added experimental .this pragma

compiler/seminst.nim

@@ -10,6 +10,47 @@
 # This module implements the instantiation of generic procs.
 # included from sem.nim
 
+proc addObjFieldsToLocalScope(c: PContext; n: PNode) =
+  template rec(n) = addObjFieldsToLocalScope(c, n)
+  case n.kind
+  of nkRecList:
+    for i in countup(0, len(n)-1):
+      rec n[i]
+  of nkRecCase:
+    if n.len > 0: rec n.sons[0]
+    for i in countup(1, len(n)-1):
+      if n[i].kind in {nkOfBranch, nkElse}: rec lastSon(n[i])
+  of nkSym:
+    let f = n.sym
+    if f.kind == skField and fieldVisible(c, f):
+      c.currentScope.symbols.strTableIncl(f, onConflictKeepOld=true)
+      incl(f.flags, sfUsed)
+      # it is not an error to shadow fields via parameters
+  else: discard
+
+proc rawPushProcCon(c: PContext, owner: PSym) =
+  var x: PProcCon
+  new(x)
+  x.owner = owner
+  x.next = c.p
+  c.p = x
+
+proc rawHandleSelf(c: PContext; owner: PSym) =
+  if c.selfName != nil and owner.kind in {skProc, skMethod, skConverter, skIterator, skMacro} and owner.typ != nil:
+    let params = owner.typ.n
+    if params.len > 1:
+      let arg = params[1].sym
+      if arg.name.id == c.selfName.id:
+        c.p.selfSym = arg
+        arg.flags.incl sfIsSelf
+        let t = c.p.selfSym.typ.skipTypes(abstractPtrs)
+        if t.kind == tyObject:
+          addObjFieldsToLocalScope(c, t.n)
+
+proc pushProcCon*(c: PContext; owner: PSym) =
+  rawPushProcCon(c, owner)
+  rawHandleSelf(c, owner)
+
 iterator instantiateGenericParamList(c: PContext, n: PNode, pt: TIdTable): PSym =
   internalAssert n.kind == nkGenericParams
   for i, a in n.pairs:
@@ -248,7 +289,7 @@ proc generateInstance(c: PContext, fn: PSym, pt: TIdTable,
     addDecl(c, s)
     entry.concreteTypes[i] = s.typ
     inc i
-  pushProcCon(c, result)
+  rawPushProcCon(c, result)
   instantiateProcType(c, pt, result, info)
   for j in 1 .. result.typ.len-1:
     entry.concreteTypes[i] = result.typ.sons[j]
@@ -263,6 +304,7 @@ proc generateInstance(c: PContext, fn: PSym, pt: TIdTable,
     # a ``compiles`` context but this is the lesser evil. See
     # bug #1055 (tevilcompiles).
     #if c.compilesContextId == 0:
+    rawHandleSelf(c, result)
     entry.compilesId = c.compilesContextId
     fn.procInstCache.safeAdd(entry)
     c.generics.add(makeInstPair(fn, entry))