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Auto merge of rust-lang#90161 - JohnTitor:rollup-1j2qc8m, r=JohnTitor
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Rollup of 14 pull requests

Successful merges:

 - rust-lang#87537 (Clarify undefined behaviour in binary heap, btree and hashset docs)
 - rust-lang#88624 (Stabilize feature `saturating_div` for rust 1.58.0)
 - rust-lang#89257 (Give better error for `macro_rules name`)
 - rust-lang#89665 (Ensure that pushing empty path works as before on verbatim paths)
 - rust-lang#89895 (Don't mark for loop iter expression as desugared)
 - rust-lang#89922 (Update E0637 description to mention `&` w/o an explicit lifetime name)
 - rust-lang#89944 (Change `Duration::[try_]from_secs_{f32, f64}` underflow error)
 - rust-lang#89991 (rustc_ast: Turn `MutVisitor::token_visiting_enabled` into a constant)
 - rust-lang#90028 (Reject closures in patterns)
 - rust-lang#90069 (Fix const qualification when executed after promotion)
 - rust-lang#90078 (Add a regression test for issue-83479)
 - rust-lang#90114 (Add some tests for const_generics_defaults)
 - rust-lang#90115 (Add test for issue rust-lang#78561)
 - rust-lang#90129 (triagebot: Treat `I-*nominated` like `I-nominated`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
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bors committed Oct 22, 2021
2 parents 68a698b + ea8a896 commit 45b600c
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Showing 52 changed files with 692 additions and 168 deletions.
12 changes: 5 additions & 7 deletions compiler/rustc_ast/src/mut_visit.rs
View file
Expand Up @@ -37,9 +37,7 @@ pub trait MutVisitor: Sized {
/// Mutable token visiting only exists for the `macro_rules` token marker and should not be
/// used otherwise. Token visitor would be entirely separate from the regular visitor if
/// the marker didn't have to visit AST fragments in nonterminal tokens.
fn token_visiting_enabled(&self) -> bool {
false
}
const VISIT_TOKENS: bool = false;

// Methods in this trait have one of three forms:
//
Expand Down Expand Up @@ -363,7 +361,7 @@ pub fn visit_mac_args<T: MutVisitor>(args: &mut MacArgs, vis: &mut T) {
}
MacArgs::Eq(eq_span, token) => {
vis.visit_span(eq_span);
if vis.token_visiting_enabled() {
if T::VISIT_TOKENS {
visit_token(token, vis);
} else {
// The value in `#[key = VALUE]` must be visited as an expression for backward
Expand Down Expand Up @@ -682,7 +680,7 @@ pub fn visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {

// No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
pub fn visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
if vis.token_visiting_enabled() && !tts.is_empty() {
if T::VISIT_TOKENS && !tts.is_empty() {
let tts = Lrc::make_mut(tts);
visit_vec(tts, |(tree, _is_joint)| visit_tt(tree, vis));
}
Expand All @@ -692,14 +690,14 @@ pub fn visit_attr_annotated_tts<T: MutVisitor>(
AttrAnnotatedTokenStream(tts): &mut AttrAnnotatedTokenStream,
vis: &mut T,
) {
if vis.token_visiting_enabled() && !tts.is_empty() {
if T::VISIT_TOKENS && !tts.is_empty() {
let tts = Lrc::make_mut(tts);
visit_vec(tts, |(tree, _is_joint)| visit_attr_annotated_tt(tree, vis));
}
}

pub fn visit_lazy_tts_opt_mut<T: MutVisitor>(lazy_tts: Option<&mut LazyTokenStream>, vis: &mut T) {
if vis.token_visiting_enabled() {
if T::VISIT_TOKENS {
if let Some(lazy_tts) = lazy_tts {
let mut tts = lazy_tts.create_token_stream();
visit_attr_annotated_tts(&mut tts, vis);
Expand Down
39 changes: 18 additions & 21 deletions compiler/rustc_ast_lowering/src/expr.rs
View file
Expand Up @@ -1332,15 +1332,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
body: &Block,
opt_label: Option<Label>,
) -> hir::Expr<'hir> {
let orig_head_span = head.span;
// expand <head>
let mut head = self.lower_expr_mut(head);
let desugared_span = self.mark_span_with_reason(
DesugaringKind::ForLoop(ForLoopLoc::Head),
orig_head_span,
None,
);
head.span = self.lower_span(desugared_span);
let head = self.lower_expr_mut(head);
let desugared_span =
self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), head.span, None);
let e_span = self.lower_span(e.span);

let iter = Ident::with_dummy_span(sym::iter);

