From fad7d220fd2daefe8ee778b8cafbbeaf2dda4fc5 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sat, 19 Aug 2023 23:27:50 +0000
Subject: [PATCH 1/2] Warn on elided lifetimes in associated constants
---
compiler/rustc_lint/src/context.rs | 8 ++
compiler/rustc_lint_defs/src/builtin.rs | 42 ++++++++++
compiler/rustc_lint_defs/src/lib.rs | 4 +
compiler/rustc_resolve/src/late.rs | 79 +++++++++++++------
...nfer-placeholder-in-non-suggestable-pos.rs | 2 +
...-placeholder-in-non-suggestable-pos.stderr | 16 +++-
.../ui/consts/assoc-const-elided-lifetime.rs | 19 +++++
.../consts/assoc-const-elided-lifetime.stderr | 33 ++++++++
8 files changed, 178 insertions(+), 25 deletions(-)
create mode 100644 tests/ui/consts/assoc-const-elided-lifetime.rs
create mode 100644 tests/ui/consts/assoc-const-elided-lifetime.stderr
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index f73797415bc7a..aabefb729f3d4 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -966,6 +966,14 @@ pub trait LintContext: Sized {
Applicability::MachineApplicable
);
}
+ BuiltinLintDiagnostics::AssociatedConstElidedLifetime { elided, span } => {
+ db.span_suggestion_verbose(
+ if elided { span.shrink_to_hi() } else { span },
+ "use the `'static` lifetime",
+ if elided { "'static " } else { "'static" },
+ Applicability::MachineApplicable
+ );
+ }
}
// Rewrap `db`, and pass control to the user.
decorate(db)
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 96c31a90da865..0aa37642b740f 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -3376,6 +3376,7 @@ declare_lint_pass! {
DEPRECATED_IN_FUTURE,
DEPRECATED_WHERE_CLAUSE_LOCATION,
DUPLICATE_MACRO_ATTRIBUTES,
+ ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
ELIDED_LIFETIMES_IN_PATHS,
EXPORTED_PRIVATE_DEPENDENCIES,
FFI_UNWIND_CALLS,
@@ -4527,3 +4528,44 @@ declare_lint! {
reference: "issue #114095 <https://github.com/rust-lang/rust/issues/114095>",
};
}
+
+declare_lint! {
+ /// The `elided_lifetimes_in_associated_constant` lint detects elided lifetimes
+ /// that were erroneously allowed in associated constants.
+ ///
+ /// ### Example
+ ///
+ /// ```rust,compile_fail
+ /// #![deny(elided_lifetimes_in_associated_constant)]
+ ///
+ /// struct Foo;
+ ///
+ /// impl Foo {
+ /// const STR: &str = "hello, world";
+ /// }
+ /// ```
+ ///
+ /// {{produces}}
+ ///
+ /// ### Explanation
+ ///
+ /// Previous version of Rust
+ ///
+ /// Implicit static-in-const behavior was decided [against] for associated
+ /// constants because of ambiguity. This, however, regressed and the compiler
+ /// erroneously treats elided lifetimes in associated constants as lifetime
+ /// parameters on the impl.
+ ///
+ /// This is a [future-incompatible] lint to transition this to a
+ /// hard error in the future.
+ ///
+ /// [against]: https://github.com/rust-lang/rust/issues/38831
+ /// [future-incompatible]: ../index.md#future-incompatible-lints
+ pub ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
+ Warn,
+ "elided lifetimes cannot be used in associated constants in impls",
+ @future_incompatible = FutureIncompatibleInfo {
+ reason: FutureIncompatibilityReason::FutureReleaseError,
+ reference: "issue #115010 <https://github.com/rust-lang/rust/issues/115010>",
+ };
+}
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index f350957f72f1c..d68d084725483 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -572,6 +572,10 @@ pub enum BuiltinLintDiagnostics {
/// The span of the unnecessarily-qualified path to remove.
removal_span: Span,
},
+ AssociatedConstElidedLifetime {
+ elided: bool,
+ span: Span,
+ },
}
/// Lints that are buffered up early on in the `Session` before the
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index c87db96a5dd92..22d084c8e0b5c 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -311,6 +311,10 @@ enum LifetimeRibKind {
/// error on default object bounds (e.g., `Box<dyn Foo>`).
AnonymousReportError,
+ /// Resolves elided lifetimes to `'static`, but gives a warning that this behavior
+ /// is a bug and will be reverted soon.
+ AnonymousWarnToStatic(NodeId),
+
/// Signal we cannot find which should be the anonymous lifetime.
