Merging upstream version 1.76.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 239 insertions, 173 deletions

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index bef9f469c..f9b66239b 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -8,6 +8,134 @@ use crate::{declare_lint, declare_lint_pass, FutureIncompatibilityReason};
 use rustc_span::edition::Edition;
 use rustc_span::symbol::sym;
 
+declare_lint_pass! {
+    /// Does nothing as a lint pass, but registers some `Lint`s
+    /// that are used by other parts of the compiler.
+    HardwiredLints => [
+        // tidy-alphabetical-start
+        ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
+        AMBIGUOUS_ASSOCIATED_ITEMS,
+        AMBIGUOUS_GLOB_IMPORTS,
+        AMBIGUOUS_GLOB_REEXPORTS,
+        ARITHMETIC_OVERFLOW,
+        ASM_SUB_REGISTER,
+        BAD_ASM_STYLE,
+        BARE_TRAIT_OBJECTS,
+        BINDINGS_WITH_VARIANT_NAME,
+        BREAK_WITH_LABEL_AND_LOOP,
+        BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE,
+        CENUM_IMPL_DROP_CAST,
+        COHERENCE_LEAK_CHECK,
+        COINDUCTIVE_OVERLAP_IN_COHERENCE,
+        CONFLICTING_REPR_HINTS,
+        CONST_EVALUATABLE_UNCHECKED,
+        CONST_ITEM_MUTATION,
+        CONST_PATTERNS_WITHOUT_PARTIAL_EQ,
+        DEAD_CODE,
+        DEPRECATED,
+        DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
+        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,
+        FORBIDDEN_LINT_GROUPS,
+        FUNCTION_ITEM_REFERENCES,
+        FUZZY_PROVENANCE_CASTS,
+        HIDDEN_GLOB_REEXPORTS,
+        ILL_FORMED_ATTRIBUTE_INPUT,
+        ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
+        INCOMPLETE_INCLUDE,
+        INDIRECT_STRUCTURAL_MATCH,
+        INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
+        INLINE_NO_SANITIZE,
+        INVALID_DOC_ATTRIBUTES,
+        INVALID_MACRO_EXPORT_ARGUMENTS,
+        INVALID_TYPE_PARAM_DEFAULT,
+        IRREFUTABLE_LET_PATTERNS,
+        LARGE_ASSIGNMENTS,
+        LATE_BOUND_LIFETIME_ARGUMENTS,
+        LEGACY_DERIVE_HELPERS,
+        LONG_RUNNING_CONST_EVAL,
+        LOSSY_PROVENANCE_CASTS,
+        MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
+        MACRO_USE_EXTERN_CRATE,
+        META_VARIABLE_MISUSE,
+        MISSING_ABI,
+        MISSING_FRAGMENT_SPECIFIER,
+        MUST_NOT_SUSPEND,
+        NAMED_ARGUMENTS_USED_POSITIONALLY,
+        NON_EXHAUSTIVE_OMITTED_PATTERNS,
+        NONTRIVIAL_STRUCTURAL_MATCH,
+        ORDER_DEPENDENT_TRAIT_OBJECTS,
+        OVERLAPPING_RANGE_ENDPOINTS,
+        PATTERNS_IN_FNS_WITHOUT_BODY,
+        POINTER_STRUCTURAL_MATCH,
+        PRIVATE_BOUNDS,
+        PRIVATE_INTERFACES,
+        PROC_MACRO_BACK_COMPAT,
+        PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
+        PUB_USE_OF_PRIVATE_EXTERN_CRATE,
+        REFINING_IMPL_TRAIT,
+        RENAMED_AND_REMOVED_LINTS,
+        REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
+        RUST_2021_INCOMPATIBLE_CLOSURE_CAPTURES,
+        RUST_2021_INCOMPATIBLE_OR_PATTERNS,
+        RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
+        RUST_2021_PRELUDE_COLLISIONS,
+        SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
