Fix codegen for set[T] parameters

Sometimes sets are materialized as arrays and we must treat them as
such: the CPP backend is pickier than the C one and would sometimes
produce invalid code.

Fixes #8967

1 files changed, 10 insertions, 0 deletions

diff --git a/tests/ccgbugs/t8967.nim b/tests/ccgbugs/t8967.nim
new file mode 100644
index 000000000..e342b7eae
--- /dev/null
+++ b/tests/ccgbugs/t8967.nim
@@ -0,0 +1,10 @@
+discard """
+  targets: "c cpp"
+"""
+
+import marshal
+
+let orig: set[char] = {'A'..'Z'}
+let m = $$orig
+let old = to[set[char]](m)
+doAssert orig - old == {}