Port diagnostic::do_not_recommend to new attr parsing

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};
@@ -197,6 +198,7 @@ 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 +113,12 @@ 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::do_not_recommend are not validated
+                // if the arguments are delimited.
+                // See https://doc.rust-lang.org/reference/attributes/diagnostics.html#r-attributes.diagnostic.namespace.unknown-invalid-syntax
+                if parts == &[sym::rustc_dummy]
+                    || parts == &[sym::diagnostic, sym::do_not_recommend]
+                {
                     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>;

compiler/rustc_middle/src/ty/context.rs

@@ -3540,7 +3540,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
     /// Whether this is a trait implementation that has `#[diagnostic::do_not_recommend]`
     pub fn do_not_recommend_impl(self, def_id: DefId) -> bool {
-        self.get_diagnostic_attr(def_id, sym::do_not_recommend).is_some()
+        find_attr!(self.get_all_attrs(def_id), AttributeKind::DoNotRecommend { .. })
     }
 
     pub fn is_trivial_const<P>(self, def_id: P) -> bool

compiler/rustc_middle/src/ty/mod.rs

@@ -51,7 +51,7 @@ use rustc_query_system::ich::StableHashingContext;
 use rustc_serialize::{Decodable, Encodable};
 pub use rustc_session::lint::RegisteredTools;
 use rustc_span::hygiene::MacroKind;
-use rustc_span::{DUMMY_SP, ExpnId, ExpnKind, Ident, Span, Symbol, sym};
+use rustc_span::{DUMMY_SP, ExpnId, ExpnKind, Ident, Span, Symbol};
 pub use rustc_type_ir::data_structures::{DelayedMap, DelayedSet};
 pub use rustc_type_ir::fast_reject::DeepRejectCtxt;
 #[allow(
@@ -1819,37 +1819,6 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    /// Get an attribute from the diagnostic attribute namespace
-    ///
-    /// This function requests an attribute with the following structure:
-    ///
-    /// `#[diagnostic::$attr]`
-    ///
-    /// This function performs feature checking, so if an attribute is returned
-    /// it can be used by the consumer
-    pub fn get_diagnostic_attr(
-        self,
-        did: impl Into<DefId>,
-        attr: Symbol,
-    ) -> Option<&'tcx hir::Attribute> {
-        let did: DefId = did.into();
-        if did.as_local().is_some() {
-            // it's a crate local item, we need to check feature flags
-            if rustc_feature::is_stable_diagnostic_attribute(attr, self.features()) {
-                self.get_attrs_by_path(did, &[sym::diagnostic, sym::do_not_recommend]).next()
-            } else {
-                None
-            }
-        } else {
-            // we filter out unstable diagnostic attributes before
-            // encoding attributes
-            debug_assert!(rustc_feature::encode_cross_crate(attr));
-            self.attrs_for_def(did)
-                .iter()
-                .find(|a| matches!(a.path().as_ref(), [sym::diagnostic, a] if *a == attr))
-        }
-    }
-
     pub fn get_attrs_by_path(
         self,
         did: DefId,

compiler/rustc_passes/messages.ftl

@@ -246,9 +246,6 @@ passes_implied_feature_not_exist =
 
 passes_incorrect_crate_type = lang items are not allowed in stable dylibs
 
-passes_incorrect_do_not_recommend_args =
-    `#[diagnostic::do_not_recommend]` does not expect any arguments
-
 passes_incorrect_do_not_recommend_location =
     `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
 

