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Use more slice patterns inside the compiler

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This commit is contained in:
León Orell Valerian Liehr 2024-08-07 12:41:49 +02:00
parent 60d146580c
commit c4c518d2d4
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GPG key ID: D17A07215F68E713
40 changed files with 191 additions and 221 deletions
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12
compiler/rustc_ast/src/ast.rs
View file

@ -585,7 +585,9 @@ pub fn to_ty(&self) -> Option<P<Ty>> {
}
// A slice/array pattern `[P]` can be reparsed as `[T]`, an unsized array,
// when `P` can be reparsed as a type `T`.
PatKind::Slice(pats) if pats.len() == 1 => pats[0].to_ty().map(TyKind::Slice)?,
PatKind::Slice(pats) if let [pat] = pats.as_slice() => {
pat.to_ty().map(TyKind::Slice)?
}
// A tuple pattern `(P0, .., Pn)` can be reparsed as `(T0, .., Tn)`
// assuming `T0` to `Tn` are all syntactically valid as types.
PatKind::Tuple(pats) => {
@ -1187,8 +1189,8 @@ impl Expr {
/// Does not ensure that the path resolves to a const param, the caller should check this.
pub fn is_potential_trivial_const_arg(&self) -> bool {
let this = if let ExprKind::Block(block, None) = &self.kind
&& block.stmts.len() == 1
&& let StmtKind::Expr(expr) = &block.stmts[0].kind
&& let [stmt] = block.stmts.as_slice()
&& let StmtKind::Expr(expr) = &stmt.kind
{
expr
} else {
@ -1248,7 +1250,9 @@ pub fn to_ty(&self) -> Option<P<Ty>> {
expr.to_ty().map(|ty| TyKind::Array(ty, expr_len.clone()))?
}
ExprKind::Array(exprs) if exprs.len() == 1 => exprs[0].to_ty().map(TyKind::Slice)?,
ExprKind::Array(exprs) if let [expr] = exprs.as_slice() => {
expr.to_ty().map(TyKind::Slice)?
}
ExprKind::Tup(exprs) => {
let tys = exprs.iter().map(|expr| expr.to_ty()).collect::<Option<ThinVec<_>>>()?;

4
compiler/rustc_ast_lowering/src/delegation.rs
View file

@ -275,8 +275,8 @@ fn lower_delegation_body(
// FIXME(fn_delegation): Alternatives for target expression lowering:
// https://github.com/rust-lang/rfcs/pull/3530#issuecomment-2197170600.
fn lower_target_expr(&mut self, block: &Block) -> hir::Expr<'hir> {
if block.stmts.len() == 1
&& let StmtKind::Expr(expr) = &block.stmts[0].kind
if let [stmt] = block.stmts.as_slice()
&& let StmtKind::Expr(expr) = &stmt.kind
{
return self.lower_expr_mut(expr);
}

4
compiler/rustc_ast_pretty/src/pprust/state.rs
View file

@ -502,8 +502,8 @@ fn print_comment(&mut self, cmnt: Comment) {
if !self.is_beginning_of_line() {
self.word(" ");
}
if cmnt.lines.len() == 1 {
self.word(cmnt.lines[0].clone());
if let [line] = cmnt.lines.as_slice() {
self.word(line.clone());
self.hardbreak()
} else {
self.visual_align();

4
compiler/rustc_ast_pretty/src/pprust/state/item.rs
View file

@ -783,8 +783,8 @@ fn print_use_tree(&mut self, tree: &ast::UseTree) {
}
if items.is_empty() {
self.word("{}");
} else if items.len() == 1 {
self.print_use_tree(&items[0].0);
} else if let [(item, _)] = items.as_slice() {
self.print_use_tree(item);
} else {
self.cbox(INDENT_UNIT);
self.word("{");

14
compiler/rustc_attr/src/builtin.rs
View file

@ -665,12 +665,12 @@ pub fn eval_condition(
res & eval_condition(mi.meta_item().unwrap(), sess, features, eval)
}),
sym::not => {
if mis.len() != 1 {
let [mi] = mis.as_slice() else {
dcx.emit_err(session_diagnostics::ExpectedOneCfgPattern { span: cfg.span });
return false;
}
};
!eval_condition(mis[0].meta_item().unwrap(), sess, features, eval)
!eval_condition(mi.meta_item().unwrap(), sess, features, eval)
}
sym::target => {
if let Some(features) = features
@ -1051,10 +1051,10 @@ pub fn parse_repr_attr(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
MetaItemKind::List(nested_items) => {
if meta_item.has_name(sym::align) {
recognised = true;
if nested_items.len() == 1 {
if let [nested_item] = nested_items.as_slice() {
sess.dcx().emit_err(
session_diagnostics::IncorrectReprFormatExpectInteger {
span: nested_items[0].span(),
span: nested_item.span(),
},
);
} else {
@ -1066,10 +1066,10 @@ pub fn parse_repr_attr(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
}
} else if meta_item.has_name(sym::packed) {
recognised = true;
if nested_items.len() == 1 {
if let [nested_item] = nested_items.as_slice() {
sess.dcx().emit_err(
session_diagnostics::IncorrectReprFormatPackedExpectInteger {
span: nested_items[0].span(),
span: nested_item.span(),
},
);
} else {

