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Auto merge of #60435 - Centril:rollup-aa5lmuw, r=Centril
Rollup of 7 pull requests Successful merges: - #60287 (Use references for variances_of) - #60327 (Search for incompatible universes in borrow errors) - #60330 (Suggest using an inclusive range instead of an exclusive range when the endpoint overflows by 1) - #60366 (build-gcc: Create missing cc symlink) - #60369 (Support ZSTs in DispatchFromDyn) - #60404 (Implement `BorrowMut<str>` for `String`) - #60417 (Rename hir::ExprKind::Use to ::DropTemps and improve docs.) Failed merges: r? @ghost
2 parents 6cc24f2 + e5b6997 commit 9b67bd4

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‎src/ci/docker/dist-x86_64-linux/build-gcc.sh

+1
Original file line numberDiff line numberDiff line change
@@ -32,6 +32,7 @@ hide_output ../gcc-$GCC/configure \
3232
--enable-languages=c,c++
3333
hide_output make -j10
3434
hide_output make install
35+
ln -s gcc /rustroot/bin/cc
3536

3637
cd ..
3738
rm -rf gcc-build

‎src/liballoc/str.rs

+9-1
Original file line numberDiff line numberDiff line change
@@ -28,7 +28,7 @@
2828
// It's cleaner to just turn off the unused_imports warning than to fix them.
2929
#![allow(unused_imports)]
3030

31-
use core::borrow::Borrow;
31+
use core::borrow::{Borrow, BorrowMut};
3232
use core::str::pattern::{Pattern, Searcher, ReverseSearcher, DoubleEndedSearcher};
3333
use core::mem;
3434
use core::ptr;
@@ -190,6 +190,14 @@ impl Borrow<str> for String {
190190
}
191191
}
192192

193+
#[stable(feature = "string_borrow_mut", since = "1.36.0")]
194+
impl BorrowMut<str> for String {
195+
#[inline]
196+
fn borrow_mut(&mut self) -> &mut str {
197+
&mut self[..]
198+
}
199+
}
200+
193201
#[stable(feature = "rust1", since = "1.0.0")]
194202
impl ToOwned for str {
195203
type Owned = String;

‎src/librustc/arena.rs

+8
Original file line numberDiff line numberDiff line change
@@ -144,6 +144,14 @@ impl<'tcx> Arena<'tcx> {
144144
}
145145
}
146146

147+
#[inline]
148+
pub fn alloc_slice<T: Copy>(&self, value: &[T]) -> &mut [T] {
149+
if value.len() == 0 {
150+
return &mut []
151+
}
152+
self.dropless.alloc_slice(value)
153+
}
154+
147155
pub fn alloc_from_iter<
148156
T: ArenaAllocatable,
149157
I: IntoIterator<Item = T>

‎src/librustc/cfg/construct.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -369,7 +369,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
369369
hir::ExprKind::AddrOf(_, ref e) |
370370
hir::ExprKind::Cast(ref e, _) |
371371
hir::ExprKind::Type(ref e, _) |
372-
hir::ExprKind::Use(ref e) |
372+
hir::ExprKind::DropTemps(ref e) |
373373
hir::ExprKind::Unary(_, ref e) |
374374
hir::ExprKind::Field(ref e, _) |
375375
hir::ExprKind::Yield(ref e) |

‎src/librustc/hir/intravisit.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -1029,7 +1029,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
10291029
visitor.visit_expr(subexpression);
10301030
visitor.visit_ty(typ)
10311031
}
1032-
ExprKind::Use(ref subexpression) => {
1032+
ExprKind::DropTemps(ref subexpression) => {
10331033
visitor.visit_expr(subexpression);
10341034
}
10351035
ExprKind::If(ref head_expression, ref if_block, ref optional_else) => {

‎src/librustc/hir/lowering.rs

+73-7
Original file line numberDiff line numberDiff line change
@@ -4671,7 +4671,7 @@ impl<'a> LoweringContext<'a> {
46714671
// The construct was introduced in #21984.
46724672
// FIXME(60253): Is this still necessary?
46734673
// Also, add the attributes to the outer returned expr node.
4674-
return self.expr_use(head_sp, match_expr, e.attrs.clone())
4674+
return self.expr_drop_temps(head_sp, match_expr, e.attrs.clone())
46754675
}
46764676

46774677
// Desugar `ExprKind::Try`
@@ -5030,15 +5030,19 @@ impl<'a> LoweringContext<'a> {
50305030
)
50315031
}
50325032

