bugfix: detect captures in non-closure inner procs

compiler/lambdalifting.nim

@@ -764,7 +764,10 @@ proc semCaptureSym*(s, owner: PSym) =
       var o = owner.skipGenericOwner
       while o.kind != skModule and o != nil:
         if s.owner == o:
-          owner.typ.callConv = ccClosure
+          if owner.typ.callConv in {ccClosure, ccDefault} or owner.kind == skIterator:
+            owner.typ.callConv = ccClosure
+          else:
+            discard "do not produce an error here, but later"
           #echo "computing .closure for ", owner.name.s, " ", owner.info, " because of ", s.name.s
         o = o.skipGenericOwner
     # since the analysis is not entirely correct, we don't set 'tfCapturesEnv'

tests/closure/tinvalidclosure3.nim

@@ -0,0 +1,12 @@
+discard """
+  line: 9
+  errormsg: "illegal capture 'x'"
+"""
+
+proc outer(arg: string) =
+  var x = 0
+  proc inner {.inline.} =
+    echo "inner", x
+  inner()
+
+outer("abc")