Allow custom pragma on iterators [backport] (#20344)

Allow custom pragma on iterators

(cherry picked from commit 3a5e38a)

Author: Menduist

compiler/pragmas.nim

@@ -1242,7 +1242,7 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
     elif comesFromPush and whichKeyword(ident) != wInvalid:
       discard "ignore the .push pragma; it doesn't apply"
     else:
-      if sym == nil or (sym.kind in {skVar, skLet, skParam,
+      if sym == nil or (sym.kind in {skVar, skLet, skParam, skIterator,
                         skField, skProc, skFunc, skConverter, skMethod, skType}):
         n[i] = semCustomPragma(c, it)
       elif sym != nil:

tests/pragmas/tcustom_pragma.nim

@@ -383,6 +383,13 @@ block:
 
   discard Hello(a: 1.0, b: 12)
 
+# custom pragma on iterators
+block:
+  template prag {.pragma.}
+  {.push prag.}
+  proc hello = discard
+  iterator hello2: int = discard
+
 # issue #11511
 when false:
   template myAttr {.pragma.}