Rollup merge of #130294 - nnethercote:more-lifetimes, r=lcnr

Lifetime cleanups

The last commit is very opinionated, let's see how we go.

r? `@oli-obk`

compiler/rustc_mir_transform/src/check_alignment.rs

@@ -62,14 +62,14 @@ impl<'tcx> crate::MirPass<'tcx> for CheckAlignment {
     }
 }
 
-struct PointerFinder<'tcx, 'a> {
+struct PointerFinder<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     local_decls: &'a mut LocalDecls<'tcx>,
     param_env: ParamEnv<'tcx>,
     pointers: Vec<(Place<'tcx>, Ty<'tcx>)>,
 }
 
-impl<'tcx, 'a> Visitor<'tcx> for PointerFinder<'tcx, 'a> {
+impl<'a, 'tcx> Visitor<'tcx> for PointerFinder<'a, 'tcx> {
     fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
         // We want to only check reads and writes to Places, so we specifically exclude
         // Borrow and RawBorrow.

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -554,13 +554,13 @@ impl<'tcx> Patch<'tcx> {
     }
 }
 
-struct Collector<'tcx, 'locals> {
+struct Collector<'a, 'tcx> {
     patch: Patch<'tcx>,
-    local_decls: &'locals LocalDecls<'tcx>,
+    local_decls: &'a LocalDecls<'tcx>,
 }
 
-impl<'tcx, 'locals> Collector<'tcx, 'locals> {
-    pub(crate) fn new(tcx: TyCtxt<'tcx>, local_decls: &'locals LocalDecls<'tcx>) -> Self {
+impl<'a, 'tcx> Collector<'a, 'tcx> {
+    pub(crate) fn new(tcx: TyCtxt<'tcx>, local_decls: &'a LocalDecls<'tcx>) -> Self {
         Self { patch: Patch::new(tcx), local_decls }
     }
 
@@ -722,7 +722,7 @@ fn try_write_constant<'tcx>(
 
 impl<'mir, 'tcx>
     ResultsVisitor<'mir, 'tcx, Results<'tcx, ValueAnalysisWrapper<ConstAnalysis<'_, 'tcx>>>>
-    for Collector<'tcx, '_>
+    for Collector<'_, 'tcx>
 {
     type Domain = State<FlatSet<Scalar>>;
 
@@ -839,9 +839,9 @@ impl<'tcx> MutVisitor<'tcx> for Patch<'tcx> {
     }
 }
 
-struct OperandCollector<'a, 'locals, 'tcx> {
+struct OperandCollector<'a, 'b, 'tcx> {
     state: &'a State<FlatSet<Scalar>>,
-    visitor: &'a mut Collector<'tcx, 'locals>,
+    visitor: &'a mut Collector<'b, 'tcx>,
     ecx: &'a mut InterpCx<'tcx, DummyMachine>,
     map: &'a Map<'tcx>,
 }

compiler/rustc_mir_transform/src/deduplicate_blocks.rs

@@ -98,7 +98,7 @@ fn find_duplicates(body: &Body<'_>) -> FxHashMap<BasicBlock, BasicBlock> {
     duplicates
 }
 
-struct BasicBlockHashable<'tcx, 'a> {
+struct BasicBlockHashable<'a, 'tcx> {
     basic_block_data: &'a BasicBlockData<'tcx>,
 }
 

compiler/rustc_mir_transform/src/elaborate_box_derefs.rs

@@ -38,7 +38,7 @@ pub(super) fn build_projection<'tcx>(
     ]
 }
 
-struct ElaborateBoxDerefVisitor<'tcx, 'a> {
+struct ElaborateBoxDerefVisitor<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     unique_did: DefId,
     nonnull_did: DefId,
@@ -46,7 +46,7 @@ struct ElaborateBoxDerefVisitor<'tcx, 'a> {
     patch: MirPatch<'tcx>,
 }
 
-impl<'tcx, 'a> MutVisitor<'tcx> for ElaborateBoxDerefVisitor<'tcx, 'a> {
+impl<'a, 'tcx> MutVisitor<'tcx> for ElaborateBoxDerefVisitor<'a, 'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }

compiler/rustc_mir_transform/src/errors.rs

@@ -89,7 +89,7 @@ pub(crate) struct FnItemRef {
     pub ident: String,
 }
 
-pub(crate) struct MustNotSupend<'tcx, 'a> {
+pub(crate) struct MustNotSupend<'a, 'tcx> {
     pub tcx: TyCtxt<'tcx>,
     pub yield_sp: Span,
     pub reason: Option<MustNotSuspendReason>,

compiler/rustc_mir_transform/src/instsimplify.rs

@@ -63,13 +63,13 @@ impl<'tcx> crate::MirPass<'tcx> for InstSimplify {
     }
 }
 
-struct InstSimplifyContext<'tcx, 'a> {
+struct InstSimplifyContext<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     local_decls: &'a LocalDecls<'tcx>,
     param_env: ParamEnv<'tcx>,
 }
 
-impl<'tcx> InstSimplifyContext<'tcx, '_> {
+impl<'tcx> InstSimplifyContext<'_, 'tcx> {
     fn should_simplify(&self, source_info: &SourceInfo, rvalue: &Rvalue<'tcx>) -> bool {
         self.should_simplify_custom(source_info, "Rvalue", rvalue)
     }

compiler/rustc_mir_transform/src/jump_threading.rs

@@ -117,7 +117,7 @@ struct ThreadingOpportunity {
     target: BasicBlock,
 }
 
-struct TOFinder<'tcx, 'a> {
+struct TOFinder<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     ecx: InterpCx<'tcx, DummyMachine>,
@@ -183,7 +183,7 @@ impl<'a> ConditionSet<'a> {
     }
 }
 
-impl<'tcx, 'a> TOFinder<'tcx, 'a> {
+impl<'a, 'tcx> TOFinder<'a, 'tcx> {
     fn is_empty(&self, state: &State<ConditionSet<'a>>) -> bool {
         state.all_bottom()
     }

compiler/rustc_mir_transform/src/match_branches.rs

@@ -295,7 +295,7 @@ struct SimplifyToExp {
 }
 
 #[derive(Clone, Copy)]
-enum ExpectedTransformKind<'tcx, 'a> {
+enum ExpectedTransformKind<'a, 'tcx> {
     /// Identical statements.
     Same(&'a StatementKind<'tcx>),
     /// Assignment statements have the same value.

compiler/rustc_mir_transform/src/ssa.rs

@@ -235,7 +235,7 @@ impl SsaLocals {
     }
 }
 
-struct SsaVisitor<'tcx, 'a> {
+struct SsaVisitor<'a, 'tcx> {
     body: &'a Body<'tcx>,
     dominators: &'a Dominators<BasicBlock>,
     assignments: IndexVec<Local, Set1<DefLocation>>,
@@ -261,7 +261,7 @@ impl SsaVisitor<'_, '_> {
     }
 }
 
-impl<'tcx> Visitor<'tcx> for SsaVisitor<'tcx, '_> {
+impl<'tcx> Visitor<'tcx> for SsaVisitor<'_, 'tcx> {
     fn visit_local(&mut self, local: Local, ctxt: PlaceContext, loc: Location) {
         match ctxt {
             PlaceContext::MutatingUse(MutatingUseContext::Projection)