test always instantiating nominal generic insts

compiler/semtypinst.nim

@@ -80,7 +80,7 @@ type
     owner*: PSym              # where this instantiation comes from
     recursionLimit: int
 
-proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType
+proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType, isInstValue = false): PType
 proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym, t: PType): PSym
 proc replaceTypeVarsN*(cl: var TReplTypeVars, n: PNode; start=0; expectedType: PType = nil): PNode
 
@@ -95,8 +95,8 @@ template checkMetaInvariants(cl: TReplTypeVars, t: PType) = # noop code
       debug t
       writeStackTrace()
 
-proc replaceTypeVarsT*(cl: var TReplTypeVars, t: PType): PType =
-  result = replaceTypeVarsTAux(cl, t)
+proc replaceTypeVarsT*(cl: var TReplTypeVars, t: PType, isInstValue = false): PType =
+  result = replaceTypeVarsTAux(cl, t, isInstValue)
   checkMetaInvariants(cl, result)
 
 proc prepareNode*(cl: var TReplTypeVars, n: PNode): PNode =
@@ -481,7 +481,7 @@ proc handleGenericInvocation(cl: var TReplTypeVars, t: PType): PType =
     return
 
   let bbody = last body
-  var newbody = replaceTypeVarsT(cl, bbody)
+  var newbody = replaceTypeVarsT(cl, bbody, isInstValue = true)
   cl.skipTypedesc = oldSkipTypedesc
   newbody.flags = newbody.flags + (t.flags + body.flags - tfInstClearedFlags)
   result.flags = result.flags + newbody.flags - tfInstClearedFlags
@@ -578,7 +578,7 @@ proc propagateFieldFlags(t: PType, n: PNode) =
       propagateFieldFlags(t, son)
   else: discard
 
-proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
+proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType, isInstValue = false): PType =
   template bailout =
     if (t.sym == nil) or (t.sym != nil and sfGeneratedType in t.sym.flags):
       # In the first case 't.sym' can be 'nil' if the type is a ref/ptr, see
@@ -712,7 +712,10 @@ proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
     propagateToOwner(result, result.last)
 
   else:
-    if containsGenericType(t):
+    if containsGenericType(t) or
+        # nominal types as direct generic instantiation values
+        # are re-instantiated even if they don't contain generic fields
+        (isInstValue and t.kind in {tyDistinct, tyEnum, tyObject}):
       #if not cl.allowMetaTypes:
       bailout()
       result = instCopyType(cl, t)

tests/arc/tphantomgeneric1.nim

@@ -0,0 +1,19 @@
+discard """
+  output: '''
+int
+float
+'''
+"""
+
+# issue #22479
+
+type Obj[T] = object
+
+proc `=destroy`[T](self: var Obj[T]) =
+  echo T
+
+block:
+  let intObj = Obj[int]()
+
+block:
+  let floatObj = Obj[float]()

tests/arc/tphantomgeneric2.nim

@@ -0,0 +1,33 @@
+discard """
+  output: '''
+created Phantom[system.float] with value 1
+created Phantom[system.string] with value 2
+created Phantom[system.byte] with value 3
+destroyed Phantom[system.byte] with value 3
+destroyed Phantom[system.string] with value 2
+destroyed Phantom[system.float] with value 1
+'''
+"""
+
+# issue #24374
+
+type Phantom[T] = object
+  value: int
+  # markerField: T
+
+proc initPhantom[T](value: int): Phantom[T] =
+  doAssert value >= 0
+  echo "created " & $Phantom[T] & " with value " & $value
+  result = Phantom[T](value: value)
+
+proc `=wasMoved`[T](x: var Phantom[T]) =
+  x.value = -1
+
+proc `=destroy`[T](x: Phantom[T]) =
+  if x.value >= 0:
+    echo "destroyed " & $Phantom[T] & " with value " & $x.value
+
+let
+  x = initPhantom[float](1)
+  y = initPhantom[string](2)
+  z = initPhantom[byte](3)