diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs index 6b079fc87cc..d9ebc40aa2c 100644 --- a/src/liballoc/collections/btree/map.rs +++ b/src/liballoc/collections/btree/map.rs @@ -770,8 +770,8 @@ impl BTreeMap { } // First, we merge `self` and `other` into a sorted sequence in linear time. - let self_iter = mem::replace(self, BTreeMap::new()).into_iter(); - let other_iter = mem::replace(other, BTreeMap::new()).into_iter(); + let self_iter = mem::take(self).into_iter(); + let other_iter = mem::take(other).into_iter(); let iter = MergeIter { left: self_iter.peekable(), right: other_iter.peekable(), diff --git a/src/liballoc/collections/linked_list.rs b/src/liballoc/collections/linked_list.rs index 40a82d6feaa..ca9e78bb459 100644 --- a/src/liballoc/collections/linked_list.rs +++ b/src/liballoc/collections/linked_list.rs @@ -708,7 +708,7 @@ impl LinkedList { let len = self.len(); assert!(at <= len, "Cannot split off at a nonexistent index"); if at == 0 { - return mem::replace(self, Self::new()); + return mem::take(self); } else if at == len { return Self::new(); } diff --git a/src/liballoc/str.rs b/src/liballoc/str.rs index 40104554fe5..70a93157c9e 100644 --- a/src/liballoc/str.rs +++ b/src/liballoc/str.rs @@ -203,7 +203,7 @@ impl ToOwned for str { } fn clone_into(&self, target: &mut String) { - let mut b = mem::replace(target, String::new()).into_bytes(); + let mut b = mem::take(target).into_bytes(); self.as_bytes().clone_into(&mut b); *target = unsafe { String::from_utf8_unchecked(b) } } diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs index 9c4a208f0f9..2e7a934a769 100644 --- a/src/librustc/hir/lowering.rs +++ b/src/librustc/hir/lowering.rs @@ -1278,8 +1278,8 @@ impl<'a> LoweringContext<'a> { let was_in_loop_condition = self.is_in_loop_condition; self.is_in_loop_condition = false; - let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new()); - let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new()); + let catch_scopes = mem::take(&mut self.catch_scopes); + let loop_scopes = mem::take(&mut self.loop_scopes); let ret = f(self); self.catch_scopes = catch_scopes; self.loop_scopes = loop_scopes; diff --git a/src/librustc/infer/nll_relate/mod.rs b/src/librustc/infer/nll_relate/mod.rs index a1a93eb5521..a0621af0537 100644 --- a/src/librustc/infer/nll_relate/mod.rs +++ b/src/librustc/infer/nll_relate/mod.rs @@ -364,7 +364,7 @@ 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::replace(pair.vid_scopes(self), vec![]); + 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); diff --git a/src/librustc/infer/outlives/obligations.rs b/src/librustc/infer/outlives/obligations.rs index 0ae4446ee63..e1470e4ef02 100644 --- a/src/librustc/infer/outlives/obligations.rs +++ b/src/librustc/infer/outlives/obligations.rs @@ -112,7 +112,7 @@ 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::replace(&mut *self.region_obligations.borrow_mut(), vec![]) + ::std::mem::take(&mut *self.region_obligations.borrow_mut()) } /// Process the region obligations that must be proven (during diff --git a/src/librustc/infer/region_constraints/mod.rs b/src/librustc/infer/region_constraints/mod.rs index f2235fe8d6d..b27c39c4f71 100644 --- a/src/librustc/infer/region_constraints/mod.rs +++ b/src/librustc/infer/region_constraints/mod.rs @@ -410,7 +410,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> { *any_unifications = false; } - mem::replace(data, RegionConstraintData::default()) + mem::take(data) } pub fn data(&self) -> &RegionConstraintData<'tcx> { diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs index 114684b1524..1a188bad11b 100644 --- a/src/librustc/middle/region.rs +++ b/src/librustc/middle/region.rs @@ -1375,7 +1375,7 @@ impl<'tcx> Visitor<'tcx> for RegionResolutionVisitor<'tcx> { let outer_ec = mem::replace(&mut