ElisionFailure,
@@ -1148,6 +1152,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
}
LifetimeRibKind::AnonymousCreateParameter { .. }
| LifetimeRibKind::AnonymousReportError
+ | LifetimeRibKind::AnonymousWarnToStatic(_)
| LifetimeRibKind::Elided(_)
| LifetimeRibKind::ElisionFailure
| LifetimeRibKind::ConcreteAnonConst(_)
@@ -1515,6 +1520,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
// lifetime would be illegal.
LifetimeRibKind::Item
| LifetimeRibKind::AnonymousReportError
+ | LifetimeRibKind::AnonymousWarnToStatic(_)
| LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
// An anonymous lifetime is legal here, and bound to the right
// place, go ahead.
@@ -1576,7 +1582,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
| LifetimeRibKind::Elided(_)
| LifetimeRibKind::Generics { .. }
| LifetimeRibKind::ElisionFailure
- | LifetimeRibKind::AnonymousReportError => {}
+ | LifetimeRibKind::AnonymousReportError
+ | LifetimeRibKind::AnonymousWarnToStatic(_) => {}
}
}
@@ -1616,6 +1623,25 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
self.record_lifetime_res(lifetime.id, res, elision_candidate);
return;
}
+ LifetimeRibKind::AnonymousWarnToStatic(node_id) => {
+ self.record_lifetime_res(lifetime.id, LifetimeRes::Static, elision_candidate);
+ let msg = if elided {
+ "`&` without an explicit lifetime name cannot be used here"
+ } else {
+ "`'_` cannot be used here"
+ };
+ self.r.lint_buffer.buffer_lint_with_diagnostic(
+ lint::builtin::ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
+ node_id,
+ lifetime.ident.span,
+ msg,
+ lint::BuiltinLintDiagnostics::AssociatedConstElidedLifetime {
+ elided,
+ span: lifetime.ident.span,
+ },
+ );
+ return;
+ }
LifetimeRibKind::AnonymousReportError => {
let (msg, note) = if elided {
(
@@ -1811,7 +1837,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
//
// impl Foo for std::cell::Ref<u32> // note lack of '_
// async fn foo(_: std::cell::Ref<u32>) { ... }
- LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
+ LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. }
+ | LifetimeRibKind::AnonymousWarnToStatic(_) => {
let sess = self.r.tcx.sess;
let mut err = rustc_errors::struct_span_err!(
sess,
@@ -2898,7 +2925,6 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
match &item.kind {
AssocItemKind::Const(box ast::ConstItem { generics, ty, expr, .. }) => {
debug!("resolve_implementation AssocItemKind::Const");
-
self.with_generic_param_rib(
&generics.params,
RibKind::AssocItem,
@@ -2908,28 +2934,33 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
kind: LifetimeBinderKind::ConstItem,
},
|this| {
- // If this is a trait impl, ensure the const
- // exists in trait
- this.check_trait_item(
- item.id,
- item.ident,
- &item.kind,
- ValueNS,
- item.span,
- seen_trait_items,
- |i, s, c| ConstNotMemberOfTrait(i, s, c),
- );
+ this.with_lifetime_rib(
+ LifetimeRibKind::AnonymousWarnToStatic(item.id),
+ |this| {
+ // If this is a trait impl, ensure the const
+ // exists in trait
+ this.check_trait_item(
+ item.id,
+ item.ident,
+ &item.kind,
+ ValueNS,
+ item.span,
+ seen_trait_items,
+ |i, s, c| ConstNotMemberOfTrait(i, s, c),
+ );
- this.visit_generics(generics);
- this.visit_ty(ty);
- if let Some(expr) = expr {
- // We allow arbitrary const expressions inside of associated consts,
- // even if they are potentially not const evaluatable.
- //
- // Type parameters can already be used and as associated consts are
- // not used as part of the type system, this is far less surprising.
- this.resolve_const_body(expr, None);
- }
+ this.visit_generics(generics);
+ this.visit_ty(ty);
+ if let Some(expr) = expr {
+ // We allow arbitrary const expressions inside of associated consts,
+ // even if they are potentially not const evaluatable.
+ //
+ // Type parameters can already be used and as associated consts are
+ // not used as part of the type system, this is far less surprising.
