Port #[no_implicit_prelude] to the new attribute parsing infrastructure

Author: JonathanBrouwer

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -278,6 +278,9 @@ pub enum AttributeKind {
     /// Represents `#[naked]`
     Naked(Span),
 
+    /// Represents `#[no_implicit_prelude]`
+    NoImplicitPrelude(Span),
+
     /// Represents `#[no_mangle]`
     NoMangle(Span),
 

compiler/rustc_attr_data_structures/src/encode_cross_crate.rs

@@ -35,6 +35,7 @@ impl AttributeKind {
             MayDangle(..) => No,
             MustUse { .. } => Yes,
             Naked(..) => No,
+            NoImplicitPrelude(..) => No,
             NoMangle(..) => No,
             Optimize(..) => No,
             PubTransparent(..) => Yes,

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -35,6 +35,7 @@ pub(crate) mod link_attrs;
 pub(crate) mod lint_helpers;
 pub(crate) mod loop_match;
 pub(crate) mod must_use;
+pub(crate) mod no_implicit_prelude;
 pub(crate) mod repr;
 pub(crate) mod semantics;
 pub(crate) mod stability;

compiler/rustc_attr_parsing/src/attributes/no_implicit_prelude.rs

@@ -0,0 +1,25 @@
+use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
+use rustc_span::sym;
+
+use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct NoImplicitPreludeParser;
+
+impl<S: Stage> SingleAttributeParser<S> for NoImplicitPreludeParser {
+    const PATH: &[rustc_span::Symbol] = &[sym::no_implicit_prelude];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepLast;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const TEMPLATE: AttributeTemplate = template!(Word);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        if let Err(span) = args.no_args() {
+            cx.expected_no_args(span);
+            return None;
+        }
+
+        Some(AttributeKind::NoImplicitPrelude(cx.attr_span))
+    }
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -26,6 +26,7 @@ use crate::attributes::link_attrs::{LinkNameParser, LinkSectionParser};
 use crate::attributes::lint_helpers::{AsPtrParser, PubTransparentParser};
 use crate::attributes::loop_match::{ConstContinueParser, LoopMatchParser};
 use crate::attributes::must_use::MustUseParser;
+use crate::attributes::no_implicit_prelude::NoImplicitPreludeParser;
 use crate::attributes::repr::{AlignParser, ReprParser};
 use crate::attributes::semantics::MayDangleParser;
 use crate::attributes::stability::{
@@ -127,6 +128,7 @@ attribute_parsers!(
         Single<LoopMatchParser>,
         Single<MayDangleParser>,
         Single<MustUseParser>,
+        Single<NoImplicitPreludeParser>,
         Single<NoMangleParser>,
         Single<OptimizeParser>,
         Single<PubTransparentParser>,

compiler/rustc_passes/src/check_attr.rs

@@ -183,6 +183,14 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::Naked(attr_span)) => {
                     self.check_naked(hir_id, *attr_span, span, target)
                 }
+                Attribute::Parsed(AttributeKind::NoImplicitPrelude(attr_span)) => self
+                    .check_generic_attr(
+                        hir_id,
+                        sym::no_implicit_prelude,
+                        *attr_span,
+                        target,
+                        Target::Mod,
+                    ),
                 Attribute::Parsed(AttributeKind::TrackCaller(attr_span)) => {
                     self.check_track_caller(hir_id, *attr_span, attrs, span, target)
                 }
@@ -292,16 +300,13 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::macro_use, ..] | [sym::macro_escape, ..] => {
                             self.check_macro_use(hir_id, attr, target)
                         }
-                        [sym::path, ..] => self.check_generic_attr(hir_id, attr, target, Target::Mod),
+                        [sym::path, ..] => self.check_generic_attr_unparsed(hir_id, attr, target, Target::Mod),
                         [sym::macro_export, ..] => self.check_macro_export(hir_id, attr, target),
                         [sym::ignore, ..] | [sym::should_panic, ..] => {
-                            self.check_generic_attr(hir_id, attr, target, Target::Fn)
+                            self.check_generic_attr_unparsed(hir_id, attr, target, Target::Fn)
                         }
                         [sym::automatically_derived, ..] => {
-                            self.check_generic_attr(hir_id, attr, target, Target::Impl)
-                        }
-                        [sym::no_implicit_prelude, ..] => {
-                            self.check_generic_attr(hir_id, attr, target, Target::Mod)
+                            self.check_generic_attr_unparsed(hir_id, attr, target, Target::Impl)
                         }
                         [sym::rustc_object_lifetime_default, ..] => self.check_object_lifetime_default(hir_id),
                         [sym::proc_macro, ..] => {
@@ -311,7 +316,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             self.check_proc_macro(hir_id, target, ProcMacroKind::Attribute);
                         }
                         [sym::proc_macro_derive, ..] => {
-                            self.check_generic_attr(hir_id, attr, target, Target::Fn);
+                            self.check_generic_attr_unparsed(hir_id, attr, target, Target::Fn);
                             self.check_proc_macro(hir_id, target, ProcMacroKind::Derive)
                         }
                         [sym::autodiff_forward, ..] | [sym::autodiff_reverse, ..] => {
@@ -620,7 +625,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_generic_attr(
+    /// FIXME: Remove when all attributes are ported to the new parser
+    fn check_generic_attr_unparsed(
         &self,
         hir_id: HirId,
         attr: &Attribute,
@@ -643,6 +649,27 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
+    fn check_generic_attr(
+        &self,
+        hir_id: HirId,
+        attr_name: Symbol,
+        attr_span: Span,
+        target: Target,
+        allowed_target: Target,
+    ) {
+        if target != allowed_target {
+            self.tcx.emit_node_span_lint(
+                UNUSED_ATTRIBUTES,
+                hir_id,
+                attr_span,
+                errors::OnlyHasEffectOn {
+                    attr_name: attr_name.to_string(),
+                    target_name: allowed_target.name().replace(' ', "_"),
+                },
+            );
+        }
+    }
+
     /// Checks if `#[naked]` is applied to a function definition.
     fn check_naked(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
         match target {

tests/ui/lint/unused/unused-attr-duplicate.stderr

@@ -140,18 +140,6 @@ note: attribute also specified here
 LL | #![no_std]
    | ^^^^^^^^^^
 
-error: unused attribute
-  --> $DIR/unused-attr-duplicate.rs:25:1
-   |
-LL | #![no_implicit_prelude]
-   | ^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
-   |
-note: attribute also specified here
-  --> $DIR/unused-attr-duplicate.rs:24:1
-   |
-LL | #![no_implicit_prelude]
-   | ^^^^^^^^^^^^^^^^^^^^^^^
-
 error: unused attribute
   --> $DIR/unused-attr-duplicate.rs:27:1
    |
@@ -302,5 +290,17 @@ LL | #[link_section = ".bss"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 
+error: unused attribute
+  --> $DIR/unused-attr-duplicate.rs:25:1
+   |
+LL | #![no_implicit_prelude]
+   | ^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/unused-attr-duplicate.rs:24:1
+   |
+LL | #![no_implicit_prelude]
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+
 error: aborting due to 24 previous errors