self.expr_and_pat_count, 0); let outer_cx = self.cx; - let outer_ts = mem::replace(&mut self.terminating_scopes, FxHashSet::default()); + let outer_ts = mem::take(&mut self.terminating_scopes); self.terminating_scopes.insert(body.value.hir_id.local_id); if let Some(root_id) = self.cx.root_id { diff --git a/src/librustc/middle/resolve_lifetime.rs b/src/librustc/middle/resolve_lifetime.rs index 412346bab25..dada3a87be5 100644 --- a/src/librustc/middle/resolve_lifetime.rs +++ b/src/librustc/middle/resolve_lifetime.rs @@ -18,7 +18,7 @@ use errors::{Applicability, DiagnosticBuilder}; use rustc_macros::HashStable; use std::borrow::Cow; use std::cell::Cell; -use std::mem::replace; +use std::mem::{replace, take}; use syntax::ast; use syntax::attr; use syntax::ptr::P; @@ -441,7 +441,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { fn visit_nested_body(&mut self, body: hir::BodyId) { // Each body has their own set of labels, save labels. - let saved = replace(&mut self.labels_in_fn, vec![]); + let saved = take(&mut self.labels_in_fn); let body = self.tcx.hir().body(body); extract_labels(self, body); self.with( @@ -1405,9 +1405,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> { lifetime_uses, .. } = self; - let labels_in_fn = replace(&mut self.labels_in_fn, vec![]); - let xcrate_object_lifetime_defaults = - replace(&mut self.xcrate_object_lifetime_defaults, DefIdMap::default()); + let labels_in_fn = take(&mut self.labels_in_fn); + let xcrate_object_lifetime_defaults = take(&mut self.xcrate_object_lifetime_defaults); let mut this = LifetimeContext { tcx: *tcx, map: map, diff --git a/src/librustc_codegen_llvm/back/archive.rs b/src/librustc_codegen_llvm/back/archive.rs index e0e26e9af25..ca3b2b84655 100644 --- a/src/librustc_codegen_llvm/back/archive.rs +++ b/src/librustc_codegen_llvm/back/archive.rs @@ -205,8 +205,8 @@ impl<'a> LlvmArchiveBuilder<'a> { } fn build_with_llvm(&mut self, kind: ArchiveKind) -> io::Result<()> { - let removals = mem::replace(&mut self.removals, Vec::new()); - let mut additions = mem::replace(&mut self.additions, Vec::new()); + let removals = mem::take(&mut self.removals); + let mut additions = mem::take(&mut self.additions); let mut strings = Vec::new(); let mut members = Vec::new(); diff --git a/src/librustc_codegen_ssa/back/command.rs b/src/librustc_codegen_ssa/back/command.rs index 78570cce57d..d610805b5bb 100644 --- a/src/librustc_codegen_ssa/back/command.rs +++ b/src/librustc_codegen_ssa/back/command.rs @@ -110,7 +110,7 @@ impl Command { } pub fn take_args(&mut self) -> Vec { - mem::replace(&mut self.args, Vec::new()) + mem::take(&mut self.args) } /// Returns a `true` if we're pretty sure that this'll blow OS spawn limits, diff --git a/src/librustc_codegen_ssa/back/write.rs b/src/librustc_codegen_ssa/back/write.rs index 309187ca2ea..5ca38273269 100644 --- a/src/librustc_codegen_ssa/back/write.rs +++ b/src/librustc_codegen_ssa/back/write.rs @@ -1345,12 +1345,9 @@ fn start_executing_work( assert!(!started_lto); started_lto = true; - let needs_fat_lto = - mem::replace(&mut needs_fat_lto, Vec::new()); - let needs_thin_lto = - mem::replace(&mut needs_thin_lto, Vec::new()); - let import_only_modules = - mem::replace(&mut lto_import_only_modules, Vec::new()); + let needs_fat_lto = mem::take(&mut needs_fat_lto); + let needs_thin_lto = mem::take(&mut needs_thin_lto); + let import_only_modules = mem::take(&mut lto_import_only_modules); for (work, cost) in generate_lto_work(&cgcx, needs_fat_lto, needs_thin_lto, import_only_modules) { diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs index 4872440f5bd..58009167e3c 100644 --- a/src/librustc_mir/borrow_check/mod.rs +++ b/src/librustc_mir/borrow_check/mod.rs @@ -275,7 +275,7 @@ fn do_mir_borrowck<'a, 'tcx>( mbcx.analyze_results(&mut