make move use =wasMoved internally (nim-lang#22032)

* make `move` use `=wasMoved` internally * fixes tests * fixes spawn finally * fixes views * rename to internalMove * add a test case

Author: ringabout

compiler/ccgexprs.nim

@@ -2357,7 +2357,8 @@ proc genMove(p: BProc; n: PNode; d: var TLoc) =
  else:
  if d.k == locNone: getTemp(p, n.typ, d)
  genAssignment(p, d, a, {})
- resetLoc(p, a)
+ if p.config.selectedGC notin {gcArc, gcAtomicArc, gcOrc}:
+ resetLoc(p, a)
 
 proc genDestroy(p: BProc; n: PNode) =
  if optSeqDestructors in p.config.globalOptions:

compiler/liftdestructors.nim

@@ -553,7 +553,7 @@ proc fillSeqOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
  body.add setLenSeqCall(c, t, x, y)
  forallElements(c, t, body, x, y)
  of attachedSink:
- let moveCall = genBuiltin(c, mMove, "move", x)
+ let moveCall = genBuiltin(c, mMove, "internalMove", x)
  moveCall.add y
  doAssert t.destructor != nil
  moveCall.add destructorCall(c, t.destructor, x)
@@ -586,7 +586,7 @@ proc useSeqOrStrOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
  body.add newHookCall(c, t.assignment, x, y)
  of attachedSink:
  # we always inline the move for better performance:
- let moveCall = genBuiltin(c, mMove, "move", x)
+ let moveCall = genBuiltin(c, mMove, "internalMove", x)
  moveCall.add y
  doAssert t.destructor != nil
  moveCall.add destructorCall(c, t.destructor, x)
@@ -617,7 +617,7 @@ proc fillStrOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
  of attachedAsgn, attachedDeepCopy, attachedDup:
  body.add callCodegenProc(c.g, "nimAsgnStrV2", c.info, genAddr(c, x), y)
  of attachedSink:
- let moveCall = genBuiltin(c, mMove, "move", x)
+ let moveCall = genBuiltin(c, mMove, "internalMove", x)
  moveCall.add y
  doAssert t.destructor != nil
  moveCall.add destructorCall(c, t.destructor, x)

compiler/lowerings.nim

@@ -66,8 +66,17 @@ proc newFastMoveStmt*(g: ModuleGraph, le, ri: PNode): PNode =
  result = newNodeI(nkFastAsgn, le.info, 2)
  result[0] = le
  result[1] = newNodeIT(nkCall, ri.info, ri.typ)
- result[1].add newSymNode(getSysMagic(g, ri.info, "move", mMove))
- result[1].add ri
+ if g.config.selectedGC in {gcArc, gcAtomicArc, gcOrc}:
+ result[1].add newSymNode(getCompilerProc(g, "internalMove"))
+ result[1].add ri
+ result = newTreeI(nkStmtList, le.info, result,
+ newTree(nkCall, newSymNode(
+ getSysMagic(g, ri.info, "=wasMoved", mWasMoved)),
+ ri
+ ))
+ else:
+ result[1].add newSymNode(getSysMagic(g, ri.info, "move", mMove))
+ result[1].add ri
 
 proc lowerTupleUnpacking*(g: ModuleGraph; n: PNode; idgen: IdGenerator; owner: PSym): PNode =
  assert n.kind == nkVarTuple

lib/system.nim

@@ -147,10 +147,26 @@ proc wasMoved*[T](obj: var T) {.inline, noSideEffect.} =
  {.cast(raises: []), cast(tags: []).}:
  `=wasMoved`(obj)
 
-proc move*[T](x: var T): T {.magic: "Move", noSideEffect.} =
- result = x
- {.cast(raises: []), cast(tags: []).}:
- `=wasMoved`(x)
+const notJSnotNims = not defined(js) and not defined(nimscript)
+const arcLikeMem = defined(gcArc) or defined(gcAtomicArc) or defined(gcOrc)
+
+when notJSnotNims and arcLikeMem:
+ proc internalMove[T](x: var T): T {.magic: "Move", noSideEffect, compilerproc.} =
+ result = x
+
+ proc move*[T](x: var T): T {.noSideEffect, nodestroy.} =
+ {.cast(noSideEffect).}:
+ when nimvm:
+ result = internalMove(x)
+ else:
+ result = internalMove(x)
+ {.cast(raises: []), cast(tags: []).}:
+ `=wasMoved`(x)
+else:
+ proc move*[T](x: var T): T {.magic: "Move", noSideEffect.} =
+ result = x
+ {.cast(raises: []), cast(tags: []).}:
+ `=wasMoved`(x)
 
 type
  range*[T]{.magic: "Range".} ## Generic type to construct range types.
@@ -415,7 +431,6 @@ include "system/inclrtl"
 const NoFakeVars = defined(nimscript) ## `true` if the backend doesn't support \
  ## "fake variables" like `var EBADF {.importc.}: cint`.
 
-const notJSnotNims = not defined(js) and not defined(nimscript)
 
 when not defined(js) and not defined(nimSeqsV2):
  type

tests/destructor/twasmoved.nim

@@ -0,0 +1,14 @@
+type
+ Foo = object
+ id: int
+
+proc `=wasMoved`(x: var Foo) =
+ x.id = -1
+
+proc foo =
+ var s = Foo(id: 999)
+ var m = move s
+ doAssert s.id == -1
+ doAssert m.id == 999
+
+foo()