From 6274bc35dd155b2de2b24b32df18ee60b4b97eff Mon Sep 17 00:00:00 2001
From: Bung <crc32@qq.com>
Date: Fri, 21 Oct 2022 15:26:46 +0800
Subject: [PATCH] fix #19426 compile error using when/elif/else and typedesc in
 template (#20550)

(cherry picked from commit 04c48e3c5b7a98b065d9f3a96575a304a60a9290)
---
 compiler/semfold.nim      |  1 +
 tests/whenstmt/t19426.nim | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 tests/whenstmt/t19426.nim

diff --git a/compiler/semfold.nim b/compiler/semfold.nim
index bba04e19d1..9fb118843c 100644
--- a/compiler/semfold.nim
+++ b/compiler/semfold.nim
@@ -454,6 +454,7 @@ proc foldArrayAccess(m: PSym, n: PNode; idgen: IdGenerator; g: ModuleGraph): PNo
 
 proc foldFieldAccess(m: PSym, n: PNode; idgen: IdGenerator; g: ModuleGraph): PNode =
   # a real field access; proc calls have already been transformed
+  if n[1].kind != nkSym: return nil
   var x = getConstExpr(m, n[0], idgen, g)
   if x == nil or x.kind notin {nkObjConstr, nkPar, nkTupleConstr}: return
 
diff --git a/tests/whenstmt/t19426.nim b/tests/whenstmt/t19426.nim
new file mode 100644
index 0000000000..95fb54a9e4
--- /dev/null
+++ b/tests/whenstmt/t19426.nim
@@ -0,0 +1,16 @@
+type
+  MyInt = object
+    bitWidth: int
+
+template toRealType*(t: MyInt): typedesc =
+  when t.bitWidth == 32: int32
+  elif t.bitWidth == 64: int64
+  else: {.error.}
+
+proc doFail(T: typedesc): T = default(T)
+
+proc test =
+  const myInt = MyInt(bitWidth:32)
+  discard doFail(toRealType(myInt))
+
+test()
\ No newline at end of file