Rollup merge of #97292 - compiler-errors:tcxify-rustc, r=davidtwco

Lifetime variance fixes for rustc

#97287 migrates rustc to a `Ty` type that is invariant over its lifetime `'tcx`, so I need to fix a bunch of places that assume that `Ty<'a>` and `Ty<'b>` can be unified by shortening both to some common lifetime.

This is doable, since many lifetimes are already `'tcx`, so all this PR does is be a bit more explicit that elided lifetimes are actually `'tcx`.

Split out from #97287 so the compiler team can review independently.

7 files changed, 41 insertions, 36 deletions

diff --git a/compiler/rustc_middle/src/mir/interpret/allocation.rs b/compiler/rustc_middle/src/mir/interpret/allocation.rs
index 760fe1edbdb..6252dc1670c 100644
--- a/compiler/rustc_middle/src/mir/interpret/allocation.rs
+++ b/compiler/rustc_middle/src/mir/interpret/allocation.rs
@@ -171,7 +171,7 @@ impl<Tag> Allocation<Tag> {
 
     /// Try to create an Allocation of `size` bytes, failing if there is not enough memory
     /// available to the compiler to do so.
-    pub fn uninit(size: Size, align: Align, panic_on_fail: bool) -> InterpResult<'static, Self> {
+    pub fn uninit<'tcx>(size: Size, align: Align, panic_on_fail: bool) -> InterpResult<'tcx, Self> {
         let bytes = Box::<[u8]>::try_new_zeroed_slice(size.bytes_usize()).map_err(|_| {
             // This results in an error that can happen non-deterministically, since the memory
             // available to the compiler can change between runs. Normally queries are always
diff --git a/compiler/rustc_middle/src/mir/interpret/value.rs b/compiler/rustc_middle/src/mir/interpret/value.rs
index eeee170f43f..d00dae85367 100644
--- a/compiler/rustc_middle/src/mir/interpret/value.rs
+++ b/compiler/rustc_middle/src/mir/interpret/value.rs
@@ -397,38 +397,38 @@ impl<'tcx, Tag: Provenance> Scalar<Tag> {
     /// Converts the scalar to produce an unsigned integer of the given size.
     /// Fails if the scalar is a pointer.
     #[inline]
-    pub fn to_uint(self, size: Size) -> InterpResult<'static, u128> {
+    pub fn to_uint(self, size: Size) -> InterpResult<'tcx, u128> {
         self.to_bits(size)
     }
 
     /// Converts the scalar to produce a `u8`. Fails if the scalar is a pointer.
-    pub fn to_u8(self) -> InterpResult<'static, u8> {
+    pub fn to_u8(self) -> InterpResult<'tcx, u8> {
         self.to_uint(Size::from_bits(8)).map(|v| u8::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce a `u16`. Fails if the scalar is a pointer.
-    pub fn to_u16(self) -> InterpResult<'static, u16> {
+    pub fn to_u16(self) -> InterpResult<'tcx, u16> {
         self.to_uint(Size::from_bits(16)).map(|v| u16::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce a `u32`. Fails if the scalar is a pointer.
-    pub fn to_u32(self) -> InterpResult<'static, u32> {
+    pub fn to_u32(self) -> InterpResult<'tcx, u32> {
         self.to_uint(Size::from_bits(32)).map(|v| u32::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce a `u64`. Fails if the scalar is a pointer.
-    pub fn to_u64(self) -> InterpResult<'static, u64> {
+    pub fn to_u64(self) -> InterpResult<'tcx, u64> {
         self.to_uint(Size::from_bits(64)).map(|v| u64::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce a `u128`. Fails if the scalar is a pointer.
-    pub fn to_u128(self) -> InterpResult<'static, u128> {
+    pub fn to_u128(self) -> InterpResult<'tcx, u128> {
         self.to_uint(Size::from_bits(128))
     }
 
     /// Converts the scalar to produce a machine-pointer-sized unsigned integer.
     /// Fails if the scalar is a pointer.
-    pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'static, u64> {
+    pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> {
         let b = self.to_uint(cx.data_layout().pointer_size)?;
         Ok(u64::try_from(b).unwrap())
     }
@@ -436,51 +436,51 @@ impl<'tcx, Tag: Provenance> Scalar<Tag> {
     /// Converts the scalar to produce a signed integer of the given size.
     /// Fails if the scalar is a pointer.
     #[inline]
-    pub fn to_int(self, size: Size) -> InterpResult<'static, i128> {
+    pub fn to_int(self, size: Size) -> InterpResult<'tcx, i128> {
         let b = self.to_bits(size)?;
         Ok(size.sign_extend(b) as i128)
     }
 
