Auto merge of #132460 - lcnr:questionable-uwu, r=compiler-errors

Use `TypingMode` throughout the compiler instead of `ParamEnv`

Hopefully the biggest single PR as part of https://github.com/rust-lang/types-team/issues/128.

## `infcx.typing_env` while defining opaque types

I don't know how'll be able to correctly handle opaque types when using something taking a `TypingEnv` while defining opaque types. To correctly handle the opaques we need to be able to pass in the current `opaque_type_storage` and return constraints, i.e. we need to use a proper canonical query. We should migrate all the queries used during HIR typeck and borrowck where this matters to proper canonical queries. This is

## `layout_of` and `Reveal::All`

We convert the `ParamEnv` to `Reveal::All` right at the start of the `layout_of` query, so I've changed callers of `layout_of` to already use a post analysis `TypingEnv` when encountering it.

https://github.com/rust-lang/rust/blob/ca87b535a05097df6abbe2a031b057de2cefac5b/compiler/rustc_ty_utils/src/layout.rs#L51

## `Ty::is_[unpin|sized|whatever]`

I haven't migrated `fn is_item_raw` to use `TypingEnv`, will do so in a followup PR, this should significantly reduce the amount of `typing_env.param_env`. At some point there will probably be zero such uses as using the type system while ignoring the `typing_mode` is incorrect.

## `MirPhase` and phase-transitions

When inside of a MIR-body, we can mostly use its `MirPhase` to figure out the right `typing_mode`. This does not work during phase transitions, most notably when transitioning from `Analysis` to `Runtime`:

https://github.com/rust-lang/rust/blob/dae7ac133b9eda152784c075facb31a6688c92b1/compiler/rustc_mir_transform/src/lib.rs#L606-L625

All these passes still run with `MirPhase::Analysis`, but we should only use `Reveal::All` once we're run the `RevealAll` pass. This required me to manually construct the right `TypingEnv` in all these passes. Given that it feels somewhat easy to accidentally miss this going forward, I would maybe like to change `Body::phase` to an `Option` and replace it at the start of phase transitions. This then makes it clear that the MIR is currently in a weird state.

r? `@ghost`

1 files changed, 7 insertions, 11 deletions

diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index d2d5facbbdc..5651bf469d5 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -333,10 +333,14 @@ fn mir_keys(tcx: TyCtxt<'_>, (): ()) -> FxIndexSet<LocalDefId> {
 }
 
 fn mir_const_qualif(tcx: TyCtxt<'_>, def: LocalDefId) -> ConstQualifs {
-    let const_kind = tcx.hir().body_const_context(def);
-
+    // N.B., this `borrow()` is guaranteed to be valid (i.e., the value
+    // cannot yet be stolen), because `mir_promoted()`, which steals
+    // from `mir_built()`, forces this query to execute before
+    // performing the steal.
+    let body = &tcx.mir_built(def).borrow();
+    let ccx = check_consts::ConstCx::new(tcx, body);
     // No need to const-check a non-const `fn`.
-    match const_kind {
+    match ccx.const_kind {
         Some(ConstContext::Const { .. } | ConstContext::Static(_) | ConstContext::ConstFn) => {}
         None => span_bug!(
             tcx.def_span(def),
@@ -344,20 +348,12 @@ fn mir_const_qualif(tcx: TyCtxt<'_>, def: LocalDefId) -> ConstQualifs {
         ),
     }
 
-    // N.B., this `borrow()` is guaranteed to be valid (i.e., the value
-    // cannot yet be stolen), because `mir_promoted()`, which steals
-    // from `mir_built()`, forces this query to execute before
-    // performing the steal.
-    let body = &tcx.mir_built(def).borrow();
-
     if body.return_ty().references_error() {
         // It's possible to reach here without an error being emitted (#121103).
         tcx.dcx().span_delayed_bug(body.span, "mir_const_qualif: MIR had errors");
         return Default::default();
     }
 
-    let ccx = check_consts::ConstCx { body, tcx, const_kind, param_env: tcx.param_env(def) };
-
     let mut validator = check_consts::check::Checker::new(&ccx);
     validator.check_body();