do not track 'raise Defect' in the .raises: [] clause anymore (#14298)

* do not track 'raise Defect' in the .raises: [] clause anymore

* --panics:on maps 'raise Defect' to an unrecoverable fatal error

* make tests green again

* update the documentation too

compiler/sempass2.nim

@@ -315,7 +315,10 @@ proc addEffect(a: PEffects, e, comesFrom: PNode) =
     # we only track the first node that can have the effect E in order
     # to safe space and time.
     if sameType(a.graph.excType(aa[i]), a.graph.excType(e)): return
-  throws(a.exc, e, comesFrom)
+
+  if e.typ != nil:
+    if optNimV1Emulation in a.config.globalOptions or not isDefectException(e.typ):
+      throws(a.exc, e, comesFrom)
 
 proc addTag(a: PEffects, e, comesFrom: PNode) =
   var aa = a.tags

compiler/types.nim

@@ -1672,6 +1672,17 @@ proc isException*(t: PType): bool =
     t = skipTypes(t[0], abstractPtrs)
   return false
 
+proc isDefectException*(t: PType): bool =
+  var t = t.skipTypes(abstractPtrs)
+  while t.kind == tyObject:
+    if t.sym != nil and t.sym.owner != nil and
+        sfSystemModule in t.sym.owner.flags and
+        t.sym.name.s == "Defect":
+      return true
+    if t[0] == nil: break
+    t = skipTypes(t[0], abstractPtrs)
+  return false
+
 proc isSinkTypeForParam*(t: PType): bool =
   # a parameter like 'seq[owned T]' must not be used only once, but its
   # elements must, so we detect this case here: