3 files changed, 32 insertions, 1 deletions
diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-identifier-formatting.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-identifier-formatting.exp
new file mode 100644
index 000000000000..074f5f07f5f0
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-identifier-formatting.exp
@@ -0,0 +1 @@
+{ "'quoted'" = false; "-20°" = false; "2normal" = false; "45 44 43-'3 2 1" = false; "9front" = false; Very2Normal = true; VeryNormal = true; _'12 = true; "_'12.5" = false; __internal = true; _internal = true; abort = true; assert = true; "attr.path" = false; false = true; foldl' = true; normal = true; normal2 = true; null = true; or = true; throw = true; true = true; x = true; x' = true; x'' = true; "😀" = false; }
diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-identifier-formatting.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-identifier-formatting.nix
new file mode 100644
index 000000000000..8f9aa2823801
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-identifier-formatting.nix
@@ -0,0 +1,30 @@
+{
+  __internal = true;
+  _internal = true;
+  normal = true;
+  VeryNormal = true;
+  normal2 = true;
+  Very2Normal = true;
+  _'12 = true;
+  foldl' = true;
+  x = true;
+  x' = true;
+  x'' = true;
+
+  true = true;
+  false = true;
+  null = true;
+  or = true;
+  "assert" = true; # -ish
+  throw = true;
+  abort = true;
+
+  "9front" = false;
+  "2normal" = false;
+  "-20°" = false;
+  "45 44 43-'3 2 1" = false;
+  "attr.path" = false;
+  "'quoted'" = false;
+  "_'12.5" = false;
+  "😀" = false;
+}
diff --git a/tvix/eval/src/value/string.rs b/tvix/eval/src/value/string.rs
index 5b2cb83a17de..9ebdf687d284 100644
--- a/tvix/eval/src/value/string.rs
+++ b/tvix/eval/src/value/string.rs
@@ -168,7 +168,7 @@ fn is_valid_nix_identifier(s: &str) -> bool {
     }
     for c in chars {
         match c {
-            'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '-' => (),
+            'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '-' | '\'' => (),
             _ => return false,
         }
     }