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E0379: Provide suggestions

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This commit is contained in:
León Orell Valerian Liehr 2024-01-02 00:57:30 +01:00
parent ae8e401c9f
commit aa799049d7
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GPG Key ID: D17A07215F68E713
11 changed files with 228 additions and 51 deletions
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7
compiler/rustc_ast_passes/messages.ftl
View File

@ -241,6 +241,13 @@ ast_passes_trait_fn_const =
[true] trait impls
*[false] traits
} cannot be const
.const_context_label = this declares all associated functions implicitly const
.remove_const_sugg = remove the `const`{$requires_multiple_changes ->
[true] {" ..."}
*[false] {""}
}
.make_impl_const_sugg = ... and declare the impl to be const instead
.make_trait_const_sugg = ... and declare the trait to be a `#[const_trait]` instead
ast_passes_trait_object_single_bound = only a single explicit lifetime bound is permitted

130
compiler/rustc_ast_passes/src/ast_validation.rs
View File

@ -46,6 +46,21 @@ enum DisallowTildeConstContext<'a> {
Item,
}
enum TraitOrTraitImpl<'a> {
Trait { span: Span, constness: Option<Span> },
TraitImpl { constness: Const, polarity: ImplPolarity, trait_ref: &'a TraitRef },
}
impl<'a> TraitOrTraitImpl<'a> {
fn constness(&self) -> Option<Span> {
match self {
Self::Trait { constness: Some(span), .. }
| Self::TraitImpl { constness: Const::Yes(span), .. } => Some(*span),
_ => None,
}
}
}
struct AstValidator<'a> {
session: &'a Session,
features: &'a Features,
@ -53,11 +68,7 @@ struct AstValidator<'a> {
/// The span of the `extern` in an `extern { ... }` block, if any.
extern_mod: Option<&'a Item>,
/// Are we inside a trait impl?
in_trait_impl: bool,
/// Are we inside a const trait defn or impl?
in_const_trait_or_impl: bool,
outer_trait_or_trait_impl: Option<TraitOrTraitImpl<'a>>,
has_proc_macro_decls: bool,
@ -78,24 +89,28 @@ struct AstValidator<'a> {
impl<'a> AstValidator<'a> {
fn with_in_trait_impl(
&mut self,
is_in: bool,
constness: Option<Const>,
trait_: Option<(Const, ImplPolarity, &'a TraitRef)>,
f: impl FnOnce(&mut Self),
) {
let old = mem::replace(&mut self.in_trait_impl, is_in);
let old_const = mem::replace(
&mut self.in_const_trait_or_impl,
matches!(constness, Some(Const::Yes(_))),
let old = mem::replace(
&mut self.outer_trait_or_trait_impl,
trait_.map(|(constness, polarity, trait_ref)| TraitOrTraitImpl::TraitImpl {
constness,
polarity,
trait_ref,
}),
);
f(self);
self.in_trait_impl = old;
self.in_const_trait_or_impl = old_const;
self.outer_trait_or_trait_impl = old;
}
fn with_in_trait(&mut self, is_const: bool, f: impl FnOnce(&mut Self)) {
let old = mem::replace(&mut self.in_const_trait_or_impl, is_const);
fn with_in_trait(&mut self, span: Span, constness: Option<Span>, f: impl FnOnce(&mut Self)) {
let old = mem::replace(
&mut self.outer_trait_or_trait_impl,
Some(TraitOrTraitImpl::Trait { span, constness }),
);
f(self);
self.in_const_trait_or_impl = old;
self.outer_trait_or_trait_impl = old;
}
fn with_banned_impl_trait(&mut self, f: impl FnOnce(&mut Self)) {
@ -291,10 +306,48 @@ fn deny_unnamed_field(&self, field: &FieldDef) {
}
}
fn check_trait_fn_not_const(&self, constness: Const) {
if let Const::Yes(span) = constness {
self.dcx().emit_err(errors::TraitFnConst { span, in_impl: self.in_trait_impl });
}
fn check_trait_fn_not_const(&self, constness: Const, parent: &TraitOrTraitImpl<'a>) {
let Const::Yes(span) = constness else {
return;
};
let make_impl_const_sugg = if self.features.const_trait_impl
&& let TraitOrTraitImpl::TraitImpl {
constness: Const::No,
polarity: ImplPolarity::Positive,
trait_ref,
} = parent
{
Some(trait_ref.path.span.shrink_to_lo())
} else {
None
};
let make_trait_const_sugg = if self.features.const_trait_impl
&& let TraitOrTraitImpl::Trait { span, constness: None } = parent
{
Some(span.shrink_to_lo())
} else {
None
};
let parent_constness = parent.constness();
self.dcx().emit_err(errors::TraitFnConst {
span,
in_impl: matches!(parent, TraitOrTraitImpl::TraitImpl { .. }),
const_context_label: parent_constness,
