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Implement macro-based deref!() syntax for deref patterns

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Stop using `box PAT` syntax for deref patterns, as it's misleading and
also causes their semantics being tangled up.
This commit is contained in:
Michael Goulet 2024-03-20 16:53:50 -04:00
parent 2627e9f301
commit 2d633317f3
31 changed files with 123 additions and 35 deletions
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7
compiler/rustc_ast/src/ast.rs
View File

@ -621,7 +621,9 @@ pub fn walk(&self, it: &mut impl FnMut(&Pat) -> bool) {
| PatKind::Or(s) => s.iter().for_each(|p| p.walk(it)),
// Trivial wrappers over inner patterns.
PatKind::Box(s) | PatKind::Ref(s, _) | PatKind::Paren(s) => s.walk(it),
PatKind::Box(s) | PatKind::Deref(s) | PatKind::Ref(s, _) | PatKind::Paren(s) => {
s.walk(it)
}
// These patterns do not contain subpatterns, skip.
PatKind::Wild
@ -792,6 +794,9 @@ pub enum PatKind {
/// A `box` pattern.
Box(P<Pat>),
/// A `deref` pattern (currently `deref!()` macro-based syntax).
Deref(P<Pat>),
/// A reference pattern (e.g., `&mut (a, b)`).
Ref(P<Pat>, Mutability),

1
compiler/rustc_ast/src/mut_visit.rs
View File

@ -1295,6 +1295,7 @@ pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
fields.flat_map_in_place(|field| vis.flat_map_pat_field(field));
}
PatKind::Box(inner) => vis.visit_pat(inner),
PatKind::Deref(inner) => vis.visit_pat(inner),
PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
visit_opt(e1, |e| vis.visit_expr(e));

5
compiler/rustc_ast/src/visit.rs
View File

@ -576,7 +576,10 @@ pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) -> V::Res
try_visit!(visitor.visit_path(path, pattern.id));
walk_list!(visitor, visit_pat_field, fields);
}
PatKind::Box(subpattern) | PatKind::Ref(subpattern, _) | PatKind::Paren(subpattern) => {
PatKind::Box(subpattern)
| PatKind::Deref(subpattern)
| PatKind::Ref(subpattern, _)
| PatKind::Paren(subpattern) => {
try_visit!(visitor.visit_pat(subpattern));
}
PatKind::Ident(_, ident, optional_subpattern) => {

3
compiler/rustc_ast_lowering/src/pat.rs
View File

@ -91,6 +91,9 @@ fn lower_pat_mut(&mut self, mut pattern: &Pat) -> hir::Pat<'hir> {
PatKind::Box(inner) => {
break hir::PatKind::Box(self.lower_pat(inner));
}
PatKind::Deref(inner) => {
break hir::PatKind::Deref(self.lower_pat(inner));
}
PatKind::Ref(inner, mutbl) => {
break hir::PatKind::Ref(self.lower_pat(inner), *mutbl);
}

10
compiler/rustc_ast_passes/src/feature_gate.rs
View File

@ -413,10 +413,7 @@ fn visit_pat(&mut self, pattern: &'a ast::Pat) {
}
}
PatKind::Box(..) => {
if !self.features.deref_patterns {
// Allow box patterns under `deref_patterns`.
gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
}
gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
}
PatKind::Range(_, Some(_), Spanned { node: RangeEnd::Excluded, .. }) => {
gate!(
@ -610,10 +607,7 @@ macro_rules! gate_all_legacy_dont_use {
};
}
if !visitor.features.deref_patterns {
// Allow box patterns under `deref_patterns`.
gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
}
gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
gate_all_legacy_dont_use!(trait_alias, "trait aliases are experimental");
// Despite being a new feature, `where T: Trait<Assoc(): Sized>`, which is RTN syntax now,
// used to be gated under associated_type_bounds, which are right above, so RTN needs to

6
compiler/rustc_ast_pretty/src/pprust/state.rs
View File

@ -1626,6 +1626,12 @@ fn print_pat(&mut self, pat: &ast::Pat) {
self.word("box ");
self.print_pat(inner);
}
PatKind::Deref(inner) => {
self.word("deref!");
self.popen();
self.print_pat(inner);
self.pclose();
}
PatKind::Ref(inner, mutbl) => {
self.word("&");
if mutbl.is_mut() {

