Fix destructor tests

tests/destructor/tprevent_assign2.nim

@@ -1,12 +1,7 @@
 discard """
   errormsg: "'=' is not available for type <Foo>; requires a copy because it's not the last read of 'otherTree'"
-
-  cmd: "nim check --hint[Performance]:off $file"
-  nimout: '''
-tprevent_assign2.nim(53, 31) Error: '=' is not available for type <Foo>; requires a copy because it's not the last read of 'otherTree'; another read is done here: tprevent_assign2.nim(52, 13)
-tprevent_assign2.nim(55, 31) Error: '=' is not available for type <Foo>; requires a copy because it's not the last read of 'otherTree'; another read is done here: tprevent_assign2.nim(52, 13)
-tprevent_assign2.nim(66, 29) Error: '=' is not available for type <Foo>; requires a copy because it's not the last read of 'otherTree'; another read is done here: tprevent_assign2.nim(68, 9)
-'''
+  file: "tprevent_assign2.nim"
+  line: 48
 """
 
 type
@@ -56,17 +51,5 @@ proc preventThis() =
       else:
         discard
 
-proc preventThis2() =
-  var otherTree: Foo
-  try:
-    try:
-      otherTree = createTree(44)
-      echo otherTree
-    finally:
-      take2(createTree(34), otherTree)
-  finally:
-    echo otherTree
-
 allowThis()
 preventThis()
-preventThis2()

tests/destructor/tprevent_assign3.nim

@@ -0,0 +1,53 @@
+discard """
+  errormsg: "'=' is not available for type <Foo>; requires a copy because it's not the last read of 'otherTree'"
+  file: "tprevent_assign3.nim"
+  line: 46
+"""
+
+type
+  Foo = object
+    x: int
+
+proc `=destroy`(f: var Foo) = f.x = 0
+proc `=`(a: var Foo; b: Foo) {.error.} # = a.x = b.x
+proc `=sink`(a: var Foo; b: Foo) = a.x = b.x
+
+proc createTree(x: int): Foo =
+  Foo(x: x)
+
+proc take2(a, b: sink Foo) =
+  echo a.x, " ", b.x
+
+proc allowThis() =
+  var otherTree: Foo
+  try:
+    for i in 0..3:
+      while true:
+        #if i == 0:
+        otherTree = createTree(44)
+        case i
+        of 0:
+          echo otherTree
+          take2(createTree(34), otherTree)
+        of 1:
+          take2(createTree(34), otherTree)
+        else:
+          discard
+  finally:
+    discard
+
+proc preventThis2() =
+  var otherTree: Foo
+  try:
+    try:
+      otherTree = createTree(44)
+      echo otherTree
+    finally:
+      take2(createTree(34), otherTree)
+  finally:
+    echo otherTree
+
+allowThis()
+preventThis2()
+
+