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Rollup merge of #111215 - BoxyUwU:resolve_anon_consts_differently, r=cjgillot

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Various changes to name resolution of anon consts

Sorry this PR is kind of all over the place ^^'

Fixes #111012

- Rewrites anon const nameres to all go through `fn resolve_anon_const` explicitly instead of `visit_anon_const` to ensure that we do not accidentally resolve anon consts as if they are allowed to use generics when they aren't. Also means that we dont have bits of code for resolving anon consts that will get out of sync (i.e. legacy const generics and resolving path consts that were parsed as type arguments)
- Renames two of the `LifetimeRibKind`, `AnonConst -> ConcreteAnonConst` and `ConstGeneric -> ConstParamTy`
- Noticed while doing this that under `generic_const_exprs` all lifetimes currently get resolved to errors without any error being emitted which was causing a bunch of tests to pass without their bugs having been fixed, incidentally fixed that in this PR and marked those tests as `// known-bug:`. I'm fine to break those since `generic_const_exprs` is a very unstable incomplete feature and this PR _does_ make generic_const_exprs "less broken" as a whole, also I can't be assed to figure out what the underlying causes of all of them are. This PR reopens #77357 #83993
- Changed `generics_of` to stop providing generics and predicates to enum variant discriminant anon consts since those are not allowed to use generic parameters
- Updated the error for non 'static lifetime in const arguments and the error for non 'static lifetime in const param tys to use `derive(Diagnostic)`

I have a vague idea why const-arg-in-const-arg.rs, in-closure.rs and simple.rs have started failing which is unfortunate since these were deliberately made to work, I think lifetime resolution being broken just means this regressed at some point and nobody noticed because the tests were not testing anything :( I'm fine breaking these too for the same reason as the tests for #77357 #83993. I couldn't get `// known-bug` to work for these ICEs and just kept getting different stderr between CI and local `--bless` so I just removed them and will create an issue to track re-adding (and fixing) the bugs if this PR lands.

r? `@cjgillot` cc `@compiler-errors`
This commit is contained in:
Matthias Krüger 2023-05-09 20:49:32 +02:00 • committed by GitHub
commit 363d158cd8
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70 changed files with 870 additions and 638 deletions
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13
compiler/rustc_ast/src/ast.rs
View file

@ -120,6 +120,12 @@ impl Path {
pub fn is_global(&self) -> bool {
!self.segments.is_empty() && self.segments[0].ident.name == kw::PathRoot
}
/// If this path is a single identifier with no arguments, does not ensure
/// that the path resolves to a const param, the caller should check this.
pub fn is_potential_trivial_const_arg(&self) -> bool {
self.segments.len() == 1 && self.segments[0].args.is_none()
}
}
/// A segment of a path: an identifier, an optional lifetime, and a set of types.
@ -1154,7 +1160,9 @@ impl Expr {
///
/// If this is not the case, name resolution does not resolve `N` when using
/// `min_const_generics` as more complex expressions are not supported.
pub fn is_potential_trivial_const_param(&self) -> bool {
///
/// Does not ensure that the path resolves to a const param, the caller should check this.
pub fn is_potential_trivial_const_arg(&self) -> bool {
let this = if let ExprKind::Block(block, None) = &self.kind
&& block.stmts.len() == 1
&& let StmtKind::Expr(expr) = &block.stmts[0].kind
@ -1165,8 +1173,7 @@ impl Expr {
};
if let ExprKind::Path(None, path) = &this.kind
&& path.segments.len() == 1
&& path.segments[0].args.is_none()
&& path.is_potential_trivial_const_arg()
{
true
} else {

5
compiler/rustc_ast/src/visit.rs
View file

@ -188,6 +188,9 @@ pub trait Visitor<'ast>: Sized {
fn visit_variant(&mut self, v: &'ast Variant) {
walk_variant(self, v)
}
fn visit_variant_discr(&mut self, discr: &'ast AnonConst) {
self.visit_anon_const(discr);
}
fn visit_label(&mut self, label: &'ast Label) {
walk_label(self, label)
}
@ -380,7 +383,7 @@ where
visitor.visit_ident(variant.ident);
visitor.visit_vis(&variant.vis);
visitor.visit_variant_data(&variant.data);
walk_list!(visitor, visit_anon_const, &variant.disr_expr);
walk_list!(visitor, visit_variant_discr, &variant.disr_expr);
walk_list!(visitor, visit_attribute, &variant.attrs);
}