7
compiler/rustc_hir/src/hir.rs
View File

@ -1015,7 +1015,7 @@ fn walk_short_(&self, it: &mut impl FnMut(&Pat<'hir>) -> bool) -> bool {
use PatKind::*;
match self.kind {
Wild | Never | Lit(_) | Range(..) | Binding(.., None) | Path(_) | Err(_) => true,
Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_short_(it),
Box(s) | Deref(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_short_(it),
Struct(_, fields, _) => fields.iter().all(|field| field.pat.walk_short_(it)),
TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().all(|p| p.walk_short_(it)),
Slice(before, slice, after) => {
@ -1042,7 +1042,7 @@ fn walk_(&self, it: &mut impl FnMut(&Pat<'hir>) -> bool) {
use PatKind::*;
match self.kind {
Wild | Never | Lit(_) | Range(..) | Binding(.., None) | Path(_) | Err(_) => {}
Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_(it),
Box(s) | Deref(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_(it),
Struct(_, fields, _) => fields.iter().for_each(|field| field.pat.walk_(it)),
TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().for_each(|p| p.walk_(it)),
Slice(before, slice, after) => {
@ -1185,6 +1185,9 @@ pub enum PatKind<'hir> {
/// A `box` pattern.
Box(&'hir Pat<'hir>),
/// A `deref` pattern (currently `deref!()` macro-based syntax).
Deref(&'hir Pat<'hir>),
/// A reference pattern (e.g., `&mut (a, b)`).
Ref(&'hir Pat<'hir>, Mutability),

4
compiler/rustc_hir/src/intravisit.rs
View File

@ -660,7 +660,9 @@ pub fn walk_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v Pat<'v>) -> V:
PatKind::Tuple(tuple_elements, _) => {
walk_list!(visitor, visit_pat, tuple_elements);
}
PatKind::Box(ref subpattern) | PatKind::Ref(ref subpattern, _) => {
PatKind::Box(ref subpattern)
| PatKind::Deref(ref subpattern)
| PatKind::Ref(ref subpattern, _) => {
try_visit!(visitor.visit_pat(subpattern));
}
PatKind::Binding(_, _hir_id, ident, ref optional_subpattern) => {

2
compiler/rustc_hir_analysis/src/check/region.rs
View File

@ -668,7 +668,7 @@ fn is_binding_pat(pat: &hir::Pat<'_>) -> bool {
| PatKind::TupleStruct(_, subpats, _)
| PatKind::Tuple(subpats, _) => subpats.iter().any(|p| is_binding_pat(p)),
PatKind::Box(subpat) => is_binding_pat(subpat),
PatKind::Box(subpat) | PatKind::Deref(subpat) => is_binding_pat(subpat),
PatKind::Ref(_, _)
| PatKind::Binding(hir::BindingAnnotation(hir::ByRef::No, _), ..)

6
compiler/rustc_hir_pretty/src/lib.rs
View File

@ -1808,6 +1808,12 @@ fn print_pat(&mut self, pat: &hir::Pat<'_>) {
self.pclose();
}
}
PatKind::Deref(inner) => {
self.word("deref!");
self.popen();
self.print_pat(inner);
self.pclose();
}
PatKind::Ref(inner, mutbl) => {
let is_range_inner = matches!(inner.kind, PatKind::Range(..));
self.word("&");

1
compiler/rustc_hir_typeck/src/expr_use_visitor.rs
View File

@ -463,6 +463,7 @@ fn maybe_read_scrutinee<'t>(
}
PatKind::Or(_)
| PatKind::Box(_)
| PatKind::Deref(_)
| PatKind::Ref(..)
| PatKind::Wild
| PatKind::Err(_) => {

2
compiler/rustc_hir_typeck/src/mem_categorization.rs
View File

@ -719,7 +719,7 @@ fn cat_pattern_<F>(
self.cat_pattern_(place_with_id, subpat, op)?;
}
PatKind::Box(subpat) | PatKind::Ref(subpat, _) => {
PatKind::Box(subpat) | PatKind::Ref(subpat, _) | PatKind::Deref(subpat) => {
// box p1, &p1, &mut p1. we can ignore the mutability of
// PatKind::Ref since that information is already contained
// in the type.