state); // entry point for DataflowResultsConsumer // Convert any reservation warnings into lints. - let reservation_warnings = mem::replace(&mut mbcx.reservation_warnings, Default::default()); + let reservation_warnings = mem::take(&mut mbcx.reservation_warnings); for (_, (place, span, location, bk, borrow)) in reservation_warnings { let mut initial_diag = mbcx.report_conflicting_borrow(location, (&place, span), bk, &borrow); diff --git a/src/librustc_mir/build/matches/simplify.rs b/src/librustc_mir/build/matches/simplify.rs index b1b5233fbc8..7125eb6850b 100644 --- a/src/librustc_mir/build/matches/simplify.rs +++ b/src/librustc_mir/build/matches/simplify.rs @@ -28,7 +28,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { candidate: &mut Candidate<'pat, 'tcx>) { // repeatedly simplify match pairs until fixed point is reached loop { - let match_pairs = mem::replace(&mut candidate.match_pairs, vec![]); + let match_pairs = mem::take(&mut candidate.match_pairs); let mut changed = false; for match_pair in match_pairs { match self.simplify_match_pair(match_pair, candidate) { diff --git a/src/librustc_mir/util/def_use.rs b/src/librustc_mir/util/def_use.rs index fac752dbf02..59821440c66 100644 --- a/src/librustc_mir/util/def_use.rs +++ b/src/librustc_mir/util/def_use.rs @@ -31,7 +31,7 @@ impl DefUseAnalysis { self.clear(); let mut finder = DefUseFinder { - info: mem::replace(&mut self.info, IndexVec::new()), + info: mem::take(&mut self.info), }; finder.visit_body(body); self.info = finder.info diff --git a/src/librustc_resolve/macros.rs b/src/librustc_resolve/macros.rs index 392a46a262f..c544b3f4603 100644 --- a/src/librustc_resolve/macros.rs +++ b/src/librustc_resolve/macros.rs @@ -946,7 +946,7 @@ impl<'a> Resolver<'a> { }; let macro_resolutions = - mem::replace(&mut *module.multi_segment_macro_resolutions.borrow_mut(), Vec::new()); + mem::take(&mut *module.multi_segment_macro_resolutions.borrow_mut()); for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions { // FIXME: Path resolution will ICE if segment IDs present. for seg in &mut path { seg.id = None; } @@ -973,7 +973,7 @@ impl<'a> Resolver<'a> { } let macro_resolutions = - mem::replace(&mut *module.single_segment_macro_resolutions.borrow_mut(), Vec::new()); + mem::take(&mut *module.single_segment_macro_resolutions.borrow_mut()); for (ident, kind, parent_scope, initial_binding) in macro_resolutions { match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind), &parent_scope, true, true, ident.span) { @@ -998,7 +998,7 @@ impl<'a> Resolver<'a> { } } - let builtin_attrs = mem::replace(&mut *module.builtin_attrs.borrow_mut(), Vec::new()); + let builtin_attrs = mem::take(&mut *module.builtin_attrs.borrow_mut()); for (ident, parent_scope) in builtin_attrs { let _ = self.early_resolve_ident_in_lexical_scope( ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span diff --git a/src/librustc_resolve/resolve_imports.rs b/src/librustc_resolve/resolve_imports.rs index f69849bb4a9..404d728d880 100644 --- a/src/librustc_resolve/resolve_imports.rs +++ b/src/librustc_resolve/resolve_imports.rs @@ -682,7 +682,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> { let mut prev_num_indeterminates = self.indeterminate_imports.len() + 1; while self.indeterminate_imports.len() < prev_num_indeterminates { prev_num_indeterminates = self.indeterminate_imports.len(); - for import in mem::replace(&mut self.indeterminate_imports, Vec::new()) { + for import in mem::take(&mut self.indeterminate_imports) { match self.resolve_import(&import) { true => self.determined_imports.push(import), false => self.indeterminate_imports.push(import), diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs index 661883f2ac1..bd4cf9d2086 100644 --- a/src/librustc_typeck/check/method/probe.rs +++ b/src/librustc_typeck/check/method/probe.rs @@ -970,9 +970,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> { debug!