8
compiler/rustc_ast_lowering/src/lib.rs
View file

@ -1190,13 +1190,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
// parsing. We try to resolve that ambiguity by attempting resolution in both the
// type and value namespaces. If we resolved the path in the value namespace, we
// transform it into a generic const argument.
TyKind::Path(qself, path) => {
TyKind::Path(None, path) => {
if let Some(res) = self
.resolver
.get_partial_res(ty.id)
.and_then(|partial_res| partial_res.full_res())
{
if !res.matches_ns(Namespace::TypeNS) {
if !res.matches_ns(Namespace::TypeNS)
&& path.is_potential_trivial_const_arg()
{
debug!(
"lower_generic_arg: Lowering type argument as const argument: {:?}",
ty,
@ -1218,7 +1220,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let path_expr = Expr {
id: ty.id,
kind: ExprKind::Path(qself.clone(), path.clone()),
kind: ExprKind::Path(None, path.clone()),
span,
attrs: AttrVec::new(),
tokens: None,

4
compiler/rustc_error_codes/src/error_codes/E0771.md
View file

@ -1,9 +1,11 @@
#### Note: this error code is no longer emitted by the compiler
A non-`'static` lifetime was used in a const generic. This is currently not
allowed.
Erroneous code example:
```compile_fail,E0771
```compile_fail,E0770
#![feature(adt_const_params)]
fn function_with_str<'a, const STRING: &'a str>() {} // error!

31
compiler/rustc_hir_analysis/src/collect/generics_of.rs
View file

@ -51,7 +51,15 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
// of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
None
} else if tcx.lazy_normalization() {
if let Some(param_id) = tcx.hir().opt_const_param_default_param_def_id(hir_id) {
let parent_node = tcx.hir().get_parent(hir_id);
if let Node::Variant(Variant { disr_expr: Some(constant), .. }) = parent_node
&& constant.hir_id == hir_id
{
// enum variant discriminants are not allowed to use any kind of generics
None
} else if let Some(param_id) =
tcx.hir().opt_const_param_default_param_def_id(hir_id)
{
// If the def_id we are calling generics_of on is an anon ct default i.e:
//
// struct Foo<const N: usize = { .. }>;
@ -94,15 +102,15 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
has_self: generics.has_self,
has_late_bound_regions: generics.has_late_bound_regions,
};
} else {
// HACK(eddyb) this provides the correct generics when
// `feature(generic_const_expressions)` is enabled, so that const expressions
// used with const generics, e.g. `Foo<{N+1}>`, can work at all.
//
// Note that we do not supply the parent generics when using
// `min_const_generics`.
Some(parent_def_id.to_def_id())
}
// HACK(eddyb) this provides the correct generics when
// `feature(generic_const_expressions)` is enabled, so that const expressions
// used with const generics, e.g. `Foo<{N+1}>`, can work at all.
//
// Note that we do not supply the parent generics when using
// `min_const_generics`.
Some(parent_def_id.to_def_id())
} else {
let parent_node = tcx.hir().get_parent(hir_id);
match parent_node {
@ -115,11 +123,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
{
Some(parent_def_id.to_def_id())
}
Node::Variant(Variant { disr_expr: Some(constant), .. })
if constant.hir_id == hir_id =>
{
Some(parent_def_id.to_def_id())
}
Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
Some(tcx.typeck_root_def_id(def_id.to_def_id()))
}

29
compiler/rustc_resolve/messages.ftl
View file

@ -145,6 +145,15 @@ resolve_param_in_ty_of_const_param =
the type of const parameters must not depend on other generic parameters
.label = the type must not depend on the parameter `{$name}`
resolve_type_param_in_ty_of_const_param =
type parameters may not be used in the type of const parameters
resolve_const_param_in_ty_of_const_param =
const parameters may not be used in the type of const parameters
resolve_lifetime_param_in_ty_of_const_param =
lifetime parameters may not be used in the type of const parameters
resolve_self_in_generic_param_default =
generic parameters cannot use `Self` in their defaults
.label = `Self` in generic parameter default
@ -156,12 +165,15 @@ resolve_param_in_non_trivial_anon_const =
resolve_param_in_non_trivial_anon_const_help =
use `#![feature(generic_const_exprs)]` to allow generic const expressions
resolve_param_in_non_trivial_anon_const_sub_type =
resolve_type_param_in_non_trivial_anon_const =
type parameters may not be used in const expressions
resolve_param_in_non_trivial_anon_const_sub_non_type =
resolve_const_param_in_non_trivial_anon_const =
const parameters may only be used as standalone arguments, i.e. `{$name}`
resolve_lifetime_param_in_non_trivial_anon_const =
lifetime parameters may not be used in const expressions
resolve_unreachable_label =
use of unreachable label `{$name}`
.label = unreachable label `{$name}`
@ -233,3 +245,16 @@ resolve_macro_use_extern_crate_self = `#[macro_use]` is not supported on `extern
resolve_accessible_unsure = not sure whether the path is accessible or not
.note = the type may have associated items, but we are currently not checking them
resolve_param_in_enum_discriminant =
generic parameters may not be used in enum discriminant values
.label = cannot perform const operation using `{$name}`
resolve_type_param_in_enum_discriminant =
type parameters may not be used in enum discriminant values
resolve_const_param_in_enum_discriminant =
const parameters may not be used in enum discriminant values
resolve_lifetime_param_in_enum_discriminant =
lifetime parameters may not be used in enum discriminant values

