Merge from rustc

1 files changed, 44 insertions, 11 deletions

diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 51cfbf59471..51d809bd65d 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -25,6 +25,7 @@
 #![feature(hash_set_entry)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
+#![feature(map_try_insert)]
 #![feature(negative_impls)]
 #![feature(read_buf)]
 #![feature(round_char_boundary)]
@@ -85,9 +86,9 @@ use std::str::FromStr;
 use std::{fmt, iter};
 
 use md5::{Digest, Md5};
-use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{Hash64, Hash128, HashStable, StableHasher};
 use rustc_data_structures::sync::{FreezeLock, FreezeWriteGuard, Lock, Lrc};
+use rustc_data_structures::unord::UnordMap;
 use sha1::Sha1;
 use sha2::Sha256;
 
@@ -103,7 +104,7 @@ pub struct SessionGlobals {
     span_interner: Lock<span_encoding::SpanInterner>,
     /// Maps a macro argument token into use of the corresponding metavariable in the macro body.
     /// Collisions are possible and processed in `maybe_use_metavar_location` on best effort basis.
-    metavar_spans: Lock<FxHashMap<Span, Span>>,
+    metavar_spans: MetavarSpansMap,
     hygiene_data: Lock<hygiene::HygieneData>,
 
     /// The session's source map, if there is one. This field should only be
@@ -177,9 +178,42 @@ pub fn create_default_session_globals_then<R>(f: impl FnOnce() -> R) -> R {
 // deserialization.
 scoped_tls::scoped_thread_local!(static SESSION_GLOBALS: SessionGlobals);
 
+#[derive(Default)]
+pub struct MetavarSpansMap(FreezeLock<UnordMap<Span, (Span, bool)>>);
+
+impl MetavarSpansMap {
+    pub fn insert(&self, span: Span, var_span: Span) -> bool {
+        match self.0.write().try_insert(span, (var_span, false)) {
+            Ok(_) => true,
+            Err(entry) => entry.entry.get().0 == var_span,
+        }
+    }
+
+    /// Read a span and record that it was read.
+    pub fn get(&self, span: Span) -> Option<Span> {
+        if let Some(mut mspans) = self.0.try_write() {
+            if let Some((var_span, read)) = mspans.get_mut(&span) {
+                *read = true;
+                Some(*var_span)
+            } else {
+                None
+            }
+        } else {
+            if let Some((span, true)) = self.0.read().get(&span) { Some(*span) } else { None }
+        }
+    }
+
+    /// Freeze the set, and return the spans which have been read.
+    ///
+    /// After this is frozen, no spans that have not been read can be read.
+    pub fn freeze_and_get_read_spans(&self) -> UnordMap<Span, Span> {
+        self.0.freeze().items().filter(|(_, (_, b))| *b).map(|(s1, (s2, _))| (*s1, *s2)).collect()
+    }
+}
+
 #[inline]
-pub fn with_metavar_spans<R>(f: impl FnOnce(&mut FxHashMap<Span, Span>) -> R) -> R {
-    with_session_globals(|session_globals| f(&mut session_globals.metavar_spans.lock()))
+pub fn with_metavar_spans<R>(f: impl FnOnce(&MetavarSpansMap) -> R) -> R {
+    with_session_globals(|session_globals| f(&session_globals.metavar_spans))
 }
 
 // FIXME: We should use this enum or something like it to get rid of the
@@ -305,8 +339,8 @@ impl RealFileName {
 #[derive(Debug, Eq, PartialEq, Clone, Ord, PartialOrd, Hash, Decodable, Encodable)]
 pub enum FileName {
     Real(RealFileName),
-    /// Call to `quote!`.
-    QuoteExpansion(Hash64),
+    /// Strings provided as `--cfg [cfgspec]`.
+    CfgSpec(Hash64),
     /// Command line.
     Anon(Hash64),
     /// Hack in `src/librustc_ast/parse.rs`.
@@ -353,7 +387,7 @@ impl fmt::Display for FileNameDisplay<'_> {
             Real(ref name) => {
                 write!(fmt, "{}", name.to_string_lossy(self.display_pref))
             }
-            QuoteExpansion(_) => write!(fmt, "<quote expansion>"),
+            CfgSpec(_) => write!(fmt, "<cfgspec>"),
             MacroExpansion(_) => write!(fmt, "<macro expansion>"),
             Anon(_) => write!(fmt, "<anon>"),
             ProcMacroSourceCode(_) => write!(fmt, "<proc-macro source code>"),
@@ -384,7 +418,7 @@ impl FileName {
             | ProcMacroSourceCode(_)
             | CliCrateAttr(_)
             | Custom(_)
-            | QuoteExpansion(_)
+            | CfgSpec(_)
             | DocTest(_, _)
             | InlineAsm(_) => false,
         }
@@ -425,7 +459,7 @@ impl FileName {
     pub fn cfg_spec_source_code(src: &str) -> FileName {
         let mut hasher = StableHasher::new();
         src.hash(&mut hasher);
-        FileName::QuoteExpansion(hasher.finish())
+        FileName::CfgSpec(hasher.finish())
     }
 
     pub fn cli_crate_attr_source_code(src: &str) -> FileName {
@@ -872,8 +906,7 @@ impl Span {
 
     /// Check if you can select metavar spans for the given spans to get matching contexts.
     fn try_metavars(a: SpanData, b: SpanData, a_orig: Span, b_orig: Span) -> (SpanData, SpanData) {
-        let get = |mspans: &FxHashMap<_, _>, s| mspans.get(&s).copied();
-        match with_metavar_spans(|mspans| (get(mspans, a_orig), get(mspans, b_orig))) {
+        match with_metavar_spans(|mspans| (mspans.get(a_orig), mspans.get(b_orig))) {
             (None, None) => {}
             (Some(meta_a), None) => {
                 let meta_a = meta_a.data();