Expand All @@ -1354,23 +1350,24 @@ impl<'hir> LoweringContext<'_, 'hir> {
// `::std::option::Option::Some(val) => __next = val`
let pat_arm = {
let val_ident = Ident::with_dummy_span(sym::val);
let (val_pat, val_pat_hid) = self.pat_ident(pat.span, val_ident);
let val_expr = self.expr_ident(pat.span, val_ident, val_pat_hid);
let next_expr = self.expr_ident(pat.span, next_ident, next_pat_hid);
let pat_span = self.lower_span(pat.span);
let (val_pat, val_pat_hid) = self.pat_ident(pat_span, val_ident);
let val_expr = self.expr_ident(pat_span, val_ident, val_pat_hid);
let next_expr = self.expr_ident(pat_span, next_ident, next_pat_hid);
let assign = self.arena.alloc(self.expr(
pat.span,
hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat.span)),
pat_span,
hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat_span)),
ThinVec::new(),
));
let some_pat = self.pat_some(pat.span, val_pat);
let some_pat = self.pat_some(pat_span, val_pat);
self.arm(some_pat, assign)
};

// `::std::option::Option::None => break`
let break_arm = {
let break_expr =
self.with_loop_scope(e.id, |this| this.expr_break_alloc(e.span, ThinVec::new()));
let pat = self.pat_none(e.span);
self.with_loop_scope(e.id, |this| this.expr_break_alloc(e_span, ThinVec::new()));
let pat = self.pat_none(e_span);
self.arm(pat, break_expr)
};

Expand Down Expand Up @@ -1416,10 +1413,10 @@ impl<'hir> LoweringContext<'_, 'hir> {

let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
let body_expr = self.expr_block(body_block, ThinVec::new());
let body_stmt = self.stmt_expr(body.span, body_expr);
let body_stmt = self.stmt_expr(body_block.span, body_expr);

let loop_block = self.block_all(
e.span,
e_span,
arena_vec![self; next_let, match_stmt, pat_let, body_stmt],
None,
);
Expand All @@ -1429,7 +1426,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
loop_block,
self.lower_label(opt_label),
hir::LoopSource::ForLoop,
self.lower_span(e.span.with_hi(orig_head_span.hi())),
self.lower_span(e_span.with_hi(head.span.hi())),
);
let loop_expr = self.arena.alloc(hir::Expr {
hir_id: self.lower_node_id(e.id),
Expand All @@ -1442,7 +1439,7 @@ impl<'hir> LoweringContext<'_, 'hir> {

let into_iter_span = self.mark_span_with_reason(
DesugaringKind::ForLoop(ForLoopLoc::IntoIter),
orig_head_span,
head.span,
None,
);

Expand All @@ -1458,7 +1455,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
// #82462: to correctly diagnose borrow errors, the block that contains
// the iter expr needs to have a span that covers the loop body.
let desugared_full_span =
self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e.span, None);
self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e_span, None);

let match_expr = self.arena.alloc(self.expr_match(
desugared_full_span,
Expand Down
60 changes: 30 additions & 30 deletions compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View file
Expand Up @@ -11,7 +11,6 @@ use rustc_middle::mir::{
};
use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
use rustc_mir_dataflow::move_paths::{InitKind, MoveOutIndex, MovePathIndex};
use rustc_span::source_map::DesugaringKind;
use rustc_span::symbol::sym;
use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
use rustc_trait_selection::infer::InferCtxtExt;
Expand Down Expand Up @@ -247,6 +246,36 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
place_name, partially_str, loop_message
),
);
let sess = self.infcx.tcx.sess;
let ty = used_place.ty(self.body, self.infcx.tcx).ty;
// If we have a `&mut` ref, we need to reborrow.
if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
// If we are in a loop this will be suggested later.
if !is_loop_move {
err.span_suggestion_verbose(
move_span.shrink_to_lo(),
&format!(
"consider creating a fresh reborrow of {} here",
self.describe_place(moved_place.as_ref())
.map(|n| format!("`{}`", n))
.unwrap_or_else(
|| "the mutable reference".to_string()
),
),
"&mut *".to_string(),
Applicability::MachineApplicable,
);
}
} else if let Ok(snippet) =
sess.source_map().span_to_snippet(move_span)
{
err.span_suggestion(
move_span,
"consider borrowing to avoid moving into the for loop",
format!("&{}", snippet),
Applicability::MaybeIncorrect,
);
}
} else {
err.span_label(
fn_call_span,
Expand Down Expand Up @@ -315,35 +344,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
in_pattern = true;
}
}

