Rollup merge of #150086 - Bryntet:parse_never_return_null_pointer, r=JonathanBrouwer

Port `#[rustc_never_returns_null_ptr]` to attribute parser

Ports `#[rustc_never_returns_null_ptr]` to be parsed using the attribute parser

r? `@JonathanBrouwer`

compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs

@@ -13,6 +13,21 @@ impl<S: Stage> NoArgsAttributeParser<S> for RustcMainParser {
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcMain;
 }
 
+pub(crate) struct RustcNeverReturnsNullPointerParser;
+
+impl<S: Stage> NoArgsAttributeParser<S> for RustcNeverReturnsNullPointerParser {
+    const PATH: &[Symbol] = &[sym::rustc_never_returns_null_ptr];
+    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::RustcNeverReturnsNullPointer;
+}
+
 pub(crate) struct RustcLayoutScalarValidRangeStartParser;
 
 impl<S: Stage> SingleAttributeParser<S> for RustcLayoutScalarValidRangeStartParser {

compiler/rustc_attr_parsing/src/context.rs

@@ -61,8 +61,9 @@ use crate::attributes::prototype::CustomMirParser;
 use crate::attributes::repr::{AlignParser, AlignStaticParser, ReprParser};
 use crate::attributes::rustc_internal::{
     RustcLayoutScalarValidRangeEndParser, RustcLayoutScalarValidRangeStartParser,
-    RustcLegacyConstGenericsParser, RustcMainParser, RustcObjectLifetimeDefaultParser,
+    RustcLegacyConstGenericsParser, RustcMainParser, RustcNeverReturnsNullPointerParser,
-    RustcScalableVectorParser, RustcSimdMonomorphizeLaneLimitParser,
+    RustcObjectLifetimeDefaultParser, RustcScalableVectorParser,
+    RustcSimdMonomorphizeLaneLimitParser,
 };
 use crate::attributes::semantics::MayDangleParser;
 use crate::attributes::stability::{
@@ -255,6 +256,7 @@ attribute_parsers!(
         Single<WithoutArgs<PubTransparentParser>>,
         Single<WithoutArgs<RustcCoherenceIsCoreParser>>,
         Single<WithoutArgs<RustcMainParser>>,
+        Single<WithoutArgs<RustcNeverReturnsNullPointerParser>>,
         Single<WithoutArgs<RustcPassIndirectlyInNonRusticAbisParser>>,
         Single<WithoutArgs<RustcShouldNotBeCalledOnConstItems>>,
         Single<WithoutArgs<SpecializationTraitParser>>,

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -878,6 +878,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_main]`.
     RustcMain,
 
+    /// Represents `#[rustc_never_returns_null_ptr]`
+    RustcNeverReturnsNullPointer,
+
     /// Represents `#[rustc_object_lifetime_default]`.
     RustcObjectLifetimeDefault,
 

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -95,6 +95,7 @@ impl AttributeKind {
             RustcLayoutScalarValidRangeStart(..) => Yes,
             RustcLegacyConstGenerics { .. } => Yes,
             RustcMain => No,
+            RustcNeverReturnsNullPointer => Yes,
             RustcObjectLifetimeDefault => No,
             RustcPassIndirectlyInNonRusticAbis(..) => No,
             RustcScalableVector { .. } => Yes,

compiler/rustc_lint/src/ptr_nulls.rs

@@ -1,5 +1,6 @@
 use rustc_ast::LitKind;
-use rustc_hir::{BinOpKind, Expr, ExprKind, TyKind};
+use rustc_hir::attrs::AttributeKind;
+use rustc_hir::{BinOpKind, Expr, ExprKind, TyKind, find_attr};
 use rustc_middle::ty::RawPtr;
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::{Span, sym};
@@ -72,14 +73,14 @@ fn useless_check<'a, 'tcx: 'a>(
         e = e.peel_blocks();
         if let ExprKind::MethodCall(_, _expr, [], _) = e.kind
             && let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
-            && cx.tcx.has_attr(def_id, sym::rustc_never_returns_null_ptr)
+            && find_attr!(cx.tcx.get_all_attrs(def_id), AttributeKind::RustcNeverReturnsNullPointer)
             && let Some(fn_name) = cx.tcx.opt_item_ident(def_id)
         {
             return Some(UselessPtrNullChecksDiag::FnRet { fn_name });
         } else if let ExprKind::Call(path, _args) = e.kind
             && let ExprKind::Path(ref qpath) = path.kind
             && let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
-            && cx.tcx.has_attr(def_id, sym::rustc_never_returns_null_ptr)
+            && find_attr!(cx.tcx.get_all_attrs(def_id), AttributeKind::RustcNeverReturnsNullPointer)
             && let Some(fn_name) = cx.tcx.opt_item_ident(def_id)
         {
             return Some(UselessPtrNullChecksDiag::FnRet { fn_name });

compiler/rustc_passes/src/check_attr.rs

@@ -257,6 +257,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::NoLink
                     | AttributeKind::RustcLayoutScalarValidRangeStart(..)
                     | AttributeKind::RustcLayoutScalarValidRangeEnd(..)
+                    | AttributeKind::RustcNeverReturnsNullPointer
                     | AttributeKind::RustcScalableVector { .. }
                     | AttributeKind::RustcSimdMonomorphizeLaneLimit(..)
                     | AttributeKind::RustcShouldNotBeCalledOnConstItems(..)
@@ -307,9 +308,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::rustc_no_implicit_autorefs, ..] => {
                             self.check_applied_to_fn_or_method(hir_id, attr.span(), span, target)
                         }
-                        [sym::rustc_never_returns_null_ptr, ..] => {
-                            self.check_applied_to_fn_or_method(hir_id, attr.span(), span, target)
-                        }
                         [sym::rustc_lint_query_instability, ..] => {
                             self.check_applied_to_fn_or_method(hir_id, attr.span(), span, target)
                         }