From 3b53ed1577607446cc68167013613b2329c3ab26 Mon Sep 17 00:00:00 2001
From: Marek Kaput <marek.kaput@swmansion.com>
Date: Tue, 17 Feb 2026 15:11:58 +0100
Subject: [PATCH 1/2] fix: preserve fn newline metadata after semicolons

Capture newline metadata for anonymous functions when the separator is a semicolon token that carries newline count.

This aligns cases like `fn ;\n -> :ok end` with Elixir metadata while avoiding incorrect `newlines: 0` for same-line semicolons.

Adds deterministic regression assertions in the property-regression test block.
---
 lib/spitfire.ex        | 13 ++++++++++++-
 test/spitfire_test.exs |  4 ++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/spitfire.ex b/lib/spitfire.ex
index 50c54b9..51cb57f 100644
--- a/lib/spitfire.ex
+++ b/lib/spitfire.ex
@@ -2109,7 +2109,18 @@ defmodule Spitfire do
     trace "parse_anon_function", trace_meta(parser) do
       meta = current_meta(parser)
 
-      newlines = get_newlines(parser)
+      semicolon_newlines =
+        case peek_newlines(parser, :";") do
+          nl when is_integer(nl) and nl > 0 -> nl
+          _ -> nil
+        end
+
+      newlines =
+        case peek_newlines(parser) || semicolon_newlines do
+          nil -> []
+          nl -> [newlines: nl]
+        end
+
       parser = parser |> next_token() |> eat_eoe()
 
       # fn creates its own stab scope
diff --git a/test/spitfire_test.exs b/test/spitfire_test.exs
index aeb8e42..1c9e9f1 100644
--- a/test/spitfire_test.exs
+++ b/test/spitfire_test.exs
@@ -2295,6 +2295,10 @@ defmodule SpitfireTest do
 
       # In-match operator (<-) in map keys - should be part of key, not wrap it
       assert Spitfire.parse("%{s\\\\r => 1}") == s2q("%{s\\\\r => 1}")
+
+      # Fn args with semicolon/newline trivia
+      assert Spitfire.parse("fn ;\n -> :ok end") == s2q("fn ;\n -> :ok end")
+      assert Spitfire.parse("fn ; -> :ok end") == s2q("fn ; -> :ok end")
     end
   end
 

From 100d8c7d569176245477142f45f5a81a1bfef7f3 Mon Sep 17 00:00:00 2001
From: Marek Kaput <marek.kaput@swmansion.com>
Date: Wed, 18 Feb 2026 09:27:50 +0100
Subject: [PATCH 2/2] fmt

---
 test/spitfire_test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/spitfire_test.exs b/test/spitfire_test.exs
index 0698aba..0cdf80f 100644
--- a/test/spitfire_test.exs
+++ b/test/spitfire_test.exs
@@ -2299,7 +2299,7 @@ defmodule SpitfireTest do
       # Fn args with semicolon/newline trivia
       assert Spitfire.parse("fn ;\n -> :ok end") == s2q("fn ;\n -> :ok end")
       assert Spitfire.parse("fn ; -> :ok end") == s2q("fn ; -> :ok end")
-      
+
       # Struct type with dot-call target
       assert Spitfire.parse("%e.(){}") == s2q("%e.(){}")
       assert Spitfire.parse("%e.(1){}") == s2q("%e.(1){}")