Auto merge of #151056 - mejrs:do_not_recommend, r=<try>

Port `diagnostic::do_not_recommend` to new attr parsing

Author: bors

compiler/rustc_attr_parsing/src/attributes/do_not_recommend.rs

@@ -0,0 +1,31 @@
+use rustc_feature::{AttributeTemplate, template};
+use rustc_hir::attrs::AttributeKind;
+use rustc_hir::lints::AttributeLintKind;
+use rustc_session::lint::builtin::MALFORMED_DIAGNOSTIC_ATTRIBUTES;
+use rustc_span::{Symbol, sym};
+
+use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+use crate::target_checking::{ALL_TARGETS, AllowedTargets};
+
+pub(crate) struct DoNotRecommendParser;
+impl<S: Stage> SingleAttributeParser<S> for DoNotRecommendParser {
+    const PATH: &[Symbol] = &[sym::diagnostic, sym::do_not_recommend];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); // Checked in check_attr.
+    const TEMPLATE: AttributeTemplate = template!(Word /*doesn't matter */);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
+        let attr_span = cx.attr_span;
+        if !matches!(args, ArgParser::NoArgs) {
+            cx.emit_lint(
+                MALFORMED_DIAGNOSTIC_ATTRIBUTES,
+                AttributeLintKind::DoNotRecommendDoesNotExpectArgs,
+                attr_span,
+            );
+        }
+        Some(AttributeKind::DoNotRecommend { attr_span })
+    }
+}

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -39,6 +39,7 @@ pub(crate) mod confusables;
 pub(crate) mod crate_level;
 pub(crate) mod debugger;
 pub(crate) mod deprecation;
+pub(crate) mod do_not_recommend;
 pub(crate) mod doc;
 pub(crate) mod dummy;
 pub(crate) mod inline;

compiler/rustc_attr_parsing/src/context.rs

@@ -34,6 +34,7 @@ use crate::attributes::crate_level::{
 };
 use crate::attributes::debugger::DebuggerViualizerParser;
 use crate::attributes::deprecation::DeprecationParser;
+use crate::attributes::do_not_recommend::DoNotRecommendParser;
 use crate::attributes::doc::DocParser;
 use crate::attributes::dummy::DummyParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
@@ -201,6 +202,7 @@ attribute_parsers!(
         Single<CrateNameParser>,
         Single<CustomMirParser>,
         Single<DeprecationParser>,
+        Single<DoNotRecommendParser>,
         Single<DummyParser>,
         Single<ExportNameParser>,
         Single<IgnoreParser>,

compiler/rustc_attr_parsing/src/parser.rs

@@ -113,8 +113,9 @@ impl ArgParser {
         Some(match value {
             AttrArgs::Empty => Self::NoArgs,
             AttrArgs::Delimited(args) => {
-                // The arguments of rustc_dummy are not validated if the arguments are delimited
-                if parts == &[sym::rustc_dummy] {
+                // The arguments of rustc_dummy and diagnostic attributes are not validated
+                // if the arguments are delimited
+                if parts == &[sym::rustc_dummy] || parts[0] == sym::diagnostic {
                     return Some(ArgParser::List(MetaItemListParser {
                         sub_parsers: ThinVec::new(),
                         span: args.dspan.entire(),

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -731,6 +731,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_do_not_implement_via_object]`.
     DoNotImplementViaObject(Span),
 
+    /// Represents `#[diagnostic::do_not_recommend]`.
+    DoNotRecommend { attr_span: Span },
+
     /// Represents [`#[doc]`](https://doc.rust-lang.org/stable/rustdoc/write-documentation/the-doc-attribute.html).
     /// Represents all other uses of the [`#[doc]`](https://doc.rust-lang.org/stable/rustdoc/write-documentation/the-doc-attribute.html)
     /// attribute.

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -44,6 +44,7 @@ impl AttributeKind {
             DenyExplicitImpl(..) => No,
             Deprecation { .. } => Yes,
             DoNotImplementViaObject(..) => No,
+            DoNotRecommend { .. } => Yes,
             Doc(_) => Yes,
             DocComment { .. } => Yes,
             Dummy => No,

compiler/rustc_lint/messages.ftl

@@ -480,6 +480,9 @@ lint_improper_ctypes_unsafe_binder = unsafe binders are incompatible with foreig
 lint_improper_gpu_kernel_arg = passing type `{$ty}` to a function with "gpu-kernel" ABI may have unexpected behavior
     .help = use primitive types and raw pointers to get reliable behavior
 
+lint_incorrect_do_not_recommend_args =
+    `#[diagnostic::do_not_recommend]` does not expect any arguments
+
 lint_int_to_ptr_transmutes = transmuting an integer to a pointer creates a pointer without provenance
     .note = this is dangerous because dereferencing the resulting pointer is undefined behavior
     .note_exposed_provenance = exposed provenance semantics can be used to create a pointer based on some previously exposed provenance

compiler/rustc_lint/src/early/diagnostics.rs

@@ -419,5 +419,9 @@ pub fn decorate_attribute_lint(
         &AttributeLintKind::DocTestLiteral => lints::DocTestLiteral.decorate_lint(diag),
 
         &AttributeLintKind::AttrCrateLevelOnly => lints::AttrCrateLevelOnly.decorate_lint(diag),
+
+        &AttributeLintKind::DoNotRecommendDoesNotExpectArgs => {
+            lints::DoNotRecommendDoesNotExpectArgs.decorate_lint(diag)
+        }
     }
 }

compiler/rustc_lint/src/lints.rs

@@ -3317,3 +3317,7 @@ pub(crate) struct DocTestLiteral;
 #[diag(lint_attr_crate_level)]
 #[note]
 pub(crate) struct AttrCrateLevelOnly;
+
+#[derive(LintDiagnostic)]
+#[diag(lint_incorrect_do_not_recommend_args)]
+pub(crate) struct DoNotRecommendDoesNotExpectArgs;

compiler/rustc_lint_defs/src/lib.rs

@@ -821,6 +821,7 @@ pub enum AttributeLintKind {
     },
     DocTestLiteral,
     AttrCrateLevelOnly,
+    DoNotRecommendDoesNotExpectArgs,
 }
 
 pub type RegisteredTools = FxIndexSet<Ident>;