if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() {
let sess = self.infcx.tcx.sess;
let ty = used_place.ty(self.body, self.infcx.tcx).ty;
// If we have a `&mut` ref, we need to reborrow.
if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
// If we are in a loop this will be suggested later.
if !is_loop_move {
err.span_suggestion_verbose(
move_span.shrink_to_lo(),
&format!(
"consider creating a fresh reborrow of {} here",
self.describe_place(moved_place.as_ref())
.map(|n| format!("`{}`", n))
.unwrap_or_else(|| "the mutable reference".to_string()),
),
"&mut *".to_string(),
Applicability::MachineApplicable,
);
}
} else if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) {
err.span_suggestion(
move_span,
"consider borrowing to avoid moving into the for loop",
format!("&{}", snippet),
Applicability::MaybeIncorrect,
);
}
}
}

use_spans.var_span_label_path_only(
Expand Down
21 changes: 11 additions & 10 deletions compiler/rustc_borrowck/src/diagnostics/move_errors.rs
View file
Expand Up @@ -5,11 +5,10 @@ use rustc_middle::ty;
use rustc_mir_dataflow::move_paths::{
IllegalMoveOrigin, IllegalMoveOriginKind, LookupResult, MoveError, MovePathIndex,
};
use rustc_span::source_map::DesugaringKind;
use rustc_span::{sym, Span, DUMMY_SP};
use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions;

use crate::diagnostics::UseSpans;
use crate::diagnostics::{FnSelfUseKind, UseSpans};
use crate::prefixes::PrefixSet;
use crate::MirBorrowckCtxt;

Expand Down Expand Up @@ -400,19 +399,21 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
| ty::Opaque(def_id, _) => def_id,
_ => return err,
};
let is_option = self.infcx.tcx.is_diagnostic_item(sym::Option, def_id);
let is_result = self.infcx.tcx.is_diagnostic_item(sym::Result, def_id);
if (is_option || is_result) && use_spans.map_or(true, |v| !v.for_closure()) {
let diag_name = self.infcx.tcx.get_diagnostic_name(def_id);
if matches!(diag_name, Some(sym::Option | sym::Result))
&& use_spans.map_or(true, |v| !v.for_closure())
{
err.span_suggestion_verbose(
span.shrink_to_hi(),
&format!(
"consider borrowing the `{}`'s content",
if is_option { "Option" } else { "Result" }
),
&format!("consider borrowing the `{}`'s content", diag_name.unwrap()),
".as_ref()".to_string(),
Applicability::MaybeIncorrect,
);
} else if matches!(span.desugaring_kind(), Some(DesugaringKind::ForLoop(_))) {
} else if let Some(UseSpans::FnSelfUse {
kind: FnSelfUseKind::Normal { implicit_into_iter: true, .. },
..
}) = use_spans
{
let suggest = match self.infcx.tcx.get_diagnostic_item(sym::IntoIterator) {
Some(def_id) => self.infcx.tcx.infer_ctxt().enter(|infcx| {
type_known_to_meet_bound_modulo_regions(
Expand Down
11 changes: 9 additions & 2 deletions compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
View file
Expand Up @@ -46,6 +46,9 @@ pub trait Qualif {
/// Whether this `Qualif` is cleared when a local is moved from.
const IS_CLEARED_ON_MOVE: bool = false;

/// Whether this `Qualif` might be evaluated after the promotion and can encounter a promoted.
const ALLOW_PROMOTED: bool = false;

/// Extracts the field of `ConstQualifs` that corresponds to this `Qualif`.
fn in_qualifs(qualifs: &ConstQualifs) -> bool;

Expand Down Expand Up @@ -129,6 +132,7 @@ pub struct NeedsNonConstDrop;
impl Qualif for NeedsNonConstDrop {
const ANALYSIS_NAME: &'static str = "flow_needs_nonconst_drop";
const IS_CLEARED_ON_MOVE: bool = true;
const ALLOW_PROMOTED: bool = true;

