Size ptr tuple (#10846)

* fixes #10117
* Add support for recursive tuples
* detect in generics

compiler/semtypes.nim

@@ -448,6 +448,10 @@ proc semTuple(c: PContext, n: PNode, prev: PType): PType =
       styleCheckDef(c.config, a.sons[j].info, field)
       onDef(field.info, field)
   if result.n.len == 0: result.n = nil
+  if isTupleRecursive(result):
+    localError(c.config, n.info, errIllegalRecursionInTypeX % typeToString(result))
+
+
 
 proc semIdentVis(c: PContext, kind: TSymKind, n: PNode,
                  allowed: TSymFlags): PSym =

compiler/semtypinst.nim

@@ -24,7 +24,7 @@ proc checkConstructedType*(conf: ConfigRef; info: TLineInfo, typ: PType) =
   if t.kind in tyTypeClasses: discard
   elif t.kind in {tyVar, tyLent} and t.sons[0].kind in {tyVar, tyLent}:
     localError(conf, info, "type 'var var' is not allowed")
-  elif computeSize(conf, t) == szIllegalRecursion:
+  elif computeSize(conf, t) == szIllegalRecursion or isTupleRecursive(t):
     localError(conf, info,  "illegal recursion in type '" & typeToString(t) & "'")
   when false:
     if t.kind == tyObject and t.sons[0] != nil:
@@ -682,4 +682,3 @@ proc prepareMetatypeForSigmatch*(p: PContext, pt: TIdTable, info: TLineInfo,
 template generateTypeInstance*(p: PContext, pt: TIdTable, arg: PNode,
                                t: PType): untyped =
   generateTypeInstance(p, pt, arg.info, t)
-

compiler/sizealignoffsetimpl.nim

@@ -272,14 +272,6 @@ proc computeSizeAlign(conf: ConfigRef; typ: PType) =
       typ.align = szIllegalRecursion
       return
 
-    # recursive tuplers are not allowed and should be detected in the frontend
-    if base.kind == tyTuple:
-      computeSizeAlign(conf, base)
-      if base.size < 0:
-        typ.size = base.size
-        typ.align = base.align
-        return
-
     typ.align = int16(conf.target.ptrSize)
     if typ.kind == tySequence and conf.selectedGC == gcDestructors:
       typ.size = conf.target.ptrSize * 2

compiler/types.nim

@@ -1514,3 +1514,23 @@ proc typeMismatch*(conf: ConfigRef; info: TLineInfo, formal, actual: PType) =
       of efLockLevelsDiffer:
         msg.add "\nlock levels differ"
     localError(conf, info, msg)
+
+proc isTupleRecursive(t: PType, cycleDetector: var IntSet): bool =
+  if t == nil: return
+  case t.kind:
+    of tyTuple:
+      if cycleDetector.containsOrIncl(t.id):
+        return true
+      var cycleDetectorCopy: IntSet
+      for i in  0..<t.len:
+        assign(cycleDetectorCopy, cycleDetector)
+        if isTupleRecursive(t[i], cycleDetectorCopy):
+          return true
+    of tyAlias, tyRef, tyPtr, tyGenericInst, tyVar, tyLent, tySink, tyArray, tyUncheckedArray, tySequence:
+      return isTupleRecursive(t.lastSon, cycleDetector)
+    else:
+      discard
+
+proc isTupleRecursive*(t: PType): bool =
+  var cycleDetector = initIntSet()
+  isTupleRecursive(t, cycleDetector)