rustc: reintroduce lifetime bounds where necessary.

Author: eddyb

src/librustc/infer/lattice.rs

@@ -41,7 +41,7 @@ pub trait LatticeDir<'f, 'tcx>: TypeRelation<'tcx> {
     fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()>;
 }
 
-pub fn super_lattice_tys<'a, 'tcx, L>(
+pub fn super_lattice_tys<'a, 'tcx: 'a, L>(
     this: &mut L,
     a: Ty<'tcx>,
     b: Ty<'tcx>,

src/librustc/traits/select.rs

@@ -3788,9 +3788,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         matcher.relate(previous, current).is_ok()
     }
 
-    fn push_stack<'o, 's>(
+    fn push_stack<'o>(
         &mut self,
-        previous_stack: TraitObligationStackList<'s, 'tcx>,
+        previous_stack: TraitObligationStackList<'o, 'tcx>,
         obligation: &'o TraitObligation<'tcx>,
     ) -> TraitObligationStack<'o, 'tcx> {
         let fresh_trait_ref = obligation

src/librustc_codegen_ssa/base.rs

@@ -366,7 +366,7 @@ pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     bx.memcpy(dst, dst_align, src, src_align, bx.cx().const_usize(size), flags);
 }
 
-pub fn codegen_instance<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
+pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
     cx: &'a Bx::CodegenCx,
     instance: Instance<'tcx>,
 ) {

src/librustc_codegen_ssa/mono_item.rs

@@ -17,7 +17,7 @@ pub trait MonoItemExt<'a, 'tcx> {
     fn to_raw_string(&self) -> String;
 }
 
-impl<'a, 'tcx> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {
+impl<'a, 'tcx: 'a> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {
     fn define<Bx: BuilderMethods<'a, 'tcx>>(&self, cx: &'a Bx::CodegenCx) {
         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
                self.to_string(cx.tcx(), true),

src/librustc_metadata/creader.rs

@@ -289,11 +289,14 @@ impl<'a> CrateLoader<'a> {
         (cnum, cmeta)
     }
 
-    fn load_proc_macro<'b> (
+    fn load_proc_macro<'b>(
         &mut self,
         locate_ctxt: &mut locator::Context<'b>,
         path_kind: PathKind,
-    ) -> Option<(LoadResult, Option<Library>)> {
+    ) -> Option<(LoadResult, Option<Library>)>
+    where
+        'a: 'b,
+    {
         // Use a new locator Context so trying to load a proc macro doesn't affect the error
         // message we emit
         let mut proc_macro_locator = locate_ctxt.clone();

src/librustc_metadata/decoder.rs

@@ -38,7 +38,7 @@ use log::debug;
 pub struct DecodeContext<'a, 'tcx> {
     opaque: opaque::Decoder<'a>,
     cdata: Option<&'a CrateMetadata>,
-    sess: Option<&'a Session>,
+    sess: Option<&'tcx Session>,
     tcx: Option<TyCtxt<'tcx>>,
 
     // Cache the last used source_file for translating spans as an optimization.
@@ -54,10 +54,8 @@ pub struct DecodeContext<'a, 'tcx> {
 pub trait Metadata<'a, 'tcx>: Copy {
     fn raw_bytes(self) -> &'a [u8];
     fn cdata(self) -> Option<&'a CrateMetadata> { None }
-    fn sess(self) -> Option<&'a Session> { None }
-    fn tcx(self) -> Option<TyCtxt<'tcx>> {
-        None
-        }
+    fn sess(self) -> Option<&'tcx Session> { None }
+    fn tcx(self) -> Option<TyCtxt<'tcx>> { None }
 
     fn decoder(self, pos: usize) -> DecodeContext<'a, 'tcx> {
         let tcx = self.tcx();
@@ -82,13 +80,13 @@ impl<'a, 'tcx> Metadata<'a, 'tcx> for &'a MetadataBlob {
 }
 
 
-impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a MetadataBlob, &'a Session) {
+impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a MetadataBlob, &'tcx Session) {
     fn raw_bytes(self) -> &'a [u8] {
         let (blob, _) = self;
         &blob.0
     }
 
