Rollup of 10 pull requests

compiler/rustc_ast_pretty/src/pp.rs

@@ -491,12 +491,9 @@ impl Printer {
     }
 
     fn get_top(&mut self) -> PrintStackElem {
-        match self.print_stack.last() {
-            Some(el) => *el,
-            None => {
-                PrintStackElem { offset: 0, pbreak: PrintStackBreak::Broken(Breaks::Inconsistent) }
-            }
-        }
+        *self.print_stack.last().unwrap_or({
+            &PrintStackElem { offset: 0, pbreak: PrintStackBreak::Broken(Breaks::Inconsistent) }
+        })
     }
 
     fn print_begin(&mut self, b: BeginToken, l: isize) {

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -122,7 +122,7 @@ unsafe fn configure_llvm(sess: &Session) {
 
     llvm::LLVMInitializePasses();
 
-    ::rustc_llvm::initialize_available_targets();
+    rustc_llvm::initialize_available_targets();
 
     llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr());
 }

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -1175,7 +1175,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
     // necessary. There's already optimizations in place to avoid sending work
     // back to the coordinator if LTO isn't requested.
     return thread::spawn(move || {
-        let max_workers = ::num_cpus::get();
+        let max_workers = num_cpus::get();
         let mut worker_id_counter = 0;
         let mut free_worker_ids = Vec::new();
         let mut get_worker_id = |free_worker_ids: &mut Vec<usize>| {

compiler/rustc_codegen_ssa/src/base.rs

@@ -695,7 +695,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
         total_codegen_time.into_inner(),
     );
 
-    ::rustc_incremental::assert_module_sources::assert_module_sources(tcx);
+    rustc_incremental::assert_module_sources::assert_module_sources(tcx);
 
     symbol_names_test::report_symbol_names(tcx);
 
@@ -754,8 +754,8 @@ impl<B: ExtraBackendMethods> Drop for AbortCodegenOnDrop<B> {
 }
 
 fn finalize_tcx(tcx: TyCtxt<'_>) {
-    tcx.sess.time("assert_dep_graph", || ::rustc_incremental::assert_dep_graph(tcx));
-    tcx.sess.time("serialize_dep_graph", || ::rustc_incremental::save_dep_graph(tcx));
+    tcx.sess.time("assert_dep_graph", || rustc_incremental::assert_dep_graph(tcx));
+    tcx.sess.time("serialize_dep_graph", || rustc_incremental::save_dep_graph(tcx));
 
     // We assume that no queries are run past here. If there are new queries
     // after this point, they'll show up as "<unknown>" in self-profiling data.

compiler/rustc_codegen_ssa/src/traits/mod.rs

@@ -85,7 +85,7 @@ impl<'tcx, T> CodegenMethods<'tcx> for T where
 }
 
 pub trait HasCodegen<'tcx>:
-    Backend<'tcx> + ::std::ops::Deref<Target = <Self as HasCodegen<'tcx>>::CodegenCx>
+    Backend<'tcx> + std::ops::Deref<Target = <Self as HasCodegen<'tcx>>::CodegenCx>
 {
     type CodegenCx: CodegenMethods<'tcx>
         + BackendTypes<

compiler/rustc_data_structures/src/fingerprint.rs

@@ -71,8 +71,8 @@ impl Fingerprint {
     }
 }
 
-impl ::std::fmt::Display for Fingerprint {
-    fn fmt(&self, formatter: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+impl std::fmt::Display for Fingerprint {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(formatter, "{:x}-{:x}", self.0, self.1)
     }
 }

compiler/rustc_data_structures/src/obligation_forest/mod.rs

@@ -129,7 +129,7 @@ pub enum ProcessResult<O, E> {
 struct ObligationTreeId(usize);
 
 type ObligationTreeIdGenerator =
-    ::std::iter::Map<::std::ops::RangeFrom<usize>, fn(usize) -> ObligationTreeId>;
+    std::iter::Map<std::ops::RangeFrom<usize>, fn(usize) -> ObligationTreeId>;
 
 pub struct ObligationForest<O: ForestObligation> {
     /// The list of obligations. In between calls to `process_obligations`,

compiler/rustc_data_structures/src/sorted_map.rs

@@ -93,7 +93,7 @@ impl<K: Ord, V> SortedMap<K, V> {
 
     /// Iterate over elements, sorted by key
     #[inline]
-    pub fn iter(&self) -> ::std::slice::Iter<'_, (K, V)> {
+    pub fn iter(&self) -> std::slice::Iter<'_, (K, V)> {
         self.data.iter()
     }
 