("pick: actual search failed, assemble diagnotics"); - let static_candidates = mem::replace(&mut self.static_candidates, vec![]); + let static_candidates = mem::take(&mut self.static_candidates); let private_candidate = self.private_candidate.take(); - let unsatisfied_predicates = mem::replace(&mut self.unsatisfied_predicates, vec![]); + let unsatisfied_predicates = mem::take(&mut self.unsatisfied_predicates); // things failed, so lets look at all traits, for diagnostic purposes now: self.reset(); diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs index 3fe048a6986..8fec433e56d 100644 --- a/src/librustdoc/clean/mod.rs +++ b/src/librustdoc/clean/mod.rs @@ -4408,7 +4408,7 @@ pub fn enter_impl_trait(cx: &DocContext<'_>, f: F) -> R where F: FnOnce() -> R, { - let old_bounds = mem::replace(&mut *cx.impl_trait_bounds.borrow_mut(), Default::default()); + let old_bounds = mem::take(&mut *cx.impl_trait_bounds.borrow_mut()); let r = f(); assert!(cx.impl_trait_bounds.borrow().is_empty()); *cx.impl_trait_bounds.borrow_mut() = old_bounds; diff --git a/src/librustdoc/clean/simplify.rs b/src/librustdoc/clean/simplify.rs index 36e6a6003df..e4fba73b820 100644 --- a/src/librustdoc/clean/simplify.rs +++ b/src/librustdoc/clean/simplify.rs @@ -131,7 +131,7 @@ pub fn ty_params(mut params: Vec) -> Vec { - *bounds = ty_bounds(mem::replace(bounds, Vec::new())); + *bounds = ty_bounds(mem::take(bounds)); } _ => panic!("expected only type parameters"), } diff --git a/src/librustdoc/html/render.rs b/src/librustdoc/html/render.rs index 2080637ecb4..2d6503c9445 100644 --- a/src/librustdoc/html/render.rs +++ b/src/librustdoc/html/render.rs @@ -660,7 +660,7 @@ pub fn run(mut krate: clean::Crate, deref_trait_did, deref_mut_trait_did, owned_box_did, - masked_crates: mem::replace(&mut krate.masked_crates, Default::default()), + masked_crates: mem::take(&mut krate.masked_crates), param_names: external_param_names, aliases: Default::default(), }; diff --git a/src/librustdoc/passes/collapse_docs.rs b/src/librustdoc/passes/collapse_docs.rs index 8666ba357b8..e15a95e2e1a 100644 --- a/src/librustdoc/passes/collapse_docs.rs +++ b/src/librustdoc/passes/collapse_docs.rs @@ -46,7 +46,7 @@ fn collapse(doc_strings: &mut Vec) { let mut docs = vec![]; let mut last_frag: Option = None; - for frag in replace(doc_strings, vec![]) { + for frag in take(doc_strings) { if let Some(mut curr_frag) = last_frag.take() { let curr_kind = curr_frag.kind(); let new_kind = frag.kind(); diff --git a/src/libstd/panicking.rs b/src/libstd/panicking.rs index 797d85e941d..952fd9ebfdf 100644 --- a/src/libstd/panicking.rs +++ b/src/libstd/panicking.rs @@ -364,7 +364,7 @@ fn continue_panic_fmt(info: &PanicInfo<'_>) -> ! { unsafe impl<'a> BoxMeUp for PanicPayload<'a> { fn box_me_up(&mut self) -> *mut (dyn Any + Send) { - let contents = mem::replace(self.fill(), String::new()); + let contents = mem::take(self.fill()); Box::into_raw(Box::new(contents)) } diff --git a/src/libstd/sync/mpsc/sync.rs b/src/libstd/sync/mpsc/sync.rs index 3c4f8e077c9..f8fcd3ff5a5 100644 --- a/src/libstd/sync/mpsc/sync.rs +++ b/src/libstd/sync/mpsc/sync.rs @@ -383,7 +383,7 @@ impl Packet { // needs to be careful to destroy the data *outside* of the lock to // prevent deadlock. let _data = if guard.cap != 0 { - mem::replace(&mut guard.buf.buf, Vec::new()) + mem::take(&mut guard.buf.buf) } else { Vec::new() }; diff --git a/src/libstd/sys/windows/pipe.rs b/src/libstd/sys/windows/pipe.rs index 493ee8a9a2d..c77f30dfc71 100644 --- a/src/libstd/sys/windows/pipe.rs +++ b/src/libstd/sys/windows/pipe.rs @@ -342,7 +342,7 @@ impl<'a> Drop for AsyncPipe<'a> { // If anything here fails, there's not really much