compiler/rustc_passes/src/check_attr.rs

@@ -43,8 +43,8 @@ use rustc_middle::{bug, span_bug};
 use rustc_session::config::CrateType;
 use rustc_session::lint;
 use rustc_session::lint::builtin::{
-    CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, MALFORMED_DIAGNOSTIC_ATTRIBUTES,
-    MISPLACED_DIAGNOSTIC_ATTRIBUTES, UNUSED_ATTRIBUTES,
+    CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, MISPLACED_DIAGNOSTIC_ATTRIBUTES,
+    UNUSED_ATTRIBUTES,
 };
 use rustc_session::parse::feature_err;
 use rustc_span::edition::Edition;
@@ -223,6 +223,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::RustcMustImplementOneOf { attr_span, fn_names }) => {
                     self.check_rustc_must_implement_one_of(*attr_span, fn_names, hir_id,target)
                 },
+                Attribute::Parsed(AttributeKind::DoNotRecommend{attr_span}) => {self.check_do_not_recommend(*attr_span, hir_id, target, item)},
                 Attribute::Parsed(
                     AttributeKind::EiiDeclaration { .. }
                     | AttributeKind::EiiForeignItem
@@ -313,9 +314,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Unparsed(attr_item) => {
                     style = Some(attr_item.style);
                     match attr.path().as_slice() {
-                        [sym::diagnostic, sym::do_not_recommend, ..] => {
-                            self.check_do_not_recommend(attr.span(), hir_id, target, attr, item)
-                        }
                         [sym::diagnostic, sym::on_unimplemented, ..] => {
                             self.check_diagnostic_on_unimplemented(attr.span(), hir_id, target)
                         }
@@ -568,14 +566,12 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks if `#[diagnostic::do_not_recommend]` is applied on a trait impl and that it has no
-    /// arguments.
+    /// Checks if `#[diagnostic::do_not_recommend]` is applied on a trait impl
     fn check_do_not_recommend(
         &self,
         attr_span: Span,
         hir_id: HirId,
         target: Target,
-        attr: &Attribute,
         item: Option<ItemLike<'_>>,
     ) {
         if !matches!(target, Target::Impl { .. })
@@ -592,14 +588,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 errors::IncorrectDoNotRecommendLocation,
             );
         }
-        if !attr.is_word() {
-            self.tcx.emit_node_span_lint(
-                MALFORMED_DIAGNOSTIC_ATTRIBUTES,
-                hir_id,
-                attr_span,
-                errors::DoNotRecommendDoesNotExpectArgs,
-            );
-        }
     }
 
     /// Checks if `#[diagnostic::on_unimplemented]` is applied to a trait definition

compiler/rustc_passes/src/errors.rs

@@ -20,10 +20,6 @@ use crate::lang_items::Duplicate;
 #[diag(passes_incorrect_do_not_recommend_location)]
 pub(crate) struct IncorrectDoNotRecommendLocation;
 
-#[derive(LintDiagnostic)]
-#[diag(passes_incorrect_do_not_recommend_args)]
-pub(crate) struct DoNotRecommendDoesNotExpectArgs;
-
 #[derive(Diagnostic)]
 #[diag(passes_autodiff_attr)]
 pub(crate) struct AutoDiffAttr {

compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs

@@ -434,7 +434,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
         } = candidate.kind()
             && tcx.do_not_recommend_impl(impl_def_id)
         {
-            trace!("#[do_not_recommend] -> exit");
+            trace!("#[diagnostic::do_not_recommend] -> exit");
             return ControlFlow::Break(self.obligation.clone());
         }
 

tests/ui/attributes/malformed-attrs.stderr

@@ -729,21 +729,14 @@ help: use `#[rustc_align(...)]` instead
 LL | #[repr]
    | ^^^^^^^
 
-warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/malformed-attrs.rs:155:1
-   |
-LL | #[diagnostic::do_not_recommend()]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[warn(malformed_diagnostic_attributes)]` (part of `#[warn(unknown_or_malformed_diagnostic_attributes)]`) on by default
-
 warning: missing options for `on_unimplemented` attribute
   --> $DIR/malformed-attrs.rs:144:1
    |
 LL | #[diagnostic::on_unimplemented]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: at least one of the `message`, `note` and `label` options are expected
+   = note: `#[warn(malformed_diagnostic_attributes)]` (part of `#[warn(unknown_or_malformed_diagnostic_attributes)]`) on by default
 
 warning: malformed `on_unimplemented` attribute
   --> $DIR/malformed-attrs.rs:146:1
@@ -823,6 +816,12 @@ LL | #[no_implicit_prelude = 23]
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = help: `#[no_implicit_prelude]` can be applied to crates and modules
 
