fixes #2057

tests/template/t2do.nim

@@ -0,0 +1,22 @@
+discard """
+  output: "8.0"
+"""
+
+# bug #2057
+
+proc mpf_get_d(x: int): float = float(x)
+proc mpf_cmp_d(a: int; b: float): int = 0
+
+template toFloatHelper(result: expr; tooSmall, tooLarge: stmt) {.immediate.} =
+  result = mpf_get_d(a)
+  if result == 0.0 and mpf_cmp_d(a,0.0) != 0:
+    tooSmall
+  if result == Inf:
+    tooLarge
+
+proc toFloat*(a: int): float =
+  toFloatHelper(result)
+    do: raise newException(ValueError, "number too small"):
+        raise newException(ValueError, "number too large")
+
+echo toFloat(8)