19
compiler/rustc_resolve/src/diagnostics.rs
View file

@ -864,18 +864,15 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
ResolutionError::ForwardDeclaredGenericParam => {
self.tcx.sess.create_err(errs::ForwardDeclaredGenericParam { span })
}
ResolutionError::ParamInTyOfConstParam(name) => {
self.tcx.sess.create_err(errs::ParamInTyOfConstParam { span, name })
}
ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
ResolutionError::ParamInTyOfConstParam { name, param_kind: is_type } => self
.tcx
.sess
.create_err(errs::ParamInTyOfConstParam { span, name, param_kind: is_type }),
ResolutionError::ParamInNonTrivialAnonConst { name, param_kind: is_type } => {
self.tcx.sess.create_err(errs::ParamInNonTrivialAnonConst {
span,
name,
sub_is_type: if is_type {
errs::ParamInNonTrivialAnonConstIsType::AType
} else {
errs::ParamInNonTrivialAnonConstIsType::NotAType { name }
},
param_kind: is_type,
help: self
.tcx
.sess
@ -883,6 +880,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
.then_some(errs::ParamInNonTrivialAnonConstHelp),
})
}
ResolutionError::ParamInEnumDiscriminant { name, param_kind: is_type } => self
.tcx
.sess
.create_err(errs::ParamInEnumDiscriminant { span, name, param_kind: is_type }),
ResolutionError::SelfInGenericParamDefault => {
self.tcx.sess.create_err(errs::SelfInGenericParamDefault { span })
}

47
compiler/rustc_resolve/src/errors.rs
View file

@ -326,6 +326,18 @@ pub(crate) struct ParamInTyOfConstParam {
#[label]
pub(crate) span: Span,
pub(crate) name: Symbol,
#[subdiagnostic]
pub(crate) param_kind: Option<ParamKindInTyOfConstParam>,
}
#[derive(Subdiagnostic)]
pub(crate) enum ParamKindInTyOfConstParam {
#[note(resolve_type_param_in_ty_of_const_param)]
Type,
#[note(resolve_const_param_in_ty_of_const_param)]
Const,
#[note(resolve_lifetime_param_in_ty_of_const_param)]
Lifetime,
}
#[derive(Diagnostic)]
@ -344,7 +356,7 @@ pub(crate) struct ParamInNonTrivialAnonConst {
pub(crate) span: Span,
pub(crate) name: Symbol,
#[subdiagnostic]
pub(crate) sub_is_type: ParamInNonTrivialAnonConstIsType,
pub(crate) param_kind: ParamKindInNonTrivialAnonConst,
#[subdiagnostic]
pub(crate) help: Option<ParamInNonTrivialAnonConstHelp>,
}
@ -354,11 +366,13 @@ pub(crate) struct ParamInNonTrivialAnonConst {
pub(crate) struct ParamInNonTrivialAnonConstHelp;
#[derive(Subdiagnostic)]
pub(crate) enum ParamInNonTrivialAnonConstIsType {
#[note(resolve_param_in_non_trivial_anon_const_sub_type)]
AType,
#[help(resolve_param_in_non_trivial_anon_const_sub_non_type)]
NotAType { name: Symbol },
pub(crate) enum ParamKindInNonTrivialAnonConst {
#[note(resolve_type_param_in_non_trivial_anon_const)]
Type,
#[help(resolve_const_param_in_non_trivial_anon_const)]
Const { name: Symbol },
#[note(resolve_lifetime_param_in_non_trivial_anon_const)]
Lifetime,
}
#[derive(Diagnostic)]
@ -539,3 +553,24 @@ pub(crate) struct CfgAccessibleUnsure {
#[primary_span]
pub(crate) span: Span,
}
#[derive(Diagnostic)]
#[diag(resolve_param_in_enum_discriminant)]
pub(crate) struct ParamInEnumDiscriminant {
#[primary_span]
#[label]
pub(crate) span: Span,
pub(crate) name: Symbol,
#[subdiagnostic]
pub(crate) param_kind: ParamKindInEnumDiscriminant,
}
#[derive(Subdiagnostic)]
pub(crate) enum ParamKindInEnumDiscriminant {
#[note(resolve_type_param_in_enum_discriminant)]
Type,
#[note(resolve_const_param_in_enum_discriminant)]
Const,
#[note(resolve_lifetime_param_in_enum_discriminant)]
Lifetime,
}