remove_const_sugg: (
self.session.source_map().span_extend_while(span, |c| c == ' ').unwrap_or(span),
match parent_constness {
Some(_) => rustc_errors::Applicability::MachineApplicable,
None => rustc_errors::Applicability::MaybeIncorrect,
},
),
requires_multiple_changes: make_impl_const_sugg.is_some()
|| make_trait_const_sugg.is_some(),
make_impl_const_sugg,
make_trait_const_sugg,
});
}
fn check_fn_decl(&self, fn_decl: &FnDecl, self_semantic: SelfSemantic) {
@ -817,7 +870,7 @@ fn visit_item(&mut self, item: &'a Item) {
self_ty,
items,
}) => {
self.with_in_trait_impl(true, Some(*constness), |this| {
self.with_in_trait_impl(Some((*constness, *polarity, t)), |this| {
this.visibility_not_permitted(
&item.vis,
errors::VisibilityNotPermittedNote::TraitImpl,
@ -963,8 +1016,9 @@ fn visit_item(&mut self, item: &'a Item) {
}
}
ItemKind::Trait(box Trait { is_auto, generics, bounds, items, .. }) => {
let is_const_trait = attr::contains_name(&item.attrs, sym::const_trait);
self.with_in_trait(is_const_trait, |this| {
let is_const_trait =
attr::find_by_name(&item.attrs, sym::const_trait).map(|attr| attr.span);
self.with_in_trait(item.span, is_const_trait, |this| {
if *is_auto == IsAuto::Yes {
// Auto traits cannot have generics, super traits nor contain items.
this.deny_generic_params(generics, item.ident.span);
@ -977,8 +1031,9 @@ fn visit_item(&mut self, item: &'a Item) {
// context for the supertraits.
this.visit_vis(&item.vis);
this.visit_ident(item.ident);
let disallowed =
(!is_const_trait).then(|| DisallowTildeConstContext::Trait(item.span));
let disallowed = is_const_trait
.is_none()
.then(|| DisallowTildeConstContext::Trait(item.span));
this.with_tilde_const(disallowed, |this| {
this.visit_generics(generics);
walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits)
@ -1342,7 +1397,12 @@ fn visit_fn(&mut self, fk: FnKind<'a>, span: Span, id: NodeId) {
let tilde_const_allowed =
matches!(fk.header(), Some(FnHeader { constness: ast::Const::Yes(_), .. }))
|| matches!(fk.ctxt(), Some(FnCtxt::Assoc(_)) if self.in_const_trait_or_impl);
|| matches!(fk.ctxt(), Some(FnCtxt::Assoc(_)))
&& self
.outer_trait_or_trait_impl
.as_ref()
.and_then(TraitOrTraitImpl::constness)
.is_some();
let disallowed = (!tilde_const_allowed).then(|| DisallowTildeConstContext::Fn(fk));
self.with_tilde_const(disallowed, |this| visit::walk_fn(this, fk));
@ -1353,7 +1413,7 @@ fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) {
self.check_nomangle_item_asciionly(item.ident, item.span);
}
if ctxt == AssocCtxt::Trait || !self.in_trait_impl {
if ctxt == AssocCtxt::Trait || self.outer_trait_or_trait_impl.is_none() {
self.check_defaultness(item.span, item.kind.defaultness());
}
@ -1401,10 +1461,10 @@ fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) {
);
}
if ctxt == AssocCtxt::Trait || self.in_trait_impl {
if let Some(parent) = &self.outer_trait_or_trait_impl {
self.visibility_not_permitted(&item.vis, errors::VisibilityNotPermittedNote::TraitImpl);
if let AssocItemKind::Fn(box Fn { sig, .. }) = &item.kind {
self.check_trait_fn_not_const(sig.header.constness);
self.check_trait_fn_not_const(sig.header.constness, parent);
}
}
@ -1414,7 +1474,11 @@ fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) {
match &item.kind {
AssocItemKind::Fn(box Fn { sig, generics, body, .. })
if self.in_const_trait_or_impl
if self
.outer_trait_or_trait_impl
.as_ref()
.and_then(TraitOrTraitImpl::constness)
.is_some()
|| ctxt == AssocCtxt::Trait
|| matches!(sig.header.constness, Const::Yes(_)) =>
{
@ -1430,8 +1494,7 @@ fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) {
);
self.visit_fn(kind, item.span, item.id);
}
_ => self
.with_in_trait_impl(false, None, |this| visit::walk_assoc_item(this, item, ctxt)),
_ => self.with_in_trait_impl(None, |this| visit::walk_assoc_item(this, item, ctxt)),
}
}
}
@ -1547,8 +1610,7 @@ pub fn check_crate(
session,
features,
extern_mod: None,
in_trait_impl: false,
in_const_trait_or_impl: false,
outer_trait_or_trait_impl: None,
has_proc_macro_decls: false,
outer_impl_trait: None,
disallow_tilde_const: Some(DisallowTildeConstContext::Item),