+        SINGLE_USE_LIFETIMES,
+        SOFT_UNSTABLE,
+        STABLE_FEATURES,
+        SUSPICIOUS_AUTO_TRAIT_IMPLS,
+        TEST_UNSTABLE_LINT,
+        TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
+        TRIVIAL_CASTS,
+        TRIVIAL_NUMERIC_CASTS,
+        TYVAR_BEHIND_RAW_POINTER,
+        UNCONDITIONAL_PANIC,
+        UNCONDITIONAL_RECURSION,
+        UNDEFINED_NAKED_FUNCTION_ABI,
+        UNEXPECTED_CFGS,
+        UNFULFILLED_LINT_EXPECTATIONS,
+        UNINHABITED_STATIC,
+        UNKNOWN_CRATE_TYPES,
+        UNKNOWN_LINTS,
+        UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
+        UNNAMEABLE_TEST_ITEMS,
+        UNNAMEABLE_TYPES,
+        UNREACHABLE_CODE,
+        UNREACHABLE_PATTERNS,
+        UNSAFE_OP_IN_UNSAFE_FN,
+        UNSTABLE_NAME_COLLISIONS,
+        UNSTABLE_SYNTAX_PRE_EXPANSION,
+        UNSUPPORTED_CALLING_CONVENTIONS,
+        UNUSED_ASSIGNMENTS,
+        UNUSED_ASSOCIATED_TYPE_BOUNDS,
+        UNUSED_ATTRIBUTES,
+        UNUSED_CRATE_DEPENDENCIES,
+        UNUSED_EXTERN_CRATES,
+        UNUSED_FEATURES,
+        UNUSED_IMPORTS,
+        UNUSED_LABELS,
+        UNUSED_LIFETIMES,
+        UNUSED_MACRO_RULES,
+        UNUSED_MACROS,
+        UNUSED_MUT,
+        UNUSED_QUALIFICATIONS,
+        UNUSED_TUPLE_STRUCT_FIELDS,
+        UNUSED_UNSAFE,
+        UNUSED_VARIABLES,
+        USELESS_DEPRECATED,
+        WARNINGS,
+        WHERE_CLAUSES_OBJECT_SAFETY,
+        WRITES_THROUGH_IMMUTABLE_POINTER,
+        // tidy-alphabetical-end
+    ]
+}
+
 declare_lint! {
     /// The `forbidden_lint_groups` lint detects violations of
     /// `forbid` applied to a lint group. Due to a bug in the compiler,
@@ -3135,7 +3263,7 @@ declare_lint! {
     /// ### Example
     ///
     /// ```text
-    /// rustc --check-cfg 'names()'
+    /// rustc --check-cfg 'cfg()'
     /// ```
     ///
     /// ```rust,ignore (needs command line option)
@@ -3146,7 +3274,7 @@ declare_lint! {
     /// This will produce:
     ///
     /// ```text
-    /// warning: unknown condition name used
+    /// warning: unexpected `cfg` condition name: `widnows`
     ///  --> lint_example.rs:1:7
     ///   |
     /// 1 | #[cfg(widnows)]
@@ -3157,9 +3285,10 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// This lint is only active when a `--check-cfg='names(...)'` option has been passed
-    /// to the compiler and triggers whenever an unknown condition name or value is used.
-    /// The known condition include names or values passed in `--check-cfg`, `--cfg`, and some
+    /// This lint is only active when `--check-cfg` arguments are being passed
+    /// to the compiler and triggers whenever an unexpected condition name or value is used.
+    ///
+    /// The known condition include names or values passed in `--check-cfg`, and some
     /// well-knows names and values built into the compiler.
     pub UNEXPECTED_CFGS,
     Warn,
@@ -3348,133 +3477,6 @@ declare_lint! {
     "name introduced by a private item shadows a name introduced by a public glob re-export",
 }
 
-declare_lint_pass! {
-    /// Does nothing as a lint pass, but registers some `Lint`s
-    /// that are used by other parts of the compiler.
