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Move binder and polarity parsing into parse_generic_ty_bound

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This commit is contained in:
Michael Goulet 2024-06-28 19:37:21 -04:00
parent 036b38ced3
commit 3bc3247200
7 changed files with 204 additions and 40 deletions
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98
compiler/rustc_parse/src/parser/ty.rs
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@ -18,7 +18,7 @@ use rustc_ast::{
};
use rustc_errors::{Applicability, PResult};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{Span, Symbol};
use rustc_span::{ErrorGuaranteed, Span, Symbol};
use thin_vec::{thin_vec, ThinVec};
#[derive(Copy, Clone, PartialEq)]
@ -280,7 +280,7 @@ impl<'a> Parser<'a> {
// Function pointer type or bound list (trait object type) starting with a poly-trait.
// `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
// `for<'lt> Trait1<'lt> + Trait2 + 'a`
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
if self.check_fn_front_matter(false, Case::Sensitive) {
self.parse_ty_bare_fn(
lo,
@ -833,12 +833,9 @@ impl<'a> Parser<'a> {
let lo = self.token.span;
let leading_token = self.prev_token.clone();
let has_parens = self.eat(&token::OpenDelim(Delimiter::Parenthesis));
let inner_lo = self.token.span;
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)?
self.parse_generic_lt_bound(lo, has_parens)?
} else if self.eat_keyword(kw::Use) {
// parse precise captures, if any. This is `use<'lt, 'lt, P, P>`; a list of
// lifetimes and ident params (including SelfUpper). These are validated later
@ -848,7 +845,7 @@ impl<'a> Parser<'a> {
let (args, args_span) = self.parse_precise_capturing_args()?;
GenericBound::Use(args, use_span.to(args_span))
} else {
self.parse_generic_ty_bound(lo, has_parens, modifiers, &leading_token)?
self.parse_generic_ty_bound(lo, has_parens, &leading_token)?
};
Ok(bound)
@ -858,50 +855,64 @@ impl<'a> Parser<'a> {
/// ```ebnf
/// LT_BOUND = LIFETIME
/// ```
fn parse_generic_lt_bound(
&mut self,
lo: Span,
inner_lo: Span,
has_parens: bool,
) -> PResult<'a, GenericBound> {
let bound = GenericBound::Outlives(self.expect_lifetime());
fn parse_generic_lt_bound(&mut self, lo: Span, has_parens: bool) -> PResult<'a, GenericBound> {
let lt = self.expect_lifetime();
let bound = GenericBound::Outlives(lt);
if has_parens {
// FIXME(Centril): Consider not erroring here and accepting `('lt)` instead,
// possibly introducing `GenericBound::Paren(P<GenericBound>)`?
self.recover_paren_lifetime(lo, inner_lo)?;
self.recover_paren_lifetime(lo, lt.ident.span)?;
}
Ok(bound)
}
/// Emits an error if any trait bound modifiers were present.
fn error_lt_bound_with_modifiers(&self, modifiers: TraitBoundModifiers) {
match modifiers.constness {
fn error_lt_bound_with_modifiers(
&self,
modifiers: TraitBoundModifiers,
binder_span: Option<Span>,
) -> ErrorGuaranteed {
let TraitBoundModifiers { constness, asyncness, polarity } = modifiers;
match constness {
BoundConstness::Never => {}
BoundConstness::Always(span) | BoundConstness::Maybe(span) => {
self.dcx().emit_err(errors::ModifierLifetime {
span,
modifier: modifiers.constness.as_str(),
});
return self
.dcx()
.emit_err(errors::ModifierLifetime { span, modifier: constness.as_str() });
}
}
match modifiers.polarity {
match polarity {
BoundPolarity::Positive => {}
BoundPolarity::Negative(span) | BoundPolarity::Maybe(span) => {
self.dcx().emit_err(errors::ModifierLifetime {
span,
modifier: modifiers.polarity.as_str(),
});
return self
.dcx()
.emit_err(errors::ModifierLifetime { span, modifier: polarity.as_str() });
}
}
match asyncness {
BoundAsyncness::Normal => {}
BoundAsyncness::Async(span) => {
return self
.dcx()
.emit_err(errors::ModifierLifetime { span, modifier: asyncness.as_str() });
}
}
if let Some(span) = binder_span {
return self.dcx().emit_err(errors::ModifierLifetime { span, modifier: "for<...>" });
}
unreachable!("lifetime bound intercepted in `parse_generic_ty_bound` but no modifiers?")
