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Rollup merge of #110791 - compiler-errors:negative-bounds, r=oli-obk

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Implement negative bounds for internal testing purposes

Implements partial support the `!` negative polarity on trait bounds. This is incomplete, but should allow us to at least be able to play with the feature.

Not even gonna consider them as a public-facing feature, but I'm implementing them because would've been nice to have in UI tests, for example in #110671.
This commit is contained in:
Dylan DPC 2023-05-04 00:17:23 +05:30 • committed by GitHub
commit 80df4ab403
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42 changed files with 481 additions and 188 deletions
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2
compiler/rustc_parse/src/parser/diagnostics.rs
View file

@ -1284,7 +1284,7 @@ impl<'a> Parser<'a> {
}
self.bump(); // `+`
let bounds = self.parse_generic_bounds(None)?;
let bounds = self.parse_generic_bounds()?;
let sum_span = ty.span.to(self.prev_token.span);
let sub = match &ty.kind {

4
compiler/rustc_parse/src/parser/generics.rs
View file

@ -78,7 +78,7 @@ impl<'a> Parser<'a> {
}
self.restore_snapshot(snapshot);
}
self.parse_generic_bounds(colon_span)?
self.parse_generic_bounds()?
} else {
Vec::new()
};
@ -419,7 +419,7 @@ impl<'a> Parser<'a> {
// or with mandatory equality sign and the second type.
let ty = self.parse_ty_for_where_clause()?;
if self.eat(&token::Colon) {
let bounds = self.parse_generic_bounds(Some(self.prev_token.span))?;
let bounds = self.parse_generic_bounds()?;
Ok(ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
span: lo.to(self.prev_token.span),
bound_generic_params: lifetime_defs,

10
compiler/rustc_parse/src/parser/item.rs
View file

@ -788,11 +788,7 @@ impl<'a> Parser<'a> {
// Parse optional colon and supertrait bounds.
let had_colon = self.eat(&token::Colon);
let span_at_colon = self.prev_token.span;
let bounds = if had_colon {
self.parse_generic_bounds(Some(self.prev_token.span))?
} else {
Vec::new()
};
let bounds = if had_colon { self.parse_generic_bounds()? } else { Vec::new() };
let span_before_eq = self.prev_token.span;
if self.eat(&token::Eq) {
@ -802,7 +798,7 @@ impl<'a> Parser<'a> {
self.sess.emit_err(errors::BoundsNotAllowedOnTraitAliases { span });
}
let bounds = self.parse_generic_bounds(None)?;
let bounds = self.parse_generic_bounds()?;
generics.where_clause = self.parse_where_clause()?;
self.expect_semi()?;
@ -883,7 +879,7 @@ impl<'a> Parser<'a> {
// Parse optional colon and param bounds.
let bounds =
if self.eat(&token::Colon) { self.parse_generic_bounds(None)? } else { Vec::new() };
if self.eat(&token::Colon) { self.parse_generic_bounds()? } else { Vec::new() };
let before_where_clause = self.parse_where_clause()?;
let ty = if self.eat(&token::Eq) { Some(self.parse_ty()?) } else { None };

2
compiler/rustc_parse/src/parser/path.rs
View file

@ -606,7 +606,7 @@ impl<'a> Parser<'a> {
let kind = if self.eat(&token::Colon) {
// Parse associated type constraint bound.
let bounds = self.parse_generic_bounds(Some(self.prev_token.span))?;
let bounds = self.parse_generic_bounds()?;
AssocConstraintKind::Bound { bounds }
} else if self.eat(&token::Eq) {
self.parse_assoc_equality_term(ident, self.prev_token.span)?