82
compiler/rustc_resolve/src/ident.rs
View file

@ -13,8 +13,10 @@ use rustc_span::{Span, DUMMY_SP};
use std::ptr;
use crate::errors::{ParamKindInEnumDiscriminant, ParamKindInNonTrivialAnonConst};
use crate::late::{
ConstantHasGenerics, ConstantItemKind, HasGenericParams, PathSource, Rib, RibKind,
ConstantHasGenerics, ConstantItemKind, HasGenericParams, NoConstantGenericsReason, PathSource,
Rib, RibKind,
};
use crate::macros::{sub_namespace_match, MacroRulesScope};
use crate::{errors, AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy, Finalize};
@ -1153,7 +1155,13 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
}
RibKind::ConstParamTy => {
if let Some(span) = finalize {
self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
self.report_error(
span,
ParamInTyOfConstParam {
name: rib_ident.name,
param_kind: None,
},
);
}
return Res::Err;
}
@ -1188,11 +1196,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
}
RibKind::ConstantItem(trivial, _) => {
let features = self.tcx.sess.features_untracked();
// HACK(min_const_generics): We currently only allow `N` or `{ N }`.
if !(trivial == ConstantHasGenerics::Yes
|| features.generic_const_exprs)
{
if let ConstantHasGenerics::No(cause) = trivial {
// HACK(min_const_generics): If we encounter `Self` in an anonymous
// constant we can't easily tell if it's generic at this stage, so
// we instead remember this and then enforce the self type to be
@ -1210,13 +1214,22 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
}
} else {
if let Some(span) = finalize {
self.report_error(
span,
ResolutionError::ParamInNonTrivialAnonConst {
name: rib_ident.name,
is_type: true,
},
);
let error = match cause {
NoConstantGenericsReason::IsEnumDiscriminant => {
ResolutionError::ParamInEnumDiscriminant {
name: rib_ident.name,
param_kind: ParamKindInEnumDiscriminant::Type,
}
}
NoConstantGenericsReason::NonTrivialConstArg => {
ResolutionError::ParamInNonTrivialAnonConst {
name: rib_ident.name,
param_kind:
ParamKindInNonTrivialAnonConst::Type,
}
}
};
self.report_error(span, error);
self.tcx.sess.delay_span_bug(span, CG_BUG_STR);
}
@ -1233,7 +1246,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
if let Some(span) = finalize {
self.report_error(
span,
ResolutionError::ParamInTyOfConstParam(rib_ident.name),
ResolutionError::ParamInTyOfConstParam {
name: rib_ident.name,
param_kind: Some(errors::ParamKindInTyOfConstParam::Type),
},
);
}
return Res::Err;
@ -1264,20 +1280,25 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
| RibKind::ForwardGenericParamBan => continue,
RibKind::ConstantItem(trivial, _) => {
let features = self.tcx.sess.features_untracked();
// HACK(min_const_generics): We currently only allow `N` or `{ N }`.
if !(trivial == ConstantHasGenerics::Yes
|| features.generic_const_exprs)
{
if let ConstantHasGenerics::No(cause) = trivial {
if let Some(span) = finalize {
self.report_error(
span,
ResolutionError::ParamInNonTrivialAnonConst {
name: rib_ident.name,
is_type: false,
},
);
self.tcx.sess.delay_span_bug(span, CG_BUG_STR);
let error = match cause {
NoConstantGenericsReason::IsEnumDiscriminant => {
ResolutionError::ParamInEnumDiscriminant {
name: rib_ident.name,
param_kind: ParamKindInEnumDiscriminant::Const,
}
}
NoConstantGenericsReason::NonTrivialConstArg => {
ResolutionError::ParamInNonTrivialAnonConst {
name: rib_ident.name,
param_kind: ParamKindInNonTrivialAnonConst::Const {
name: rib_ident.name,
},
}
}
};
self.report_error(span, error);
}
return Res::Err;
@ -1291,7 +1312,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
if let Some(span) = finalize {
self.report_error(
span,
ResolutionError::ParamInTyOfConstParam(rib_ident.name),
ResolutionError::ParamInTyOfConstParam {
name: rib_ident.name,
param_kind: Some(errors::ParamKindInTyOfConstParam::Const),
},
);
}
return Res::Err;