-    fn sess(self) -> Option<&'a Session> {
+    fn sess(self) -> Option<&'tcx Session> {
         let (_, sess) = self;
         Some(sess)
     }
@@ -104,14 +102,14 @@ impl<'a, 'tcx> Metadata<'a, 'tcx> for &'a CrateMetadata {
     }
 }
 
-impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a CrateMetadata, &'a Session) {
+impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a CrateMetadata, &'tcx Session) {
     fn raw_bytes(self) -> &'a [u8] {
         self.0.raw_bytes()
     }
     fn cdata(self) -> Option<&'a CrateMetadata> {
         Some(self.0)
     }
-    fn sess(self) -> Option<&'a Session> {
+    fn sess(self) -> Option<&'tcx Session> {
         Some(&self.1)
     }
 }
@@ -136,11 +134,11 @@ impl<'a, 'tcx, T: Decodable> Lazy<T> {
     }
 }
 
-impl<'a, 'tcx, T: Decodable> LazySeq<T> {
+impl<'a: 'x, 'tcx: 'x, 'x, T: Decodable> LazySeq<T> {
     pub fn decode<M: Metadata<'a, 'tcx>>(
         self,
         meta: M,
-    ) -> impl Iterator<Item = T> + Captures<'tcx> + 'a {
+    ) -> impl Iterator<Item = T> + Captures<'a> + Captures<'tcx> + 'x {
         let mut dcx = meta.decoder(self.position);
         dcx.lazy_state = LazyState::NodeStart(self.position);
         (0..self.len).map(move |_| T::decode(&mut dcx).unwrap())

src/librustc_mir/borrow_check/mod.rs

@@ -1693,7 +1693,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
     fn move_path_closest_to<'a>(
         &mut self,
         place: &'a Place<'tcx>,
-    ) -> Result<(&'a Place<'tcx>, MovePathIndex), NoMovePathFound> {
+    ) -> Result<(&'a Place<'tcx>, MovePathIndex), NoMovePathFound> where 'cx: 'a {
         let mut last_prefix = place;
         for prefix in self.prefixes(place, PrefixSet::All) {
             if let Some(mpi) = self.move_path_for_place(prefix) {

src/librustc_mir/build/matches/mod.rs

@@ -1691,7 +1691,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         &mut self,
         block: BasicBlock,
         bindings: impl IntoIterator<Item = &'b Binding<'tcx>>,
-    ) {
+    ) where 'tcx: 'b {
         debug!("bind_matched_candidate_for_arm_body(block={:?})", block);
 
         let re_erased = self.hir.tcx().lifetimes.re_erased;

src/librustc_mir/dataflow/mod.rs

@@ -297,7 +297,7 @@ impl<'a, 'tcx, BD> DataflowBuilder<'a, 'tcx, BD> where BD: BitDenotation<'tcx>
 /// underlying flow analysis results, because it needs to handle cases
 /// where we are combining the results of *multiple* flow analyses
 /// (e.g., borrows + inits + uninits).
-pub(crate) trait DataflowResultsConsumer<'a, 'tcx> {
+pub(crate) trait DataflowResultsConsumer<'a, 'tcx: 'a> {
     type FlowState: FlowsAtLocation;
 
     // Observation Hooks: override (at least one of) these to get analysis feedback.

src/librustc_mir/hair/pattern/_match.rs

@@ -709,7 +709,8 @@ fn all_constructors<'a, 'tcx>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
 fn max_slice_length<'p, 'a, 'tcx, I>(
     cx: &mut MatchCheckCtxt<'a, 'tcx>,
     patterns: I) -> u64
-    where I: Iterator<Item=&'p Pattern<'tcx>>
+    where I: Iterator<Item=&'p Pattern<'tcx>>,
+        'tcx: 'p,
 {
     // The exhaustiveness-checking paper does not include any details on
     // checking variable-length slice patterns. However, they are matched
@@ -1709,7 +1710,7 @@ fn patterns_for_variant<'p, 'tcx>(
 /// different patterns.
 /// Structure patterns with a partial wild pattern (Foo { a: 42, .. }) have their missing
 /// fields filled with wild patterns.
-fn specialize<'p, 'a, 'tcx>(
+fn specialize<'p, 'a: 'p, 'tcx>(
     cx: &mut MatchCheckCtxt<'a, 'tcx>,
     r: &[&'p Pattern<'tcx>],
     constructor: &Constructor<'tcx>,

