Rollup merge of #64462 - petrochenkov:remattr, r=Centril

feature_gate: Remove dead code from attribute checking

https://github.com/rust-lang/rust/pull/63468 is merged, so all attributes go through name resolution now, so we can remove code that previously performed some checks for attributes not going through resolution.

13 files changed, 63 insertions, 161 deletions

diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 3cfae1686df..e8e8da67334 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -41,7 +41,6 @@ use syntax::mut_visit::MutVisitor;
 use syntax::parse::{self, PResult};
 use syntax::util::node_count::NodeCounter;
 use syntax::symbol::Symbol;
-use syntax::feature_gate::AttributeType;
 use syntax_pos::FileName;
 use syntax_ext;
 
@@ -219,7 +218,6 @@ impl BoxedResolver {
 
 pub struct PluginInfo {
     syntax_exts: Vec<NamedSyntaxExtension>,
-    attributes: Vec<(Symbol, AttributeType)>,
 }
 
 pub fn register_plugins<'a>(
@@ -312,12 +310,9 @@ pub fn register_plugins<'a>(
     }
 
     *sess.plugin_llvm_passes.borrow_mut() = llvm_passes;
-    *sess.plugin_attributes.borrow_mut() = attributes.clone();
+    *sess.plugin_attributes.borrow_mut() = attributes;
 
-    Ok((krate, PluginInfo {
-        syntax_exts,
-        attributes,
-    }))
+    Ok((krate, PluginInfo { syntax_exts }))
 }
 
 fn configure_and_expand_inner<'a>(
@@ -329,7 +324,6 @@ fn configure_and_expand_inner<'a>(
     crate_loader: &'a mut CrateLoader<'a>,
     plugin_info: PluginInfo,
 ) -> Result<(ast::Crate, Resolver<'a>)> {
-    let attributes = plugin_info.attributes;
     time(sess, "pre ast expansion lint checks", || {
         lint::check_ast_crate(
             sess,
@@ -522,7 +516,6 @@ fn configure_and_expand_inner<'a>(
             &krate,
             &sess.parse_sess,
             &sess.features_untracked(),
-            &attributes,
             sess.opts.unstable_features,
         );
     });
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 87e2d721f89..b80c530731d 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -26,7 +26,7 @@ use syntax_pos::{Span, DUMMY_SP, FileName};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
 use std::io::ErrorKind;
-use std::{iter, mem};
+use std::{iter, mem, slice};
 use std::ops::DerefMut;
 use std::rc::Rc;
 use std::path::PathBuf;
@@ -1019,7 +1019,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
         let features = self.cx.ecfg.features.unwrap();
         for attr in attrs.iter() {
-            self.check_attribute_inner(attr, features);
+            feature_gate::check_attribute(attr, self.cx.parse_sess, features);
 
             // macros are expanded before any lint passes so this warning has to be hardcoded
             if attr.path == sym::derive {
@@ -1029,15 +1029,6 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
             }
         }
     }
-
-    fn check_attribute(&mut self, at: &ast::Attribute) {
-        let features = self.cx.ecfg.features.unwrap();
-        self.check_attribute_inner(at, features);
-    }
-
-    fn check_attribute_inner(&mut self, at: &ast::Attribute, features: &Features) {
-        feature_gate::check_attribute(at, self.cx.parse_sess, features);
-    }
 }
 
 impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
@@ -1445,7 +1436,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
 
                 if let Some(file) = it.value_str() {
                     let err_count = self.cx.parse_sess.span_diagnostic.err_count();
-                    self.check_attribute(&at);
+                    self.check_attributes(slice::from_ref(at));
                     if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
                         // avoid loading the file if they haven't enabled the feature
                         return noop_visit_attribute(at, self);
diff --git a/src/libsyntax/feature_gate/builtin_attrs.rs b/src/libsyntax/feature_gate/builtin_attrs.rs
index 763c3ffd782..b6e13200f32 100644
--- a/src/libsyntax/feature_gate/builtin_attrs.rs
+++ b/src/libsyntax/feature_gate/builtin_attrs.rs
@@ -79,6 +79,7 @@ pub enum AttributeType {
     CrateLevel,
 }
 