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/malformed-attrs.rs:155:1
+   |
+LL | #[diagnostic::do_not_recommend()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 warning: `#[automatically_derived]` attribute cannot be used on modules
   --> $DIR/malformed-attrs.rs:196:1
    |

tests/ui/diagnostic_namespace/do_not_recommend/does_not_acccept_args.current.stderr

@@ -1,22 +1,28 @@
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/does_not_acccept_args.rs:11:1
+  --> $DIR/does_not_acccept_args.rs:12:1
    |
 LL | #[diagnostic::do_not_recommend(not_accepted)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(malformed_diagnostic_attributes)]` (part of `#[warn(unknown_or_malformed_diagnostic_attributes)]`) on by default
 
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/does_not_acccept_args.rs:15:1
+  --> $DIR/does_not_acccept_args.rs:16:1
    |
 LL | #[diagnostic::do_not_recommend(not_accepted = "foo")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/does_not_acccept_args.rs:19:1
+  --> $DIR/does_not_acccept_args.rs:20:1
    |
 LL | #[diagnostic::do_not_recommend(not_accepted(42))]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: 3 warnings emitted
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:24:1
+   |
+LL | #[diagnostic::do_not_recommend(x = y + z)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 4 warnings emitted
 

tests/ui/diagnostic_namespace/do_not_recommend/does_not_acccept_args.next.stderr

@@ -1,22 +1,28 @@
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/does_not_acccept_args.rs:11:1
+  --> $DIR/does_not_acccept_args.rs:12:1
    |
 LL | #[diagnostic::do_not_recommend(not_accepted)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(malformed_diagnostic_attributes)]` (part of `#[warn(unknown_or_malformed_diagnostic_attributes)]`) on by default
 
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/does_not_acccept_args.rs:15:1
+  --> $DIR/does_not_acccept_args.rs:16:1
    |
 LL | #[diagnostic::do_not_recommend(not_accepted = "foo")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
-  --> $DIR/does_not_acccept_args.rs:19:1
+  --> $DIR/does_not_acccept_args.rs:20:1
    |
 LL | #[diagnostic::do_not_recommend(not_accepted(42))]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: 3 warnings emitted
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:24:1
+   |
+LL | #[diagnostic::do_not_recommend(x = y + z)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 4 warnings emitted
 

tests/ui/diagnostic_namespace/do_not_recommend/does_not_acccept_args.rs

@@ -7,6 +7,7 @@
 trait Foo {}
 trait Bar {}
 trait Baz {}
+trait Boo {}
 
 #[diagnostic::do_not_recommend(not_accepted)]
 //~^ WARNING `#[diagnostic::do_not_recommend]` does not expect any arguments
@@ -20,4 +21,8 @@ impl<T> Bar for T where T: Send {}
 //~^ WARNING `#[diagnostic::do_not_recommend]` does not expect any arguments
 impl<T> Baz for T where T: Send {}
 
+#[diagnostic::do_not_recommend(x = y + z)]
+//~^ WARNING `#[diagnostic::do_not_recommend]` does not expect any arguments
+impl<T> Boo for T where T: Send {}
+
 fn main() {}

tests/ui/unpretty/diagnostic-attr.stdout

@@ -11,5 +11,5 @@ use ::std::prelude::rust_2015::*;
 "My Label", note = "Note 1", note = "Note 2")]
 trait ImportantTrait<A> { }
 
-#[diagnostic::do_not_recommend]
+#[attr = DoNotRecommend]
 impl <T> ImportantTrait<T> for T where T: Clone { }