4
compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs
View file

@ -206,8 +206,8 @@ pub(crate) fn add_suggestion(&self, mbcx: &mut MirBorrowckCtxt<'_, '_, '_, '_>)
// If there is exactly one suggestable constraints, then just suggest it. Otherwise, emit a
// list of diagnostics.
let mut diag = if suggested.len() == 1 {
mbcx.dcx().struct_help(match suggested.last().unwrap() {
let mut diag = if let [constraint] = suggested.as_slice() {
mbcx.dcx().struct_help(match constraint {
SuggestedConstraint::Outlives(a, bs) => {
let bs: SmallVec<[String; 2]> = bs.iter().map(|r| r.to_string()).collect();
format!("add bound `{a}: {}`", bs.join(" + "))

7
compiler/rustc_builtin_macros/src/asm.rs
View file

@ -745,10 +745,9 @@ fn expand_preparsed_asm(
unused_operands.push((args.operands[idx].1, msg));
}
}
match unused_operands.len() {
0 => {}
1 => {
let (sp, msg) = unused_operands.into_iter().next().unwrap();
match unused_operands[..] {
[] => {}
[(sp, msg)] => {
ecx.dcx()
.struct_span_err(sp, msg)
.with_span_label(sp, msg)

8
compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
View file

@ -378,8 +378,8 @@ fn into_expr(self, cx: &ExtCtxt<'_>, span: Span) -> P<Expr> {
None => cx.expr_block(cx.block(span, ThinVec::new())),
Some(expr) => expr,
}
} else if self.0.len() == 1
&& let ast::StmtKind::Expr(expr) = &self.0[0].kind
} else if let [stmt] = self.0.as_slice()
&& let ast::StmtKind::Expr(expr) = &stmt.kind
&& self.1.is_none()
{
// There's only a single statement expression. Pull it out.
@ -1273,7 +1273,7 @@ fn expand_enum_method_body<'b>(
}
FieldlessVariantsStrategy::Default => (),
}
} else if variants.len() == 1 {
} else if let [variant] = variants.as_slice() {
// If there is a single variant, we don't need an operation on
// the discriminant(s). Just use the most degenerate result.
return self.call_substructure_method(
@ -1281,7 +1281,7 @@ fn expand_enum_method_body<'b>(
trait_,
type_ident,
nonselflike_args,
&EnumMatching(0, &variants[0], Vec::new()),
&EnumMatching(0, variant, Vec::new()),
);
}
}

8
compiler/rustc_builtin_macros/src/format.rs
View file

@ -180,8 +180,8 @@ fn make_format_args(
Ok((mut err, suggested)) => {
if !suggested {
if let ExprKind::Block(block, None) = &efmt.kind
&& block.stmts.len() == 1
&& let StmtKind::Expr(expr) = &block.stmts[0].kind
&& let [stmt] = block.stmts.as_slice()
&& let StmtKind::Expr(expr) = &stmt.kind
&& let ExprKind::Path(None, path) = &expr.kind
&& path.is_potential_trivial_const_arg()
{
@ -196,8 +196,8 @@ fn make_format_args(
} else {
let sugg_fmt = match args.explicit_args().len() {
0 => "{}".to_string(),
_ => {
format!("{}{{}}", "{} ".repeat(args.explicit_args().len()))
count => {
format!("{}{{}}", "{} ".repeat(count))
}
};
err.span_suggestion(

6
compiler/rustc_data_structures/src/transitive_relation.rs
View file

@ -203,9 +203,9 @@ pub fn postdom_upper_bound(&self, a: T, b: T) -> Option<T> {
/// exists). See `postdom_upper_bound` for details.
pub fn mutual_immediate_postdominator(&self, mut mubs: Vec<T>) -> Option<T> {
loop {
match mubs.len() {
0 => return None,
1 => return Some(mubs[0]),
match mubs[..] {
[] => return None,
[mub] => return Some(mub),
_ => {
let m = mubs.pop().unwrap();
let n = mubs.pop().unwrap();

