Auto merge of #69570 - Dylan-DPC:rollup-d6boczt, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #69477 (docs: add mention of async blocks in move keyword docs)
 - #69504 (Use assert_ne in hash tests)
 - #69546 (use to_vec() instead of .iter().cloned().collect() to convert slices to vecs.)
 - #69551 (use is_empty() instead of len() == x  to determine if structs are empty.)
 - #69563 (Fix no_std detection for target triples)
 - #69567 (use .to_string() instead of format!() macro to create strings)

Failed merges:

r? @ghost

src/bootstrap/config.rs

@@ -180,7 +180,7 @@ pub struct Target {
 impl Target {
     pub fn from_triple(triple: &str) -> Self {
         let mut target: Self = Default::default();
-        if triple.contains("-none-") || triple.contains("nvptx") {
+        if triple.contains("-none") || triple.contains("nvptx") {
             target.no_std = true;
         }
         target

src/libcore/slice/mod.rs

@@ -3823,7 +3823,7 @@ where
         // The last index of self.v is already checked and found to match
         // by the last iteration, so we start searching a new match
         // one index to the left.
-        let remainder = if self.v.len() == 0 { &[] } else { &self.v[..(self.v.len() - 1)] };
+        let remainder = if self.v.is_empty() { &[] } else { &self.v[..(self.v.len() - 1)] };
         let idx = remainder.iter().rposition(|x| (self.pred)(x)).map(|idx| idx + 1).unwrap_or(0);
         if idx == 0 {
             self.finished = true;
@@ -4033,7 +4033,7 @@ where
             return None;
         }
 
-        let idx_opt = if self.v.len() == 0 {
+        let idx_opt = if self.v.is_empty() {
             None
         } else {
             // work around borrowck limitations

src/libcore/tests/hash/sip.rs

@@ -238,7 +238,7 @@ fn test_siphash_2_4() {
 #[cfg(target_pointer_width = "32")]
 fn test_hash_usize() {
     let val = 0xdeadbeef_deadbeef_u64;
-    assert!(hash(&(val as u64)) != hash(&(val as usize)));
+    assert_ne!(hash(&(val as u64)), hash(&(val as usize)));
     assert_eq!(hash(&(val as u32)), hash(&(val as usize)));
 }
 
@@ -247,7 +247,7 @@ fn test_hash_usize() {
 fn test_hash_usize() {
     let val = 0xdeadbeef_deadbeef_u64;
     assert_eq!(hash(&(val as u64)), hash(&(val as usize)));
-    assert!(hash(&(val as u32)) != hash(&(val as usize)));
+    assert_ne!(hash(&(val as u32)), hash(&(val as usize)));
 }
 
 #[test]
@@ -262,14 +262,14 @@ fn test_hash_idempotent() {
 fn test_hash_no_bytes_dropped_64() {
     let val = 0xdeadbeef_deadbeef_u64;
 
-    assert!(hash(&val) != hash(&zero_byte(val, 0)));
-    assert!(hash(&val) != hash(&zero_byte(val, 1)));
-    assert!(hash(&val) != hash(&zero_byte(val, 2)));
-    assert!(hash(&val) != hash(&zero_byte(val, 3)));
-    assert!(hash(&val) != hash(&zero_byte(val, 4)));
-    assert!(hash(&val) != hash(&zero_byte(val, 5)));
-    assert!(hash(&val) != hash(&zero_byte(val, 6)));
-    assert!(hash(&val) != hash(&zero_byte(val, 7)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 0)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 1)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 2)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 3)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 4)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 5)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 6)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 7)));
 
     fn zero_byte(val: u64, byte: usize) -> u64 {
         assert!(byte < 8);
@@ -281,10 +281,10 @@ fn test_hash_no_bytes_dropped_64() {
 fn test_hash_no_bytes_dropped_32() {
     let val = 0xdeadbeef_u32;
 
-    assert!(hash(&val) != hash(&zero_byte(val, 0)));
-    assert!(hash(&val) != hash(&zero_byte(val, 1)));
-    assert!(hash(&val) != hash(&zero_byte(val, 2)));
-    assert!(hash(&val) != hash(&zero_byte(val, 3)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 0)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 1)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 2)));
+    assert_ne!(hash(&val), hash(&zero_byte(val, 3)));
 
     fn zero_byte(val: u32, byte: usize) -> u32 {
         assert!(byte < 4);
@@ -299,14 +299,17 @@ fn test_hash_no_concat_alias() {
     let u = ("a", "abb");
 
     assert!(s != t && t != u);
-    assert!(hash(&s) != hash(&t) && hash(&s) != hash(&u));
+    assert_ne!(s, t);
+    assert_ne!(t, u);
+    assert_ne!(hash(&s), hash(&t));
+    assert_ne!(hash(&s), hash(&u));
 
     let u = [1, 0, 0, 0];
     let v = (&u[..1], &u[1..3], &u[3..]);
     let w = (&u[..], &u[4..4], &u[4..4]);
 
