Add possibility of deprecating attributes

Author: Nick Cameron

src/librustc/lint/mod.rs

@@ -314,5 +314,4 @@ pub enum LintSource {
 pub type LevelSource = (Level, LintSource);
 
 pub mod builtin;
-
 mod context;

src/librustc_lint/builtin.rs

@@ -39,11 +39,11 @@ use rustc::traits::{self, Reveal};
 use rustc::hir::map as hir_map;
 use util::nodemap::NodeSet;
 use lint::{Level, LateContext, LintContext, LintArray, Lint};
-use lint::{LintPass, LateLintPass};
+use lint::{LintPass, LateLintPass, EarlyLintPass, EarlyContext};
 
 use std::collections::HashSet;
 
-use syntax::ast;
+use syntax::{ast, feature_gate};
 use syntax::attr;
 use syntax_pos::Span;
 
@@ -741,6 +741,40 @@ impl LateLintPass for Deprecated {
     }
 }
 
+declare_lint! {
+    DEPRECATED_ATTR,
+    Warn,
+    "detects use of deprecated attributes"
+}
+
+/// Checks for use of attributes which have been deprecated.
+#[derive(Clone)]
+pub struct DeprecatedAttr;
+
+impl LintPass for DeprecatedAttr {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(DEPRECATED_ATTR)
+    }
+}
+
+impl EarlyLintPass for DeprecatedAttr {
+    fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
+        let name = &*attr.name();
+        for &(n, _, ref g) in feature_gate::KNOWN_ATTRIBUTES {
+            if n == name {
+                if let &feature_gate::AttributeGate::Gated(feature_gate::Stability::Deprecated,
+                                                           ref name,
+                                                           ..) = g {
+                    cx.span_lint(DEPRECATED,
+                                 attr.span,
+                                 &format!("use of deprecated attribute: {}", name));
+                }
+                return;
+            }
+        }
+    }
+}
+
 declare_lint! {
     pub UNCONDITIONAL_RECURSION,
     Warn,

src/librustc_lint/lib.rs

@@ -103,6 +103,7 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
 
     add_early_builtin!(sess,
                        UnusedParens,
+                       DeprecatedAttr,
                        );
 
     add_builtin!(sess,