55
compiler/rustc_driver_impl/src/lib.rs
View file

@ -335,12 +335,11 @@ fn run_compiler(
config.input = input;
true // has input: normal compilation
}
Ok(None) => match matches.free.len() {
0 => false, // no input: we will exit early
1 => panic!("make_input should have provided valid inputs"),
_ => default_early_dcx.early_fatal(format!(
"multiple input filenames provided (first two filenames are `{}` and `{}`)",
matches.free[0], matches.free[1],
Ok(None) => match matches.free.as_slice() {
[] => false, // no input: we will exit early
[_] => panic!("make_input should have provided valid inputs"),
[fst, snd, ..] => default_early_dcx.early_fatal(format!(
"multiple input filenames provided (first two filenames are `{fst}` and `{snd}`)"
)),
},
};
@ -488,34 +487,30 @@ fn make_input(
early_dcx: &EarlyDiagCtxt,
free_matches: &[String],
) -> Result<Option<Input>, ErrorGuaranteed> {
if free_matches.len() == 1 {
let ifile = &free_matches[0];
if ifile == "-" {
let mut src = String::new();
if io::stdin().read_to_string(&mut src).is_err() {
// Immediately stop compilation if there was an issue reading
// the input (for example if the input stream is not UTF-8).
let reported = early_dcx
.early_err("couldn't read from stdin, as it did not contain valid UTF-8");
return Err(reported);
}
if let Ok(path) = env::var("UNSTABLE_RUSTDOC_TEST_PATH") {
let line = env::var("UNSTABLE_RUSTDOC_TEST_LINE").expect(
"when UNSTABLE_RUSTDOC_TEST_PATH is set \
let [ifile] = free_matches else { return Ok(None) };
if ifile == "-" {
let mut src = String::new();
if io::stdin().read_to_string(&mut src).is_err() {
// Immediately stop compilation if there was an issue reading
// the input (for example if the input stream is not UTF-8).
let reported =
early_dcx.early_err("couldn't read from stdin, as it did not contain valid UTF-8");
return Err(reported);
}
if let Ok(path) = env::var("UNSTABLE_RUSTDOC_TEST_PATH") {
let line = env::var("UNSTABLE_RUSTDOC_TEST_LINE").expect(
"when UNSTABLE_RUSTDOC_TEST_PATH is set \
UNSTABLE_RUSTDOC_TEST_LINE also needs to be set",
);
let line = isize::from_str_radix(&line, 10)
.expect("UNSTABLE_RUSTDOC_TEST_LINE needs to be an number");
let file_name = FileName::doc_test_source_code(PathBuf::from(path), line);
Ok(Some(Input::Str { name: file_name, input: src }))
} else {
Ok(Some(Input::Str { name: FileName::anon_source_code(&src), input: src }))
}
);
let line = isize::from_str_radix(&line, 10)
.expect("UNSTABLE_RUSTDOC_TEST_LINE needs to be an number");
let file_name = FileName::doc_test_source_code(PathBuf::from(path), line);
Ok(Some(Input::Str { name: file_name, input: src }))
} else {
Ok(Some(Input::File(PathBuf::from(ifile))))
Ok(Some(Input::Str { name: FileName::anon_source_code(&src), input: src }))
}
} else {
Ok(None)
Ok(Some(Input::File(PathBuf::from(ifile))))
}
}

29
compiler/rustc_errors/src/emitter.rs
View file

@ -231,17 +231,17 @@ fn primary_span_formatted(
) {
if let Some((sugg, rest)) = suggestions.split_first() {
let msg = self.translate_message(&sugg.msg, fluent_args).map_err(Report::new).unwrap();
if rest.is_empty() &&
if rest.is_empty()
// ^ if there is only one suggestion
// don't display multi-suggestions as labels
sugg.substitutions.len() == 1 &&
&& let [substitution] = sugg.substitutions.as_slice()
// don't display multipart suggestions as labels
sugg.substitutions[0].parts.len() == 1 &&
&& let [part] = substitution.parts.as_slice()
// don't display long messages as labels
msg.split_whitespace().count() < 10 &&
&& msg.split_whitespace().count() < 10
// don't display multiline suggestions as labels
!sugg.substitutions[0].parts[0].snippet.contains('\n') &&
![
&& !part.snippet.contains('\n')
&& ![
// when this style is set we want the suggestion to be a message, not inline
SuggestionStyle::HideCodeAlways,
// trivial suggestion for tooling's sake, never shown
@ -250,8 +250,8 @@ fn primary_span_formatted(
SuggestionStyle::ShowAlways,
].contains(&sugg.style)
{
let substitution = &sugg.substitutions[0].parts[0].snippet.trim();
let msg = if substitution.is_empty() || sugg.style.hide_inline() {
let snippet = part.snippet.trim();
let msg = if snippet.is_empty() || sugg.style.hide_inline() {
// This substitution is only removal OR we explicitly don't want to show the
// code inline (`hide_inline`). Therefore, we don't show the substitution.
format!("help: {msg}")
@ -260,19 +260,18 @@ fn primary_span_formatted(
format!(
"help: {}{}: `{}`",
msg,
if self.source_map().is_some_and(|sm| is_case_difference(
sm,
substitution,
sugg.substitutions[0].parts[0].span,
)) {
if self
.source_map()
.is_some_and(|sm| is_case_difference(sm, snippet, part.span,))
{
" (notice the capitalization)"
} else {
""
},
substitution,
snippet,
)
};
primary_span.push_span_label(sugg.substitutions[0].parts[0].span, msg);
primary_span.push_span_label(part.span, msg);
// We return only the modified primary_span
suggestions.clear();

10
compiler/rustc_errors/src/lib.rs
View file

@ -2024,11 +2024,11 @@ pub fn a_or_an(s: &str) -> &'static str {
///
/// Take a list ["a", "b", "c"] and output a display friendly version "a, b and c"
pub fn display_list_with_comma_and<T: std::fmt::Display>(v: &[T]) -> String {
match v.len() {
0 => "".to_string(),
1 => v[0].to_string(),
2 => format!("{} and {}", v[0], v[1]),
_ => format!("{}, {}", v[0], display_list_with_comma_and(&v[1..])),
match v {
[] => "".to_string(),
[a] => a.to_string(),
[a, b] => format!("{a} and {b}"),
[a, v @ ..] => format!("{a}, {}", display_list_with_comma_and(v)),
}
}

