new gensym handling (#11985)

* new .gensym implementation
* make astspec test green again
* introduce a --useVersion switch to group compatibility switches
* fixes #10180
* fixes #11494 
* fixes #11483
* object constructor fields and named parameters are also not gensym'ed
* disabled broken package

compiler/evaltempl.nim

@@ -10,7 +10,7 @@
 ## Template evaluation engine. Now hygienic.
 
 import
-  strutils, options, ast, astalgo, msgs, renderer, lineinfos
+  strutils, options, ast, astalgo, msgs, renderer, lineinfos, idents
 
 type
   TemplCtx = object
@@ -20,6 +20,7 @@ type
     mapping: TIdTable # every gensym'ed symbol needs to be mapped to some
                       # new symbol
     config: ConfigRef
+    ic: IdentCache
 
 proc copyNode(ctx: TemplCtx, a, b: PNode): PNode =
   result = copyNode(a)
@@ -52,7 +53,11 @@ proc evalTemplateAux(templ, actual: PNode, c: var TemplCtx, result: PNode) =
           #if x.kind == skParam and x.owner.kind == skModule:
           #  internalAssert c.config, false
           idTablePut(c.mapping, s, x)
-        result.add newSymNode(x, if c.instLines: actual.info else: templ.info)
+        if sfGenSym in s.flags and optNimV019 notin c.config.globalOptions:
+          result.add newIdentNode(getIdent(c.ic, x.name.s & "`gensym" & $x.id),
+            if c.instLines: actual.info else: templ.info)
+        else:
+          result.add newSymNode(x, if c.instLines: actual.info else: templ.info)
     else:
       result.add copyNode(c, templ, actual)
   of nkNone..nkIdent, nkType..nkNilLit: # atom
@@ -160,7 +165,9 @@ proc wrapInComesFrom*(info: TLineInfo; sym: PSym; res: PNode): PNode =
     result.typ = res.typ
 
 proc evalTemplate*(n: PNode, tmpl, genSymOwner: PSym;
-                   conf: ConfigRef; fromHlo=false): PNode =
+                   conf: ConfigRef;
+                   ic: IdentCache;
+                   fromHlo=false): PNode =
   inc(conf.evalTemplateCounter)
   if conf.evalTemplateCounter > evalTemplateLimit:
     globalError(conf, n.info, errTemplateInstantiationTooNested)
@@ -172,6 +179,7 @@ proc evalTemplate*(n: PNode, tmpl, genSymOwner: PSym;
   ctx.owner = tmpl
   ctx.genSymOwner = genSymOwner
   ctx.config = conf
+  ctx.ic = ic
   initIdTable(ctx.mapping)
 
   let body = tmpl.getBody