6
compiler/rustc_hir_typeck/src/pat.rs
View File

@ -210,10 +210,8 @@ fn check_pat(&self, pat: &'tcx Pat<'tcx>, expected: Ty<'tcx>, pat_info: PatInfo<
PatKind::Tuple(elements, ddpos) => {
self.check_pat_tuple(pat.span, elements, ddpos, expected, pat_info)
}
PatKind::Box(inner) if self.tcx.features().deref_patterns => {
self.check_pat_deref(pat.span, inner, expected, pat_info)
}
PatKind::Box(inner) => self.check_pat_box(pat.span, inner, expected, pat_info),
PatKind::Deref(inner) => self.check_pat_deref(pat.span, inner, expected, pat_info),
PatKind::Ref(inner, mutbl) => self.check_pat_ref(pat, inner, mutbl, expected, pat_info),
PatKind::Slice(before, slice, after) => {
self.check_pat_slice(pat.span, before, slice, after, expected, pat_info)
@ -297,6 +295,7 @@ fn calc_adjust_mode(&self, pat: &'tcx Pat<'tcx>, opt_path_res: Option<Res>) -> A
| PatKind::TupleStruct(..)
| PatKind::Tuple(..)
| PatKind::Box(_)
| PatKind::Deref(_)
| PatKind::Range(..)
| PatKind::Slice(..) => AdjustMode::Peel,
// A never pattern behaves somewhat like a literal or unit variant.
@ -762,6 +761,7 @@ fn borrow_pat_suggestion(&self, err: &mut Diag<'_>, pat: &Pat<'_>) {
| PatKind::Binding(..)
| PatKind::Path(..)
| PatKind::Box(..)
| PatKind::Deref(_)
| PatKind::Ref(..)
| PatKind::Lit(..)
| PatKind::Range(..)

2
compiler/rustc_lint/src/unused.rs
View File

@ -1183,7 +1183,7 @@ fn check_pat(&mut self, cx: &EarlyContext<'_>, p: &ast::Pat) {
self.check_unused_parens_pat(cx, &f.pat, false, false, keep_space);
},
// Avoid linting on `i @ (p0 | .. | pn)` and `box (p0 | .. | pn)`, #64106.
Ident(.., Some(p)) | Box(p) => self.check_unused_parens_pat(cx, p, true, false, keep_space),
Ident(.., Some(p)) | Box(p) | Deref(p) => self.check_unused_parens_pat(cx, p, true, false, keep_space),
// Avoid linting on `&(mut x)` as `&mut x` has a different meaning, #55342.
// Also avoid linting on `& mut? (p0 | .. | pn)`, #64106.
Ref(p, m) => self.check_unused_parens_pat(cx, p, true, *m == Mutability::Not, keep_space),

2
compiler/rustc_middle/src/thir.rs
View File

@ -1179,7 +1179,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{subpattern}")
}
PatKind::DerefPattern { ref subpattern } => {
write!(f, "k#deref {subpattern}")
write!(f, "deref!({subpattern})")
}
PatKind::Constant { value } => write!(f, "{value}"),
PatKind::InlineConstant { def: _, ref subpattern } => {

2
compiler/rustc_mir_build/src/thir/pattern/mod.rs
View File

@ -257,7 +257,7 @@ fn lower_pattern_unadjusted(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Box<Pat<'tc
return self.lower_path(qpath, pat.hir_id, pat.span);
}
hir::PatKind::Box(subpattern) if self.tcx.features().deref_patterns => {
hir::PatKind::Deref(subpattern) => {
PatKind::DerefPattern { subpattern: self.lower_pattern(subpattern) }
}
hir::PatKind::Ref(subpattern, _) | hir::PatKind::Box(subpattern) => {

20
compiler/rustc_parse/src/parser/pat.rs
View File

@ -498,11 +498,14 @@ fn parse_pat_with_range_pat(
} else {
PatKind::Lit(const_expr)
}
} else if self.is_builtin() {
self.parse_pat_builtin()?
}
// Don't eagerly error on semantically invalid tokens when matching
// declarative macros, as the input to those doesn't have to be
// semantically valid. For attribute/derive proc macros this is not the
// case, so doing the recovery for them is fine.
} else if self.can_be_ident_pat()
else if self.can_be_ident_pat()
|| (self.is_lit_bad_ident().is_some() && self.may_recover())
{
// Parse `ident @ pat`
@ -1119,6 +1122,21 @@ fn isnt_pattern_start(&self) -> bool {
.contains(&self.token.kind)
}
fn parse_pat_builtin(&mut self) -> PResult<'a, PatKind> {
self.parse_builtin(|self_, _lo, ident| {
Ok(match ident.name {
// builtin#deref(PAT)
sym::deref => Some(ast::PatKind::Deref(self_.parse_pat_allow_top_alt(
None,
RecoverComma::Yes,
RecoverColon::Yes,
CommaRecoveryMode::LikelyTuple,
)?)),
_ => None,
})
})
}
/// Parses `box pat`
fn parse_pat_box(&mut self) -> PResult<'a, PatKind> {
let box_span = self.prev_token.span;