we can do, so we leak // the buffer/OVERLAPPED pointers to ensure we're at least memory safe. if self.pipe.cancel_io().is_err() || self.result().is_err() { - let buf = mem::replace(self.dst, Vec::new()); + let buf = mem::take(self.dst); let overlapped = Box::new(unsafe { mem::zeroed() }); let overlapped = mem::replace(&mut self.overlapped, overlapped); mem::forget((buf, overlapped)); diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs index 5473f55aa33..c0f721b466e 100644 --- a/src/libsyntax/ext/expand.rs +++ b/src/libsyntax/ext/expand.rs @@ -307,7 +307,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> { } else { self.resolve_imports(); if undetermined_invocations.is_empty() { break } - invocations = mem::replace(&mut undetermined_invocations, Vec::new()); + invocations = mem::take(&mut undetermined_invocations); force = !mem::replace(&mut progress, false); continue }; diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs index ea7f8e356aa..e04fd2ddc05 100644 --- a/src/libsyntax/ext/tt/transcribe.rs +++ b/src/libsyntax/ext/tt/transcribe.rs @@ -249,7 +249,7 @@ pub fn transcribe( quoted::TokenTree::Delimited(mut span, delimited) => { span = span.apply_mark(cx.current_expansion.mark); stack.push(Frame::Delimited { forest: delimited, idx: 0, span }); - result_stack.push(mem::replace(&mut result, Vec::new())); + result_stack.push(mem::take(&mut result)); } // Nothing much to do here. Just push the token to the result, being careful to diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index 696b5f48385..8ac20f33908 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -7699,7 +7699,7 @@ impl<'a> Parser<'a> { let mut tokens = Vec::new(); let prev_collecting = match self.token_cursor.frame.last_token { LastToken::Collecting(ref mut list) => { - Some(mem::replace(list, Vec::new())) + Some(mem::take(list)) } LastToken::Was(ref mut last) => { tokens.extend(last.take()); @@ -7717,7 +7717,7 @@ impl<'a> Parser<'a> { // Pull out the tokens that we've collected from the call to `f` above. let mut collected_tokens = match *last_token { - LastToken::Collecting(ref mut v) => mem::replace(v, Vec::new()), + LastToken::Collecting(ref mut v) => mem::take(v), LastToken::Was(_) => panic!("our vector went away?"), }; diff --git a/src/libsyntax/test.rs b/src/libsyntax/test.rs index f90b76721ee..156fab8834c 100644 --- a/src/libsyntax/test.rs +++ b/src/libsyntax/test.rs @@ -120,8 +120,8 @@ impl<'a> MutVisitor for TestHarnessGenerator<'a> { // We don't want to recurse into anything other than mods, since // mods or tests inside of functions will break things if let ast::ItemKind::Mod(mut module) = item.node { - let tests = mem::replace(&mut self.tests, Vec::new()); - let tested_submods = mem::replace(&mut self.tested_submods, Vec::new()); + let tests = mem::take(&mut self.tests); + let tested_submods = mem::take(&mut self.tested_submods); noop_visit_mod(&mut module, self); let tests = mem::replace(&mut self.tests, tests); let tested_submods = mem::replace(&mut self.tested_submods, tested_submods); diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs index 35caf82dd71..6053b538ff3 100644 --- a/src/tools/compiletest/src/runtest.rs +++ b/src/tools/compiletest/src/runtest.rs @@ -3608,7 +3608,7 @@ fn nocomment_mir_line(line: &str) -> &str { fn read2_abbreviated(mut child: Child) -> io::Result { use crate::read2::read2; - use std::mem::replace; + use std::mem::take; const HEAD_LEN: usize = 160 * 1024; const TAIL_LEN: usize = 256 * 1024; @@ -3632,7 +3632,7 @@ fn read2_abbreviated(mut child: Child) -> io::Result { return; } let tail = bytes.split_off(new_len - TAIL_LEN).into_boxed_slice(); - let head = replace(bytes, Vec::new()); + let head = take(bytes); let skipped = new_len - HEAD_LEN - TAIL_LEN; ProcOutput::Abbreviated { head,