     /// Converts the scalar to produce an `i8`. Fails if the scalar is a pointer.
-    pub fn to_i8(self) -> InterpResult<'static, i8> {
+    pub fn to_i8(self) -> InterpResult<'tcx, i8> {
         self.to_int(Size::from_bits(8)).map(|v| i8::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce an `i16`. Fails if the scalar is a pointer.
-    pub fn to_i16(self) -> InterpResult<'static, i16> {
+    pub fn to_i16(self) -> InterpResult<'tcx, i16> {
         self.to_int(Size::from_bits(16)).map(|v| i16::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce an `i32`. Fails if the scalar is a pointer.
-    pub fn to_i32(self) -> InterpResult<'static, i32> {
+    pub fn to_i32(self) -> InterpResult<'tcx, i32> {
         self.to_int(Size::from_bits(32)).map(|v| i32::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce an `i64`. Fails if the scalar is a pointer.
-    pub fn to_i64(self) -> InterpResult<'static, i64> {
+    pub fn to_i64(self) -> InterpResult<'tcx, i64> {
         self.to_int(Size::from_bits(64)).map(|v| i64::try_from(v).unwrap())
     }
 
     /// Converts the scalar to produce an `i128`. Fails if the scalar is a pointer.
-    pub fn to_i128(self) -> InterpResult<'static, i128> {
+    pub fn to_i128(self) -> InterpResult<'tcx, i128> {
         self.to_int(Size::from_bits(128))
     }
 
     /// Converts the scalar to produce a machine-pointer-sized signed integer.
     /// Fails if the scalar is a pointer.
-    pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'static, i64> {
+    pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, i64> {
         let b = self.to_int(cx.data_layout().pointer_size)?;
         Ok(i64::try_from(b).unwrap())
     }
 
     #[inline]
-    pub fn to_f32(self) -> InterpResult<'static, Single> {
+    pub fn to_f32(self) -> InterpResult<'tcx, Single> {
         // Going through `u32` to check size and truncation.
         Ok(Single::from_bits(self.to_u32()?.into()))
     }
 
     #[inline]
-    pub fn to_f64(self) -> InterpResult<'static, Double> {
+    pub fn to_f64(self) -> InterpResult<'tcx, Double> {
         // Going through `u64` to check size and truncation.
         Ok(Double::from_bits(self.to_u64()?.into()))
     }
@@ -534,7 +534,7 @@ impl<Tag> ScalarMaybeUninit<Tag> {
     }
 
     #[inline]
-    pub fn check_init(self) -> InterpResult<'static, Scalar<Tag>> {
+    pub fn check_init<'tcx>(self) -> InterpResult<'tcx, Scalar<Tag>> {
         match self {
             ScalarMaybeUninit::Scalar(scalar) => Ok(scalar),
             ScalarMaybeUninit::Uninit => throw_ub!(InvalidUninitBytes(None)),
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 1eca22d3812..9f8b22c8afc 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -13,6 +13,7 @@ use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
 use crate::ty::{self, List, Ty, TyCtxt};
 use crate::ty::{AdtDef, InstanceDef, Region, ScalarInt, UserTypeAnnotationIndex};
 
+use rustc_data_structures::captures::Captures;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::{CtorKind, Namespace};
 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
@@ -484,7 +485,7 @@ impl<'tcx> Body<'tcx> {
 
     /// Returns an iterator over all user-declared mutable locals.
     #[inline]
-    pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
+    pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
         (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
             let local = Local::new(index);
             let decl = &self.local_decls[local];
@@ -498,7 +499,9 @@ impl<'tcx> Body<'tcx> {
 
     /// Returns an iterator over all user-declared mutable arguments and locals.
     #[inline]
-    pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
+    pub fn mut_vars_and_args_iter<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = Local> + Captures<'tcx> + 'a {
         (1..self.local_decls.len()).filter_map(move |index| {
             let local = Local::new(index);
             let decl = &self.local_decls[local];
diff --git a/compiler/rustc_middle/src/mir/patch.rs b/compiler/rustc_middle/src/mir/patch.rs
index 3bcb8f9c34c..1bc53d3c9f1 100644
--- a/compiler/rustc_middle/src/mir/patch.rs
+++ b/compiler/rustc_middle/src/mir/patch.rs
@@ -192,7 +192,7 @@ impl<'tcx> MirPatch<'tcx> {
         }
     }
 
-    pub fn source_info_for_location(&self, body: &Body<'_>, loc: Location) -> SourceInfo {
+    pub fn source_info_for_location(&self, body: &Body<'tcx>, loc: Location) -> SourceInfo {
         let data = match loc.block.index().checked_sub(body.basic_blocks().len()) {
             Some(new) => &self.new_blocks[new],
             None => &body[loc.block],
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 4d30c0e35e4..4006b2fcf17 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -115,8 +115,6 @@ impl Hash for ObligationCause<'_> {
     }
 }
 