-    HardwiredLints => [
-        // tidy-alphabetical-start
-        ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
-        AMBIGUOUS_ASSOCIATED_ITEMS,
-        AMBIGUOUS_GLOB_IMPORTS,
-        AMBIGUOUS_GLOB_REEXPORTS,
-        ARITHMETIC_OVERFLOW,
-        ASM_SUB_REGISTER,
-        BAD_ASM_STYLE,
-        BARE_TRAIT_OBJECTS,
-        BINDINGS_WITH_VARIANT_NAME,
-        BREAK_WITH_LABEL_AND_LOOP,
-        BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE,
-        CENUM_IMPL_DROP_CAST,
-        COHERENCE_LEAK_CHECK,
-        COINDUCTIVE_OVERLAP_IN_COHERENCE,
-        CONFLICTING_REPR_HINTS,
-        CONST_EVALUATABLE_UNCHECKED,
-        CONST_ITEM_MUTATION,
-        CONST_PATTERNS_WITHOUT_PARTIAL_EQ,
-        DEAD_CODE,
-        DEPRECATED,
-        DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-        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,
-        FORBIDDEN_LINT_GROUPS,
-        FUNCTION_ITEM_REFERENCES,
-        FUZZY_PROVENANCE_CASTS,
-        HIDDEN_GLOB_REEXPORTS,
-        ILL_FORMED_ATTRIBUTE_INPUT,
-        ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
-        IMPLIED_BOUNDS_ENTAILMENT,
-        INCOMPLETE_INCLUDE,
-        INDIRECT_STRUCTURAL_MATCH,
-        INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
-        INLINE_NO_SANITIZE,
-        INVALID_DOC_ATTRIBUTES,
-        INVALID_MACRO_EXPORT_ARGUMENTS,
-        INVALID_TYPE_PARAM_DEFAULT,
-        IRREFUTABLE_LET_PATTERNS,
-        LARGE_ASSIGNMENTS,
-        LATE_BOUND_LIFETIME_ARGUMENTS,
-        LEGACY_DERIVE_HELPERS,
-        LONG_RUNNING_CONST_EVAL,
-        LOSSY_PROVENANCE_CASTS,
-        MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
-        MACRO_USE_EXTERN_CRATE,
-        META_VARIABLE_MISUSE,
-        MISSING_ABI,
-        MISSING_FRAGMENT_SPECIFIER,
-        MUST_NOT_SUSPEND,
-        NAMED_ARGUMENTS_USED_POSITIONALLY,
-        NON_EXHAUSTIVE_OMITTED_PATTERNS,
-        NONTRIVIAL_STRUCTURAL_MATCH,
-        ORDER_DEPENDENT_TRAIT_OBJECTS,
-        OVERLAPPING_RANGE_ENDPOINTS,
-        PATTERNS_IN_FNS_WITHOUT_BODY,
-        POINTER_STRUCTURAL_MATCH,
-        PRIVATE_BOUNDS,
-        PRIVATE_INTERFACES,
-        PROC_MACRO_BACK_COMPAT,
-        PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
-        PUB_USE_OF_PRIVATE_EXTERN_CRATE,
-        REFINING_IMPL_TRAIT,
-        RENAMED_AND_REMOVED_LINTS,
-        REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
-        RUST_2021_INCOMPATIBLE_CLOSURE_CAPTURES,
-        RUST_2021_INCOMPATIBLE_OR_PATTERNS,
-        RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
-        RUST_2021_PRELUDE_COLLISIONS,
-        SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
-        SINGLE_USE_LIFETIMES,
-        SOFT_UNSTABLE,
-        STABLE_FEATURES,
-        SUSPICIOUS_AUTO_TRAIT_IMPLS,
-        TEST_UNSTABLE_LINT,
-        TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
-        TRIVIAL_CASTS,
-        TRIVIAL_NUMERIC_CASTS,
-        TYVAR_BEHIND_RAW_POINTER,
-        UNCONDITIONAL_PANIC,
-        UNCONDITIONAL_RECURSION,
-        UNDEFINED_NAKED_FUNCTION_ABI,
-        UNFULFILLED_LINT_EXPECTATIONS,
-        UNINHABITED_STATIC,
-        UNKNOWN_CRATE_TYPES,
-        UNKNOWN_LINTS,
-        UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
-        UNNAMEABLE_TEST_ITEMS,
-        UNNAMEABLE_TYPES,
-        UNREACHABLE_CODE,
-        UNREACHABLE_PATTERNS,
-        UNSAFE_OP_IN_UNSAFE_FN,
-        UNSTABLE_NAME_COLLISIONS,
-        UNSTABLE_SYNTAX_PRE_EXPANSION,
-        UNSUPPORTED_CALLING_CONVENTIONS,
-        UNUSED_ASSIGNMENTS,
-        UNUSED_ASSOCIATED_TYPE_BOUNDS,
-        UNUSED_ATTRIBUTES,
-        UNUSED_CRATE_DEPENDENCIES,
-        UNUSED_EXTERN_CRATES,
-        UNUSED_FEATURES,
-        UNUSED_IMPORTS,
-        UNUSED_LABELS,
-        UNUSED_LIFETIMES,
-        UNUSED_MACRO_RULES,
-        UNUSED_MACROS,
-        UNUSED_MUT,
-        UNUSED_QUALIFICATIONS,
