluating + checking `IMPL_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:7:27
    |

tests/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait-default.stderr

@@ -4,11 +4,6 @@ error[E0391]: cycle detected when elaborating drops for `FooDefault::BAR`
 LL |     const BAR: u32 = DEFAULT_REF_BAR;
    |                      ^^^^^^^^^^^^^^^
    |
-note: ...which requires const-evaluating + checking `DEFAULT_REF_BAR`...
-  --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:11:1
-   |
-LL | const DEFAULT_REF_BAR: u32 = <GlobalDefaultRef>::BAR;
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires const-evaluating + checking `DEFAULT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:11:30
    |

tests/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait.stderr

@@ -4,11 +4,6 @@ error[E0391]: cycle detected when elaborating drops for `<impl at $DIR/issue-249
 LL |     const BAR: u32 = TRAIT_REF_BAR;
    |                      ^^^^^^^^^^^^^
    |
-note: ...which requires const-evaluating + checking `TRAIT_REF_BAR`...
-  --> $DIR/issue-24949-assoc-const-static-recursion-trait.rs:7:1
-   |
-LL | const TRAIT_REF_BAR: u32 = <GlobalTraitRef>::BAR;
-   | ^^^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires const-evaluating + checking `TRAIT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait.rs:7:28
    |

tests/ui/layout/layout-cycle.stderr

@@ -2,6 +2,7 @@ error[E0391]: cycle detected when computing layout of `S<S<()>>`
    |
    = note: ...which requires computing layout of `<S<()> as Tr>::I`...
    = note: ...which again requires computing layout of `S<S<()>>`, completing the cycle
+   = note: cycle used when computing layout of `S<S<()>>`
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
 error: failed to get layout for S<S<()>>: a cycle occurred during layout computation