5033-
/// Wrap the given `expr` in `hir::ExprKind::Use`.
5033+
/// Wrap the given `expr` in a terminating scope using `hir::ExprKind::DropTemps`.
50345034
///
5035-
/// In terms of drop order, it has the same effect as
5036-
/// wrapping `expr` in `{ let _t = $expr; _t }` but
5037-
/// should provide better compile-time performance.
5035+
/// In terms of drop order, it has the same effect as wrapping `expr` in
5036+
/// `{ let _t = $expr; _t }` but should provide better compile-time performance.
50385037
///
50395038
/// The drop order can be important in e.g. `if expr { .. }`.
5040-
fn expr_use(&mut self, span: Span, expr: P<hir::Expr>, attrs: ThinVec<Attribute>) -> hir::Expr {
5041-
self.expr(span, hir::ExprKind::Use(expr), attrs)
5039+
fn expr_drop_temps(
5040+
&mut self,
5041+
span: Span,
5042+
expr: P<hir::Expr>,
5043+
attrs: ThinVec<Attribute>
5044+
) -> hir::Expr {
5045+
self.expr(span, hir::ExprKind::DropTemps(expr), attrs)
50425046
}
50435047

50445048
fn expr_match(
@@ -5400,3 +5404,65 @@ fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
54005404
body_ids.sort_by_key(|b| bodies[b].value.span);
54015405
body_ids
54025406
}
5407+
5408+
/// Checks if the specified expression is a built-in range literal.
5409+
/// (See: `LoweringContext::lower_expr()`).
5410+
pub fn is_range_literal(sess: &Session, expr: &hir::Expr) -> bool {
5411+
use hir::{Path, QPath, ExprKind, TyKind};
5412+
5413+
// Returns whether the given path represents a (desugared) range,
5414+
// either in std or core, i.e. has either a `::std::ops::Range` or
5415+
// `::core::ops::Range` prefix.
5416+
fn is_range_path(path: &Path) -> bool {
5417+
let segs: Vec<_> = path.segments.iter().map(|seg| seg.ident.as_str().to_string()).collect();
5418+
let segs: Vec<_> = segs.iter().map(|seg| &**seg).collect();
5419+
5420+
// "{{root}}" is the equivalent of `::` prefix in `Path`.
5421+
if let ["{{root}}", std_core, "ops", range] = segs.as_slice() {
5422+
(*std_core == "std" || *std_core == "core") && range.starts_with("Range")
5423+
} else {
5424+
false
5425+
}
5426+
};
5427+
5428+
// Check whether a span corresponding to a range expression is a
5429+
// range literal, rather than an explicit struct or `new()` call.
5430+
fn is_lit(sess: &Session, span: &Span) -> bool {
5431+
let source_map = sess.source_map();
5432+
let end_point = source_map.end_point(*span);
5433+
5434+
if let Ok(end_string) = source_map.span_to_snippet(end_point) {
5435+
!(end_string.ends_with("}") || end_string.ends_with(")"))
5436+
} else {
5437+
false
5438+
}
5439+
};
5440+
5441+
match expr.node {
5442+
// All built-in range literals but `..=` and `..` desugar to `Struct`s.
5443+
ExprKind::Struct(ref qpath, _, _) => {
5444+
if let QPath::Resolved(None, ref path) = **qpath {
5445+
return is_range_path(&path) && is_lit(sess, &expr.span);
5446+
}
5447+
}
5448+
5449+
// `..` desugars to its struct path.
5450+
ExprKind::Path(QPath::Resolved(None, ref path)) => {
5451+
return is_range_path(&path) && is_lit(sess, &expr.span);
5452+
}
5453+
5454+
// `..=` desugars into `::std::ops::RangeInclusive::new(...)`.
5455+
ExprKind::Call(ref func, _) => {
5456+
if let ExprKind::Path(QPath::TypeRelative(ref ty, ref segment)) = func.node {
5457+
if let TyKind::Path(QPath::Resolved(None, ref path)) = ty.node {
5458+
let new_call = segment.ident.as_str() == "new";
5459+
return is_range_path(&path) && is_lit(sess, &expr.span) && new_call;
5460+
}
5461+
}
5462+
}
5463+
5464+
_ => {}
5465+
}
5466+
5467+
false
5468+
}