+#[derive(Clone, Copy)]
 pub enum AttributeGate {
     /// Is gated by a given feature gate, reason
     /// and function to check if enabled
diff --git a/src/libsyntax/feature_gate/check.rs b/src/libsyntax/feature_gate/check.rs
index 5711b269ff0..b4491a87f06 100644
--- a/src/libsyntax/feature_gate/check.rs
+++ b/src/libsyntax/feature_gate/check.rs
@@ -1,7 +1,7 @@
 use super::{active::{ACTIVE_FEATURES, Features}, Feature, State as FeatureState};
 use super::accepted::ACCEPTED_FEATURES;
 use super::removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
-use super::builtin_attrs::{AttributeGate, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
+use super::builtin_attrs::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
 
 use crate::ast::{
     self, AssocTyConstraint, AssocTyConstraintKind, NodeId, GenericParam, GenericParamKind,
@@ -32,16 +32,10 @@ pub enum Stability {
     Deprecated(&'static str, Option<&'static str>),
 }
 
-struct Context<'a> {
-    features: &'a Features,
-    parse_sess: &'a ParseSess,
-    plugin_attributes: &'a [(Symbol, AttributeType)],
-}
-
 macro_rules! gate_feature_fn {
     ($cx: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $level: expr) => {{
         let (cx, has_feature, span,
-             name, explain, level) = ($cx, $has_feature, $span, $name, $explain, $level);
+             name, explain, level) = (&*$cx, $has_feature, $span, $name, $explain, $level);
         let has_feature: bool = has_feature(&$cx.features);
         debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
         if !has_feature && !span.allows_unstable($name) {
@@ -62,68 +56,8 @@ macro_rules! gate_feature {
     };
 }
 
-impl<'a> Context<'a> {
-    fn check_attribute(
-        &self,
-        attr: &ast::Attribute,
-        attr_info: Option<&BuiltinAttribute>,
-        is_macro: bool
-    ) {
-        debug!("check_attribute(attr = {:?})", attr);
-        if let Some(&(name, ty, _template, ref gateage)) = attr_info {
-            if let AttributeGate::Gated(_, name, desc, ref has_feature) = *gateage {
-                if !attr.span.allows_unstable(name) {
-                    gate_feature_fn!(
-                        self, has_feature, attr.span, name, desc, GateStrength::Hard
-                    );
-                }
-            } else if name == sym::doc {
-                if let Some(content) = attr.meta_item_list() {
-                    if content.iter().any(|c| c.check_name(sym::include)) {
-                        gate_feature!(self, external_doc, attr.span,
-                            "`#[doc(include = \"...\")]` is experimental"
-                        );
-                    }
-                }
-            }
-            debug!("check_attribute: {:?} is builtin, {:?}, {:?}", attr.path, ty, gateage);
-            return;
-        } else {
-            for segment in &attr.path.segments {
-                if segment.ident.as_str().starts_with("rustc") {
-                    let msg = "attributes starting with `rustc` are \
-                               reserved for use by the `rustc` compiler";
-                    gate_feature!(self, rustc_attrs, segment.ident.span, msg);
-                }
-            }
-        }
-        for &(n, ty) in self.plugin_attributes {
-            if attr.path == n {
-                // Plugins can't gate attributes, so we don't check for it
-                // unlike the code above; we only use this loop to
-                // short-circuit to avoid the checks below.
-                debug!("check_attribute: {:?} is registered by a plugin, {:?}", attr.path, ty);
-                return;
-            }
-        }
-        if !is_macro && !attr::is_known(attr) {
-            // Only run the custom attribute lint during regular feature gate
-            // checking. Macro gating runs before the plugin attributes are
-            // registered, so we skip this in that case.
-            let msg = format!("the attribute `{}` is currently unknown to the compiler and \
-                               may have meaning added to it in the future", attr.path);
-            gate_feature!(self, custom_attribute, attr.span, &msg);
-        }
-    }
-}
-
-pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) {
-    let cx = Context { features, parse_sess, plugin_attributes: &[] };
-    cx.check_attribute(
-        attr,
-        attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name).map(|a| *a)),
-        true
-    );
+crate fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) {
+    PostExpansionVisitor { parse_sess, features }.visit_attribute(attr)
 }
 
 fn find_lang_feature_issue(feature: Symbol) -> Option<u32> {
@@ -238,21 +172,21 @@ pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &str =
     "unsized tuple coercion is not stable enough for use and is subject to change";
 
 struct PostExpansionVisitor<'a> {
-    context: &'a Context<'a>,
-    builtin_attributes: &'static FxHashMap<Symbol, &'static BuiltinAttribute>,
+    parse_sess: &'a ParseSess,
+    features: &'a Features,
 }
 