-    assert!(v != w);
-    assert!(hash(&v) != hash(&w));
+    assert_ne!(v, w);
+    assert_ne!(hash(&v), hash(&w));
 }
 
 #[test]

src/librustc/arena.rs

@@ -250,7 +250,7 @@ impl<'tcx> Arena<'tcx> {
 
     #[inline]
     pub fn alloc_slice<T: Copy>(&self, value: &[T]) -> &mut [T] {
-        if value.len() == 0 {
+        if value.is_empty() {
             return &mut [];
         }
         self.dropless.alloc_slice(value)

src/librustc/dep_graph/graph.rs

@@ -809,7 +809,7 @@ impl DepGraph {
             dep_node
         );
 
-        if unlikely!(diagnostics.len() > 0) {
+        if unlikely!(!diagnostics.is_empty()) {
             self.emit_diagnostics(tcx, data, dep_node_index, prev_dep_node_index, diagnostics);
         }
 

src/librustc/ich/hcx.rs

@@ -19,7 +19,7 @@ use smallvec::SmallVec;
 use std::cmp::Ord;
 
 fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
-    debug_assert!(ich::IGNORED_ATTRIBUTES.len() > 0);
+    debug_assert!(!ich::IGNORED_ATTRIBUTES.is_empty());
     ich::IGNORED_ATTRIBUTES.iter().map(|&s| s).collect()
 }
 

src/librustc/ich/impls_syntax.rs

@@ -14,7 +14,7 @@ impl<'ctx> rustc_target::HashStableContext for StableHashingContext<'ctx> {}
 
 impl<'a> HashStable<StableHashingContext<'a>> for [ast::Attribute] {
     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        if self.len() == 0 {
+        if self.is_empty() {
             self.len().hash_stable(hcx, hasher);
             return;
         }

src/librustc/mir/interpret/error.rs

@@ -171,7 +171,7 @@ impl<'tcx> ConstEvalErr<'tcx> {
             // Skip the last, which is just the environment of the constant.  The stacktrace
             // is sometimes empty because we create "fake" eval contexts in CTFE to do work
             // on constant values.
-            if self.stacktrace.len() > 0 {
+            if !self.stacktrace.is_empty() {
                 for frame_info in &self.stacktrace[..self.stacktrace.len() - 1] {
                     err.span_label(frame_info.call_site, frame_info.to_string());
                 }

src/librustc/mir/mod.rs

@@ -2219,7 +2219,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                 });
                 let region = if print_region {
                     let mut region = region.to_string();
-                    if region.len() > 0 {
+                    if !region.is_empty() {
                         region.push(' ');
                     }
                     region

src/librustc/query/mod.rs

@@ -18,7 +18,7 @@ use std::borrow::Cow;
 
 fn describe_as_module(def_id: DefId, tcx: TyCtxt<'_>) -> String {
     if def_id.is_top_level_module() {
-        format!("top-level module")
+        "top-level module".to_string()
     } else {
         format!("module `{}`", tcx.def_path_str(def_id))
     }

src/librustc/ty/context.rs

@@ -2473,7 +2473,7 @@ impl<'tcx> TyCtxt<'tcx> {
         // FIXME consider asking the input slice to be sorted to avoid
         // re-interning permutations, in which case that would be asserted
         // here.
-        if preds.len() == 0 {
+        if preds.is_empty() {
             // The macro-generated method below asserts we don't intern an empty slice.
             List::empty()
         } else {
@@ -2482,31 +2482,31 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn intern_type_list(self, ts: &[Ty<'tcx>]) -> &'tcx List<Ty<'tcx>> {
-        if ts.len() == 0 { List::empty() } else { self._intern_type_list(ts) }
+        if ts.is_empty() { List::empty() } else { self._intern_type_list(ts) }
     }
 
     pub fn intern_substs(self, ts: &[GenericArg<'tcx>]) -> &'tcx List<GenericArg<'tcx>> {
-        if ts.len() == 0 { List::empty() } else { self._intern_substs(ts) }
+        if ts.is_empty() { List::empty() } else { self._intern_substs(ts) }
     }
 
     pub fn intern_projs(self, ps: &[ProjectionKind]) -> &'tcx List<ProjectionKind> {
-        if ps.len() == 0 { List::empty() } else { self._intern_projs(ps) }
+        if ps.is_empty() { List::empty() } else { self._intern_projs(ps) }
     }
 
     pub fn intern_place_elems(self, ts: &[PlaceElem<'tcx>]) -> &'tcx List<PlaceElem<'tcx>> {
-        if ts.len() == 0 { List::empty() } else { self._intern_place_elems(ts) }
+        if ts.is_empty() { List::empty() } else { self._intern_place_elems(ts) }
     }
 
     pub fn intern_canonical_var_infos(self, ts: &[CanonicalVarInfo]) -> CanonicalVarInfos<'tcx> {
-        if ts.len() == 0 { List::empty() } else { self._intern_canonical_var_infos(ts) }
+        if ts.is_empty() { List::empty() } else { self._intern_canonical_var_infos(ts) }
     }
 
     pub fn intern_clauses(self, ts: &[Clause<'tcx>]) -> Clauses<'tcx> {
-        if ts.len() == 0 { List::empty() } else { self._intern_clauses(ts) }
+        if ts.is_empty() { List::empty() } else { self._intern_clauses(ts) }
     }
 
     pub fn intern_goals(self, ts: &[Goal<'tcx>]) -> Goals<'tcx> {
-        if ts.len() == 0 { List::empty() } else { self._intern_goals(ts) }
+        if ts.is_empty() { List::empty() } else { self._intern_goals(ts) }
     }
 
     pub fn mk_fn_sig<I>(

src/librustc/ty/instance.rs

@@ -314,7 +314,7 @@ impl<'tcx> Instance<'tcx> {
     ) -> Option<Instance<'tcx>> {
         debug!("resolve(def_id={:?}, substs={:?})", def_id, substs);
         let fn_sig = tcx.fn_sig(def_id);
-        let is_vtable_shim = fn_sig.inputs().skip_binder().len() > 0
+        let is_vtable_shim = !fn_sig.inputs().skip_binder().is_empty()
             && fn_sig.input(0).skip_binder().is_param(0)
             && tcx.generics_of(def_id).has_self;
         if is_vtable_shim {

src/librustc/ty/layout.rs

@@ -798,7 +798,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                     // (Typechecking will reject discriminant-sizing attrs.)
 
                     let v = present_first.unwrap();
-                    let kind = if def.is_enum() || variants[v].len() == 0 {
+                    let kind = if def.is_enum() || variants[v].is_empty() {
                         StructKind::AlwaysSized
                     } else {
                         let param_env = tcx.param_env(def.did);

src/librustc/ty/mod.rs

@@ -698,7 +698,7 @@ impl<T: Copy> List<T> {
     fn from_arena<'tcx>(arena: &'tcx Arena<'tcx>, slice: &[T]) -> &'tcx List<T> {
         assert!(!mem::needs_drop::<T>());
         assert!(mem::size_of::<T>() != 0);
-        assert!(slice.len() != 0);
+        assert!(!slice.is_empty());
 
         // Align up the size of the len (usize) field
         let align = mem::align_of::<T>();

src/librustc_ast_lowering/path.rs

@@ -229,7 +229,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         err.span_label(data.span, "only `Fn` traits may use parentheses");
                         if let Ok(snippet) = self.sess.source_map().span_to_snippet(data.span) {
                             // Do not suggest going from `Trait()` to `Trait<>`
-                            if data.inputs.len() > 0 {
+                            if !data.inputs.is_empty() {
                                 if let Some(split) = snippet.find('(') {
                                     let trait_name = &snippet[0..split];
                                     let args = &snippet[split + 1..snippet.len() - 1];

src/librustc_ast_pretty/pprust.rs

@@ -791,7 +791,7 @@ impl<'a> PrintState<'a> for State<'a> {
                     s.print_generic_arg(generic_arg)
                 });
 
-                let mut comma = data.args.len() != 0;
+                let mut comma = !data.args.is_empty();
 
                 for constraint in data.constraints.iter() {
                     if comma {

src/librustc_attr/builtin.rs

@@ -53,7 +53,7 @@ fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
                     err.span_suggestion(
                         span,
                         "consider removing the prefix",
-                        format!("{}", &lint_str[1..]),
+                        lint_str[1..].to_string(),
                         Applicability::MaybeIncorrect,
                     );
                 }

src/librustc_builtin_macros/concat.rs

@@ -49,7 +49,7 @@ pub fn expand_concat(
             }
         }
     }
-    if missing_literal.len() > 0 {
+    if !missing_literal.is_empty() {
         let mut err = cx.struct_span_err(missing_literal, "expected a literal");
         err.note("only literals (like `\"foo\"`, `42` and `3.14`) can be passed to `concat!()`");
         err.emit();

src/librustc_builtin_macros/deriving/generic/mod.rs

@@ -588,14 +588,14 @@ impl<'a> TraitDef<'a> {
                         span: self.span,
                         bound_generic_params: wb.bound_generic_params.clone(),
                         bounded_ty: wb.bounded_ty.clone(),
-                        bounds: wb.bounds.iter().cloned().collect(),
+                        bounds: wb.bounds.to_vec(),
                     })
                 }
                 ast::WherePredicate::RegionPredicate(ref rb) => {
                     ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
                         span: self.span,
                         lifetime: rb.lifetime,
-                        bounds: rb.bounds.iter().cloned().collect(),
+                        bounds: rb.bounds.to_vec(),
                     })
                 }
                 ast::WherePredicate::EqPredicate(ref we) => {

src/librustc_builtin_macros/format.rs

@@ -1096,7 +1096,7 @@ pub fn expand_preparsed_format_args(
         cx.str_pieces.push(s);
     }
 
