Move ATTRIBUTE_WHITELIST and CRATE_ATTRS to KNOWN_ATTRIBUTES in syntax::feature_gate

Author: Manishearth

src/librustc/lint/builtin.rs

@@ -47,6 +47,7 @@ use syntax::{abi, ast, ast_map};
 use syntax::ast_util::is_shift_binop;
 use syntax::attr::{self, AttrMetaMethods};
 use syntax::codemap::{self, Span};
+use syntax::feature_gate::{KNOWN_ATTRIBUTES, AttributeType};
 use syntax::parse::token;
 use syntax::ast::{TyIs, TyUs, TyI8, TyU8, TyI16, TyU16, TyI32, TyU32, TyI64, TyU64};
 use syntax::ast_util;
@@ -640,67 +641,15 @@ impl LintPass for UnusedAttributes {
     }
 
     fn check_attribute(&mut self, cx: &Context, attr: &ast::Attribute) {
-        static ATTRIBUTE_WHITELIST: &'static [&'static str] = &[
-            // FIXME: #14408 whitelist docs since rustdoc looks at them
-            "doc",
-
-            // FIXME: #14406 these are processed in trans, which happens after the
-            // lint pass
-            "cold",
-            "export_name",
-            "inline",
-            "link",
-            "link_name",
-            "link_section",
-            "linkage",
-            "no_builtins",
-            "no_mangle",
-            "no_split_stack",
-            "no_stack_check",
-            "packed",
-            "static_assert",
-            "thread_local",
-            "no_debug",
-            "omit_gdb_pretty_printer_section",
-            "unsafe_no_drop_flag",
-
-            // used in resolve
-            "prelude_import",
-
-            // FIXME: #14407 these are only looked at on-demand so we can't
-            // guarantee they'll have already been checked
-            "deprecated",
-            "must_use",
-            "stable",
-            "unstable",
-            "rustc_on_unimplemented",
-            "rustc_error",
-
-            // FIXME: #19470 this shouldn't be needed forever
-            "old_orphan_check",
-            "old_impl_check",
-            "rustc_paren_sugar", // FIXME: #18101 temporary unboxed closure hack
-        ];
-
-        static CRATE_ATTRS: &'static [&'static str] = &[
-            "crate_name",
-            "crate_type",
-            "feature",
-            "no_start",
-            "no_main",
-            "no_std",
-            "no_builtins",
-        ];
-
-        for &name in ATTRIBUTE_WHITELIST {
-            if attr.check_name(name) {
+        for &(ref name, ty) in KNOWN_ATTRIBUTES {
+            if ty == AttributeType::Whitelisted && attr.check_name(name) {
                 break;
             }
         }
 
         if !attr::is_used(attr) {
             cx.span_lint(UNUSED_ATTRIBUTES, attr.span, "unused attribute");
-            if CRATE_ATTRS.contains(&&attr.name()[]) {
+            if KNOWN_ATTRIBUTES.contains(&(&attr.name()[], AttributeType::CrateLevel)) {
                 let msg = match attr.node.style {
                     ast::AttrOuter => "crate-level attribute should be an inner \
                                        attribute: add an exclamation mark: #![foo]",

src/libsyntax/feature_gate.rs

@@ -23,6 +23,7 @@
 //! becomes stable.
 
 use self::Status::*;
+use self::AttributeType::*;
 
 use abi::RustIntrinsic;
 use ast::NodeId;
@@ -152,6 +153,74 @@ enum Status {
     Accepted,
 }
 
+// Attributes that have a special meaning to rustc or rustdoc
+pub static KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType)] = &[
+
+    // FIXME: #14408 whitelist docs since rustdoc looks at them
+    ("doc", Whitelisted),
+
+    // FIXME: #14406 these are processed in trans, which happens after the
+    // lint pass
+    ("cold", Whitelisted),
+    ("export_name", Whitelisted),
+    ("inline", Whitelisted),
+    ("link", Whitelisted),
+    ("link_name", Whitelisted),
+    ("link_section", Whitelisted),
+    ("linkage", Whitelisted),
+    ("no_builtins", Whitelisted),
+    ("no_mangle", Whitelisted),
+    ("no_split_stack", Whitelisted),
+    ("no_stack_check", Whitelisted),
+    ("packed", Whitelisted),
+    ("static_assert", Whitelisted),
+    ("thread_local", Whitelisted),
+    ("no_debug", Whitelisted),
+    ("omit_gdb_pretty_printer_section", Whitelisted),
+    ("unsafe_no_drop_flag", Whitelisted),
+
+    // used in resolve
+    ("prelude_import", Whitelisted),
+
+    // FIXME: #14407 these are only looked at on-demand so we can't
+    // guarantee they'll have already been checked
+    ("deprecated", Whitelisted),
+    ("must_use", Whitelisted),
+    ("stable", Whitelisted),
+    ("unstable", Whitelisted),
+    ("rustc_on_unimplemented", Whitelisted),
+    ("rustc_error", Whitelisted),
+
+    // FIXME: #19470 this shouldn't be needed forever
+    ("old_orphan_check", Whitelisted),
+    ("old_impl_check", Whitelisted),
+    ("rustc_paren_sugar", Whitelisted), // FIXME: #18101 temporary unboxed closure hack
+
+    // Crate level attributes
+    ("crate_name", CrateLevel),
+    ("crate_type", CrateLevel),
+    ("feature", CrateLevel),
+    ("no_start", CrateLevel),
+    ("no_main", CrateLevel),
+    ("no_std", CrateLevel),
+    ("no_builtins", CrateLevel),
+];
+
+#[derive(PartialEq, Copy)]
+pub enum AttributeType {
+    /// Normal, builtin attribute that is consumed
+    /// by the compiler before the unused_attribute check
+    Normal,
+
+    /// Builtin attribute that may not be consumed by the compiler
+    /// before the unused_attribute check. These attributes
+    /// will be ignored by the unused_attribute lint
+    Whitelisted,
+
+    /// Builtin attribute that is only allowed at the crate level
+    CrateLevel,
+}
+
 /// A set of features to be used by later passes.
 pub struct Features {
     pub unboxed_closures: bool,