8
compiler/rustc_expand/src/base.rs
View file

@ -1306,12 +1306,12 @@ pub fn parse_macro_name_and_helper_attrs(
// that it's of the form `#[proc_macro_derive(Foo)]` or
// `#[proc_macro_derive(Foo, attributes(A, ..))]`
let list = attr.meta_item_list()?;
if list.len() != 1 && list.len() != 2 {
let ([trait_attr] | [trait_attr, _]) = list.as_slice() else {
dcx.emit_err(errors::AttrNoArguments { span: attr.span });
return None;
}
let Some(trait_attr) = list[0].meta_item() else {
dcx.emit_err(errors::NotAMetaItem { span: list[0].span() });
};
let Some(trait_attr) = trait_attr.meta_item() else {
dcx.emit_err(errors::NotAMetaItem { span: trait_attr.span() });
return None;
};
let trait_ident = match trait_attr.ident() {

11
compiler/rustc_hir_typeck/src/expr.rs
View file

@ -2734,15 +2734,8 @@ fn ban_take_value_of_method(
} else if let ty::RawPtr(ptr_ty, _) = expr_t.kind()
&& let ty::Adt(adt_def, _) = ptr_ty.kind()
&& let ExprKind::Field(base_expr, _) = expr.kind
&& adt_def.variants().len() == 1
&& adt_def
.variants()
.iter()
.next()
.unwrap()
.fields
.iter()
.any(|f| f.ident(self.tcx) == field)
&& let [variant] = &adt_def.variants().raw
&& variant.fields.iter().any(|f| f.ident(self.tcx) == field)
{
err.multipart_suggestion(
"to access the field, dereference first",

8
compiler/rustc_hir_typeck/src/method/confirm.rs
View file

@ -654,17 +654,17 @@ fn upcast(
traits::upcast_choices(self.tcx, source_trait_ref, target_trait_def_id);
// must be exactly one trait ref or we'd get an ambig error etc
if upcast_trait_refs.len() != 1 {
let [upcast_trait_ref] = upcast_trait_refs.as_slice() else {
span_bug!(
self.span,
"cannot uniquely upcast `{:?}` to `{:?}`: `{:?}`",
source_trait_ref,
target_trait_def_id,
upcast_trait_refs
);
}
)
};
upcast_trait_refs.into_iter().next().unwrap()
*upcast_trait_ref
}
fn instantiate_binder_with_fresh_vars<T>(&self, value: ty::Binder<'tcx, T>) -> T

43
compiler/rustc_hir_typeck/src/method/suggest.rs
View file

@ -321,19 +321,18 @@ pub fn report_method_error(
);
};
let suggest_for_privacy =
|err: &mut Diag<'_>, mut msg: String, sugg: Vec<String>| {
if sugg.len() == 1 {
let msg = format!("\
|err: &mut Diag<'_>, mut msg: String, suggs: Vec<String>| {
if let [sugg] = suggs.as_slice() {
err.help(format!("\
trait `{}` provides `{item_name}` is implemented but not reachable",
sugg[0].trim()
);
err.help(msg);
sugg.trim(),
));
} else {
msg += &format!(" but {} not reachable", pluralize!("is", sugg.len()));
msg += &format!(" but {} not reachable", pluralize!("is", suggs.len()));
err.span_suggestions(
span,
msg,
sugg,
suggs,
Applicability::MaybeIncorrect,
);
}
@ -2988,11 +2987,11 @@ pub(crate) fn note_unmet_impls_on_type(
}
}
if local_spans.primary_span().is_some() {
let msg = if local_preds.len() == 1 {
let msg = if let [local_pred] = local_preds.as_slice() {
format!(
"an implementation of `{}` might be missing for `{}`",
local_preds[0].trait_ref.print_trait_sugared(),
local_preds[0].self_ty()
local_pred.trait_ref.print_trait_sugared(),
local_pred.self_ty()
)
} else {
format!(
@ -3034,11 +3033,11 @@ pub(crate) fn note_unmet_impls_on_type(
}
}
if foreign_spans.primary_span().is_some() {
let msg = if foreign_preds.len() == 1 {
let msg = if let [foreign_pred] = foreign_preds.as_slice() {
format!(
"the foreign item type `{}` doesn't implement `{}`",
foreign_preds[0].self_ty(),
foreign_preds[0].trait_ref.print_trait_sugared()
foreign_pred.self_ty(),
foreign_pred.trait_ref.print_trait_sugared()
)
} else {
format!(
@ -3388,26 +3387,26 @@ fn suggest_valid_traits(
);
self.suggest_use_candidates(candidates, |accessible_sugg, inaccessible_sugg, span| {
let suggest_for_access = |err: &mut Diag<'_>, mut msg: String, sugg: Vec<_>| {
let suggest_for_access = |err: &mut Diag<'_>, mut msg: String, suggs: Vec<_>| {
msg += &format!(
"; perhaps you want to import {one_of}",
one_of = if sugg.len() == 1 { "it" } else { "one of them" },
one_of = if suggs.len() == 1 { "it" } else { "one of them" },
);
err.span_suggestions(span, msg, sugg, Applicability::MaybeIncorrect);
err.span_suggestions(span, msg, suggs, Applicability::MaybeIncorrect);
};
let suggest_for_privacy = |err: &mut Diag<'_>, sugg: Vec<String>| {
let suggest_for_privacy = |err: &mut Diag<'_>, suggs: Vec<String>| {
let msg = format!(
"{this_trait_is} implemented but not reachable",
this_trait_is = if sugg.len() == 1 {
format!("trait `{}` which provides `{item_name}` is", sugg[0].trim())
this_trait_is = if let [sugg] = suggs.as_slice() {
format!("trait `{}` which provides `{item_name}` is", sugg.trim())
} else {
format!("the following traits which provide `{item_name}` are")
}
);
if sugg.len() == 1 {
if suggs.len() == 1 {
err.help(msg);
} else {
err.span_suggestions(span, msg, sugg, Applicability::MaybeIncorrect);
err.span_suggestions(span, msg, suggs, Applicability::MaybeIncorrect);
}
};
if accessible_sugg.is_empty() {