src/librustc_mir/interpret/visitor.rs

@@ -122,7 +122,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Value<'mir, 'tcx, M> for MPlaceTy<'tcx,
 macro_rules! make_value_visitor {
     ($visitor_trait_name:ident, $($mutability:ident)?) => {
         // How to traverse a value and what to do when we are at the leaves.
-        pub trait $visitor_trait_name<'mir, 'tcx, M: Machine<'mir, 'tcx>>: Sized {
+        pub trait $visitor_trait_name<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>: Sized {
             type V: Value<'mir, 'tcx, M>;
 
             /// The visitor must have an `InterpretCx` in it.

src/librustc_mir/monomorphize/partitioning.rs

@@ -766,9 +766,10 @@ fn numbered_codegen_unit_name(
     name_builder.build_cgu_name_no_mangle(LOCAL_CRATE, &["cgu"], Some(index))
 }
 
-fn debug_dump<'a, 'b, 'tcx, I>(tcx: TyCtxt<'tcx>, label: &str, cgus: I)
+fn debug_dump<'a, 'tcx, I>(tcx: TyCtxt<'tcx>, label: &str, cgus: I)
 where
-    I: Iterator<Item = &'b CodegenUnit<'tcx>>,
+    I: Iterator<Item = &'a CodegenUnit<'tcx>>,
+    'tcx: 'a,
 {
     if cfg!(debug_assertions) {
         debug!("{}", label);
@@ -796,6 +797,7 @@ where
 fn assert_symbols_are_distinct<'a, 'tcx, I>(tcx: TyCtxt<'tcx>, mono_items: I)
 where
     I: Iterator<Item = &'a MonoItem<'tcx>>,
+    'tcx: 'a,
 {
     let mut symbols: Vec<_> = mono_items.map(|mono_item| {
         (mono_item, mono_item.symbol_name(tcx))

src/librustc_mir/util/elaborate_drops.rs

@@ -111,7 +111,8 @@ pub fn elaborate_drop<'b, 'tcx, D>(
     succ: BasicBlock,
     unwind: Unwind,
     bb: BasicBlock)
-    where D: DropElaborator<'b, 'tcx>
+    where D: DropElaborator<'b, 'tcx>,
+    'tcx: 'b,
 {
     DropCtxt {
         elaborator, source_info, place, path, succ, unwind
@@ -121,6 +122,7 @@ pub fn elaborate_drop<'b, 'tcx, D>(
 impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D>
 where
     D: DropElaborator<'b, 'tcx>,
+    'tcx: 'b,
 {
     fn place_ty(&self, place: &Place<'tcx>) -> Ty<'tcx> {
         place.ty(self.elaborator.body(), self.tcx()).ty

src/librustc_save_analysis/lib.rs

@@ -960,8 +960,8 @@ impl<'l> PathCollector<'l> {
     }
 }
 
-impl<'l, 'a> Visitor<'a> for PathCollector<'l> {
-    fn visit_pat(&mut self, p: &'a ast::Pat) {
+impl<'l> Visitor<'l> for PathCollector<'l> {
+    fn visit_pat(&mut self, p: &'l ast::Pat) {
         match p.node {
             PatKind::Struct(ref path, ..) => {
                 self.collected_paths.push((p.id, path));

src/librustc_typeck/collect.rs

@@ -1786,7 +1786,7 @@ fn impl_polarity<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> hir::ImplPolarity {
 /// the lifetimes that are declared. For fns or methods, we have to
 /// screen out those that do not appear in any where-clauses etc using
 /// `resolve_lifetime::early_bound_lifetimes`.
-fn early_bound_lifetimes_from_generics<'a, 'tcx>(
+fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
     tcx: TyCtxt<'tcx>,
     generics: &'a hir::Generics,
 ) -> impl Iterator<Item = &'a hir::GenericParam> + Captures<'tcx> {