fn in_qualifs(qualifs: &ConstQualifs) -> bool {
qualifs.needs_non_const_drop
Expand Down Expand Up @@ -310,9 +314,12 @@ where
// Check the qualifs of the value of `const` items.
if let Some(ct) = constant.literal.const_for_ty() {
if let ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs_: _, promoted }) = ct.val {
assert!(promoted.is_none());
// Use qualifs of the type for the promoted. Promoteds in MIR body should be possible
// only for `NeedsNonConstDrop` with precise drop checking. This is the only const
// check performed after the promotion. Verify that with an assertion.
assert!(promoted.is_none() || Q::ALLOW_PROMOTED);
// Don't peek inside trait associated constants.
if cx.tcx.trait_of_item(def.did).is_none() {
if promoted.is_none() && cx.tcx.trait_of_item(def.did).is_none() {
let qualifs = if let Some((did, param_did)) = def.as_const_arg() {
cx.tcx.at(constant.span).mir_const_qualif_const_arg((did, param_did))
} else {
Expand Down
36 changes: 26 additions & 10 deletions compiler/rustc_error_codes/src/error_codes/E0637.md
View file
@@ -1,35 +1,51 @@
An underscore `_` character has been used as the identifier for a lifetime.
`'_` lifetime name or `&T` without an explicit lifetime name has been used
on illegal place.

Erroneous code example:

```compile_fail,E0106,E0637
fn longest<'_>(str1: &'_ str, str2: &'_ str) -> &'_ str {
//^^ `'_` is a reserved lifetime name
fn underscore_lifetime<'_>(str1: &'_ str, str2: &'_ str) -> &'_ str {
//^^ `'_` is a reserved lifetime name
if str1.len() > str2.len() {
str1
} else {
str2
}
}
fn and_without_explicit_lifetime<T>()
where
T: Into<&u32>,
//^ `&` without an explicit lifetime name
{
}
```

`'_`, cannot be used as a lifetime identifier because it is a reserved for the
anonymous lifetime. To fix this, use a lowercase letter such as 'a, or a series
of lowercase letters such as `'foo`. For more information, see [the
book][bk-no]. For more information on using the anonymous lifetime in rust
nightly, see [the nightly book][bk-al].
First, `'_` cannot be used as a lifetime identifier in some places
because it is a reserved for the anonymous lifetime. Second, `&T`
without an explicit lifetime name cannot also be used in some places.
To fix them, use a lowercase letter such as `'a`, or a series
of lowercase letters such as `'foo`. For more information about lifetime
identifier, see [the book][bk-no]. For more information on using
the anonymous lifetime in Rust 2018, see [the Rust 2018 blog post][blog-al].

Corrected example:

```
fn longest<'a>(str1: &'a str, str2: &'a str) -> &'a str {
fn underscore_lifetime<'a>(str1: &'a str, str2: &'a str) -> &'a str {
if str1.len() > str2.len() {
str1
} else {
str2
}
}
fn and_without_explicit_lifetime<'foo, T>()
where
T: Into<&'foo u32>,
{
}
```

[bk-no]: https://doc.rust-lang.org/book/appendix-02-operators.html#non-operator-symbols
[bk-al]: https://doc.rust-lang.org/nightly/edition-guide/rust-2018/ownership-and-lifetimes/the-anonymous-lifetime.html
[blog-al]: https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html#more-lifetime-elision-rules
4 changes: 1 addition & 3 deletions compiler/rustc_expand/src/mbe/transcribe.rs
View file
Expand Up @@ -19,9 +19,7 @@ use std::mem;
struct Marker(LocalExpnId, Transparency);

impl MutVisitor for Marker {
fn token_visiting_enabled(&self) -> bool {
true
}
const VISIT_TOKENS: bool = true;

fn visit_span(&mut self, span: &mut Span) {
*span = span.apply_mark(self.0.to_expn_id(), self.1)
Expand Down
5 changes: 2 additions & 3 deletions compiler/rustc_expand/src/mut_visit/tests.rs
View file
Expand Up @@ -15,9 +15,8 @@ fn print_crate_items(krate: &ast::Crate) -> String {
struct ToZzIdentMutVisitor;

impl MutVisitor for ToZzIdentMutVisitor {
fn token_visiting_enabled(&self) -> bool {
true
}
const VISIT_TOKENS: bool = true;

fn visit_ident(&mut self, ident: &mut Ident) {
*ident = Ident::from_str("zz");
}
Expand Down
3 changes: 1 addition & 2 deletions compiler/rustc_lint/src/array_into_iter.rs
View file
Expand Up @@ -134,9 +134,8 @@ impl<'tcx> LateLintPass<'tcx> for ArrayIntoIter {
Applicability::MachineApplicable,
);
if self.for_expr_span == expr.span {
let expr_span = expr.span.ctxt().outer_expn_data().call_site;
diag.span_suggestion(
receiver_arg.span.shrink_to_hi().to(expr_span.shrink_to_hi()),
receiver_arg.span.shrink_to_hi().to(expr.span.shrink_to_hi()),
"or remove `.into_iter()` to iterate by value",
String::new(),
Applicability::MaybeIncorrect,
Expand Down

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