4
compiler/rustc_lint/src/nonstandard_style.rs
View file

@ -527,11 +527,11 @@ fn check_pat(&mut self, cx: &LateContext<'_>, p: &hir::Pat<'_>) {
// Lint for constants that look like binding identifiers (#7526)
if let PatKind::Path(hir::QPath::Resolved(None, path)) = p.kind {
if let Res::Def(DefKind::Const, _) = path.res {
if path.segments.len() == 1 {
if let [segment] = path.segments {
NonUpperCaseGlobals::check_upper_case(
cx,
"constant in pattern",
&path.segments[0].ident,
&segment.ident,
);
}
}

9
compiler/rustc_lint/src/types.rs
View file

@ -211,15 +211,12 @@ fn lint_overflowing_range_endpoint<'tcx>(
if !is_range_literal(struct_expr) {
return false;
};
let ExprKind::Struct(_, eps, _) = &struct_expr.kind else { return false };
if eps.len() != 2 {
return false;
}
let ExprKind::Struct(_, [start, end], _) = &struct_expr.kind else { return false };
// We can suggest using an inclusive range
// (`..=`) instead only if it is the `end` that is
// overflowing and only by 1.
if !(eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max) {
if !(end.expr.hir_id == expr.hir_id && lit_val - 1 == max) {
return false;
};
@ -232,7 +229,7 @@ fn lint_overflowing_range_endpoint<'tcx>(
};
let sub_sugg = if expr.span.lo() == lit_span.lo() {
let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) else { return false };
let Ok(start) = cx.sess().source_map().span_to_snippet(start.span) else { return false };
UseInclusiveRange::WithoutParen {
sugg: struct_expr.span.shrink_to_lo().to(lit_span.shrink_to_hi()),
start,

10
compiler/rustc_lint/src/unused.rs
View file

@ -801,7 +801,7 @@ fn visit_expr(&mut self, expr: &'ast ast::Expr) -> ControlFlow<()> {
return;
}
let spans = match value.kind {
ast::ExprKind::Block(ref block, None) if block.stmts.len() == 1 => block.stmts[0]
ast::ExprKind::Block(ref block, None) if let [stmt] = block.stmts.as_slice() => stmt
.span
.find_ancestor_inside(value.span)
.map(|span| (value.span.with_hi(span.lo()), value.span.with_lo(span.hi()))),
@ -1537,14 +1537,12 @@ fn check_use_tree(&self, cx: &EarlyContext<'_>, use_tree: &ast::UseTree, item: &
}
// Trigger the lint only if there is one nested item
if items.len() != 1 {
return;
}
let [(tree, _)] = items.as_slice() else { return };
// Trigger the lint if the nested item is a non-self single item
let node_name = match items[0].0.kind {
let node_name = match tree.kind {
ast::UseTreeKind::Simple(rename) => {
let orig_ident = items[0].0.prefix.segments.last().unwrap().ident;
let orig_ident = tree.prefix.segments.last().unwrap().ident;
if orig_ident.name == kw::SelfLower {
return;
}

6
compiler/rustc_mir_build/src/thir/pattern/check_match.rs
View file

@ -483,9 +483,11 @@ fn check_match(
// Check if the match is exhaustive.
let witnesses = report.non_exhaustiveness_witnesses;
if !witnesses.is_empty() {
if source == hir::MatchSource::ForLoopDesugar && arms.len() == 2 {
if source == hir::MatchSource::ForLoopDesugar
&& let [_, snd_arm] = *arms
{
// the for loop pattern is not irrefutable
let pat = &self.thir[arms[1]].pattern;
let pat = &self.thir[snd_arm].pattern;
// `pat` should be `Some(<pat_field>)` from a desugared for loop.
debug_assert_eq!(pat.span.desugaring_kind(), Some(DesugaringKind::ForLoop));
let PatKind::Variant { ref subpatterns, .. } = pat.kind else { bug!() };

