From 1ff69eae17388be06221369b2bb08f8808905472 Mon Sep 17 00:00:00 2001
From: metagn <metagngn@gmail.com>
Date: Fri, 31 Jan 2025 10:44:02 +0300
Subject: [PATCH] don't mark captured field sym in template as fully used
 (#24660)

fixes #24657

(cherry picked from commit 647c6687f181ec6c68cb18ce958e3784b58a23a7)
---
 compiler/semtempl.nim        | 7 ++++++-
 tests/template/tfielduse.nim | 9 +++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 tests/template/tfielduse.nim

diff --git a/compiler/semtempl.nim b/compiler/semtempl.nim
index 69bc9092bfe40..a21f959231148 100644
--- a/compiler/semtempl.nim
+++ b/compiler/semtempl.nim
@@ -66,7 +66,12 @@ proc symChoice(c: PContext, n: PNode, s: PSym, r: TSymChoiceRule;
     # for instance 'nextTry' is both in tables.nim and astalgo.nim ...
     if not isField or sfGenSym notin s.flags:
       result = newSymNode(s, info)
-      markUsed(c, info, s)
+      if isField:
+        # possibly not final field sym
+        incl(s.flags, sfUsed)
+        markOwnerModuleAsUsed(c, s)
+      else:
+        markUsed(c, info, s)
       onUse(info, s)
     else:
       result = n
diff --git a/tests/template/tfielduse.nim b/tests/template/tfielduse.nim
new file mode 100644
index 0000000000000..ff9402d952f7a
--- /dev/null
+++ b/tests/template/tfielduse.nim
@@ -0,0 +1,9 @@
+# issue #24657
+
+proc g() {.error.} = discard
+
+type T = object
+  g: int
+
+template B(): untyped = typeof(T.g)
+type _ = B()