bjoernager/rust
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Refactor AST trait bound modifiers

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This commit is contained in:
León Orell Valerian Liehr 2023-12-20 15:22:06 +01:00
parent bf9229a2e3
commit 5e4f12b41a
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GPG key ID: D17A07215F68E713
16 changed files with 195 additions and 201 deletions
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76
compiler/rustc_parse/src/parser/ty.rs
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@ -13,37 +13,15 @@ use rustc_ast::ptr::P;
use rustc_ast::token::{self, Delimiter, Token, TokenKind};
use rustc_ast::util::case::Case;
use rustc_ast::{
self as ast, BareFnTy, BoundPolarity, FnRetTy, GenericBound, GenericBounds, GenericParam,
Generics, Lifetime, MacCall, MutTy, Mutability, PolyTraitRef, TraitBoundModifier,
TraitObjectSyntax, Ty, TyKind,
self as ast, BareFnTy, BoundConstness, BoundPolarity, FnRetTy, GenericBound, GenericBounds,
GenericParam, Generics, Lifetime, MacCall, MutTy, Mutability, PolyTraitRef,
TraitBoundModifiers, TraitObjectSyntax, Ty, TyKind,
};
use rustc_errors::{Applicability, PResult};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{Span, Symbol};
use thin_vec::{thin_vec, ThinVec};
/// Any `?`, `!`, or `~const` modifiers that appear at the start of a bound.
struct BoundModifiers {
/// `?Trait`.
bound_polarity: BoundPolarity,
/// `~const Trait`.
maybe_const: Option<Span>,
}
impl BoundModifiers {
fn to_trait_bound_modifier(&self) -> TraitBoundModifier {
match (self.bound_polarity, self.maybe_const) {
(BoundPolarity::Positive, None) => TraitBoundModifier::None,
(BoundPolarity::Negative(_), None) => TraitBoundModifier::Negative,
(BoundPolarity::Maybe(_), None) => TraitBoundModifier::Maybe,
(BoundPolarity::Positive, Some(sp)) => TraitBoundModifier::MaybeConst(sp),
(BoundPolarity::Negative(_), Some(_)) => TraitBoundModifier::MaybeConstNegative,
(BoundPolarity::Maybe(_), Some(_)) => TraitBoundModifier::MaybeConstMaybe,
}
}
}
#[derive(Copy, Clone, PartialEq)]
pub(super) enum AllowPlus {
Yes,
@ -461,7 +439,7 @@ impl<'a> Parser<'a> {
parse_plus: bool,
) -> PResult<'a, TyKind> {
let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_token.span));
let bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)];
let bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifiers::NONE)];
self.parse_remaining_bounds(bounds, parse_plus)
}
@ -800,7 +778,7 @@ impl<'a> Parser<'a> {
let has_parens = self.eat(&token::OpenDelim(Delimiter::Parenthesis));
let inner_lo = self.token.span;
let modifiers = self.parse_ty_bound_modifiers()?;
let modifiers = self.parse_trait_bound_modifiers()?;
let bound = if self.token.is_lifetime() {
self.error_lt_bound_with_modifiers(modifiers);
self.parse_generic_lt_bound(lo, inner_lo, has_parens)?
@ -831,18 +809,21 @@ impl<'a> Parser<'a> {
}
/// Emits an error if any trait bound modifiers were present.
fn error_lt_bound_with_modifiers(&self, modifiers: BoundModifiers) {
if let Some(span) = modifiers.maybe_const {
self.sess.emit_err(errors::TildeConstLifetime { span });
fn error_lt_bound_with_modifiers(&self, modifiers: TraitBoundModifiers) {
match modifiers.constness {
BoundConstness::Never => {}
BoundConstness::Maybe(span) => {
self.sess.emit_err(errors::TildeConstLifetime { span });
}
}
match modifiers.bound_polarity {
match modifiers.polarity {
BoundPolarity::Positive => {}
BoundPolarity::Negative(span) => {
self.sess.emit_err(errors::ModifierLifetime { span, sigil: "!" });
}
BoundPolarity::Maybe(span) => {
self.sess.emit_err(errors::ModifierLifetime { span, sigil: "?" });
BoundPolarity::Negative(span) | BoundPolarity::Maybe(span) => {
self.sess.emit_err(errors::ModifierLifetime {
span,
sigil: modifiers.polarity.as_str(),
});
}
}
}
@ -867,26 +848,26 @@ impl<'a> Parser<'a> {
/// If no modifiers are present, this does not consume any tokens.
///
/// ```ebnf
/// TY_BOUND_MODIFIERS = ["~const"] ["?"]
/// TRAIT_BOUND_MODIFIERS = ["~const"] ["?" | "!"]
/// ```
fn parse_ty_bound_modifiers(&mut self) -> PResult<'a, BoundModifiers> {
let maybe_const = if self.eat(&token::Tilde) {
fn parse_trait_bound_modifiers(&mut self) -> PResult<'a, TraitBoundModifiers> {
let constness = if self.eat(&token::Tilde) {
let tilde = self.prev_token.span;
self.expect_keyword(kw::Const)?;
let span = tilde.to(self.prev_token.span);
self.sess.gated_spans.gate(sym::const_trait_impl, span);
Some(span)
BoundConstness::Maybe(span)
} else if self.eat_keyword(kw::Const) {
let span = self.prev_token.span;
self.sess.gated_spans.gate(sym::const_trait_impl, span);
self.sess.emit_err(errors::ConstMissingTilde { span, start: span.shrink_to_lo() });
Some(span)
BoundConstness::Maybe(span)
} else {
None
BoundConstness::Never
};
let bound_polarity = if self.eat(&token::Question) {
let polarity = if self.eat(&token::Question) {
BoundPolarity::Maybe(self.prev_token.span)
} else if self.eat(&token::Not) {
self.sess.gated_spans.gate(sym::negative_bounds, self.prev_token.span);
@ -895,13 +876,13 @@ impl<'a> Parser<'a> {
BoundPolarity::Positive
};
Ok(BoundModifiers { bound_polarity, maybe_const })
Ok(TraitBoundModifiers { constness, polarity })
}
/// Parses a type bound according to:
/// ```ebnf
/// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
/// TY_BOUND_NOPAREN = [TY_BOUND_MODIFIERS] [for<LT_PARAM_DEFS>] SIMPLE_PATH
/// TY_BOUND_NOPAREN = [TRAIT_BOUND_MODIFIERS] [for<LT_PARAM_DEFS>] SIMPLE_PATH
/// ```
///
/// For example, this grammar accepts `~const ?for<'a: 'b> m::Trait<'a>`.
@ -909,7 +890,7 @@ impl<'a> Parser<'a> {
&mut self,
lo: Span,
has_parens: bool,
modifiers: BoundModifiers,
modifiers: TraitBoundModifiers,
leading_token: &Token,
) -> PResult<'a, GenericBound> {
let mut lifetime_defs = self.parse_late_bound_lifetime_defs()?;
@ -991,9 +972,8 @@ impl<'a> Parser<'a> {
}
}
let modifier = modifiers.to_trait_bound_modifier();
let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_token.span));
Ok(GenericBound::Trait(poly_trait, modifier))
Ok(GenericBound::Trait(poly_trait, modifiers))
}
// recovers a `Fn(..)` parenthesized-style path from `fn(..)`