19
compiler/rustc_ast_passes/src/errors.rs
View File

@ -1,7 +1,7 @@
//! Errors emitted by ast_passes.
use rustc_ast::ParamKindOrd;
use rustc_errors::AddToDiagnostic;
use rustc_errors::{AddToDiagnostic, Applicability};
use rustc_macros::{Diagnostic, Subdiagnostic};
use rustc_span::{symbol::Ident, Span, Symbol};
@ -50,6 +50,23 @@ pub struct TraitFnConst {
#[label]
pub span: Span,
pub in_impl: bool,
#[label(ast_passes_const_context_label)]
pub const_context_label: Option<Span>,
#[suggestion(ast_passes_remove_const_sugg, code = "")]
pub remove_const_sugg: (Span, Applicability),
pub requires_multiple_changes: bool,
#[suggestion(
ast_passes_make_impl_const_sugg,
code = "const ",
applicability = "maybe-incorrect"
)]
pub make_impl_const_sugg: Option<Span>,
#[suggestion(
ast_passes_make_trait_const_sugg,
code = "#[const_trait]\n",
applicability = "maybe-incorrect"
)]
pub make_trait_const_sugg: Option<Span>,
}
#[derive(Diagnostic)]

5
tests/ui/consts/const-fn-mismatch.stderr
View File

@ -2,7 +2,10 @@ error[E0379]: functions in trait impls cannot be declared const
--> $DIR/const-fn-mismatch.rs:11:5
|
LL | const fn f() -> u32 {
| ^^^^^ functions in trait impls cannot be const
| ^^^^^-
| |
| functions in trait impls cannot be const
| help: remove the `const`
error: aborting due to 1 previous error

10
tests/ui/consts/const-fn-not-in-trait.stderr
View File

@ -2,13 +2,19 @@ error[E0379]: functions in traits cannot be declared const
--> $DIR/const-fn-not-in-trait.rs:5:5
|
LL | const fn f() -> u32;
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0379]: functions in traits cannot be declared const
--> $DIR/const-fn-not-in-trait.rs:7:5
|
LL | const fn g() -> u32 {
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error: aborting due to 2 previous errors

5
tests/ui/consts/issue-54954.stderr
View File

@ -2,7 +2,10 @@ error[E0379]: functions in traits cannot be declared const
--> $DIR/issue-54954.rs:5:5
|
LL | const fn const_val<T: Sized>() -> usize {
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
--> $DIR/issue-54954.rs:1:24

15
tests/ui/feature-gates/feature-gate-min_const_fn.stderr
View File

@ -2,19 +2,28 @@ error[E0379]: functions in traits cannot be declared const
--> $DIR/feature-gate-min_const_fn.rs:6:5
|
LL | const fn foo() -> u32;
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0379]: functions in traits cannot be declared const
--> $DIR/feature-gate-min_const_fn.rs:7:5
|
LL | const fn bar() -> u32 { 0 }
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0379]: functions in trait impls cannot be declared const
--> $DIR/feature-gate-min_const_fn.rs:11:5
|
LL | const fn foo() -> u32 { 0 }
| ^^^^^ functions in trait impls cannot be const
| ^^^^^-
| |
| functions in trait impls cannot be const
| help: remove the `const`
error: aborting due to 3 previous errors