4
compiler/rustc_mir_transform/src/coverage/graph.rs
View file

@ -350,8 +350,8 @@ fn bcb_filtered_successors<'a, 'tcx>(terminator: &'a Terminator<'tcx>) -> Covera
// An inline asm terminator can normally be chained, except when it diverges or uses asm
// goto.
InlineAsm { ref targets, .. } => {
if targets.len() == 1 {
CoverageSuccessors::Chainable(targets[0])
if let [target] = targets[..] {
CoverageSuccessors::Chainable(target)
} else {
CoverageSuccessors::NotChainable(targets)
}

6
compiler/rustc_mir_transform/src/early_otherwise_branch.rs
View file

@ -309,11 +309,11 @@ fn verify_candidate_branch<'tcx>(
) -> bool {
// In order for the optimization to be correct, the branch must...
// ...have exactly one statement
if branch.statements.len() != 1 {
let [statement] = branch.statements.as_slice() else {
return false;
}
};
// ...assign the discriminant of `place` in that statement
let StatementKind::Assign(boxed) = &branch.statements[0].kind else { return false };
let StatementKind::Assign(boxed) = &statement.kind else { return false };
let (discr_place, Rvalue::Discriminant(from_place)) = &**boxed else { return false };
if *from_place != place {
return false;

6
compiler/rustc_mir_transform/src/instsimplify.rs
View file

@ -264,9 +264,7 @@ fn simplify_primitive_clone(
};
// It's definitely not a clone if there are multiple arguments
if args.len() != 1 {
return;
}
let [arg] = &args[..] else { return };
let Some(destination_block) = *target else { return };
@ -280,7 +278,7 @@ fn simplify_primitive_clone(
// These types are easily available from locals, so check that before
// doing DefId lookups to figure out what we're actually calling.
let arg_ty = args[0].node.ty(self.local_decls, self.tcx);
let arg_ty = arg.node.ty(self.local_decls, self.tcx);
let ty::Ref(_region, inner_ty, Mutability::Not) = *arg_ty.kind() else { return };

14
compiler/rustc_mir_transform/src/validate.rs
View file

@ -898,8 +898,8 @@ macro_rules! check_kinds {
self.param_env,
adt_def.non_enum_variant().fields[field].ty(self.tcx, args),
);
if fields.len() == 1 {
let src_ty = fields.raw[0].ty(self.body, self.tcx);
if let [field] = fields.raw.as_slice() {
let src_ty = field.ty(self.body, self.tcx);
if !self.mir_assign_valid_types(src_ty, dest_ty) {
self.fail(location, "union field has the wrong type");
}
@ -967,11 +967,9 @@ macro_rules! check_kinds {
self.fail(location, "RawPtr should be in runtime MIR only");
}
if fields.len() != 2 {
self.fail(location, "raw pointer aggregate must have 2 fields");
} else {
let data_ptr_ty = fields.raw[0].ty(self.body, self.tcx);
let metadata_ty = fields.raw[1].ty(self.body, self.tcx);
if let [data_ptr, metadata] = fields.raw.as_slice() {
let data_ptr_ty = data_ptr.ty(self.body, self.tcx);
let metadata_ty = metadata.ty(self.body, self.tcx);
if let ty::RawPtr(in_pointee, in_mut) = data_ptr_ty.kind() {
if *in_mut != mutability {
self.fail(location, "input and output mutability must match");
@ -998,6 +996,8 @@ macro_rules! check_kinds {
self.fail(location, "metadata for pointer-to-thin must be unit");
}
}
} else {
self.fail(location, "raw pointer aggregate must have 2 fields");
}
}
},

6
compiler/rustc_parse/src/parser/expr.rs
View file

@ -694,12 +694,12 @@ fn parse_assoc_op_cast(
// `foo: `
ExprKind::Path(None, ast::Path { segments, .. }),
token::Ident(kw::For | kw::Loop | kw::While, IdentIsRaw::No),
) if segments.len() == 1 => {
) if let [segment] = segments.as_slice() => {
let snapshot = self.create_snapshot_for_diagnostic();
let label = Label {
ident: Ident::from_str_and_span(
&format!("'{}", segments[0].ident),
segments[0].ident.span,
&format!("'{}", segment.ident),
segment.ident.span,
),
};
match self.parse_expr_labeled(label, false) {

5
compiler/rustc_parse/src/parser/item.rs
View file

@ -471,9 +471,8 @@ fn parse_item_macro(&mut self, vis: &Visibility) -> PResult<'a, MacCall> {
Err(mut err) => {
// Maybe the user misspelled `macro_rules` (issue #91227)
if self.token.is_ident()
&& path.segments.len() == 1
&& edit_distance("macro_rules", &path.segments[0].ident.to_string(), 2)
.is_some()
&& let [segment] = path.segments.as_slice()
&& edit_distance("macro_rules", &segment.ident.to_string(), 2).is_some()
{
err.span_suggestion(
path.span,

3
compiler/rustc_parse/src/parser/path.rs
View file

@ -826,7 +826,8 @@ pub(super) fn expr_is_valid_const_arg(&self, expr: &P<rustc_ast::Expr>) -> bool
// We can only resolve single-segment paths at the moment, because multi-segment paths
// require type-checking: see `visit_generic_arg` in `src/librustc_resolve/late.rs`.
ast::ExprKind::Path(None, path)
if path.segments.len() == 1 && path.segments[0].args.is_none() =>
if let [segment] = path.segments.as_slice()
&& segment.args.is_none() =>
{
true
}