266
compiler/rustc_resolve/src/late.rs
View file

@ -66,6 +66,15 @@ enum IsRepeatExpr {
Yes,
}
/// Describes whether an `AnonConst` is a type level const arg or
/// some other form of anon const (i.e. inline consts or enum discriminants)
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
enum AnonConstKind {
EnumDiscriminant,
InlineConst,
ConstArg(IsRepeatExpr),
}
impl PatternSource {
fn descr(self) -> &'static str {
match self {
@ -105,7 +114,7 @@ pub(crate) enum HasGenericParams {
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum ConstantHasGenerics {
Yes,
No,
No(NoConstantGenericsReason),
}
impl ConstantHasGenerics {
@ -114,6 +123,27 @@ impl ConstantHasGenerics {
}
}
/// Reason for why an anon const is not allowed to reference generic parameters
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum NoConstantGenericsReason {
/// Const arguments are only allowed to use generic parameters when:
/// - `feature(generic_const_exprs)` is enabled
/// or
/// - the const argument is a sole const generic paramater, i.e. `foo::<{ N }>()`
///
/// If neither of the above are true then this is used as the cause.
NonTrivialConstArg,
/// Enum discriminants are not allowed to reference generic parameters ever, this
/// is used when an anon const is in the following position:
///
/// ```rust,compile_fail
/// enum Foo<const N: isize> {
/// Variant = { N }, // this anon const is not allowed to use generics
/// }
/// ```
IsEnumDiscriminant,
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum ConstantItemKind {
Const,
@ -273,15 +303,18 @@ enum LifetimeRibKind {
/// Signal we cannot find which should be the anonymous lifetime.
ElisionFailure,
/// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
/// generics. We are disallowing this until we can decide on how we want to handle non-'static
/// lifetimes in const generics. See issue #74052 for discussion.
ConstGeneric,
/// This rib forbids usage of generic parameters inside of const parameter types.
///
/// While this is desirable to support eventually, it is difficult to do and so is
/// currently forbidden. See rust-lang/project-const-generics#28 for more info.
ConstParamTy,
/// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
/// This function will emit an error if `generic_const_exprs` is not enabled, the body
/// identified by `body_id` is an anonymous constant and `lifetime_ref` is non-static.
AnonConst,
/// Usage of generic parameters is forbidden in various positions for anon consts:
/// - const arguments when `generic_const_exprs` is not enabled
/// - enum discriminant values
///
/// This rib emits an error when a lifetime would resolve to a lifetime parameter.
ConcreteAnonConst(NoConstantGenericsReason),
/// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
Item,
@ -648,13 +681,8 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
self.resolve_block(block);
self.parent_scope.macro_rules = old_macro_rules;
}
fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
// We deal with repeat expressions explicitly in `resolve_expr`.
self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
this.resolve_anon_const(constant, IsRepeatExpr::No);
})
})
fn visit_anon_const(&mut self, _constant: &'ast AnonConst) {
bug!("encountered anon const without a manual call to `resolve_anon_const`");
}
fn visit_expr(&mut self, expr: &'ast Expr) {
self.resolve_expr(expr, None);
@ -676,7 +704,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
fn visit_ty(&mut self, ty: &'ast Ty) {
let prev = self.diagnostic_metadata.current_trait_object;
let prev_ty = self.diagnostic_metadata.current_type_path;
match ty.kind {
match &ty.kind {
TyKind::Ref(None, _) => {
// Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
// NodeId `ty.id`.
@ -685,7 +713,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
self.resolve_elided_lifetime(ty.id, span);
visit::walk_ty(self, ty);
}
TyKind::Path(ref qself, ref path) => {
TyKind::Path(qself, path) => {
self.diagnostic_metadata.current_type_path = Some(ty);
self.smart_resolve_path(ty.id, &qself, path, PathSource::Type);
@ -730,11 +758,11 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
visit::walk_ty(self, ty);
self.lifetime_elision_candidates = candidates;
}
TyKind::TraitObject(ref bounds, ..) => {
TyKind::TraitObject(bounds, ..) => {
self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
visit::walk_ty(self, ty)
}
TyKind::BareFn(ref bare_fn) => {
TyKind::BareFn(bare_fn) => {
let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
self.with_generic_param_rib(
&bare_fn.generic_params,
@ -769,6 +797,13 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
},
)
}
TyKind::Array(element_ty, length) => {
self.visit_ty(element_ty);
self.resolve_anon_const(length, AnonConstKind::ConstArg(IsRepeatExpr::No));
}
TyKind::Typeof(ct) => {
self.resolve_anon_const(ct, AnonConstKind::ConstArg(IsRepeatExpr::No))
}
_ => visit::walk_ty(self, ty),
}
self.diagnostic_metadata.current_trait_object = prev;
@ -994,36 +1029,25 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
// namespace first, and if that fails we try again in the value namespace. If
// resolution in the value namespace succeeds, we have an generic const argument on
// our hands.
if let TyKind::Path(ref qself, ref path) = ty.kind {
if let TyKind::Path(None, ref path) = ty.kind {
// We cannot disambiguate multi-segment paths right now as that requires type
// checking.
if path.segments.len() == 1 && path.segments[0].args.is_none() {
if path.is_potential_trivial_const_arg() {
let mut check_ns = |ns| {
self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
.is_some()
};
if !check_ns(TypeNS) && check_ns(ValueNS) {
// This must be equivalent to `visit_anon_const`, but we cannot call it
// directly due to visitor lifetimes so we have to copy-paste some code.
//
// Note that we might not be inside of an repeat expression here,
// but considering that `IsRepeatExpr` is only relevant for
// non-trivial constants this is doesn't matter.
self.with_constant_rib(
IsRepeatExpr::No,
ConstantHasGenerics::Yes,
None,
self.resolve_anon_const_manual(
true,
AnonConstKind::ConstArg(IsRepeatExpr::No),
|this| {
this.smart_resolve_path(
ty.id,
qself,
&None,
path,
PathSource::Expr(None),
);
if let Some(ref qself) = *qself {
this.visit_ty(&qself.ty);
}
this.visit_path(path, ty.id);
},
);
@ -1037,7 +1061,9 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
self.visit_ty(ty);
}
GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
GenericArg::Const(ct) => self.visit_anon_const(ct),
GenericArg::Const(ct) => {
self.resolve_anon_const(ct, AnonConstKind::ConstArg(IsRepeatExpr::No))
}
}
self.diagnostic_metadata.currently_processing_generics = prev;
}
@ -1053,7 +1079,9 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
match constraint.kind {
AssocConstraintKind::Equality { ref term } => match term {
Term::Ty(ty) => self.visit_ty(ty),
Term::Const(c) => self.visit_anon_const(c),
Term::Const(c) => {
self.resolve_anon_const(c, AnonConstKind::ConstArg(IsRepeatExpr::No))
}
},
AssocConstraintKind::Bound { ref bounds } => {
walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
@ -1102,8 +1130,8 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::Elided(_)
| LifetimeRibKind::ElisionFailure
| LifetimeRibKind::AnonConst
| LifetimeRibKind::ConstGeneric => {}
| LifetimeRibKind::ConcreteAnonConst(_)
| LifetimeRibKind::ConstParamTy => {}
}
}
}
@ -1164,7 +1192,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
InlineAsmOperand::Const { anon_const, .. } => {
// Although this is `DefKind::AnonConst`, it is allowed to reference outer
// generic parameters like an inline const.
self.resolve_inline_const(anon_const);
self.resolve_anon_const(anon_const, AnonConstKind::InlineConst);
}
InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
}
@ -1188,6 +1216,10 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
visit::walk_variant(self, v)
}
fn visit_variant_discr(&mut self, discr: &'ast AnonConst) {
self.resolve_anon_const(discr, AnonConstKind::EnumDiscriminant);
}
fn visit_field_def(&mut self, f: &'ast FieldDef) {
self.resolve_doc_links(&f.attrs, MaybeExported::Ok(f.id));
visit::walk_field_def(self, f)
@ -1386,7 +1418,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
this.ribs[TypeNS].push(Rib::new(RibKind::ConstParamTy));
this.ribs[ValueNS].push(Rib::new(RibKind::ConstParamTy));
this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
this.with_lifetime_rib(LifetimeRibKind::ConstParamTy, |this| {
this.visit_ty(ty)
});
this.ribs[TypeNS].pop().unwrap();
@ -1395,9 +1427,10 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
if let Some(ref expr) = default {
this.ribs[TypeNS].push(forward_ty_ban_rib);
this.ribs[ValueNS].push(forward_const_ban_rib);
this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
this.resolve_anon_const(expr, IsRepeatExpr::No)
});
this.resolve_anon_const(
expr,
AnonConstKind::ConstArg(IsRepeatExpr::No),
);
forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
}
@ -1475,8 +1508,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
LifetimeUseSet::Many
}),
LifetimeRibKind::Generics { .. }
| LifetimeRibKind::ConstGeneric => None,
LifetimeRibKind::AnonConst => {
| LifetimeRibKind::ConstParamTy => None,
LifetimeRibKind::ConcreteAnonConst(_) => {
span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
}
})
@ -1495,8 +1528,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
match rib.kind {
LifetimeRibKind::Item => break,
LifetimeRibKind::ConstGeneric => {
self.emit_non_static_lt_in_const_generic_error(lifetime);
LifetimeRibKind::ConstParamTy => {
self.emit_non_static_lt_in_const_param_ty_error(lifetime);
self.record_lifetime_res(
lifetime.id,
LifetimeRes::Error,
@ -1504,8 +1537,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
);
return;
}
LifetimeRibKind::AnonConst => {
self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
LifetimeRibKind::ConcreteAnonConst(cause) => {
self.emit_forbidden_non_static_lifetime_error(cause, lifetime);
self.record_lifetime_res(
lifetime.id,
LifetimeRes::Error,
@ -1604,9 +1637,9 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
return;
}
LifetimeRibKind::Item => break,
LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
LifetimeRibKind::AnonConst => {
// There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstParamTy => {}
LifetimeRibKind::ConcreteAnonConst(_) => {
// There is always an `Elided(LifetimeRes::Infer)` inside an `AnonConst`.
span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
}
}
@ -1826,9 +1859,9 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
break;
}
LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
LifetimeRibKind::AnonConst => {
// There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstParamTy => {}
LifetimeRibKind::ConcreteAnonConst(_) => {
// There is always an `Elided(LifetimeRes::Infer)` inside an `AnonConst`.
span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
}
}
@ -2560,7 +2593,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
}
// HACK(min_const_generics,const_evaluatable_unchecked): We
// HACK(min_const_generics, generic_const_exprs): We
// want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
// with a future compat lint for now. We do this by adding an
// additional special case for repeat expressions.
@ -2576,18 +2609,26 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
item: Option<(Ident, ConstantItemKind)>,
f: impl FnOnce(&mut Self),
) {
self.with_rib(ValueNS, RibKind::ConstantItem(may_use_generics, item), |this| {
this.with_rib(
TypeNS,
RibKind::ConstantItem(
may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
item,
),
|this| {
this.with_label_rib(RibKind::ConstantItem(may_use_generics, item), f);
},
)
});
let f = |this: &mut Self| {
this.with_rib(ValueNS, RibKind::ConstantItem(may_use_generics, item), |this| {
this.with_rib(
TypeNS,
RibKind::ConstantItem(
may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
item,
),
|this| {
this.with_label_rib(RibKind::ConstantItem(may_use_generics, item), f);
},
)
})
};
if let ConstantHasGenerics::No(cause) = may_use_generics {
self.with_lifetime_rib(LifetimeRibKind::ConcreteAnonConst(cause), f)
} else {
f(self)
}
}
fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
@ -3924,24 +3965,54 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
debug!("(resolving block) leaving block");
}
fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
self.with_constant_rib(
is_repeat,
if constant.value.is_potential_trivial_const_param() {
ConstantHasGenerics::Yes
} else {
ConstantHasGenerics::No
},
None,
|this| visit::walk_anon_const(this, constant),
fn resolve_anon_const(&mut self, constant: &'ast AnonConst, anon_const_kind: AnonConstKind) {
debug!(
"resolve_anon_const(constant: {:?}, anon_const_kind: {:?})",
constant, anon_const_kind
);
self.resolve_anon_const_manual(
constant.value.is_potential_trivial_const_arg(),
anon_const_kind,
|this| this.resolve_expr(&constant.value, None),
)
}
fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
debug!("resolve_anon_const {constant:?}");
self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
visit::walk_anon_const(this, constant)
/// There are a few places that we need to resolve an anon const but we did not parse an
/// anon const so cannot provide an `&'ast AnonConst`. Right now this is just unbraced
/// const arguments that were parsed as type arguments, and `legact_const_generics` which
/// parse as normal function argument expressions. To avoid duplicating the code for resolving
/// an anon const we have this function which lets the caller manually call `resolve_expr` or
/// `smart_resolve_path`.
fn resolve_anon_const_manual(
&mut self,
is_trivial_const_arg: bool,
anon_const_kind: AnonConstKind,
resolve_expr: impl FnOnce(&mut Self),
) {
let is_repeat_expr = match anon_const_kind {
AnonConstKind::ConstArg(is_repeat_expr) => is_repeat_expr,
_ => IsRepeatExpr::No,
};
let may_use_generics = match anon_const_kind {
AnonConstKind::EnumDiscriminant => {
ConstantHasGenerics::No(NoConstantGenericsReason::IsEnumDiscriminant)
}
AnonConstKind::InlineConst => ConstantHasGenerics::Yes,
AnonConstKind::ConstArg(_) => {
if self.r.tcx.features().generic_const_exprs || is_trivial_const_arg {
ConstantHasGenerics::Yes
} else {
ConstantHasGenerics::No(NoConstantGenericsReason::NonTrivialConstArg)
}
}
};
self.with_constant_rib(is_repeat_expr, may_use_generics, None, |this| {
this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
resolve_expr(this);
});
});
}
@ -4046,17 +4117,10 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
// Constant arguments need to be treated as AnonConst since
// that is how they will be later lowered to HIR.
if const_args.contains(&idx) {
self.with_constant_rib(
IsRepeatExpr::No,
if argument.is_potential_trivial_const_param() {
ConstantHasGenerics::Yes
} else {
ConstantHasGenerics::No
},
None,
|this| {
this.resolve_expr(argument, None);
},
self.resolve_anon_const_manual(
argument.is_potential_trivial_const_arg(),
AnonConstKind::ConstArg(IsRepeatExpr::No),
|this| this.resolve_expr(argument, None),
);
} else {
self.resolve_expr(argument, None);
@ -4115,14 +4179,10 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
}
ExprKind::Repeat(ref elem, ref ct) => {
self.visit_expr(elem);
self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
this.resolve_anon_const(ct, IsRepeatExpr::Yes)
})
});
self.resolve_anon_const(ct, AnonConstKind::ConstArg(IsRepeatExpr::Yes));
}
ExprKind::ConstBlock(ref ct) => {
self.resolve_inline_const(ct);
self.resolve_anon_const(ct, AnonConstKind::InlineConst);
}
ExprKind::Index(ref elem, ref idx) => {
self.resolve_expr(elem, Some(expr));