-        UNUSED_TUPLE_STRUCT_FIELDS,
-        UNUSED_UNSAFE,
-        UNUSED_VARIABLES,
-        USELESS_DEPRECATED,
-        WARNINGS,
-        WHERE_CLAUSES_OBJECT_SAFETY,
-        // tidy-alphabetical-end
-    ]
-}
-
 declare_lint! {
     /// The `long_running_const_eval` lint is emitted when const
     /// eval is running for a long time to ensure rustc terminates
@@ -4233,47 +4235,6 @@ declare_lint! {
 }
 
 declare_lint! {
-    /// The `implied_bounds_entailment` lint detects cases where the arguments of an impl method
-    /// have stronger implied bounds than those from the trait method it's implementing.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,compile_fail
-    /// #![deny(implied_bounds_entailment)]
-    ///
-    /// trait Trait {
-    ///     fn get<'s>(s: &'s str, _: &'static &'static ()) -> &'static str;
-    /// }
-    ///
-    /// impl Trait for () {
-    ///     fn get<'s>(s: &'s str, _: &'static &'s ()) -> &'static str {
-    ///         s
-    ///     }
-    /// }
-    ///
-    /// let val = <() as Trait>::get(&String::from("blah blah blah"), &&());
-    /// println!("{}", val);
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// Neither the trait method, which provides no implied bounds about `'s`, nor the impl,
-    /// requires the main function to prove that 's: 'static, but the impl method is allowed
-    /// to assume that `'s: 'static` within its own body.
-    ///
-    /// This can be used to implement an unsound API if used incorrectly.
-    pub IMPLIED_BOUNDS_ENTAILMENT,
-    Deny,
-    "impl method assumes more implied bounds than its corresponding trait method",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
-        reference: "issue #105572 <https://github.com/rust-lang/rust/issues/105572>",
-    };
-}
-
-declare_lint! {
     /// The `byte_slice_in_packed_struct_with_derive` lint detects cases where a byte slice field
     /// (`[u8]`) or string slice field (`str`) is used in a `packed` struct that derives one or
     /// more built-in traits.
@@ -4619,3 +4580,37 @@ declare_lint! {
         reference: "issue #115010 <https://github.com/rust-lang/rust/issues/115010>",
     };
 }
+
+declare_lint! {
+    /// The `writes_through_immutable_pointer` lint detects writes through pointers derived from
+    /// shared references.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![feature(const_mut_refs)]
+    /// const WRITE_AFTER_CAST: () = unsafe {
+    ///     let mut x = 0;
+    ///     let ptr = &x as *const i32 as *mut i32;
+    ///     *ptr = 0;
+    /// };
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Shared references are immutable (when there is no `UnsafeCell` involved),
+    /// and writing through them or through pointers derived from them is Undefined Behavior.
+    /// The compiler recently learned to detect such Undefined Behavior during compile-time
+    /// evaluation, and in the future this will raise a hard error.
+    ///
+    /// [future-incompatible]: ../index.md#future-incompatible-lints
+    pub WRITES_THROUGH_IMMUTABLE_POINTER,
+    Warn,
+    "shared references are immutable, and pointers derived from them must not be written to",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
+        reference: "issue #X <https://github.com/rust-lang/rust/issues/X>",
+    };
+}
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index 878c1a65d..a25cfe68e 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -345,12 +345,34 @@ pub struct FutureIncompatibleInfo {
 }
 
 /// The reason for future incompatibility
+///
+/// Future-incompatible lints come in roughly two categories:
+///
+/// 1. There was a mistake in the compiler (such as a soundness issue), and
+///    we're trying to fix it, but it may be a breaking change.
+/// 2. A change across an Edition boundary, typically used for the
+///    introduction of new language features that can't otherwise be
+///    introduced in a backwards-compatible way.
