fixes #23524; global variables cannot be analysed when injecting move (#23529)

fixes #23524

```nim
proc isAnalysableFieldAccess*(orig: PNode; owner: PSym): bool =
  ...
  result = n.kind == nkSym and n.sym.owner == owner and
    {sfGlobal, sfThread, sfCursor} * n.sym.flags == {} and
    (n.sym.kind != skParam or isSinkParam(n.sym))
```
In `isAnalysableFieldAccess`, globals, cursors are already rejected

compiler/injectdestructors.nim

@@ -1186,9 +1186,9 @@ proc moveOrCopy(dest, ri: PNode; c: var Con; s: var Scope, flags: set[MoveOrCopy
         # Rule 3: `=sink`(x, z); wasMoved(z)
         let snk = c.genSink(s, dest, ri, flags)
         result = newTree(nkStmtList, snk, c.genWasMoved(ri))
-      elif ri.sym.kind != skParam and ri.sym.owner == c.owner and
-          isLastRead(ri, c, s) and canBeMoved(c, dest.typ) and not isCursor(ri) and
-          not ({sfGlobal, sfPure} <= ri.sym.flags):
+      elif ri.sym.kind != skParam and
+          isAnalysableFieldAccess(ri, c.owner) and
+          isLastRead(ri, c, s) and canBeMoved(c, dest.typ):
         # Rule 3: `=sink`(x, z); wasMoved(z)
         let snk = c.genSink(s, dest, ri, flags)
         result = newTree(nkStmtList, snk, c.genWasMoved(ri))

lib/system.nim

@@ -158,9 +158,11 @@ when defined(nimHasEnsureMove):
     ## Ensures that `x` is moved to the new location, otherwise it gives
     ## an error at the compile time.
     runnableExamples:
-      var x = "Hello"
-      let y = ensureMove(x)
-      doAssert y == "Hello"
+      proc foo =
+        var x = "Hello"
+        let y = ensureMove(x)
+        doAssert y == "Hello"
+      foo()
     discard "implemented in injectdestructors"
 
 type

tests/arc/tarcmisc.nim

@@ -727,3 +727,18 @@ block: # bug #23505
 
   discard init(C)
 
+block: # bug #23524
+  type MyType = object
+    a: int
+
+  proc `=destroy`(typ: MyType) = discard
+
+  var t1 = MyType(a: 100)
+  var t2 = t1 # Should be a copy?
+
+  proc main() =
+    t2 = t1
+    doAssert t1.a == 100
+    doAssert t2.a == 100
+
+  main()

tests/destructor/tmove_objconstr.nim

@@ -137,28 +137,29 @@ doAssert seq3[0] == 1.0
 var seq4, seq5: MySeqNonCopyable
 (seq4, i, seq5) = myfunc2(2, 3)
 
-seq4 = block:
-  var tmp = newMySeq(4, 1.0)
-  tmp[0] = 3.0
-  tmp
+proc foo =
+  seq4 = block:
+    var tmp = newMySeq(4, 1.0)
+    tmp[0] = 3.0
+    tmp
 
-doAssert seq4[0] == 3.0
+  doAssert seq4[0] == 3.0
 
-import macros
 
-seq4 =
-  if i > 0: newMySeq(2, 5.0)
-  elif i < -100: raise newException(ValueError, "Parse Error")
-  else: newMySeq(2, 3.0)
+  seq4 =
+    if i > 0: newMySeq(2, 5.0)
+    elif i < -100: raise newException(ValueError, "Parse Error")
+    else: newMySeq(2, 3.0)
 
-seq4 =
-  case (char) i:
-    of 'A', {'W'..'Z'}: newMySeq(2, 5.0)
-    of 'B': quit(-1)
-    else:
-      let (x1, x2, x3) = myfunc2(2, 3)
-      x3
+  seq4 =
+    case (char) i:
+      of 'A', {'W'..'Z'}: newMySeq(2, 5.0)
+      of 'B': quit(-1)
+      else:
+        let (x1, x2, x3) = myfunc2(2, 3)
+        x3
 
+foo()
 
 #------------------------------------------------------------
 #-- Move into array constructor