support for multiple test variables and var qualifiers in user-defined type classes

compiler/ast.nim

@@ -712,7 +712,6 @@ type
                               # -1 means that the size is unkwown
     align*: int               # the type's alignment requirements
     loc*: TLoc
-    testeeName*: PIdent       # the test variable in user-defined type classes
 
   TPair*{.final.} = object 
     key*, val*: PObject
@@ -1088,7 +1087,6 @@ proc assignType(dest, src: PType) =
   dest.size = src.size
   dest.align = src.align
   dest.destructor = src.destructor
-  dest.testeeName = src.testeeName
   # this fixes 'type TLock = TSysLock':
   if src.sym != nil:
     if dest.sym != nil:

compiler/parser.nim

@@ -1624,10 +1624,23 @@ proc parseObject(p: var TParser): PNode =
     return
   addSon(result, parseObjectPart(p))
 
+proc parseTypeClassParam(p: var TParser): PNode =
+  if p.tok.tokType == tkVar:
+    getTok(p)
+    result = newNode(nkVarTy)
+    result.addSon(p.parseSymbol)
+  else:
+    result = p.parseSymbol
+
 proc parseTypeClass(p: var TParser): PNode =
   result = newNodeP(nkTypeClassTy, p)
   getTok(p)
-  addSon(result, p.parseSymbol)
+  var args = newNode(nkArgList)
+  addSon(result, args)
+  addSon(args, p.parseTypeClassParam)
+  while p.tok.TokType == tkComma:
+    getTok(p)
+    addSon(args, p.parseTypeClassParam)
   if p.tok.tokType == tkCurlyDotLe and p.validInd:
     addSon(result, parsePragma(p))
   else:

compiler/semexprs.nim

@@ -299,7 +299,7 @@ proc semOf(c: PContext, n: PNode): PNode =
   n.typ = getSysType(tyBool)
   result = n
 
-proc IsOpImpl(c: PContext, n: PNode): PNode =
+proc isOpImpl(c: PContext, n: PNode): PNode =
   InternalAssert n.sonsLen == 3 and
     n[1].kind == nkSym and n[1].sym.kind == skType and
     n[2].kind in {nkStrLit..nkTripleStrLit, nkType}
@@ -353,7 +353,7 @@ proc semIs(c: PContext, n: PNode): PNode =
 
   let t1 = n[1].typ.sons[0]
   # BUGFIX: don't evaluate this too early: ``T is void``
-  if not containsGenericType(t1): result = IsOpImpl(c, n)
+  if not containsGenericType(t1): result = isOpImpl(c, n)
 
 proc semOpAux(c: PContext, n: PNode) =
   const flags = {efDetermineType}

compiler/semtypes.nim

@@ -876,8 +876,7 @@ proc freshType(res, prev: PType): PType {.inline.} =
 proc semTypeClass(c: PContext, n: PNode, prev: PType): PType =
   # if n.sonsLen == 0: return newConstraint(c, tyTypeClass)
   result = newOrPrevType(tyTypeClass, prev, c)
-  result.testeeName = considerAcc(n[0])
-  result.n = n[3]
+  result.n = n
 
   let
     pragmas = n[1]

compiler/sigmatch.nim

@@ -751,11 +751,24 @@ proc matchUserTypeClass*(c: PContext, m: var TCandidate,
   # pushInfoContext(arg.info)
   openScope(c)
 
-  var testee = newSym(skParam, f.testeeName, f.sym, f.sym.info)
-  testee.typ = a
-  addDecl(c, testee)
+  for param in f.n[0]:
+    var
+      dummyName: PNode
+      dummyType: PType
+    
+    if param.kind == nkVarTy:
+      dummyName = param[0]
+      dummyType = makeVarType(c, a)
+    else:
+      dummyName = param
+      dummyType = a
 
-  for stmt in f.n:
+    InternalAssert dummyName.kind == nkIdent
+    var dummyParam = newSym(skParam, dummyName.ident, f.sym, f.sym.info)
+    dummyParam.typ = dummyType
+    addDecl(c, dummyParam)
+
+  for stmt in f.n[3]:
     var e = c.semTryExpr(c, copyTree(stmt))
     if e == nil:
       let expStr = renderTree(stmt, {renderNoComments})

lib/system/gc2.nim

@@ -387,8 +387,7 @@ template `--`(rc: TRefCount): expr =
   rc <% rcIncrement
 
 template `--` (rc: TRefCount, heapType: THeapType): expr =
-  (when heapType == SharedHeap: atomicDec(rc, rcIncrement) <% rcIncrement
-   else: --rc)
+  (when heapType == SharedHeap: atomicDec(rc, rcIncrement) <% rcIncrement else: --rc)
 
 template doDecRef(cc: PCell,
                   heapType = LocalHeap,