account for nil return type in tyProc sumGeneric (#23250)

fixes #23249
nim-lang · Jan 23, 2024 · ee984f8 · ee984f8
1 parent be0b847
commit ee984f8
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diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
@@ -246,7 +246,8 @@ proc sumGeneric(t: PType): int =
           result += sumGeneric(a)
       break
     of tyProc:
-      result += sumGeneric(t.returnType)
+      if t.returnType != nil:
+        result += sumGeneric(t.returnType)
       for _, a in t.paramTypes:
         result += sumGeneric(a)
       break

diff --git a/tests/overload/t23249.nim b/tests/overload/t23249.nim
@@ -0,0 +1,17 @@
+# issue #23249
+
+type Control* = object
+proc onAction*(c: Control, handler: proc(e: int) {.gcsafe.}) = discard
+proc onAction*(c: Control, handler: proc() {.gcsafe.}) = discard
+
+template setControlHandlerBlock(c: Control, p: untyped, a: untyped) =
+    when compiles(c.p(nil)):
+        c.p() do() {.gcsafe.}: a
+    else:
+        c.p = proc() {.gcsafe.} =
+            a
+
+proc mkLayout() =
+  var b: Control
+  setControlHandlerBlock(b, onAction):
+    echo "hi"