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Merge pull request #1997 from dtolnay/modifiers
Convert TraitBoundModifier into non-exhaustive struct
2 parents 8aa6a84 + 6fd3cf7 commit 2a5fef0

16 files changed

Lines changed: 100 additions & 140 deletions

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‎src/gen/clone.rs‎

Lines changed: 5 additions & 6 deletions
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‎src/gen/debug.rs‎

Lines changed: 5 additions & 11 deletions
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‎src/gen/eq.rs‎

Lines changed: 4 additions & 11 deletions
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‎src/gen/fold.rs‎

Lines changed: 10 additions & 13 deletions
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‎src/gen/hash.rs‎

Lines changed: 3 additions & 10 deletions
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‎src/gen/visit.rs‎

Lines changed: 6 additions & 11 deletions
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‎src/gen/visit_mut.rs‎

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‎src/generics.rs‎

Lines changed: 21 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -413,21 +413,27 @@ ast_struct! {
413413
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
414414
pub struct TraitBound {
415415
pub paren_token: Option<token::Paren>,
416-
pub modifier: TraitBoundModifier,
416+
pub modifiers: TraitBoundModifiers,
417417
/// The `for<'a>` in `for<'a> Foo<&'a T>`
418418
pub lifetimes: Option<BoundLifetimes>,
419419
/// The `Foo<&'a T>` in `for<'a> Foo<&'a T>`
420420
pub path: Path,
421421
}
422422
}
423423

424-
ast_enum! {
424+
ast_struct! {
425425
/// A modifier on a trait bound, currently only used for the `?` in
426426
/// `?Sized`.
427427
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
428-
pub enum TraitBoundModifier {
429-
None,
430-
Maybe(Token![?]),
428+
#[non_exhaustive]
429+
pub struct TraitBoundModifiers {
430+
pub maybe: Option<Token![?]>,
431+
}
432+
}
433+
434+
impl Default for TraitBoundModifiers {
435+
fn default() -> Self {
436+
TraitBoundModifiers { maybe: None }
431437
}
432438
}
433439

@@ -521,7 +527,7 @@ pub(crate) mod parsing {
521527
use crate::ext::IdentExt as _;
522528
use crate::generics::{
523529
BoundLifetimes, ConstParam, GenericParam, Generics, LifetimeParam, PredicateLifetime,
524-
PredicateType, TraitBound, TraitBoundModifier, TypeParam, TypeParamBound, WhereClause,
530+
PredicateType, TraitBound, TraitBoundModifiers, TypeParam, TypeParamBound, WhereClause,
525531
WherePredicate,
526532
};
527533
#[cfg(feature = "full")]
@@ -858,8 +864,8 @@ pub(crate) mod parsing {
858864
}
859865
}
860866

861-
let modifier: TraitBoundModifier = input.parse()?;
862-
if lifetimes.is_none() && matches!(modifier, TraitBoundModifier::Maybe(_)) {
867+
let maybe: Option<Token![?]> = input.parse()?;
868+
if lifetimes.is_none() && maybe.is_some() {
863869
lifetimes = input.parse()?;
864870
}
865871

@@ -874,12 +880,9 @@ pub(crate) mod parsing {
874880
}
875881

876882
if lifetimes.is_some() {
877-
match modifier {
878-
TraitBoundModifier::None => {}
879-
TraitBoundModifier::Maybe(maybe) => {
880-
let msg = "`for<...>` binder not allowed with `?` trait polarity modifier";
881-
return Err(Error::new(maybe.span, msg));
882-
}
883+
if let Some(maybe) = maybe {
884+
let msg = "`for<...>` binder not allowed with `?` trait polarity modifier";
885+
return Err(Error::new(maybe.span, msg));
883886
}
884887
}
885888

@@ -888,25 +891,14 @@ pub(crate) mod parsing {
888891
} else {
889892
Ok(Some(TraitBound {
890893
paren_token: None,
891-
modifier,
894+
modifiers: TraitBoundModifiers { maybe },
892895
lifetimes,
893896
path,
894897
}))
895898
}
896899
}
897900
}
898901

899-
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
900-
impl Parse for TraitBoundModifier {
901-
fn parse(input: ParseStream) -> Result<Self> {
902-
if input.peek(Token![?]) {
903-
input.parse().map(TraitBoundModifier::Maybe)
904-
} else {
905-
Ok(TraitBoundModifier::None)
906-
}
907-
}
908-
}
909-
910902
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
911903
impl Parse for ConstParam {
912904
fn parse(input: ParseStream) -> Result<Self> {
@@ -1154,8 +1146,8 @@ pub(crate) mod printing {
11541146
use crate::fixup::FixupContext;
11551147
use crate::generics::{
11561148
BoundLifetimes, ConstParam, GenericParam, Generics, ImplGenerics, LifetimeParam,
1157-
PredicateLifetime, PredicateType, TraitBound, TraitBoundModifier, Turbofish, TypeGenerics,
1158-
TypeParam, WhereClause,
1149+
PredicateLifetime, PredicateType, TraitBound, Turbofish, TypeGenerics, TypeParam,
1150+
WhereClause,
11591151
};
11601152
#[cfg(feature = "full")]
11611153
use crate::generics::{CapturedParam, PreciseCapture};
@@ -1347,7 +1339,7 @@ pub(crate) mod printing {
13471339
impl ToTokens for TraitBound {
13481340
fn to_tokens(&self, tokens: &mut TokenStream) {
13491341
let to_tokens = |tokens: &mut TokenStream| {
1350-
self.modifier.to_tokens(tokens);
1342+
self.modifiers.maybe.to_tokens(tokens);
13511343
self.lifetimes.to_tokens(tokens);
13521344
self.path.to_tokens(tokens);
13531345
};
@@ -1358,16 +1350,6 @@ pub(crate) mod printing {
13581350
}
13591351
}
13601352

1361-
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
1362-
impl ToTokens for TraitBoundModifier {
1363-
fn to_tokens(&self, tokens: &mut TokenStream) {
1364-
match self {
1365-
TraitBoundModifier::None => {}
1366-
TraitBoundModifier::Maybe(t) => t.to_tokens(tokens),
1367-
}
1368-
}
1369-
}
1370-
13711353
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
13721354
impl ToTokens for ConstParam {
13731355
fn to_tokens(&self, tokens: &mut TokenStream) {

‎src/lib.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -405,7 +405,7 @@ mod generics;
405405
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
406406
pub use crate::generics::{
407407
BoundLifetimes, ConstParam, GenericParam, Generics, LifetimeParam, PredicateLifetime,
408-
PredicateType, TraitBound, TraitBoundModifier, TypeParam, TypeParamBound, WhereClause,
408+
PredicateType, TraitBound, TraitBoundModifiers, TypeParam, TypeParamBound, WhereClause,
409409
WherePredicate,
410410
};
411411
#[cfg(feature = "full")]

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