 macro_rules! gate_feature_post {
     ($cx: expr, $feature: ident, $span: expr, $explain: expr) => {{
         let (cx, span) = ($cx, $span);
         if !span.allows_unstable(sym::$feature) {
-            gate_feature!(cx.context, $feature, span, $explain)
+            gate_feature!(cx, $feature, span, $explain)
         }
     }};
     ($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => {{
         let (cx, span) = ($cx, $span);
         if !span.allows_unstable(sym::$feature) {
-            gate_feature!(cx.context, $feature, span, $explain, $level)
+            gate_feature!(cx, $feature, span, $explain, $level)
         }
     }}
 }
@@ -316,50 +250,44 @@ impl<'a> PostExpansionVisitor<'a> {
 
 impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     fn visit_attribute(&mut self, attr: &ast::Attribute) {
-        let attr_info = attr.ident().and_then(|ident| {
-            self.builtin_attributes.get(&ident.name).map(|a| *a)
-        });
-
-        // Check for gated attributes.
-        self.context.check_attribute(attr, attr_info, false);
-
-        if attr.check_name(sym::doc) {
-            if let Some(content) = attr.meta_item_list() {
-                if content.len() == 1 && content[0].check_name(sym::cfg) {
-                    gate_feature_post!(&self, doc_cfg, attr.span,
-                        "`#[doc(cfg(...))]` is experimental"
-                    );
-                } else if content.iter().any(|c| c.check_name(sym::masked)) {
-                    gate_feature_post!(&self, doc_masked, attr.span,
-                        "`#[doc(masked)]` is experimental"
-                    );
-                } else if content.iter().any(|c| c.check_name(sym::spotlight)) {
-                    gate_feature_post!(&self, doc_spotlight, attr.span,
-                        "`#[doc(spotlight)]` is experimental"
-                    );
-                } else if content.iter().any(|c| c.check_name(sym::alias)) {
-                    gate_feature_post!(&self, doc_alias, attr.span,
-                        "`#[doc(alias = \"...\")]` is experimental"
-                    );
-                } else if content.iter().any(|c| c.check_name(sym::keyword)) {
-                    gate_feature_post!(&self, doc_keyword, attr.span,
-                        "`#[doc(keyword = \"...\")]` is experimental"
-                    );
-                }
-            }
+        let attr_info =
+            attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)).map(|a| **a);
+        // Check feature gates for built-in attributes.
+        if let Some((.., AttributeGate::Gated(_, name, descr, has_feature))) = attr_info {
+            gate_feature_fn!(self, has_feature, attr.span, name, descr, GateStrength::Hard);
         }
-
+        // Check input tokens for built-in and key-value attributes.
         match attr_info {
             // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
-            Some(&(name, _, template, _)) if name != sym::rustc_dummy =>
-                check_builtin_attribute(self.context.parse_sess, attr, name, template),
+            Some((name, _, template, _)) if name != sym::rustc_dummy =>
+                check_builtin_attribute(self.parse_sess, attr, name, template),
             _ => if let Some(TokenTree::Token(token)) = attr.tokens.trees().next() {
                 if token == token::Eq {
                     // All key-value attributes are restricted to meta-item syntax.
-                    attr.parse_meta(self.context.parse_sess).map_err(|mut err| err.emit()).ok();
+                    attr.parse_meta(self.parse_sess).map_err(|mut err| err.emit()).ok();
                 }
             }
         }
+        // Check unstable flavors of the `#[doc]` attribute.
+        if attr.check_name(sym::doc) {
+            for nested_meta in attr.meta_item_list().unwrap_or_default() {
+                macro_rules! gate_doc { ($($name:ident => $feature:ident)*) => {
+                    $(if nested_meta.check_name(sym::$name) {
+                        let msg = concat!("`#[doc(", stringify!($name), ")]` is experimental");
+                        gate_feature!(self, $feature, attr.span, msg);
+                    })*
+                }}
+
+                gate_doc!(
+                    include => external_doc
+                    cfg => doc_cfg
+                    masked => doc_masked
+                    spotlight => doc_spotlight
+                    alias => doc_alias
+                    keyword => doc_keyword
+                );
+            }
+        }
     }
 
     fn visit_name(&mut self, sp: Span, name: ast::Name) {
@@ -367,7 +295,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             gate_feature_post!(
                 &self,
                 non_ascii_idents,
-                self.context.parse_sess.source_map().def_span(sp),
+                self.parse_sess.source_map().def_span(sp),
                 "non-ascii idents are not fully supported"
             );
         }
@@ -423,12 +351,9 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                     }
                 }
 
