fixes #5314

compiler/ccgexprs.nim

@@ -1210,7 +1210,7 @@ proc genSeqConstr(p: BProc, t: PNode, d: var TLoc) =
 
 proc genArrToSeq(p: BProc, t: PNode, d: var TLoc) =
   var elem, a, arr: TLoc
-  if t.kind == nkBracket:
+  if t.sons[1].kind == nkBracket:
     t.sons[1].typ = t.typ
     genSeqConstr(p, t.sons[1], d)
     return

tests/async/tasync_in_seq_constr.nim

@@ -0,0 +1,17 @@
+discard """
+  output: '''@[1, 2, 3, 4]'''
+"""
+
+# bug #5314
+
+import asyncdispatch
+
+proc bar(): Future[int] {.async.} =
+    await sleepAsync(500)
+    result = 3
+
+proc foo(): Future[seq[int]] {.async.} =
+    await sleepAsync(500)
+    result = @[1, 2, await bar(), 4] # <--- The bug is here
+
+echo waitFor foo()