@@ -134,7 +134,7 @@ impl<K: Ord, V> SortedMap<K, V> {
         R: RangeBounds<K>,
     {
         let (start, end) = self.range_slice_indices(range);
-        self.data.splice(start..end, ::std::iter::empty());
+        self.data.splice(start..end, std::iter::empty());
     }
 
     /// Mutate all keys with the given function `f`. This mutation must not
@@ -241,7 +241,7 @@ impl<K: Ord, V> SortedMap<K, V> {
 
 impl<K: Ord, V> IntoIterator for SortedMap<K, V> {
     type Item = (K, V);
-    type IntoIter = ::std::vec::IntoIter<(K, V)>;
+    type IntoIter = std::vec::IntoIter<(K, V)>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.data.into_iter()

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -20,7 +20,7 @@ pub struct StableHasher {
 }
 
 impl ::std::fmt::Debug for StableHasher {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "{:?}", self.state)
     }
 }

compiler/rustc_hir/src/definitions.rs

@@ -118,7 +118,7 @@ impl DefKey {
 
         let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
 
-        ::std::mem::discriminant(data).hash(&mut hasher);
+        std::mem::discriminant(data).hash(&mut hasher);
         if let Some(name) = data.get_opt_name() {
             // Get a stable hash by considering the symbol chars rather than
             // the symbol index.

compiler/rustc_infer/src/infer/nll_relate/mod.rs

@@ -341,7 +341,7 @@ where
         // been fully instantiated and hence the set of scopes we have
         // doesn't matter -- just to be sure, put an empty vector
         // in there.
-        let old_a_scopes = ::std::mem::take(pair.vid_scopes(self));
+        let old_a_scopes = std::mem::take(pair.vid_scopes(self));
 
         // Relate the generalized kind to the original one.
         let result = pair.relate_generalized_ty(self, generalized_ty);
@@ -680,7 +680,7 @@ where
             //   itself occurs. Note that `'b` and `'c` must both
             //   include P. At the point, the call works because of
             //   subtyping (i.e., `&'b u32 <: &{P} u32`).
-            let variance = ::std::mem::replace(&mut self.ambient_variance, ty::Variance::Covariant);
+            let variance = std::mem::replace(&mut self.ambient_variance, ty::Variance::Covariant);
 
             self.relate(a.skip_binder(), b.skip_binder())?;
 
@@ -709,7 +709,7 @@ where
             // Reset ambient variance to contravariance. See the
             // covariant case above for an explanation.
             let variance =
-                ::std::mem::replace(&mut self.ambient_variance, ty::Variance::Contravariant);
+                std::mem::replace(&mut self.ambient_variance, ty::Variance::Contravariant);
 
             self.relate(a.skip_binder(), b.skip_binder())?;
 

compiler/rustc_infer/src/infer/outlives/obligations.rs

@@ -110,7 +110,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
 
     /// Trait queries just want to pass back type obligations "as is"
     pub fn take_registered_region_obligations(&self) -> Vec<(hir::HirId, RegionObligation<'tcx>)> {
-        ::std::mem::take(&mut self.inner.borrow_mut().region_obligations)
+        std::mem::take(&mut self.inner.borrow_mut().region_obligations)
     }
 
     /// Process the region obligations that must be proven (during

compiler/rustc_middle/src/ich/impls_syntax.rs

@@ -5,7 +5,7 @@ use crate::ich::StableHashingContext;
 
 use rustc_ast as ast;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_span::SourceFile;
+use rustc_span::{BytePos, NormalizedPos, SourceFile};
 
 use smallvec::SmallVec;
 
@@ -102,34 +102,28 @@ impl<'a> HashStable<StableHashingContext<'a>> for SourceFile {
     }
 }
 
-fn stable_byte_pos(pos: ::rustc_span::BytePos, source_file_start: ::rustc_span::BytePos) -> u32 {
+fn stable_byte_pos(pos: BytePos, source_file_start: BytePos) -> u32 {
     pos.0 - source_file_start.0
 }
 
-fn stable_multibyte_char(
-    mbc: ::rustc_span::MultiByteChar,
-    source_file_start: ::rustc_span::BytePos,
-) -> (u32, u32) {
-    let ::rustc_span::MultiByteChar { pos, bytes } = mbc;
+fn stable_multibyte_char(mbc: rustc_span::MultiByteChar, source_file_start: BytePos) -> (u32, u32) {
+    let rustc_span::MultiByteChar { pos, bytes } = mbc;
 
