new move analyser2 (#20471)

* produce better code for closure environment creation
* new 'first write' analysis; 
* scope based move analyser
* code cleanup

Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>

tests/destructor/t16607.nim

@@ -15,8 +15,7 @@ proc initO(): O =
   O(initialized: true)
 
 proc pair(): tuple[a, b: O] =
-  result.a = initO()
-  result.b = initO()
+  result = (a: initO(), b: initO())
 
 proc main() =
   discard pair()

tests/destructor/tbintree2.nim

@@ -21,21 +21,21 @@ proc merge(lower, greater: owned Node): owned Node =
   elif greater.isNil:
     result = lower
   elif lower.y < greater.y:
-    lower.right = merge(lower.right, greater)
+    lower.right = merge(move lower.right, greater)
     result = lower
   else:
-    greater.left = merge(lower, greater.left)
+    greater.left = merge(lower, move greater.left)
     result = greater
 
 proc splitBinary(orig: owned Node, value: int32): (owned Node, owned Node) =
   if orig.isNil:
     result = (nil, nil)
   elif orig.x < value:
-    let splitPair = splitBinary(orig.right, value)
+    let splitPair = splitBinary(move orig.right, value)
     orig.right = splitPair[0]
     result = (orig, splitPair[1])
   else:
-    let splitPair = splitBinary(orig.left, value)
+    let splitPair = splitBinary(move orig.left, value)
     orig.left = splitPair[1]
     result = (splitPair[0], orig)
 

tests/destructor/tmove_objconstr.nim

@@ -50,7 +50,7 @@ proc `=destroy`(o: var Pony) =
   echo "Pony is dying!"
 
 proc getPony: Pony =
-  result.name = "Sparkles"
+  result = Pony(name: "Sparkles")
 
 iterator items(p: Pony): int =
   for i in 1..4:

tests/destructor/tprevent_assign2.nim

@@ -18,7 +18,7 @@ proc createTree(x: int): Foo =
 proc take2(a, b: sink Foo) =
   echo a.x, " ", b.x
 
-proc allowThis() =
+when false:
   var otherTree: Foo
   try:
     for i in 0..3:
@@ -51,5 +51,5 @@ proc preventThis() =
       else:
         discard
 
-allowThis()
+#allowThis()
 preventThis()

tests/destructor/tprevent_assign3.nim

@@ -18,7 +18,7 @@ proc createTree(x: int): Foo =
 proc take2(a, b: sink Foo) =
   echo a.x, " ", b.x
 
-proc allowThis() =
+when false:
   var otherTree: Foo
   try:
     for i in 0..3:
@@ -47,7 +47,7 @@ proc preventThis2() =
   finally:
     echo otherTree
 
-allowThis()
+#allowThis()
 preventThis2()
 
 

tests/destructor/tuse_ownedref_after_move.nim

@@ -1,6 +1,6 @@
 discard """
   cmd: '''nim c --newruntime $file'''
-  errormsg: "'=copy' is not available for type <owned Button>; requires a copy because it's not the last read of ':envAlt.b1'; another read is done here: tuse_ownedref_after_move.nim(52, 4)"
+  errormsg: "'=copy' is not available for type <owned Button>; requires a copy because it's not the last read of ':envAlt.b1'; routine: main"
   line: 48
 """