this ensures libp2p continues to compile [backport] (#18908)

compiler/cgen.nim

@@ -855,10 +855,15 @@ proc closureSetup(p: BProc, prc: PSym) =
             [rdLoc(env.loc), getTypeDesc(p.module, env.typ)])
 
 proc containsResult(n: PNode): bool =
-  if n.kind == nkSym and n.sym.kind == skResult:
-    result = true
+  result = false
+  case n.kind
+  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit, nkFormalParams:
+    discard
+  of nkSym:
+    if n.sym.kind == skResult:
+      result = true
   else:
-    for i in 0..<n.safeLen:
+    for i in 0..<n.len:
       if containsResult(n[i]): return true
 
 const harmless = {nkConstSection, nkTypeSection, nkEmpty, nkCommentStmt, nkTemplateDef,

compiler/guards.nim

@@ -441,8 +441,14 @@ proc sameTree*(a, b: PNode): bool =
 proc hasSubTree(n, x: PNode): bool =
   if n.sameTree(x): result = true
   else:
-    for i in 0..n.safeLen-1:
-      if hasSubTree(n[i], x): return true
+    case n.kind
+    of nkEmpty..nkNilLit:
+      result = n.sameTree(x)
+    of nkFormalParams:
+      discard
+    else:
+      for i in 0..<n.len:
+        if hasSubTree(n[i], x): return true
 
 proc invalidateFacts*(s: var seq[PNode], n: PNode) =
   # We are able to guard local vars (as opposed to 'let' variables)!