     (pos.0 - source_file_start.0, bytes as u32)
 }
 
 fn stable_non_narrow_char(
-    swc: ::rustc_span::NonNarrowChar,
-    source_file_start: ::rustc_span::BytePos,
+    swc: rustc_span::NonNarrowChar,
+    source_file_start: BytePos,
 ) -> (u32, u32) {
     let pos = swc.pos();
     let width = swc.width();
 
     (pos.0 - source_file_start.0, width as u32)
 }
 
-fn stable_normalized_pos(
-    np: ::rustc_span::NormalizedPos,
-    source_file_start: ::rustc_span::BytePos,
-) -> (u32, u32) {
-    let ::rustc_span::NormalizedPos { pos, diff } = np;
+fn stable_normalized_pos(np: NormalizedPos, source_file_start: BytePos) -> (u32, u32) {
+    let NormalizedPos { pos, diff } = np;
 
     (pos.0 - source_file_start.0, diff)
 }

compiler/rustc_middle/src/mir/interpret/allocation.rs

@@ -40,7 +40,7 @@ pub struct Allocation<Tag = (), Extra = ()> {
     pub extra: Extra,
 }
 
-pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Clone {
+pub trait AllocationExtra<Tag>: std::fmt::Debug + Clone {
     // There is no constructor in here because the constructor's type depends
     // on `MemoryKind`, and making things sufficiently generic leads to painful
     // inference failure.

compiler/rustc_middle/src/mir/interpret/value.rs

@@ -58,7 +58,7 @@ impl<'tcx> ConstValue<'tcx> {
 
     pub fn try_to_str_slice(&self) -> Option<&'tcx str> {
         if let ConstValue::Slice { data, start, end } = *self {
-            ::std::str::from_utf8(data.inspect_with_uninit_and_ptr_outside_interpreter(start..end))
+            std::str::from_utf8(data.inspect_with_uninit_and_ptr_outside_interpreter(start..end))
                 .ok()
         } else {
             None
@@ -465,7 +465,7 @@ impl<'tcx, Tag> Scalar<Tag> {
 
     pub fn to_char(self) -> InterpResult<'tcx, char> {
         let val = self.to_u32()?;
-        match ::std::char::from_u32(val) {
+        match std::char::from_u32(val) {
             Some(c) => Ok(c),
             None => throw_ub!(InvalidChar(val)),
         }

compiler/rustc_middle/src/mir/mod.rs

@@ -775,7 +775,7 @@ mod binding_form_impl {
     impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
         fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
             use super::BindingForm::*;
-            ::std::mem::discriminant(self).hash_stable(hcx, hasher);
+            std::mem::discriminant(self).hash_stable(hcx, hasher);
 
             match self {
                 Var(binding) => binding.hash_stable(hcx, hasher),

compiler/rustc_middle/src/ty/layout.rs

@@ -1894,7 +1894,7 @@ impl<'tcx, T: HasTyCtxt<'tcx>> HasTyCtxt<'tcx> for LayoutCx<'tcx, T> {
     }
 }
 
-pub type TyAndLayout<'tcx> = ::rustc_target::abi::TyAndLayout<'tcx, Ty<'tcx>>;
+pub type TyAndLayout<'tcx> = rustc_target::abi::TyAndLayout<'tcx, Ty<'tcx>>;
 
 impl<'tcx> LayoutOf for LayoutCx<'tcx, TyCtxt<'tcx>> {
     type Ty = Ty<'tcx>;

compiler/rustc_middle/src/ty/normalize_erasing_regions.rs

@@ -23,7 +23,7 @@ impl<'tcx> TyCtxt<'tcx> {
     {
         debug!(
             "normalize_erasing_regions::<{}>(value={:?}, param_env={:?})",
-            ::std::any::type_name::<T>(),
+            std::any::type_name::<T>(),
             value,
             param_env,
         );

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1142,7 +1142,7 @@ pub trait PrettyPrinter<'tcx>:
                 // relocations (we have an active `str` reference here). We don't use this
                 // result to affect interpreter execution.
                 let slice = data.inspect_with_uninit_and_ptr_outside_interpreter(start..end);
-                let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
+                let s = std::str::from_utf8(slice).expect("non utf8 str from miri");
                 p!(write("{:?}", s));
                 Ok(self)
             }

compiler/rustc_middle/src/ty/query/on_disk_cache.rs

@@ -543,7 +543,7 @@ impl<'a, 'tcx> DecoderWithPosition for CacheDecoder<'a, 'tcx> {
 // tag matches and the correct amount of bytes was read.
 fn decode_tagged<D, T, V>(decoder: &mut D, expected_tag: T) -> Result<V, D::Error>
 where
-    T: Decodable<D> + Eq + ::std::fmt::Debug,
+    T: Decodable<D> + Eq + std::fmt::Debug,
     V: Decodable<D>,
     D: DecoderWithPosition,
 {
@@ -1023,7 +1023,7 @@ where
     let _timer = tcx
         .sess
         .prof
-        .extra_verbose_generic_activity("encode_query_results_for", ::std::any::type_name::<Q>());
+        .extra_verbose_generic_activity("encode_query_results_for", std::any::type_name::<Q>());
 