}
/// Recover on `('lifetime)` with `(` already eaten.
fn recover_paren_lifetime(&mut self, lo: Span, inner_lo: Span) -> PResult<'a, ()> {
let inner_span = inner_lo.to(self.prev_token.span);
fn recover_paren_lifetime(&mut self, lo: Span, lt_span: Span) -> PResult<'a, ()> {
self.expect(&token::CloseDelim(Delimiter::Parenthesis))?;
let span = lo.to(self.prev_token.span);
let (sugg, snippet) = if let Ok(snippet) = self.span_to_snippet(inner_span) {
let (sugg, snippet) = if let Ok(snippet) = self.span_to_snippet(lt_span) {
(Some(span), snippet)
} else {
(None, String::new())
@ -916,7 +927,7 @@ impl<'a> Parser<'a> {
/// If no modifiers are present, this does not consume any tokens.
///
/// ```ebnf
/// TRAIT_BOUND_MODIFIERS = [["~"] "const"] ["?" | "!"]
/// TRAIT_BOUND_MODIFIERS = [["~"] "const"] ["async"] ["?" | "!"]
/// ```
fn parse_trait_bound_modifiers(&mut self) -> PResult<'a, TraitBoundModifiers> {
let constness = if self.eat(&token::Tilde) {
@ -970,15 +981,23 @@ impl<'a> Parser<'a> {
/// TY_BOUND_NOPAREN = [TRAIT_BOUND_MODIFIERS] [for<LT_PARAM_DEFS>] SIMPLE_PATH
/// ```
///
/// For example, this grammar accepts `~const ?for<'a: 'b> m::Trait<'a>`.
/// For example, this grammar accepts `for<'a: 'b> ~const ?m::Trait<'a>`.
fn parse_generic_ty_bound(
&mut self,
lo: Span,
has_parens: bool,
modifiers: TraitBoundModifiers,
leading_token: &Token,
) -> PResult<'a, GenericBound> {
let mut lifetime_defs = self.parse_late_bound_lifetime_defs()?;
let modifiers = self.parse_trait_bound_modifiers()?;
let (mut lifetime_defs, binder_span) = self.parse_late_bound_lifetime_defs()?;
// Recover erroneous lifetime bound with modifiers or binder.
// e.g. `T: for<'a> 'a` or `T: ~const 'a`.
if self.token.is_lifetime() {
let _: ErrorGuaranteed = self.error_lt_bound_with_modifiers(modifiers, binder_span);
return self.parse_generic_lt_bound(lo, has_parens);
}
let mut path = if self.token.is_keyword(kw::Fn)
&& self.look_ahead(1, |tok| tok.kind == TokenKind::OpenDelim(Delimiter::Parenthesis))
&& let Some(path) = self.recover_path_from_fn()
@ -1094,16 +1113,19 @@ impl<'a> Parser<'a> {
}
/// Optionally parses `for<$generic_params>`.
pub(super) fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, ThinVec<GenericParam>> {
pub(super) fn parse_late_bound_lifetime_defs(
&mut self,
) -> PResult<'a, (ThinVec<GenericParam>, Option<Span>)> {
if self.eat_keyword(kw::For) {
let lo = self.token.span;
self.expect_lt()?;
let params = self.parse_generic_params()?;
self.expect_gt()?;
// We rely on AST validation to rule out invalid cases: There must not be type
// parameters, and the lifetime parameters must not have bounds.
Ok(params)
// We rely on AST validation to rule out invalid cases: There must not be
// type or const parameters, and parameters must not have bounds.
Ok((params, Some(lo.to(self.prev_token.span))))
} else {
Ok(ThinVec::new())
Ok((ThinVec::new(), None))
}
}