From ba17934bc1f6fce2e4f9e5494efdb90508eafecd Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Wed, 25 Oct 2023 11:12:32 -0700
Subject: [PATCH] Represent symbol value as enum to prepare for supporting env
 vars

---
 compiler/rustc_macros/src/symbols.rs | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_macros/src/symbols.rs b/compiler/rustc_macros/src/symbols.rs
index 46ae1779bbe4..4df7eb631049 100644
--- a/compiler/rustc_macros/src/symbols.rs
+++ b/compiler/rustc_macros/src/symbols.rs
@@ -53,14 +53,20 @@ impl Parse for Keyword {
 
 struct Symbol {
     name: Ident,
-    value: Option<LitStr>,
+    value: Value,
+}
+
+enum Value {
+    SameAsName,
+    String(LitStr),
 }
 
 impl Parse for Symbol {
     fn parse(input: ParseStream<'_>) -> Result<Self> {
         let name = input.parse()?;
         let colon_token: Option<Token![:]> = input.parse()?;
-        let value = if colon_token.is_some() { Some(input.parse()?) } else { None };
+        let value =
+            if colon_token.is_some() { Value::String(input.parse()?) } else { Value::SameAsName };
 
         Ok(Symbol { name, value })
     }
@@ -168,8 +174,8 @@ fn symbols_with_errors(input: TokenStream) -> (TokenStream, Vec<syn::Error>) {
     for symbol in input.symbols.iter() {
         let name = &symbol.name;
         let value = match &symbol.value {
-            Some(value) => value.value(),
-            None => name.to_string(),
+            Value::SameAsName => name.to_string(),
+            Value::String(lit) => lit.value(),
         };
         check_dup(symbol.name.span(), &value, &mut errors);
         check_order(symbol.name.span(), &name.to_string(), &mut errors);