     let state = Q::query_state(tcx);
     assert!(state.all_inactive());

compiler/rustc_middle/src/ty/util.rs

@@ -646,8 +646,8 @@ impl<'tcx> ty::TyS<'tcx> {
             }
             ty::Char => Some(std::char::MAX as u128),
             ty::Float(fty) => Some(match fty {
-                ast::FloatTy::F32 => ::rustc_apfloat::ieee::Single::INFINITY.to_bits(),
-                ast::FloatTy::F64 => ::rustc_apfloat::ieee::Double::INFINITY.to_bits(),
+                ast::FloatTy::F32 => rustc_apfloat::ieee::Single::INFINITY.to_bits(),
+                ast::FloatTy::F64 => rustc_apfloat::ieee::Double::INFINITY.to_bits(),
             }),
             _ => None,
         };

compiler/rustc_mir/src/interpret/machine.rs

@@ -3,6 +3,7 @@
 //! interpreting common C functions leak into CTFE.
 
 use std::borrow::{Borrow, Cow};
+use std::fmt::Debug;
 use std::hash::Hash;
 
 use rustc_middle::mir;
@@ -79,19 +80,19 @@ pub trait AllocMap<K: Hash + Eq, V> {
 /// and some use case dependent behaviour can instead be applied.
 pub trait Machine<'mir, 'tcx>: Sized {
     /// Additional memory kinds a machine wishes to distinguish from the builtin ones
-    type MemoryKind: ::std::fmt::Debug + ::std::fmt::Display + MayLeak + Eq + 'static;
+    type MemoryKind: Debug + std::fmt::Display + MayLeak + Eq + 'static;
 
     /// Tag tracked alongside every pointer. This is used to implement "Stacked Borrows"
     /// <https://www.ralfj.de/blog/2018/08/07/stacked-borrows.html>.
     /// The `default()` is used for pointers to consts, statics, vtables and functions.
     /// The `Debug` formatting is used for displaying pointers; we cannot use `Display`
     /// as `()` does not implement that, but it should be "nice" output.
-    type PointerTag: ::std::fmt::Debug + Copy + Eq + Hash + 'static;
+    type PointerTag: Debug + Copy + Eq + Hash + 'static;
 
     /// Machines can define extra (non-instance) things that represent values of function pointers.
     /// For example, Miri uses this to return a function pointer from `dlsym`
     /// that can later be called to execute the right thing.
-    type ExtraFnVal: ::std::fmt::Debug + Copy;
+    type ExtraFnVal: Debug + Copy;
 
     /// Extra data stored in every call frame.
     type FrameExtra;

compiler/rustc_mir/src/interpret/operand.rs

@@ -133,7 +133,7 @@ impl<Tag: Copy> std::fmt::Display for ImmTy<'tcx, Tag> {
     }
 }
 
-impl<'tcx, Tag> ::std::ops::Deref for ImmTy<'tcx, Tag> {
+impl<'tcx, Tag> std::ops::Deref for ImmTy<'tcx, Tag> {
     type Target = Immediate<Tag>;
     #[inline(always)]
     fn deref(&self) -> &Immediate<Tag> {
@@ -156,7 +156,7 @@ pub struct OpTy<'tcx, Tag = ()> {
     pub layout: TyAndLayout<'tcx>,
 }
 
-impl<'tcx, Tag> ::std::ops::Deref for OpTy<'tcx, Tag> {
+impl<'tcx, Tag> std::ops::Deref for OpTy<'tcx, Tag> {
     type Target = Operand<Tag>;
     #[inline(always)]
     fn deref(&self) -> &Operand<Tag> {
@@ -340,7 +340,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     pub fn read_str(&self, mplace: MPlaceTy<'tcx, M::PointerTag>) -> InterpResult<'tcx, &str> {
         let len = mplace.len(self)?;
         let bytes = self.memory.read_bytes(mplace.ptr, Size::from_bytes(len))?;
-        let str = ::std::str::from_utf8(bytes).map_err(|err| err_ub!(InvalidStr(err)))?;
+        let str = std::str::from_utf8(bytes).map_err(|err| err_ub!(InvalidStr(err)))?;
         Ok(str)
     }