add trait impls to proc_macro::Ident

library/proc_macro/src/bridge/mod.rs

@@ -8,7 +8,7 @@
 
 #![deny(unsafe_code)]
 
-use std::hash::Hash;
+use std::hash::{Hash, Hasher};
 use std::ops::{Bound, Range};
 use std::sync::Once;
 use std::{fmt, marker, mem, panic, thread};
@@ -449,13 +449,69 @@ pub struct Punct<Span> {
 
 compound_traits!(struct Punct<Span> { ch, joint, span });
 
-#[derive(Copy, Clone, Eq, PartialEq)]
+#[derive(Copy, Clone)]
 pub struct Ident<Span, Symbol> {
     pub sym: Symbol,
     pub is_raw: bool,
     pub span: Span,
 }
 
+impl<Span, Symbol> PartialEq for Ident<Span, Symbol>
+where
+    Symbol: PartialEq,
+{
+    fn eq(&self, other: &Self) -> bool {
+        self.sym == other.sym && self.is_raw == other.is_raw
+    }
+}
+
+impl<Span, Symbol> PartialEq<String> for Ident<Span, Symbol>
+where
+    Symbol: PartialEq<str>,
+{
+    fn eq(&self, other: &String) -> bool {
+        if self.is_raw {
+            other.strip_prefix("r#").is_some_and(|s| self.sym == *s)
+        } else {
+            self.sym == **other
+        }
+    }
+}
+
+impl<Span, Symbol> PartialEq<str> for Ident<Span, Symbol>
+where
+    Symbol: PartialEq<str>,
+{
+    fn eq(&self, other: &str) -> bool {
+        if self.is_raw {
+            other.strip_prefix("r#").is_some_and(|s| self.sym == *s)
+        } else {
+            self.sym == *other
+        }
+    }
+}
+
+impl<Span, Symbol> Eq for Ident<Span, Symbol> where Symbol: PartialEq {}
+
+impl<Span, Symbol: Hash> Hash for Ident<Span, Symbol> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.sym.hash(state);
+        self.is_raw.hash(state);
+    }
+}
+
+/// Prints the identifier as a string that should be losslessly convertible back
+/// into the same identifier.
+#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
+impl<Span, Symbol: fmt::Display> fmt::Display for Ident<Span, Symbol> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.is_raw {
+            f.write_str("r#")?;
+        }
+        fmt::Display::fmt(&self.sym, f)
+    }
+}
+
 compound_traits!(struct Ident<Span, Symbol> { sym, is_raw, span });
 
 #[derive(Clone, Eq, PartialEq)]

library/proc_macro/src/bridge/symbol.rs

@@ -11,11 +11,12 @@
 
 use std::cell::RefCell;
 use std::num::NonZero;
+use std::{cmp, str};
 
 use super::*;
 
 /// Handle for a symbol string stored within the Interner.
-#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone)]
 pub struct Symbol(NonZero<u32>);
 
 impl !Send for Symbol {}
@@ -96,6 +97,38 @@ impl fmt::Display for Symbol {
     }
 }
 
+impl PartialEq<Self> for Symbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.0 == other.0
+    }
+}
+
+impl PartialEq<str> for Symbol {
+    fn eq(&self, other: &str) -> bool {
+        self.with(|s| s == other)
+    }
+}
+
+impl Eq for Symbol {}
+
+impl Hash for Symbol {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.0.hash(state);
+    }
+}
+
+impl PartialOrd for Symbol {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Symbol {
+    fn cmp(&self, other: &Self) -> cmp::Ordering {
+        self.with(|s| other.with(|o| s.cmp(o)))
+    }
+}
+
 impl<S> Encode<S> for Symbol {
     fn encode(self, w: &mut Writer, s: &mut S) {
         self.with(|sym| sym.encode(w, s))

library/proc_macro/src/lib.rs

@@ -1032,7 +1032,7 @@ impl PartialEq<Punct> for char {
 }
 
 /// An identifier (`ident`).
-#[derive(Clone)]
+#[derive(Clone, PartialEq, Eq, Hash)]
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
 pub struct Ident(bridge::Ident<bridge::client::Span, bridge::client::Symbol>);
 
@@ -1097,10 +1097,7 @@ impl Ident {
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
 impl fmt::Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.0.is_raw {
-            f.write_str("r#")?;
-        }
-        fmt::Display::fmt(&self.0.sym, f)
+        self.0.fmt(f)
     }
 }
 
@@ -1114,6 +1111,20 @@ impl fmt::Debug for Ident {
     }
 }
 
+#[stable(feature = "proc_macro_ident_impls", since = "CURRENT_RUSTC_VERSION")]
+impl PartialEq<String> for Ident {
+    fn eq(&self, other: &String) -> bool {
+        self.0 == *other
+    }
+}
+
+#[stable(feature = "proc_macro_ident_impls", since = "CURRENT_RUSTC_VERSION")]
+impl PartialEq<str> for Ident {
+    fn eq(&self, other: &str) -> bool {
+        self.0 == *other
+    }
+}
+
 /// A literal string (`"hello"`), byte string (`b"hello"`), C string (`c"hello"`),
 /// character (`'a'`), byte character (`b'a'`), an integer or floating point number
 /// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).