-const MISC_OBLIGATION_CAUSE_CODE: ObligationCauseCode<'static> = MiscObligation;
-
 impl<'tcx> ObligationCause<'tcx> {
     #[inline]
     pub fn new(
@@ -201,7 +199,7 @@ pub struct UnifyReceiverContext<'tcx> {
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, Default)]
 pub struct InternedObligationCauseCode<'tcx> {
-    /// `None` for `MISC_OBLIGATION_CAUSE_CODE` (a common case, occurs ~60% of
+    /// `None` for `ObligationCauseCode::MiscObligation` (a common case, occurs ~60% of
     /// the time). `Some` otherwise.
     code: Option<Lrc<ObligationCauseCode<'tcx>>>,
 }
@@ -210,7 +208,11 @@ impl<'tcx> ObligationCauseCode<'tcx> {
     #[inline(always)]
     fn into(self) -> InternedObligationCauseCode<'tcx> {
         InternedObligationCauseCode {
-            code: if let MISC_OBLIGATION_CAUSE_CODE = self { None } else { Some(Lrc::new(self)) },
+            code: if let ObligationCauseCode::MiscObligation = self {
+                None
+            } else {
+                Some(Lrc::new(self))
+            },
         }
     }
 }
@@ -219,7 +221,7 @@ impl<'tcx> std::ops::Deref for InternedObligationCauseCode<'tcx> {
     type Target = ObligationCauseCode<'tcx>;
 
     fn deref(&self) -> &Self::Target {
-        self.code.as_deref().unwrap_or(&MISC_OBLIGATION_CAUSE_CODE)
+        self.code.as_deref().unwrap_or(&ObligationCauseCode::MiscObligation)
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index a7488fd44cd..30552c685a3 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2163,7 +2163,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
         }
     }
 
-    pub fn same_size(self, other: SizeSkeleton<'_>) -> bool {
+    pub fn same_size(self, other: SizeSkeleton<'tcx>) -> bool {
         match (self, other) {
             (SizeSkeleton::Known(a), SizeSkeleton::Known(b)) => a == b,
             (SizeSkeleton::Pointer { tail: a, .. }, SizeSkeleton::Pointer { tail: b, .. }) => {
diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index 48c71113d50..31a318cc68f 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -109,13 +109,13 @@ impl<'tcx> fmt::Debug for GenericArg<'tcx> {
 }
 
 impl<'tcx> Ord for GenericArg<'tcx> {
-    fn cmp(&self, other: &GenericArg<'_>) -> Ordering {
+    fn cmp(&self, other: &GenericArg<'tcx>) -> Ordering {
         self.unpack().cmp(&other.unpack())
     }
 }
 
 impl<'tcx> PartialOrd for GenericArg<'tcx> {
-    fn partial_cmp(&self, other: &GenericArg<'_>) -> Option<Ordering> {
+    fn partial_cmp(&self, other: &GenericArg<'tcx>) -> Option<Ordering> {
         Some(self.cmp(&other))
     }
 }
@@ -233,7 +233,7 @@ pub type InternalSubsts<'tcx> = List<GenericArg<'tcx>>;
 
 pub type SubstsRef<'tcx> = &'tcx InternalSubsts<'tcx>;
 
-impl<'a, 'tcx> InternalSubsts<'tcx> {
+impl<'tcx> InternalSubsts<'tcx> {
     /// Checks whether all elements of this list are types, if so, transmute.
     pub fn try_as_type_list(&'tcx self) -> Option<&'tcx List<Ty<'tcx>>> {
         if self.iter().all(|arg| matches!(arg.unpack(), GenericArgKind::Type(_))) {
@@ -249,7 +249,7 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
     /// Closure substitutions have a particular structure controlled by the
     /// compiler that encodes information like the signature and closure kind;
     /// see `ty::ClosureSubsts` struct for more comments.
-    pub fn as_closure(&'a self) -> ClosureSubsts<'a> {
+    pub fn as_closure(&'tcx self) -> ClosureSubsts<'tcx> {
         ClosureSubsts { substs: self }
     }
 
@@ -330,20 +330,20 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
     }
 
     #[inline]
-    pub fn types(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
+    pub fn types(&'tcx self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'tcx {
         self.iter()
             .filter_map(|k| if let GenericArgKind::Type(ty) = k.unpack() { Some(ty) } else { None })
     }
 
     #[inline]
-    pub fn regions(&'a self) -> impl DoubleEndedIterator<Item = ty::Region<'tcx>> + 'a {
+    pub fn regions(&'tcx self) -> impl DoubleEndedIterator<Item = ty::Region<'tcx>> + 'tcx {
         self.iter().filter_map(|k| {
             if let GenericArgKind::Lifetime(lt) = k.unpack() { Some(lt) } else { None }
         })
     }
 
     #[inline]
-    pub fn consts(&'a self) -> impl DoubleEndedIterator<Item = ty::Const<'tcx>> + 'a {
+    pub fn consts(&'tcx self) -> impl DoubleEndedIterator<Item = ty::Const<'tcx>> + 'tcx {
         self.iter().filter_map(|k| {
             if let GenericArgKind::Const(ct) = k.unpack() { Some(ct) } else { None }
         })
@@ -351,8 +351,8 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
 
     #[inline]
     pub fn non_erasable_generics(
-        &'a self,
-    ) -> impl DoubleEndedIterator<Item = GenericArgKind<'tcx>> + 'a {
+        &'tcx self,
+    ) -> impl DoubleEndedIterator<Item = GenericArgKind<'tcx>> + 'tcx {
         self.iter().filter_map(|k| match k.unpack() {
             GenericArgKind::Lifetime(_) => None,
             generic => Some(generic),