2
compiler/rustc_passes/src/hir_stats.rs
View File

@ -300,6 +300,7 @@ fn visit_pat(&mut self, p: &'v hir::Pat<'v>) {
Path,
Tuple,
Box,
Deref,
Ref,
Lit,
Range,
@ -566,6 +567,7 @@ fn visit_pat(&mut self, p: &'v ast::Pat) {
Path,
Tuple,
Box,
Deref,
Ref,
Lit,
Range,

12
library/core/src/macros/mod.rs
View File

@ -1714,6 +1714,18 @@ macro_rules! trace_macros {
builtin # type_ascribe($expr, $ty)
}
#[cfg(not(bootstrap))]
/// Unstable placeholder for deref patterns.
#[allow_internal_unstable(builtin_syntax)]
#[unstable(
feature = "deref_patterns",
issue = "87121",
reason = "placeholder syntax for deref patterns"
)]
pub macro deref($pat:pat) {
builtin # deref($pat)
}
/// Unstable implementation detail of the `rustc` compiler, do not use.
#[rustc_builtin_macro]
#[stable(feature = "rust1", since = "1.0.0")]

8
library/core/src/prelude/v1.rs
View File

@ -103,3 +103,11 @@
reason = "placeholder syntax for type ascription"
)]
pub use crate::macros::builtin::type_ascribe;
#[cfg(not(bootstrap))]
#[unstable(
feature = "deref_patterns",
issue = "87121",
reason = "placeholder syntax for deref patterns"
)]
pub use crate::macros::builtin::deref;

9
library/std/src/prelude/v1.rs
View File

@ -91,6 +91,15 @@
)]
pub use core::prelude::v1::type_ascribe;
#[cfg(not(bootstrap))]
// Do not `doc(no_inline)` either.
#[unstable(
feature = "deref_patterns",
issue = "87121",
reason = "placeholder syntax for deref patterns"
)]
pub use core::prelude::v1::deref;
// The file so far is equivalent to core/src/prelude/v1.rs. It is duplicated
// rather than glob imported because we want docs to show these re-exports as
// pointing to within `std`.

1
src/librustdoc/clean/utils.rs
View File

@ -329,6 +329,7 @@ pub(crate) fn name_from_pat(p: &hir::Pat<'_>) -> Symbol {
elts.iter().map(|p| name_from_pat(p).to_string()).collect::<Vec<String>>().join(", ")
),
PatKind::Box(p) => return name_from_pat(&*p),
PatKind::Deref(p) => format!("deref!({})", name_from_pat(&*p)),
PatKind::Ref(p, _) => return name_from_pat(&*p),
PatKind::Lit(..) => {
warn!(

2
src/tools/clippy/clippy_lints/src/equatable_if_let.rs
View File

@ -55,7 +55,7 @@ fn array_rec(pats: &[Pat<'_>]) -> bool {
| PatKind::Err(_) => false,
PatKind::Struct(_, a, etc) => !etc && a.iter().all(|x| unary_pattern(x.pat)),
PatKind::Tuple(a, etc) | PatKind::TupleStruct(_, a, etc) => etc.as_opt_usize().is_none() && array_rec(a),
PatKind::Ref(x, _) | PatKind::Box(x) => unary_pattern(x),
PatKind::Ref(x, _) | PatKind::Box(x) | PatKind::Deref(x) => unary_pattern(x),
PatKind::Path(_) | PatKind::Lit(_) => true,
}
}

2
src/tools/clippy/clippy_lints/src/matches/match_same_arms.rs
View File

@ -243,7 +243,7 @@ impl<'a> NormalizedPat<'a> {
fn from_pat(cx: &LateContext<'_>, arena: &'a DroplessArena, pat: &'a Pat<'_>) -> Self {
match pat.kind {
PatKind::Wild | PatKind::Binding(.., None) => Self::Wild,
PatKind::Binding(.., Some(pat)) | PatKind::Box(pat) | PatKind::Ref(pat, _) => {
PatKind::Binding(.., Some(pat)) | PatKind::Box(pat) | PatKind::Deref(pat) | PatKind::Ref(pat, _) => {
Self::from_pat(cx, arena, pat)
},
PatKind::Never => Self::Never,