-    if cx.invalid_refs.len() >= 1 {
+    if !cx.invalid_refs.is_empty() {
         cx.report_invalid_references(numbered_position_args);
     }
 

src/librustc_codegen_llvm/back/lto.rs

@@ -237,7 +237,7 @@ fn fat_lto(
     let module: ModuleCodegen<ModuleLlvm> = match costliest_module {
         Some((_cost, i)) => in_memory.remove(i),
         None => {
-            assert!(serialized_modules.len() > 0, "must have at least one serialized module");
+            assert!(!serialized_modules.is_empty(), "must have at least one serialized module");
             let (buffer, name) = serialized_modules.remove(0);
             info!("no in-memory regular modules to choose from, parsing {:?}", name);
             ModuleCodegen {

src/librustc_codegen_llvm/llvm_util.rs

@@ -61,7 +61,7 @@ unsafe fn configure_llvm(sess: &Session) {
     let sess_args = cg_opts.chain(tg_opts);
 
     let user_specified_args: FxHashSet<_> =
-        sess_args.clone().map(|s| llvm_arg_to_arg_name(s)).filter(|s| s.len() > 0).collect();
+        sess_args.clone().map(|s| llvm_arg_to_arg_name(s)).filter(|s| !s.is_empty()).collect();
 
     {
         // This adds the given argument to LLVM. Unless `force` is true

src/librustc_codegen_ssa/back/link.rs

@@ -1524,12 +1524,12 @@ fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(
     for &(cnum, _) in deps.iter().rev() {
         if let Some(missing) = info.missing_lang_items.get(&cnum) {
             end_with.extend(missing.iter().cloned());
-            if end_with.len() > 0 && group_end.is_none() {
+            if !end_with.is_empty() && group_end.is_none() {
                 group_end = Some(cnum);
             }
         }
         end_with.retain(|item| info.lang_item_to_crate.get(item) != Some(&cnum));
-        if end_with.len() == 0 && group_end.is_some() {
+        if end_with.is_empty() && group_end.is_some() {
             group_start = Some(cnum);
             break;
         }

src/librustc_codegen_ssa/back/write.rs

@@ -1244,11 +1244,11 @@ fn start_executing_work<B: ExtraBackendMethods>(
         while !codegen_done
             || running > 0
             || (!codegen_aborted
-                && (work_items.len() > 0
-                    || needs_fat_lto.len() > 0
-                    || needs_thin_lto.len() > 0
-                    || lto_import_only_modules.len() > 0
-                    || main_thread_worker_state != MainThreadWorkerState::Idle))
+                && !(work_items.is_empty()
+                    && needs_fat_lto.is_empty()
+                    && needs_thin_lto.is_empty()
+                    && lto_import_only_modules.is_empty()
+                    && main_thread_worker_state == MainThreadWorkerState::Idle))
         {
             // While there are still CGUs to be codegened, the coordinator has
             // to decide how to utilize the compiler processes implicit Token:
@@ -1289,7 +1289,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
                 // Perform the serial work here of figuring out what we're
                 // going to LTO and then push a bunch of work items onto our
                 // queue to do LTO
-                if work_items.len() == 0
+                if work_items.is_empty()
                     && running == 0
                     && main_thread_worker_state == MainThreadWorkerState::Idle
                 {
@@ -1354,7 +1354,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
 
             // Spin up what work we can, only doing this while we've got available
             // parallelism slots and work left to spawn.
-            while !codegen_aborted && work_items.len() > 0 && running < tokens.len() {
+            while !codegen_aborted && !work_items.is_empty() && running < tokens.len() {
                 let (item, _) = work_items.pop().unwrap();
 
                 maybe_start_llvm_timer(prof, cgcx.config(item.module_kind()), &mut llvm_start_time);

src/librustc_data_structures/profiling.rs

@@ -425,7 +425,7 @@ impl SelfProfiler {
             }
 
             // Warn about any unknown event names
-            if unknown_events.len() > 0 {
+            if !unknown_events.is_empty() {
                 unknown_events.sort();
                 unknown_events.dedup();