125
compiler/rustc_parse/src/parser/ty.rs
View file

@ -3,8 +3,7 @@ use super::{Parser, PathStyle, TokenType};
use crate::errors::{
self, DynAfterMut, ExpectedFnPathFoundFnKeyword, ExpectedMutOrConstInRawPointerType,
FnPointerCannotBeAsync, FnPointerCannotBeConst, FnPtrWithGenerics, FnPtrWithGenericsSugg,
InvalidDynKeyword, LifetimeAfterMut, NeedPlusAfterTraitObjectLifetime,
NegativeBoundsNotSupported, NegativeBoundsNotSupportedSugg, NestedCVariadicType,
InvalidDynKeyword, LifetimeAfterMut, NeedPlusAfterTraitObjectLifetime, NestedCVariadicType,
ReturnTypesUseThinArrow,
};
use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
@ -14,8 +13,9 @@ 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, FnRetTy, GenericBound, GenericBounds, GenericParam, Generics, Lifetime,
MacCall, MutTy, Mutability, PolyTraitRef, TraitBoundModifier, TraitObjectSyntax, Ty, TyKind,
self as ast, BareFnTy, BoundPolarity, FnRetTy, GenericBound, GenericBounds, GenericParam,
Generics, Lifetime, MacCall, MutTy, Mutability, PolyTraitRef, TraitBoundModifier,
TraitObjectSyntax, Ty, TyKind,
};
use rustc_errors::{Applicability, PResult};
use rustc_span::source_map::Span;
@ -23,10 +23,10 @@ use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::Symbol;
use thin_vec::{thin_vec, ThinVec};
/// Any `?` or `~const` modifiers that appear at the start of a bound.
/// Any `?`, `!`, or `~const` modifiers that appear at the start of a bound.
struct BoundModifiers {
/// `?Trait`.
maybe: Option<Span>,
bound_polarity: BoundPolarity,
/// `~const Trait`.
maybe_const: Option<Span>,
@ -34,11 +34,13 @@ struct BoundModifiers {
impl BoundModifiers {
fn to_trait_bound_modifier(&self) -> TraitBoundModifier {
match (self.maybe, self.maybe_const) {
(None, None) => TraitBoundModifier::None,
(Some(_), None) => TraitBoundModifier::Maybe,
(None, Some(_)) => TraitBoundModifier::MaybeConst,
(Some(_), Some(_)) => TraitBoundModifier::MaybeConstMaybe,
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(_)) => TraitBoundModifier::MaybeConst,
(BoundPolarity::Negative(_), Some(_)) => TraitBoundModifier::MaybeConstNegative,
(BoundPolarity::Maybe(_), Some(_)) => TraitBoundModifier::MaybeConstMaybe,
}
}
}
@ -368,7 +370,7 @@ impl<'a> Parser<'a> {
fn parse_bare_trait_object(&mut self, lo: Span, allow_plus: AllowPlus) -> PResult<'a, TyKind> {
let lt_no_plus = self.check_lifetime() && !self.look_ahead(1, |t| t.is_like_plus());
let bounds = self.parse_generic_bounds_common(allow_plus, None)?;
let bounds = self.parse_generic_bounds_common(allow_plus)?;
if lt_no_plus {
self.sess.emit_err(NeedPlusAfterTraitObjectLifetime { span: lo });
}
@ -395,7 +397,7 @@ impl<'a> Parser<'a> {
) -> PResult<'a, TyKind> {
if plus {
self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded
bounds.append(&mut self.parse_generic_bounds(Some(self.prev_token.span))?);
bounds.append(&mut self.parse_generic_bounds()?);
}
Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None))
}
@ -598,7 +600,7 @@ impl<'a> Parser<'a> {
}
})
}
let bounds = self.parse_generic_bounds(None)?;
let bounds = self.parse_generic_bounds()?;
*impl_dyn_multi = bounds.len() > 1 || self.prev_token.kind == TokenKind::BinOp(token::Plus);
Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds))
}
@ -629,7 +631,7 @@ impl<'a> Parser<'a> {
};
// Always parse bounds greedily for better error recovery.
let bounds = self.parse_generic_bounds(None)?;
let bounds = self.parse_generic_bounds()?;
*impl_dyn_multi = bounds.len() > 1 || self.prev_token.kind == TokenKind::BinOp(token::Plus);
Ok(TyKind::TraitObject(bounds, syntax))
}
@ -660,23 +662,15 @@ impl<'a> Parser<'a> {
}
}
pub(super) fn parse_generic_bounds(
&mut self,
colon_span: Option<Span>,
) -> PResult<'a, GenericBounds> {
self.parse_generic_bounds_common(AllowPlus::Yes, colon_span)
pub(super) fn parse_generic_bounds(&mut self) -> PResult<'a, GenericBounds> {
self.parse_generic_bounds_common(AllowPlus::Yes)
}
/// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`.
///
/// See `parse_generic_bound` for the `BOUND` grammar.
fn parse_generic_bounds_common(
&mut self,
allow_plus: AllowPlus,
colon_span: Option<Span>,
) -> PResult<'a, GenericBounds> {
fn parse_generic_bounds_common(&mut self, allow_plus: AllowPlus) -> PResult<'a, GenericBounds> {
let mut bounds = Vec::new();
let mut negative_bounds = Vec::new();
// In addition to looping while we find generic bounds:
// We continue even if we find a keyword. This is necessary for error recovery on,
@ -693,19 +687,12 @@ impl<'a> Parser<'a> {
self.sess.emit_err(InvalidDynKeyword { span: self.token.span });
self.bump();
}
match self.parse_generic_bound()? {
Ok(bound) => bounds.push(bound),
Err(neg_sp) => negative_bounds.push(neg_sp),
}
bounds.push(self.parse_generic_bound()?);
if allow_plus == AllowPlus::No || !self.eat_plus() {
break;
}
}
if !negative_bounds.is_empty() {
self.error_negative_bounds(colon_span, &bounds, negative_bounds);
}
Ok(bounds)
}
@ -713,55 +700,22 @@ impl<'a> Parser<'a> {
fn can_begin_bound(&mut self) -> bool {
// This needs to be synchronized with `TokenKind::can_begin_bound`.
self.check_path()
|| self.check_lifetime()
|| self.check(&token::Not) // Used for error reporting only.
|| self.check(&token::Question)
|| self.check(&token::Tilde)
|| self.check_keyword(kw::For)
|| self.check(&token::OpenDelim(Delimiter::Parenthesis))
}
fn error_negative_bounds(
&self,
colon_span: Option<Span>,
bounds: &[GenericBound],
negative_bounds: Vec<Span>,
) {
let sub = if let Some(bound_list) = colon_span {
let bound_list = bound_list.to(self.prev_token.span);
let mut new_bound_list = String::new();
if !bounds.is_empty() {
let mut snippets = bounds.iter().map(|bound| self.span_to_snippet(bound.span()));
while let Some(Ok(snippet)) = snippets.next() {
new_bound_list.push_str(" + ");
new_bound_list.push_str(&snippet);
}
new_bound_list = new_bound_list.replacen(" +", ":", 1);
}
Some(NegativeBoundsNotSupportedSugg {
bound_list,
num_bounds: negative_bounds.len(),
fixed: new_bound_list,
})
} else {
None
};
let last_span = *negative_bounds.last().expect("no negative bounds, but still error?");
self.sess.emit_err(NegativeBoundsNotSupported { negative_bounds, last_span, sub });
|| self.check_lifetime()
|| self.check(&token::Not)
|| self.check(&token::Question)
|| self.check(&token::Tilde)
|| self.check_keyword(kw::For)
|| self.check(&token::OpenDelim(Delimiter::Parenthesis))
}
/// Parses a bound according to the grammar:
/// ```ebnf
/// BOUND = TY_BOUND | LT_BOUND
/// ```
fn parse_generic_bound(&mut self) -> PResult<'a, Result<GenericBound, Span>> {
let anchor_lo = self.prev_token.span;
fn parse_generic_bound(&mut self) -> PResult<'a, GenericBound> {
let lo = self.token.span;
let has_parens = self.eat(&token::OpenDelim(Delimiter::Parenthesis));
let inner_lo = self.token.span;
let is_negative = self.eat(&token::Not);
let modifiers = self.parse_ty_bound_modifiers()?;
let bound = if self.token.is_lifetime() {
@ -771,7 +725,7 @@ impl<'a> Parser<'a> {
self.parse_generic_ty_bound(lo, has_parens, modifiers)?
};
Ok(if is_negative { Err(anchor_lo.to(self.prev_token.span)) } else { Ok(bound) })
Ok(bound)
}
/// Parses a lifetime ("outlives") bound, e.g. `'a`, according to:
@ -799,8 +753,14 @@ impl<'a> Parser<'a> {
self.sess.emit_err(errors::TildeConstLifetime { span });
}
if let Some(span) = modifiers.maybe {
self.sess.emit_err(errors::MaybeLifetime { span });
match modifiers.bound_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: "?" });
}
}
}
@ -843,9 +803,16 @@ impl<'a> Parser<'a> {
None
};
let maybe = self.eat(&token::Question).then_some(self.prev_token.span);
let bound_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);
BoundPolarity::Negative(self.prev_token.span)
} else {
BoundPolarity::Positive
};
Ok(BoundModifiers { maybe, maybe_const })
Ok(BoundModifiers { bound_polarity, maybe_const })
}
/// Parses a type bound according to: