From c22e0d414ddff0404a0adb1a8fc18d867e49ecd9 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Sat, 6 May 2017 11:53:15 +0200
Subject: [PATCH] fixes an internal compiler error when json.to is used wrongly

---
 compiler/vm.nim | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/compiler/vm.nim b/compiler/vm.nim
index 6a9545193e..3c475cf579 100644
--- a/compiler/vm.nim
+++ b/compiler/vm.nim
@@ -1651,8 +1651,16 @@ proc evalMacroCall*(module: PSym; cache: IdentCache, n, nOrig: PNode,
   for i in 0 .. <gp.len:
     if sfImmediate notin sym.flags:
       let idx = sym.typ.len + i
-      tos.slots[idx] = setupMacroParam(n.sons[idx], gp[i].sym.typ)
+      if idx < n.len:
+        tos.slots[idx] = setupMacroParam(n.sons[idx], gp[i].sym.typ)
+      else:
+        dec(evalMacroCounter)
+        c.callsite = nil
+        localError(n.info, "expected " & $gp.len &
+                   " generic parameter(s)")
     elif gp[i].sym.typ.kind in {tyStatic, tyTypeDesc}:
+      dec(evalMacroCounter)
+      c.callsite = nil
       globalError(n.info, "static[T] or typedesc nor supported for .immediate macros")
   # temporary storage:
   #for i in L .. <maxSlots: tos.slots[i] = newNode(nkEmpty)