+///
+/// See <https://rustc-dev-guide.rust-lang.org/bug-fix-procedure.html> and
+/// <https://rustc-dev-guide.rust-lang.org/diagnostics.html#future-incompatible-lints>
+/// for more information.
 #[derive(Copy, Clone, Debug)]
 pub enum FutureIncompatibilityReason {
     /// This will be an error in a future release for all editions
     ///
     /// This will *not* show up in cargo's future breakage report.
     /// The warning will hence only be seen in local crates, not in dependencies.
+    ///
+    /// Choose this variant when you are first introducing a "future
+    /// incompatible" warning that is intended to eventually be fixed in the
+    /// future. This allows crate developers an opportunity to fix the warning
+    /// before blasting all dependents with a warning they can't fix
+    /// (dependents have to wait for a new release of the affected crate to be
+    /// published).
+    ///
+    /// After a lint has been in this state for a while, consider graduating
+    /// it to [`FutureIncompatibilityReason::FutureReleaseErrorReportInDeps`].
     FutureReleaseErrorDontReportInDeps,
     /// This will be an error in a future release, and
     /// Cargo should create a report even for dependencies
@@ -358,17 +380,62 @@ pub enum FutureIncompatibilityReason {
     /// This is the *only* reason that will make future incompatibility warnings show up in cargo's
     /// reports. All other future incompatibility warnings are not visible when they occur in a
     /// dependency.
+    ///
+    /// Choose this variant after the lint has been sitting in the
+    /// [`FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps`]
+    /// state for a while, and you feel like it is ready to graduate to
+    /// warning everyone. It is a good signal that it is ready if you can
+    /// determine that all or most affected crates on crates.io have been
+    /// updated.
+    ///
+    /// After some period of time, lints with this variant can be turned into
+    /// hard errors (and the lint removed). Preferably when there is some
+    /// confidence that the number of impacted projects is very small (few
+    /// should have a broken dependency in their dependency tree).
     FutureReleaseErrorReportInDeps,
     /// Code that changes meaning in some way in a
     /// future release.
+    ///
+    /// Choose this variant when the semantics of existing code is changing,
+    /// (as opposed to
+    /// [`FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps`],
+    /// which is for when code is going to be rejected in the future).
     FutureReleaseSemanticsChange,
     /// Previously accepted code that will become an
     /// error in the provided edition
+    ///
+    /// Choose this variant for code that you want to start rejecting across
+    /// an edition boundary. This will automatically include the lint in the
+    /// `rust-20xx-compatibility` lint group, which is used by `cargo fix
+    /// --edition` to do migrations. The lint *should* be auto-fixable with
+    /// [`Applicability::MachineApplicable`].
+    ///
+    /// The lint can either be `Allow` or `Warn` by default. If it is `Allow`,
+    /// users usually won't see this warning unless they are doing an edition
+    /// migration manually or there is a problem during the migration (cargo's
+    /// automatic migrations will force the level to `Warn`). If it is `Warn`
+    /// by default, users on all editions will see this warning (only do this
+    /// if you think it is important for everyone to be aware of the change,
+    /// and to encourage people to update their code on all editions).
+    ///
+    /// See also [`FutureIncompatibilityReason::EditionSemanticsChange`] if
+    /// you have code that is changing semantics across the edition (as
+    /// opposed to being rejected).
     EditionError(Edition),
     /// Code that changes meaning in some way in
     /// the provided edition
+    ///
+    /// This is the same as [`FutureIncompatibilityReason::EditionError`],
+    /// except for situations where the semantics change across an edition. It
+    /// slightly changes the text of the diagnostic, but is otherwise the
+    /// same.
     EditionSemanticsChange(Edition),
     /// A custom reason.
+    ///
+    /// Choose this variant if the built-in text of the diagnostic of the
+    /// other variants doesn't match your situation. This is behaviorally
+    /// equivalent to
+    /// [`FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps`].
     Custom(&'static str),
 }
 
@@ -583,6 +650,10 @@ pub enum BuiltinLintDiagnostics {
         elided: bool,
         span: Span,
     },
+    RedundantImportVisibility {
+        span: Span,
+        max_vis: String,
+    },
 }
 
 /// Lints that are buffered up early on in the `Session` before the