6
compiler/rustc_parse/src/parser/stmt.rs
View file

@ -672,7 +672,7 @@ pub fn parse_full_stmt(
match &expr.kind {
ExprKind::Path(None, ast::Path { segments, .. })
if segments.len() == 1 =>
if let [segment] = segments.as_slice() =>
{
if self.token == token::Colon
&& self.look_ahead(1, |token| {
@ -689,8 +689,8 @@ pub fn parse_full_stmt(
let snapshot = self.create_snapshot_for_diagnostic();
let label = Label {
ident: Ident::from_str_and_span(
&format!("'{}", segments[0].ident),
segments[0].ident.span,
&format!("'{}", segment.ident),
segment.ident.span,
),
};
match self.parse_expr_labeled(label, false) {

4
compiler/rustc_passes/src/check_attr.rs
View file

@ -2207,8 +2207,8 @@ fn check_unused_attribute(&self, hir_id: HirId, attr: &Attribute) {
attr.name_or_empty(),
sym::allow | sym::warn | sym::deny | sym::forbid | sym::expect
) && let Some(meta) = attr.meta_item_list()
&& meta.len() == 1
&& let Some(item) = meta[0].meta_item()
&& let [meta] = meta.as_slice()
&& let Some(item) = meta.meta_item()
&& let MetaItemKind::NameValue(_) = &item.kind
&& item.path == sym::reason
{

4
compiler/rustc_passes/src/debugger_visualizer.rs
View file

@ -19,9 +19,7 @@ fn check_for_debugger_visualizer(&mut self, attr: &Attribute) {
return;
};
let hint = if hints.len() == 1 {
&hints[0]
} else {
let [hint] = hints.as_slice() else {
self.sess.dcx().emit_err(DebugVisualizerInvalid { span: attr.span });
return;
};

11
compiler/rustc_query_system/src/dep_graph/debug.rs
View file

@ -46,15 +46,14 @@ pub struct EdgeFilter {
impl EdgeFilter {
pub fn new(test: &str) -> Result<EdgeFilter, Box<dyn Error>> {
let parts: Vec<_> = test.split("->").collect();
if parts.len() != 2 {
Err(format!("expected a filter like `a&b -> c&d`, not `{test}`").into())
} else {
if let [source, target] = *test.split("->").collect::<Vec<_>>() {
Ok(EdgeFilter {
source: DepNodeFilter::new(parts[0]),
target: DepNodeFilter::new(parts[1]),
source: DepNodeFilter::new(source),
target: DepNodeFilter::new(target),
index_to_node: Lock::new(FxHashMap::default()),
})
} else {
Err(format!("expected a filter like `a&b -> c&d`, not `{test}`").into())
}
}

20
compiler/rustc_resolve/src/late.rs
View file

@ -445,8 +445,8 @@ fn descr_expected(self) -> &'static str {
Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
// the case of `::some_crate()`
ExprKind::Path(_, path)
if path.segments.len() == 2
&& path.segments[0].ident.name == kw::PathRoot =>
if let [segment, _] = path.segments.as_slice()
&& segment.ident.name == kw::PathRoot =>
{
"external crate"
}
@ -2395,15 +2395,14 @@ fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
}
fn future_proof_import(&mut self, use_tree: &UseTree) {
let segments = &use_tree.prefix.segments;
if !segments.is_empty() {
let ident = segments[0].ident;
if let [segment, rest @ ..] = use_tree.prefix.segments.as_slice() {
let ident = segment.ident;
if ident.is_path_segment_keyword() || ident.span.is_rust_2015() {
return;
}
let nss = match use_tree.kind {
UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
UseTreeKind::Simple(..) if rest.is_empty() => &[TypeNS, ValueNS][..],
_ => &[TypeNS],
};
let report_error = |this: &Self, ns| {
@ -3999,16 +3998,15 @@ fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
if this.should_report_errs() {
if candidates.is_empty() {
if path.len() == 2 && prefix_path.len() == 1 {
if path.len() == 2
&& let [segment] = prefix_path
{
// Delay to check whether methond name is an associated function or not
// ```
// let foo = Foo {};
// foo::bar(); // possibly suggest to foo.bar();
//```
err.stash(
prefix_path[0].ident.span,
rustc_errors::StashKey::CallAssocMethod,
);
err.stash(segment.ident.span, rustc_errors::StashKey::CallAssocMethod);
} else {
// When there is no suggested imports, we can just emit the error
// and suggestions immediately. Note that we bypass the usually error