‎src/librustc/hir/mod.rs

+8-6
Original file line numberDiff line numberDiff line change
@@ -1366,7 +1366,7 @@ impl Expr {
13661366
ExprKind::Unary(..) => ExprPrecedence::Unary,
13671367
ExprKind::Lit(_) => ExprPrecedence::Lit,
13681368
ExprKind::Type(..) | ExprKind::Cast(..) => ExprPrecedence::Cast,
1369-
ExprKind::Use(ref expr, ..) => expr.precedence(),
1369+
ExprKind::DropTemps(ref expr, ..) => expr.precedence(),
13701370
ExprKind::If(..) => ExprPrecedence::If,
13711371
ExprKind::While(..) => ExprPrecedence::While,
13721372
ExprKind::Loop(..) => ExprPrecedence::Loop,
@@ -1438,7 +1438,7 @@ impl Expr {
14381438
ExprKind::Binary(..) |
14391439
ExprKind::Yield(..) |
14401440
ExprKind::Cast(..) |
1441-
ExprKind::Use(..) |
1441+
ExprKind::DropTemps(..) |
14421442
ExprKind::Err => {
14431443
false
14441444
}
@@ -1488,10 +1488,12 @@ pub enum ExprKind {
14881488
Cast(P<Expr>, P<Ty>),
14891489
/// A type reference (e.g., `Foo`).
14901490
Type(P<Expr>, P<Ty>),
1491-
/// Semantically equivalent to `{ let _t = expr; _t }`.
1492-
/// Maps directly to `hair::ExprKind::Use`.
1493-
/// Only exists to tweak the drop order in HIR.
1494-
Use(P<Expr>),
1491+
/// Wraps the expression in a terminating scope.
1492+
/// This makes it semantically equivalent to `{ let _t = expr; _t }`.
1493+
///
1494+
/// This construct only exists to tweak the drop order in HIR lowering.
1495+
/// An example of that is the desugaring of `for` loops.
1496+
DropTemps(P<Expr>),
14951497
/// An `if` block, with an optional else block.
14961498
///
14971499
/// I.e., `if <expr> { <expr> } else { <expr> }`.

‎src/librustc/hir/print.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -1388,7 +1388,7 @@ impl<'a> State<'a> {
13881388
self.word_space(":")?;
13891389
self.print_type(&ty)?;
13901390
}
1391-
hir::ExprKind::Use(ref init) => {
1391+
hir::ExprKind::DropTemps(ref init) => {
13921392
// Print `{`:
13931393
self.cbox(indent_unit)?;
13941394
self.ibox(0)?;

‎src/librustc/middle/expr_use_visitor.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -520,7 +520,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
520520
self.consume_expr(&base);
521521
}
522522

523-
hir::ExprKind::Use(ref expr) => {
523+
hir::ExprKind::DropTemps(ref expr) => {
524524
self.consume_expr(&expr);
525525
}
526526

‎src/librustc/middle/liveness.rs

+3-3
Original file line numberDiff line numberDiff line change
@@ -521,7 +521,7 @@ fn visit_expr<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, expr: &'tcx Expr) {
521521
hir::ExprKind::Binary(..) |
522522
hir::ExprKind::AddrOf(..) |
523523
hir::ExprKind::Cast(..) |
524-
hir::ExprKind::Use(..) |
524+
hir::ExprKind::DropTemps(..) |
525525
hir::ExprKind::Unary(..) |
526526
hir::ExprKind::Break(..) |
527527
hir::ExprKind::Continue(_) |
@@ -1222,7 +1222,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
12221222
hir::ExprKind::AddrOf(_, ref e) |
12231223
hir::ExprKind::Cast(ref e, _) |
12241224
hir::ExprKind::Type(ref e, _) |
1225-
hir::ExprKind::Use(ref e) |
1225+
hir::ExprKind::DropTemps(ref e) |
12261226
hir::ExprKind::Unary(_, ref e) |
12271227
hir::ExprKind::Yield(ref e) |
12281228
hir::ExprKind::Repeat(ref e, _) => {
@@ -1526,7 +1526,7 @@ fn check_expr<'a, 'tcx>(this: &mut Liveness<'a, 'tcx>, expr: &'tcx Expr) {
15261526
hir::ExprKind::Match(..) | hir::ExprKind::While(..) | hir::ExprKind::Loop(..) |
15271527
hir::ExprKind::Index(..) | hir::ExprKind::Field(..) |
15281528
hir::ExprKind::Array(..) | hir::ExprKind::Tup(..) | hir::ExprKind::Binary(..) |
1529-
hir::ExprKind::Cast(..) | hir::ExprKind::Use(..) | hir::ExprKind::Unary(..) |
1529+
hir::ExprKind::Cast(..) | hir::ExprKind::DropTemps(..) | hir::ExprKind::Unary(..) |
15301530
hir::ExprKind::Ret(..) | hir::ExprKind::Break(..) | hir::ExprKind::Continue(..) |
15311531
hir::ExprKind::Lit(_) | hir::ExprKind::Block(..) | hir::ExprKind::AddrOf(..) |
15321532
hir::ExprKind::Struct(..) | hir::ExprKind::Repeat(..) |

