fixes #21110; duplicate proc definitions for inline iters (#21136)

fixes #21110; duplicate proc definitions for iters

(cherry picked from commit 88114948c4)

compiler/transf.nim

@@ -316,6 +316,14 @@ proc introduceNewLocalVars(c: PTransf, n: PNode): PNode =
     if a.kind == nkSym:
       n[1] = transformSymAux(c, a)
     return n
+  of nkProcDef: # todo optimize nosideeffects?
+    result = newTransNode(n)
+    let x = freshVar(c, n[namePos].sym)
+    idNodeTablePut(c.transCon.mapping, n[namePos].sym, x)
+    result[namePos] = x # we have to copy proc definitions for iters
+    for i in 1..<n.len:
+      result[i] = introduceNewLocalVars(c, n[i])
+    result[namePos].sym.ast = result
   else:
     result = newTransNode(n)
     for i in 0..<n.len:

tests/iter/titer.nim

@@ -112,3 +112,18 @@ let res = collect:
       fn2(v2)
 
 doAssert res == @[42, 43, 43, 44]
+
+block: # bug #21110
+  iterator p(): int =
+    when nimvm:
+      yield 0
+    else:
+      yield 0
+
+  template foo =
+    for k in p():
+      let m = ""
+      proc e() = discard m & ""
+      e()
+  static: foo()
+  foo()