13
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -650,14 +650,14 @@ fn try_lookup_name_relaxed(
let typo_sugg = self
.lookup_typo_candidate(path, following_seg, source.namespace(), is_expected)
.to_opt_suggestion();
if path.len() == 1
if let [segment] = path
&& !matches!(source, PathSource::Delegation)
&& self.self_type_is_available()
{
if let Some(candidate) =
self.lookup_assoc_candidate(ident, ns, is_expected, source.is_call())
{
let self_is_available = self.self_value_is_available(path[0].ident.span);
let self_is_available = self.self_value_is_available(segment.ident.span);
// Account for `Foo { field }` when suggesting `self.field` so we result on
// `Foo { field: self.field }`.
let pre = match source {
@ -665,7 +665,7 @@ fn try_lookup_name_relaxed(
if expr
.fields
.iter()
.any(|f| f.ident == path[0].ident && f.is_shorthand) =>
.any(|f| f.ident == segment.ident && f.is_shorthand) =>
{
format!("{path_str}: ")
}
@ -1258,8 +1258,7 @@ fn get_single_associated_item(
)
})
.collect();
if targets.len() == 1 {
let target = targets[0];
if let [target] = targets.as_slice() {
return Some(TypoSuggestion::single_item_from_ident(target.0.ident, target.1));
}
}
@ -2104,8 +2103,8 @@ fn lookup_typo_candidate(
filter_fn: &impl Fn(Res) -> bool,
) -> TypoCandidate {
let mut names = Vec::new();
if path.len() == 1 {
let mut ctxt = path.last().unwrap().ident.span.ctxt();
if let [segment] = path {
let mut ctxt = segment.ident.span.ctxt();
// Search in lexical scope.
// Walk backwards up the ribs in scope and collect candidates.

10
compiler/rustc_resolve/src/macros.rs
View file

@ -108,8 +108,8 @@ enum SubNS {
// `format!("{}", path)`, because that tries to insert
// line-breaks and is slow.
fn fast_print_path(path: &ast::Path) -> Symbol {
if path.segments.len() == 1 {
path.segments[0].ident.name
if let [segment] = path.segments.as_slice() {
segment.ident.name
} else {
let mut path_str = String::with_capacity(64);
for (i, segment) in path.segments.iter().enumerate() {
@ -724,10 +724,10 @@ fn resolve_macro_or_delegation_path(
// Possibly apply the macro helper hack
if deleg_impl.is_none()
&& kind == Some(MacroKind::Bang)
&& path.len() == 1
&& path[0].ident.span.ctxt().outer_expn_data().local_inner_macros
&& let [segment] = path.as_slice()
&& segment.ident.span.ctxt().outer_expn_data().local_inner_macros
{
let root = Ident::new(kw::DollarCrate, path[0].ident.span);
let root = Ident::new(kw::DollarCrate, segment.ident.span);
path.insert(0, Segment::from_ident(root));
}

13
compiler/rustc_session/src/options.rs
View file

@ -912,16 +912,9 @@ pub(crate) fn parse_optimization_fuel(
match v {
None => false,
Some(s) => {
let parts = s.split('=').collect::<Vec<_>>();
if parts.len() != 2 {
return false;
}
let crate_name = parts[0].to_string();
let fuel = parts[1].parse::<u64>();
if fuel.is_err() {
return false;
}
*slot = Some((crate_name, fuel.unwrap()));
let [crate_name, fuel] = *s.split('=').collect::<Vec<_>>() else { return false };
let Ok(fuel) = fuel.parse::<u64>() else { return false };
*slot = Some((crate_name.to_string(), fuel));
true
}
}

9
compiler/rustc_target/src/spec/mod.rs
View file

@ -3149,11 +3149,10 @@ macro_rules! key {
if let Some(a) = o.as_array() {
for o in a {
if let Some(s) = o.as_str() {
let p = s.split('=').collect::<Vec<_>>();
if p.len() == 2 {
let k = p[0].to_string();
let v = p[1].to_string();
base.$key_name.to_mut().push((k.into(), v.into()));
if let [k, v] = *s.split('=').collect::<Vec<_>>() {
base.$key_name
.to_mut()
.push((k.to_string().into(), v.to_string().into()))
}
}
}

3
compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
View file

@ -943,8 +943,7 @@ fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) -> Self::Result {
// The current method call returns `Result<_, ()>`
&& self.can_eq(obligation.param_env, ty, found_ty)
// There's a single argument in the method call and it is a closure
&& args.len() == 1
&& let Some(arg) = args.get(0)
&& let [arg] = args
&& let hir::ExprKind::Closure(closure) = arg.kind
// The closure has a block for its body with no tail expression
&& let body = self.tcx.hir().body(closure.body)

8
compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
View file

@ -73,10 +73,10 @@ fn impl_similar_to(
}
});
let impl_def_id_and_args = if self_match_impls.len() == 1 {
self_match_impls[0]
} else if fuzzy_match_impls.len() == 1 {
fuzzy_match_impls[0]
let impl_def_id_and_args = if let [impl_] = self_match_impls[..] {
impl_
} else if let [impl_] = fuzzy_match_impls[..] {
impl_
} else {
return None;
};

3
compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
View file

@ -5300,7 +5300,8 @@ fn visit_ty(&mut self, ty: &hir::Ty<'_>) {
match ty.kind {
hir::TyKind::Ptr(_) | hir::TyKind::Ref(..) | hir::TyKind::TraitObject(..) => {}
hir::TyKind::Path(hir::QPath::Resolved(None, path))
if path.segments.len() == 1 && path.segments[0].ident.name == self.param =>
if let [segment] = path.segments
&& segment.ident.name == self.param =>
{
if !self.nested {
debug!(?ty, "FindTypeParam::visit_ty");