2
src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs
View File

@ -242,6 +242,8 @@ fn transform_with_focus_on_idx(alternatives: &mut ThinVec<P<Pat>>, focus_idx: us
|k| matches!(k, Box(_)),
|k| always_pat!(k, Box(p) => p),
),
// FIXME(deref_patterns): Should we merge patterns here?
Deref(_) => false,
// Transform `&mut x | ... | &mut y` into `&mut (x | y)`.
Ref(target, Mutability::Mut) => extend_with_matching(
target, start, alternatives,

5
src/tools/clippy/clippy_lints/src/utils/author.rs
View File

@ -689,6 +689,11 @@ macro_rules! kind {
kind!("Box({pat})");
self.pat(pat);
},
PatKind::Deref(pat) => {
bind!(self, pat);
kind!("Deref({pat})");
self.pat(pat);
},
PatKind::Ref(pat, muta) => {
bind!(self, pat);
kind!("Ref({pat}, Mutability::{muta:?})");

1
src/tools/clippy/clippy_utils/src/hir_utils.rs
View File

@ -955,6 +955,7 @@ pub fn hash_pat(&mut self, pat: &Pat<'_>) {
}
},
PatKind::Box(pat) => self.hash_pat(pat),
PatKind::Deref(pat) => self.hash_pat(pat),
PatKind::Lit(expr) => self.hash_expr(expr),
PatKind::Or(pats) => {
for pat in pats {

2
src/tools/clippy/clippy_utils/src/lib.rs
View File

@ -1678,7 +1678,7 @@ fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>,
match pat.kind {
PatKind::Wild | PatKind::Never => false, // If `!` typechecked then the type is empty, so not refutable.
PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
PatKind::Box(pat) | PatKind::Deref(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
PatKind::Or(pats) => {
// TODO: should be the honest check, that pats is exhaustive set

8
src/tools/rustfmt/src/patterns.rs
View File

@ -55,9 +55,10 @@ fn is_short_pattern_inner(pat: &ast::Pat) -> bool {
ast::PatKind::TupleStruct(_, ref path, ref subpats) => {
path.segments.len() <= 1 && subpats.len() <= 1
}
ast::PatKind::Box(ref p) | ast::PatKind::Ref(ref p, _) | ast::PatKind::Paren(ref p) => {
is_short_pattern_inner(&*p)
}
ast::PatKind::Box(ref p)
| PatKind::Deref(ref p)
| ast::PatKind::Ref(ref p, _)
| ast::PatKind::Paren(ref p) => is_short_pattern_inner(&*p),
PatKind::Or(ref pats) => pats.iter().all(|p| is_short_pattern_inner(p)),
}
}
@ -277,6 +278,7 @@ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String>
.rewrite(context, shape.offset_left(1)?.sub_width(1)?)
.map(|inner_pat| format!("({})", inner_pat)),
PatKind::Err(_) => None,
PatKind::Deref(_) => None,
}
}
}

8
tests/ui/pattern/deref-patterns/typeck.rs
View File

@ -7,19 +7,19 @@
fn main() {
let vec: Vec<u32> = Vec::new();
match vec {
box [..] => {}
deref!([..]) => {}
_ => {}
}
match Box::new(true) {
box true => {}
deref!(true) => {}
_ => {}
}
match &Box::new(true) {
box true => {}
deref!(true) => {}
_ => {}
}
match &Rc::new(0) {
box (1..) => {}
deref!(1..) => {}
_ => {}
}
// FIXME(deref_patterns): fails to typecheck because `"foo"` has type &str but deref creates a

10
tests/ui/unboxed-closures/unboxed-closures-type-mismatch-closure-from-another-scope.stderr
View File

@ -26,12 +26,16 @@ note: closure parameter defined here
LL | let mut closure = expect_sig(|p, y| *p = y);
| ^
error[E0425]: cannot find function `deref` in this scope
error[E0423]: expected function, found macro `deref`
--> $DIR/unboxed-closures-type-mismatch-closure-from-another-scope.rs:13:5
|
LL | deref(p);
| ^^^^^ not found in this scope
| ^^^^^ not a function
|
help: use `!` to invoke the macro
|
LL | deref!(p);
| +
help: use the `.` operator to call the method `Deref::deref` on `&&()`
|
LL - deref(p);
@ -40,5 +44,5 @@ LL + p.deref();
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0308, E0425.
Some errors have detailed explanations: E0308, E0423, E0425.
For more information about an error, try `rustc --explain E0308`.