rustdoc: prefer showing enum variants as written

src/librustdoc/html/render/print_item.rs

@@ -1540,7 +1540,8 @@ fn display_c_like_variant(
 ) {
     let name = item.name.unwrap();
     if let Some(ref value) = variant.discriminant {
-        write!(w, "{} = {}", name.as_str(), value.value(cx.tcx(), true));
+        let v = value.expr(cx.tcx()).unwrap_or(value.value(cx.tcx(), true));
+        write!(w, "{} = {}", name.as_str(), v);
     } else if should_show_enum_discriminant {
         let adt_def = cx.tcx().adt_def(enum_def_id);
         let discr = adt_def.discriminant_for_variant(cx.tcx(), index);

tests/rustdoc/src-discrim.perms.html

@@ -0,0 +1,6 @@
+<code><div class="code-attribute">#[repr(u8)]</div>pub enum Permissions {
+    Guest = b'%',
+    User = b'$',
+    System = b'@',
+    Absolute = b'#',
+}</code>

tests/rustdoc/src-discrim.rs

@@ -0,0 +1,12 @@
+//! regression test for #128347
+#![crate_name = "foo"]
+
+//@ snapshot perms foo/enum.Permissions.html '//pre/code'
+
+#[repr(u8)]
+pub enum Permissions {
+    Guest = b'%',
+    User = b'$',
+    System = b'@',
+    Absolute = b'#',
+}