From 643e71e2e125a1859793f729bdb2149bc0e6b23c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Sun, 3 Dec 2017 14:10:04 +0100
Subject: [PATCH] Remove the IGNORED_ATTR_NAMES thread local

---
 src/librustc/ich/hcx.rs     | 21 ++++++---------------
 src/librustc/ich/mod.rs     |  2 +-
 src/librustc/session/mod.rs |  6 ++++++
 3 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/src/librustc/ich/hcx.rs b/src/librustc/ich/hcx.rs
index 2945b1ab912..67f6c0c2e49 100644
--- a/src/librustc/ich/hcx.rs
+++ b/src/librustc/ich/hcx.rs
@@ -19,8 +19,8 @@
 
 use std::cmp::Ord;
 use std::hash as std_hash;
-use std::cell::RefCell;
 use std::collections::HashMap;
+use std::cell::RefCell;
 
 use syntax::ast;
 
@@ -36,8 +36,10 @@
 use rustc_data_structures::accumulate_vec::AccumulateVec;
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 
-thread_local!(static IGNORED_ATTR_NAMES: RefCell<FxHashSet<Symbol>> =
-    RefCell::new(FxHashSet()));
+pub fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
+    debug_assert!(ich::IGNORED_ATTRIBUTES.len() > 0);
+    ich::IGNORED_ATTRIBUTES.iter().map(|&s| Symbol::intern(s)).collect()
+}
 
 /// This is the context state available during incr. comp. hashing. It contains
 /// enough information to transform DefIds and HirIds into stable DefPaths (i.e.
@@ -90,15 +92,6 @@ pub fn new(sess: &'gcx Session,
                -> Self {
         let hash_spans_initial = !sess.opts.debugging_opts.incremental_ignore_spans;
 
-        debug_assert!(ich::IGNORED_ATTRIBUTES.len() > 0);
-        IGNORED_ATTR_NAMES.with(|names| {
-            let mut names = names.borrow_mut();
-            if names.is_empty() {
-                names.extend(ich::IGNORED_ATTRIBUTES.iter()
-                                                    .map(|&s| Symbol::intern(s)));
-            }
-        });
-
         StableHashingContext {
             sess,
             body_resolver: BodyResolver(krate),
@@ -186,9 +179,7 @@ pub fn codemap(&mut self) -> &mut CachingCodemapView<'gcx> {
 
     #[inline]
     pub fn is_ignored_attr(&self, name: Symbol) -> bool {
-        IGNORED_ATTR_NAMES.with(|names| {
-            names.borrow().contains(&name)
-        })
+        self.sess.ignored_attr_names.contains(&name)
     }
 
     pub fn hash_hir_item_like<F: FnOnce(&mut Self)>(&mut self, f: F) {
diff --git a/src/librustc/ich/mod.rs b/src/librustc/ich/mod.rs
index cbd76ee14db..ce1bd07b14c 100644
--- a/src/librustc/ich/mod.rs
+++ b/src/librustc/ich/mod.rs
@@ -13,7 +13,7 @@
 pub use self::fingerprint::Fingerprint;
 pub use self::caching_codemap_view::CachingCodemapView;
 pub use self::hcx::{StableHashingContext, NodeIdHashingMode,
-                    hash_stable_trait_impls};
+                    hash_stable_trait_impls, compute_ignored_attr_names};
 mod fingerprint;
 mod caching_codemap_view;
 mod hcx;
diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index 94fcfb7e2aa..36f716a4a76 100644
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -14,6 +14,7 @@
 use hir::def_id::CrateNum;
 use ich::Fingerprint;
 
+use ich;
 use lint;
 use middle::allocator::AllocatorKind;
 use middle::dependency_format;
@@ -28,6 +29,7 @@
 use errors::emitter::{Emitter, EmitterWriter};
 use syntax::json::JsonEmitter;
 use syntax::feature_gate;
+use syntax::symbol::Symbol;
 use syntax::parse;
 use syntax::parse::ParseSess;
 use syntax::{ast, codemap};
@@ -112,6 +114,9 @@ pub struct Session {
 
     incr_comp_session: RefCell<IncrCompSession>,
 
+    /// A cache of attributes ignored by StableHashingContext
+    pub ignored_attr_names: FxHashSet<Symbol>,
+
     /// Some measurements that are being gathered during compilation.
     pub perf_stats: PerfStats,
 
@@ -975,6 +980,7 @@ pub fn build_session_(sopts: config::Options,
         injected_panic_runtime: Cell::new(None),
         imported_macro_spans: RefCell::new(HashMap::new()),
         incr_comp_session: RefCell::new(IncrCompSession::NotInitialized),
+        ignored_attr_names: ich::compute_ignored_attr_names(),
         perf_stats: PerfStats {
             svh_time: Cell::new(Duration::from_secs(0)),
             incr_comp_hashes_time: Cell::new(Duration::from_secs(0)),
-- 
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