Merge pull request #2496 from BlaXpirit/js-header-comma

Fix JS codegen: proc header with compiletime arguments

compiler/jsgen.nim

@@ -791,10 +791,10 @@ proc genIf(p: PProc, n: PNode, r: var TCompRes) =
 proc generateHeader(p: PProc, typ: PType): Rope =
   result = nil
   for i in countup(1, sonsLen(typ.n) - 1):
-    if result != nil: add(result, ", ")
     assert(typ.n.sons[i].kind == nkSym)
     var param = typ.n.sons[i].sym
     if isCompileTimeOnly(param.typ): continue
+    if result != nil: add(result, ", ")
     var name = mangleName(param)
     add(result, name)
     if mapType(param.typ) == etyBaseIndex:

tests/js/test2.nim

@@ -1,6 +1,7 @@
 discard """
   output: '''foo
-js 3.14'''
+js 3.14
+7'''
 """
 
 # This file tests the JavaScript generator
@@ -20,3 +21,11 @@ else:
   proc foo(val: float): string = "js " & $val
 
 echo foo(3.14)
+
+# #2495
+type C = concept x
+
+proc test(x: C, T: typedesc): T =
+  cast[T](x)
+
+echo 7.test(int8)