-                let has_feature = self.context.features.arbitrary_enum_discriminant;
+                let has_feature = self.features.arbitrary_enum_discriminant;
                 if !has_feature && !i.span.allows_unstable(sym::arbitrary_enum_discriminant) {
-                    Parser::maybe_report_invalid_custom_discriminants(
-                        self.context.parse_sess,
-                        &variants,
-                    );
+                    Parser::maybe_report_invalid_custom_discriminants(self.parse_sess, &variants);
                 }
             }
 
@@ -538,7 +463,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             ast::ExprKind::Type(..) => {
                 // To avoid noise about type ascription in common syntax errors, only emit if it
                 // is the *only* error.
-                if self.context.parse_sess.span_diagnostic.err_count() == 0 {
+                if self.parse_sess.span_diagnostic.err_count() == 0 {
                     gate_feature_post!(&self, type_ascription, e.span,
                                        "type ascription is experimental");
                 }
@@ -872,22 +797,17 @@ fn active_features_up_to(edition: Edition) -> impl Iterator<Item=&'static Featur
 }
 
 pub fn check_crate(krate: &ast::Crate,
-                   sess: &ParseSess,
+                   parse_sess: &ParseSess,
                    features: &Features,
-                   plugin_attributes: &[(Symbol, AttributeType)],
                    unstable: UnstableFeatures) {
-    maybe_stage_features(&sess.span_diagnostic, krate, unstable);
-    let ctx = Context {
-        features,
-        parse_sess: sess,
-        plugin_attributes,
-    };
+    maybe_stage_features(&parse_sess.span_diagnostic, krate, unstable);
+    let mut visitor = PostExpansionVisitor { parse_sess, features };
 
     macro_rules! gate_all {
         ($gate:ident, $msg:literal) => { gate_all!($gate, $gate, $msg); };
         ($spans:ident, $gate:ident, $msg:literal) => {
-            for span in &*sess.gated_spans.$spans.borrow() {
-                gate_feature!(&ctx, $gate, *span, $msg);
+            for span in &*parse_sess.gated_spans.$spans.borrow() {
+                gate_feature!(&visitor, $gate, *span, $msg);
             }
         }
     }
@@ -898,11 +818,7 @@ pub fn check_crate(krate: &ast::Crate,
     gate_all!(yields, generators, "yield syntax is experimental");
     gate_all!(or_patterns, "or-patterns syntax is experimental");
 
-    let visitor = &mut PostExpansionVisitor {
-        context: &ctx,
-        builtin_attributes: &*BUILTIN_ATTRIBUTE_MAP,
-    };
-    visit::walk_crate(visitor, krate);
+    visit::walk_crate(&mut visitor, krate);
 }
 
 #[derive(Clone, Copy, Hash)]
diff --git a/src/libsyntax/feature_gate/mod.rs b/src/libsyntax/feature_gate/mod.rs
index 1e41667ea41..ca13ab36205 100644
--- a/src/libsyntax/feature_gate/mod.rs
+++ b/src/libsyntax/feature_gate/mod.rs
@@ -58,7 +58,8 @@ pub use builtin_attrs::{
     deprecated_attributes, is_builtin_attr,  is_builtin_attr_name,
 };
 pub use check::{
-    check_attribute, check_crate, get_features, feature_err, emit_feature_err,
+    check_crate, get_features, feature_err, emit_feature_err,
     Stability, GateIssue, UnstableFeatures,
     EXPLAIN_STMT_ATTR_SYNTAX, EXPLAIN_UNSIZED_TUPLE_COERCION,
 };
+crate use check::check_attribute;
diff --git a/src/test/ui/feature-gates/feature-gate-doc_alias.rs b/src/test/ui/feature-gates/feature-gate-doc_alias.rs
index adb6fc217a3..c95722102d9 100644
--- a/src/test/ui/feature-gates/feature-gate-doc_alias.rs
+++ b/src/test/ui/feature-gates/feature-gate-doc_alias.rs
@@ -1,4 +1,4 @@
-#[doc(alias = "foo")] //~ ERROR: `#[doc(alias = "...")]` is experimental
+#[doc(alias = "foo")] //~ ERROR: `#[doc(alias)]` is experimental
 pub struct Foo;
 
 fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-doc_alias.stderr b/src/test/ui/feature-gates/feature-gate-doc_alias.stderr
index dddaa45de8f..540b1f5ccbe 100644
--- a/src/test/ui/feature-gates/feature-gate-doc_alias.stderr
+++ b/src/test/ui/feature-gates/feature-gate-doc_alias.stderr
@@ -1,4 +1,4 @@
-error[E0658]: `#[doc(alias = "...")]` is experimental
+error[E0658]: `#[doc(alias)]` is experimental
   --> $DIR/feature-gate-doc_alias.rs:1:1
    |
 LL | #[doc(alias = "foo")]
diff --git a/src/test/ui/feature-gates/feature-gate-doc_cfg.rs b/src/test/ui/feature-gates/feature-gate-doc_cfg.rs
index bb3846e7f6b..b12b8a10571 100644
--- a/src/test/ui/feature-gates/feature-gate-doc_cfg.rs
+++ b/src/test/ui/feature-gates/feature-gate-doc_cfg.rs
@@ -1,2 +1,2 @@
-#[doc(cfg(unix))] //~ ERROR: `#[doc(cfg(...))]` is experimental
+#[doc(cfg(unix))] //~ ERROR: `#[doc(cfg)]` is experimental
 fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-doc_cfg.stderr b/src/test/ui/feature-gates/feature-gate-doc_cfg.stderr
index 7b0a231df4c..eaa908d0037 100644
--- a/src/test/ui/feature-gates/feature-gate-doc_cfg.stderr
+++ b/src/test/ui/feature-gates/feature-gate-doc_cfg.stderr
@@ -1,4 +1,4 @@
-error[E0658]: `#[doc(cfg(...))]` is experimental
+error[E0658]: `#[doc(cfg)]` is experimental
   --> $DIR/feature-gate-doc_cfg.rs:1:1
    |
 LL | #[doc(cfg(unix))]
diff --git a/src/test/ui/feature-gates/feature-gate-doc_keyword.rs b/src/test/ui/feature-gates/feature-gate-doc_keyword.rs
index 6cdcfa67c3a..4bb9a40deb0 100644
--- a/src/test/ui/feature-gates/feature-gate-doc_keyword.rs
+++ b/src/test/ui/feature-gates/feature-gate-doc_keyword.rs
@@ -1,4 +1,4 @@
-#[doc(keyword = "match")] //~ ERROR: `#[doc(keyword = "...")]` is experimental
+#[doc(keyword = "match")] //~ ERROR: `#[doc(keyword)]` is experimental
 /// wonderful
 mod foo{}
 
diff --git a/src/test/ui/feature-gates/feature-gate-doc_keyword.stderr b/src/test/ui/feature-gates/feature-gate-doc_keyword.stderr
index abde0bea9b2..15a41d9ffa4 100644
--- a/src/test/ui/feature-gates/feature-gate-doc_keyword.stderr
+++ b/src/test/ui/feature-gates/feature-gate-doc_keyword.stderr
@@ -1,4 +1,4 @@
-error[E0658]: `#[doc(keyword = "...")]` is experimental
+error[E0658]: `#[doc(keyword)]` is experimental
   --> $DIR/feature-gate-doc_keyword.rs:1:1
    |
 LL | #[doc(keyword = "match")]
diff --git a/src/test/ui/feature-gates/feature-gate-external_doc.rs b/src/test/ui/feature-gates/feature-gate-external_doc.rs
index dec3fa18579..9d68d3ec4f5 100644
--- a/src/test/ui/feature-gates/feature-gate-external_doc.rs
+++ b/src/test/ui/feature-gates/feature-gate-external_doc.rs
@@ -1,2 +1,2 @@
-#[doc(include="asdf.md")] //~ ERROR: `#[doc(include = "...")]` is experimental
+#[doc(include="asdf.md")] //~ ERROR: `#[doc(include)]` is experimental
 fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-external_doc.stderr b/src/test/ui/feature-gates/feature-gate-external_doc.stderr
index a5a874374d1..683c0ad2174 100644
--- a/src/test/ui/feature-gates/feature-gate-external_doc.stderr
+++ b/src/test/ui/feature-gates/feature-gate-external_doc.stderr
@@ -1,4 +1,4 @@
-error[E0658]: `#[doc(include = "...")]` is experimental
+error[E0658]: `#[doc(include)]` is experimental
   --> $DIR/feature-gate-external_doc.rs:1:1
    |
 LL | #[doc(include="asdf.md")]