‎src/librustc/middle/mem_categorization.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -677,7 +677,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
677677
hir::ExprKind::Assign(..) | hir::ExprKind::AssignOp(..) |
678678
hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) |
679679
hir::ExprKind::Unary(..) | hir::ExprKind::Yield(..) |
680-
hir::ExprKind::MethodCall(..) | hir::ExprKind::Cast(..) | hir::ExprKind::Use(..) |
680+
hir::ExprKind::MethodCall(..) | hir::ExprKind::Cast(..) | hir::ExprKind::DropTemps(..) |
681681
hir::ExprKind::Array(..) | hir::ExprKind::Tup(..) | hir::ExprKind::If(..) |
682682
hir::ExprKind::Binary(..) | hir::ExprKind::While(..) |
683683
hir::ExprKind::Block(..) | hir::ExprKind::Loop(..) | hir::ExprKind::Match(..) |

‎src/librustc/middle/region.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -908,8 +908,8 @@ fn resolve_expr<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'a, 'tcx>, expr:
908908
visitor.cx.var_parent = visitor.cx.parent;
909909
}
910910

911-
hir::ExprKind::Use(ref expr) => {
912-
// `Use(expr)` does not denote a conditional scope.
911+
hir::ExprKind::DropTemps(ref expr) => {
912+
// `DropTemps(expr)` does not denote a conditional scope.
913913
// Rather, we want to achieve the same behavior as `{ let _t = expr; _t }`.
914914
terminating(expr.hir_id.local_id);
915915
}

‎src/librustc/query/mod.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -245,13 +245,13 @@ rustc_queries! {
245245

246246
/// Get a map with the variance of every item; use `item_variance`
247247
/// instead.
248-
query crate_variances(_: CrateNum) -> Lrc<ty::CrateVariancesMap> {
248+
query crate_variances(_: CrateNum) -> Lrc<ty::CrateVariancesMap<'tcx>> {
249249
desc { "computing the variances for items in this crate" }
250250
}
251251

252252
/// Maps from def-id of a type or region parameter to its
253253
/// (inferred) variance.
254-
query variances_of(_: DefId) -> Lrc<Vec<ty::Variance>> {}
254+
query variances_of(_: DefId) -> &'tcx [ty::Variance] {}
255255
}
256256

257257
TypeChecking {

‎src/librustc/ty/mod.rs

+2-6
Original file line numberDiff line numberDiff line change
@@ -332,15 +332,11 @@ pub enum Variance {
332332
/// `tcx.variances_of()` to get the variance for a *particular*
333333
/// item.
334334
#[derive(HashStable)]
335-
pub struct CrateVariancesMap {
335+
pub struct CrateVariancesMap<'tcx> {
336336
/// For each item with generics, maps to a vector of the variance
337337
/// of its generics. If an item has no generics, it will have no
338338
/// entry.
339-
pub variances: FxHashMap<DefId, Lrc<Vec<ty::Variance>>>,
340-
341-
/// An empty vector, useful for cloning.
342-
#[stable_hasher(ignore)]
343-
pub empty_variance: Lrc<Vec<ty::Variance>>,
339+
pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
344340
}
345341

346342
impl Variance {

‎src/librustc/ty/relate.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -60,7 +60,7 @@ pub trait TypeRelation<'a, 'gcx: 'a+'tcx, 'tcx: 'a> : Sized {
6060
b_subst);
6161

6262
let opt_variances = self.tcx().variances_of(item_def_id);
63-
relate_substs(self, Some(&opt_variances), a_subst, b_subst)
63+
relate_substs(self, Some(opt_variances), a_subst, b_subst)
6464
}
6565

6666
/// Switch variance for the purpose of relating `a` and `b`.
@@ -122,7 +122,7 @@ impl<'tcx> Relate<'tcx> for ty::TypeAndMut<'tcx> {
122122
}
123123

124124
pub fn relate_substs<'a, 'gcx, 'tcx, R>(relation: &mut R,
125-
variances: Option<&Vec<ty::Variance>>,
125+
variances: Option<&[ty::Variance]>,
126126
a_subst: SubstsRef<'tcx>,
127127
b_subst: SubstsRef<'tcx>)
128128
-> RelateResult<'tcx, SubstsRef<'tcx>>

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