+ this.resolve_const_body(expr, None);
+ }
+ },
+ );
},
);
}
diff --git a/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.rs b/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.rs
index 40896c32e1113..1e0b77b0d3bd3 100644
--- a/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.rs
+++ b/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.rs
@@ -5,6 +5,8 @@ trait Trait {
impl Trait for () {
const ASSOC: &dyn Fn(_) = 1i32;
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated constants
+ //~| WARN `&` without an explicit lifetime name cannot be used here
+ //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
}
fn main() {}
diff --git a/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.stderr b/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.stderr
index 993a08faba990..f8c02420f96af 100644
--- a/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.stderr
+++ b/tests/ui/associated-consts/infer-placeholder-in-non-suggestable-pos.stderr
@@ -1,9 +1,23 @@
+warning: `&` without an explicit lifetime name cannot be used here
+ --> $DIR/infer-placeholder-in-non-suggestable-pos.rs:6:18
+ |
+LL | const ASSOC: &dyn Fn(_) = 1i32;
+ | ^
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #115010 <https://github.com/rust-lang/rust/issues/115010>
+ = note: `#[warn(elided_lifetimes_in_associated_constant)]` on by default
+help: use the `'static` lifetime
+ |
+LL | const ASSOC: &'static dyn Fn(_) = 1i32;
+ | +++++++
+
error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated constants
--> $DIR/infer-placeholder-in-non-suggestable-pos.rs:6:26
|
LL | const ASSOC: &dyn Fn(_) = 1i32;
| ^ not allowed in type signatures
-error: aborting due to previous error
+error: aborting due to previous error; 1 warning emitted
For more information about this error, try `rustc --explain E0121`.
diff --git a/tests/ui/consts/assoc-const-elided-lifetime.rs b/tests/ui/consts/assoc-const-elided-lifetime.rs
new file mode 100644
index 0000000000000..10cd33a8fed59
--- /dev/null
+++ b/tests/ui/consts/assoc-const-elided-lifetime.rs
@@ -0,0 +1,19 @@
+#![deny(elided_lifetimes_in_associated_constant)]
+
+use std::marker::PhantomData;
+
+struct Foo<'a> {
+ x: PhantomData<&'a ()>,
+}
+
+impl<'a> Foo<'a> {
+ const FOO: Foo<'_> = Foo { x: PhantomData::<&()> };
+ //~^ ERROR `'_` cannot be used here
+ //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+ const BAR: &() = &();
+ //~^ ERROR `&` without an explicit lifetime name cannot be used here
+ //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+}
+
+fn main() {}
diff --git a/tests/ui/consts/assoc-const-elided-lifetime.stderr b/tests/ui/consts/assoc-const-elided-lifetime.stderr
new file mode 100644
index 0000000000000..a1eeaff4ba87b
--- /dev/null
+++ b/tests/ui/consts/assoc-const-elided-lifetime.stderr
@@ -0,0 +1,33 @@
+error: `'_` cannot be used here
+ --> $DIR/assoc-const-elided-lifetime.rs:10:20
+ |
+LL | const FOO: Foo<'_> = Foo { x: PhantomData::<&()> };
+ | ^^
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #115010 <https://github.com/rust-lang/rust/issues/115010>
+note: the lint level is defined here
+ --> $DIR/assoc-const-elided-lifetime.rs:1:9
+ |
+LL | #![deny(elided_lifetimes_in_associated_constant)]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: use the `'static` lifetime
+ |
+LL | const FOO: Foo<'static> = Foo { x: PhantomData::<&()> };
+ | ~~~~~~~
+
+error: `&` without an explicit lifetime name cannot be used here
+ --> $DIR/assoc-const-elided-lifetime.rs:14:16
+ |
+LL | const BAR: &() = &();
+ | ^
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #115010 <https://github.com/rust-lang/rust/issues/115010>
+help: use the `'static` lifetime
+ |
+LL | const BAR: &'static () = &();
+ | +++++++
+
+error: aborting due to 2 previous errors
+
From b1c609e2a6716cb76d2690d86d2d9c255cacbb18 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 21 Aug 2023 20:43:04 +0000
Subject: [PATCH 2/2] Fix elided lifetimes in rust-lang/rust
---
src/bootstrap/tool.rs | 2 +-
src/tools/rust-analyzer/crates/test-utils/src/fixture.rs | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index e6d27757ac661..07ff3da6b4aa5 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -601,7 +601,7 @@ pub struct RustAnalyzer {
}
impl RustAnalyzer {
- pub const ALLOW_FEATURES: &str =
+ pub const ALLOW_FEATURES: &'static str =
"proc_macro_internals,proc_macro_diagnostic,proc_macro_span,proc_macro_span_shrink";
}
diff --git a/src/tools/rust-analyzer/crates/test-utils/src/fixture.rs b/src/tools/rust-analyzer/crates/test-utils/src/fixture.rs
index 75e7a3fec0040..3f8b5a0896901 100644
--- a/src/tools/rust-analyzer/crates/test-utils/src/fixture.rs
+++ b/src/tools/rust-analyzer/crates/test-utils/src/fixture.rs
@@ -313,7 +313,7 @@ impl FixtureWithProjectMeta {
}
impl MiniCore {
- const RAW_SOURCE: &str = include_str!("./minicore.rs");
+ const RAW_SOURCE: &'static str = include_str!("./minicore.rs");
fn has_flag(&self, flag: &str) -> bool {
self.activated_flags.iter().any(|it| it == flag)