70
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -1,7 +1,7 @@
use crate::diagnostics::{ImportSuggestion, LabelSuggestion, TypoSuggestion};
use crate::late::{AliasPossibility, LateResolutionVisitor, RibKind};
use crate::late::{LifetimeBinderKind, LifetimeRes, LifetimeRibKind, LifetimeUseSet};
use crate::path_names_to_string;
use crate::{errors, path_names_to_string};
use crate::{Module, ModuleKind, ModuleOrUniformRoot};
use crate::{PathResult, PathSource, Segment};
@ -22,7 +22,6 @@ use rustc_hir::def::{self, CtorKind, CtorOf, DefKind};
use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
use rustc_hir::PrimTy;
use rustc_session::lint;
use rustc_session::parse::feature_err;
use rustc_session::Session;
use rustc_span::edit_distance::find_best_match_for_name;
use rustc_span::edition::Edition;
@ -35,6 +34,8 @@ use std::ops::Deref;
use thin_vec::ThinVec;
use super::NoConstantGenericsReason;
type Res = def::Res<ast::NodeId>;
/// A field or associated item from self type suggested in case of resolution failure.
@ -2316,37 +2317,56 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
}
}
pub(crate) fn emit_non_static_lt_in_const_generic_error(&self, lifetime_ref: &ast::Lifetime) {
struct_span_err!(
self.r.tcx.sess,
lifetime_ref.ident.span,
E0771,
"use of non-static lifetime `{}` in const generic",
lifetime_ref.ident
)
.note(
"for more information, see issue #74052 \
<https://github.com/rust-lang/rust/issues/74052>",
)
.emit();
pub(crate) fn emit_non_static_lt_in_const_param_ty_error(&self, lifetime_ref: &ast::Lifetime) {
self.r
.tcx
.sess
.create_err(errors::ParamInTyOfConstParam {
span: lifetime_ref.ident.span,
name: lifetime_ref.ident.name,
param_kind: Some(errors::ParamKindInTyOfConstParam::Lifetime),
})
.emit();
}
/// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
/// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
/// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
pub(crate) fn maybe_emit_forbidden_non_static_lifetime_error(
pub(crate) fn emit_forbidden_non_static_lifetime_error(
&self,
cause: NoConstantGenericsReason,
lifetime_ref: &ast::Lifetime,
) {
let feature_active = self.r.tcx.sess.features_untracked().generic_const_exprs;
if !feature_active {
feature_err(
&self.r.tcx.sess.parse_sess,
sym::generic_const_exprs,
lifetime_ref.ident.span,
"a non-static lifetime is not allowed in a `const`",
)
.emit();
match cause {
NoConstantGenericsReason::IsEnumDiscriminant => {
self.r
.tcx
.sess
.create_err(errors::ParamInEnumDiscriminant {
span: lifetime_ref.ident.span,
name: lifetime_ref.ident.name,
param_kind: errors::ParamKindInEnumDiscriminant::Lifetime,
})
.emit();
}
NoConstantGenericsReason::NonTrivialConstArg => {
assert!(!self.r.tcx.features().generic_const_exprs);
self.r
.tcx
.sess
.create_err(errors::ParamInNonTrivialAnonConst {
span: lifetime_ref.ident.span,
name: lifetime_ref.ident.name,
param_kind: errors::ParamKindInNonTrivialAnonConst::Lifetime,
help: self
.r
.tcx
.sess
.is_nightly_build()
.then_some(errors::ParamInNonTrivialAnonConstHelp),
})
.emit();
}
}
}

