Add #[rustc_panics_when_n_is_zero] attribute

Author: Urgau

compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs

@@ -85,6 +85,23 @@ impl<S: Stage> NoArgsAttributeParser<S> for RustcNeverReturnsNullPtrParser {
     ]);
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcNeverReturnsNullPtr;
 }
+
+pub(crate) struct RustcPanicsWhenNIsZeroParser;
+
+impl<S: Stage> NoArgsAttributeParser<S> for RustcPanicsWhenNIsZeroParser {
+    const PATH: &[Symbol] = &[sym::rustc_panics_when_n_is_zero];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+    ]);
+
+    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcPanicsWhenNIsZero;
+}
+
 pub(crate) struct RustcNoImplicitAutorefsParser;
 
 impl<S: Stage> NoArgsAttributeParser<S> for RustcNoImplicitAutorefsParser {

compiler/rustc_attr_parsing/src/context.rs

@@ -311,6 +311,7 @@ attribute_parsers!(
         Single<WithoutArgs<RustcNonnullOptimizationGuaranteedParser>>,
         Single<WithoutArgs<RustcNounwindParser>>,
         Single<WithoutArgs<RustcOffloadKernelParser>>,
+        Single<WithoutArgs<RustcPanicsWhenNIsZeroParser>>,
         Single<WithoutArgs<RustcParenSugarParser>>,
         Single<WithoutArgs<RustcPassByValueParser>>,
         Single<WithoutArgs<RustcPassIndirectlyInNonRusticAbisParser>>,

compiler/rustc_feature/src/builtin_attrs.rs

@@ -1274,6 +1274,10 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         EncodeCrossCrate::Yes,
         "`#[rustc_never_returns_null_ptr]` is used to mark functions returning non-null pointers"
     ),
+    rustc_attr!(
+        rustc_panics_when_n_is_zero, Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes,
+        "`#[rustc_panics_when_n_is_zero]` is used to mark functions with a const generic argument who makes the function panics when it is zero"
+    ),
     rustc_attr!(
         rustc_no_implicit_autorefs, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes,
         "`#[rustc_no_implicit_autorefs]` is used to mark functions for which an autoref to the dereference of a raw pointer should not be used as an argument"

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -1508,6 +1508,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_offload_kernel]`
     RustcOffloadKernel,
 
+    /// Represents `#[rustc_panics_when_n_is_zero]` (used for linting).
+    RustcPanicsWhenNIsZero,
+
     /// Represents `#[rustc_paren_sugar]`.
     RustcParenSugar(Span),
 

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -166,6 +166,7 @@ impl AttributeKind {
             RustcObjcClass { .. } => No,
             RustcObjcSelector { .. } => No,
             RustcOffloadKernel => Yes,
+            RustcPanicsWhenNIsZero => Yes,
             RustcParenSugar(..) => No,
             RustcPassByValue(..) => Yes,
             RustcPassIndirectlyInNonRusticAbis(..) => No,

compiler/rustc_passes/src/check_attr.rs

@@ -358,6 +358,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::RustcObjcClass { .. }
                     | AttributeKind::RustcObjcSelector { .. }
                     | AttributeKind::RustcOffloadKernel
+                    | AttributeKind::RustcPanicsWhenNIsZero
                     | AttributeKind::RustcParenSugar(..)
                     | AttributeKind::RustcPassByValue (..)
                     | AttributeKind::RustcPassIndirectlyInNonRusticAbis(..)

compiler/rustc_span/src/symbol.rs

@@ -1756,6 +1756,7 @@ symbols! {
         rustc_objc_selector,
         rustc_offload_kernel,
         rustc_on_unimplemented,
+        rustc_panics_when_n_is_zero,
         rustc_paren_sugar,
         rustc_partition_codegened,
         rustc_partition_reused,