10
tests/ui/mismatched_types/const-fn-in-trait.stderr
View File

@ -2,13 +2,19 @@ error[E0379]: functions in traits cannot be declared const
--> $DIR/const-fn-in-trait.rs:3:5
|
LL | const fn g();
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0379]: functions in trait impls cannot be declared const
--> $DIR/const-fn-in-trait.rs:7:5
|
LL | const fn f() -> u32 { 22 }
| ^^^^^ functions in trait impls cannot be const
| ^^^^^-
| |
| functions in trait impls cannot be const
| help: remove the `const`
error: aborting due to 2 previous errors

20
tests/ui/parser/fn-header-semantic-fail.stderr
View File

@ -11,13 +11,19 @@ error[E0379]: functions in traits cannot be declared const
--> $DIR/fn-header-semantic-fail.rs:18:9
|
LL | const fn ft3();
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0379]: functions in traits cannot be declared const
--> $DIR/fn-header-semantic-fail.rs:20:9
|
LL | const async unsafe extern "C" fn ft5();
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error: functions cannot be both `const` and `async`
--> $DIR/fn-header-semantic-fail.rs:20:9
@ -32,13 +38,19 @@ error[E0379]: functions in trait impls cannot be declared const
--> $DIR/fn-header-semantic-fail.rs:29:9
|
LL | const fn ft3() {}
| ^^^^^ functions in trait impls cannot be const
| ^^^^^-
| |
| functions in trait impls cannot be const
| help: remove the `const`
error[E0379]: functions in trait impls cannot be declared const
--> $DIR/fn-header-semantic-fail.rs:31:9
|
LL | const async unsafe extern "C" fn ft5() {}
| ^^^^^ functions in trait impls cannot be const
| ^^^^^-
| |
| functions in trait impls cannot be const
| help: remove the `const`
error: functions cannot be both `const` and `async`
--> $DIR/fn-header-semantic-fail.rs:31:9

10
tests/ui/rfcs/rfc-2632-const-trait-impl/effects/trait-fn-const.rs
View File

@ -7,7 +7,15 @@ trait Trait {
}
impl const Trait for () {
const fn fun() {} //~ ERROR functions in trait impls cannot be declared const
const fn fun() {} //~ ERROR functions in trait impls cannot be declared const
}
impl Trait for u32 {
const fn fun() {} //~ ERROR functions in trait impls cannot be declared const
}
trait NonConst {
const fn fun(); //~ ERROR functions in traits cannot be declared const
}
fn main() {}

48
tests/ui/rfcs/rfc-2632-const-trait-impl/effects/trait-fn-const.stderr
View File

@ -1,15 +1,59 @@
error[E0379]: functions in traits cannot be declared const
--> $DIR/trait-fn-const.rs:6:5
|
LL | #[const_trait]
| -------------- this declares all associated functions implicitly const
LL | trait Trait {
LL | const fn fun();
| ^^^^^ functions in traits cannot be const
| ^^^^^-
| |
| functions in traits cannot be const
| help: remove the `const`
error[E0379]: functions in trait impls cannot be declared const
--> $DIR/trait-fn-const.rs:10:5
|
LL | impl const Trait for () {
| ----- this declares all associated functions implicitly const
LL | const fn fun() {}
| ^^^^^-
| |
| functions in trait impls cannot be const
| help: remove the `const`
error[E0379]: functions in trait impls cannot be declared const
--> $DIR/trait-fn-const.rs:14:5
|
LL | const fn fun() {}
| ^^^^^ functions in trait impls cannot be const
|
help: remove the `const` ...
|
LL - const fn fun() {}
LL + fn fun() {}
|
help: ... and declare the impl to be const instead
|
LL | impl const Trait for u32 {
| +++++
error: aborting due to 2 previous errors
error[E0379]: functions in traits cannot be declared const
--> $DIR/trait-fn-const.rs:18:5
|
LL | const fn fun();
| ^^^^^ functions in traits cannot be const
|
help: remove the `const` ...
|
LL - const fn fun();
LL + fn fun();
|
help: ... and declare the trait to be a `#[const_trait]` instead
|
LL + #[const_trait]
LL | trait NonConst {
|
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0379`.