11
compiler/rustc_resolve/src/lib.rs
View file

@ -21,6 +21,9 @@
#[macro_use]
extern crate tracing;
use errors::{
ParamKindInEnumDiscriminant, ParamKindInNonTrivialAnonConst, ParamKindInTyOfConstParam,
};
use rustc_arena::{DroplessArena, TypedArena};
use rustc_ast::node_id::NodeMap;
use rustc_ast::{self as ast, attr, NodeId, CRATE_NODE_ID};
@ -223,11 +226,15 @@ enum ResolutionError<'a> {
/// Error E0128: generic parameters with a default cannot use forward-declared identifiers.
ForwardDeclaredGenericParam,
/// ERROR E0770: the type of const parameters must not depend on other generic parameters.
ParamInTyOfConstParam(Symbol),
ParamInTyOfConstParam { name: Symbol, param_kind: Option<ParamKindInTyOfConstParam> },
/// generic parameters must not be used inside const evaluations.
///
/// This error is only emitted when using `min_const_generics`.
ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
ParamInNonTrivialAnonConst { name: Symbol, param_kind: ParamKindInNonTrivialAnonConst },
/// generic parameters must not be used inside enum discriminants.
///
/// This error is emitted even with `generic_const_exprs`.
ParamInEnumDiscriminant { name: Symbol, param_kind: ParamKindInEnumDiscriminant },
/// Error E0735: generic parameters with a default cannot use `Self`
SelfInGenericParamDefault,
/// Error E0767: use of unreachable label