Show that a variable is cursor in --expandArc (#15002)

compiler/cursor_inference.nim

@@ -73,7 +73,7 @@ proc cursorId(c: Con; x: PSym): int =
     if c.cursors[i].s == x: return i
   return -1
 
-proc getCursors(c: Con): IntSet =
+proc getCursors(c: Con) =
   #[
   Question: if x depends on y and y depends on z then also y depends on z.
 
@@ -86,7 +86,6 @@ proc getCursors(c: Con): IntSet =
   y.s = "mutate"
 
   ]#
-  result = initIntSet()
   for cur in c.cursors:
     if not c.mayOwnData.contains(cur.s.id) and
         cur.s.typ.skipTypes({tyGenericInst, tyAlias}).kind != tyOwned:
@@ -97,7 +96,7 @@ proc getCursors(c: Con): IntSet =
             #echo "bah, not a cursor ", cur.s, " bad dependency ", d
             break doAdd
         when true:
-          result.incl cur.s.id
+          cur.s.flags.incl sfCursor
         when false:
           echo "computed as a cursor ", cur.s, " ", cur.deps, " ", c.config $ cur.s.info
 
@@ -294,7 +293,7 @@ proc analyse(c: var Con; n: PNode) =
   else:
     for child in n: analyse(c, child)
 
-proc computeCursors*(n: PNode; config: ConfigRef): IntSet =
+proc computeCursors*(n: PNode; config: ConfigRef) =
   var c = Con(config: config)
   analyse(c, n)
-  result = getCursors c
+  getCursors c

compiler/injectdestructors.nim

@@ -35,7 +35,6 @@ type
   Con = object
     owner: PSym
     g: ControlFlowGraph
-    cursors: IntSet
     graph: ModuleGraph
     otherRead: PNode
     inLoop, inSpawn: int
@@ -152,13 +151,13 @@ proc isLastRead(location: PNode; cfg: ControlFlowGraph; otherRead: var PNode; pc
 proc isCursor(n: PNode; c: Con): bool =
   case n.kind
   of nkSym:
-    result = sfCursor in n.sym.flags or c.cursors.contains(n.sym.id)
+    sfCursor in n.sym.flags
   of nkDotExpr:
-    result = sfCursor in n[1].sym.flags
+    isCursor(n[1], c)
   of nkCheckedFieldExpr:
-    result = isCursor(n[0], c)
+    isCursor(n[0], c)
   else:
-    result = false
+    false
 
 proc isLastRead(n: PNode; c: var Con): bool =
   # first we need to search for the instruction that belongs to 'n':
@@ -1043,7 +1042,7 @@ proc injectDestructorCalls*(g: ModuleGraph; owner: PSym; n: PNode): PNode =
     echoCfg(c.g)
     echo n
 
-  c.cursors = computeCursors(n, g.config)
+  computeCursors(n, g.config)
 
   var scope: Scope
   let body = p(n, c, scope, normal)

compiler/renderer.nim

@@ -865,6 +865,8 @@ proc gident(g: var TSrcGen, n: PNode) =
     if localId != 0 and n.sym.magic == mNone:
       s.add '_'
       s.addInt localId
+    if sfCursor in n.sym.flags:
+      s.add "_cursor"
   elif n.kind == nkSym and (renderIds in g.flags or sfGenSym in n.sym.flags or n.sym.kind == skTemp):
     s.add '_'
     s.addInt n.sym.id

tests/arc/topt_cursor.nim

@@ -8,14 +8,14 @@ var
   :tmpD_1
   :tmpD_2
 try:
-  var x = ("hi", 5)
-  x = if cond:
+  var x_cursor = ("hi", 5)
+  x_cursor = if cond:
     :tmpD = ("different", 54)
     :tmpD else:
     :tmpD_1 = ("string here", 80)
     :tmpD_1
   echo [
-    :tmpD_2 = `$`(x)
+    :tmpD_2 = `$`(x_cursor)
     :tmpD_2]
 finally:
   `=destroy`(:tmpD_2)

tests/arc/topt_refcursors.nim

@@ -3,19 +3,19 @@ discard """
   cmd: '''nim c --gc:arc --expandArc:traverse --hint:Performance:off $file'''
   nimout: '''--expandArc: traverse
 
-var it = root
+var it_cursor = root
 block :tmp:
   while (
-    not (it == nil)):
-    echo [it.s]
-    it = it.ri
-var jt = root
+    not (it_cursor == nil)):
+    echo [it_cursor.s]
+    it_cursor = it_cursor.ri
+var jt_cursor = root
 block :tmp_1:
   while (
-    not (jt == nil)):
-    let ri_1 = jt.ri
-    echo [jt.s]
-    jt = ri_1
+    not (jt_cursor == nil)):
+    let ri_1_cursor = jt_cursor.ri
+    echo [jt_cursor.s]
+    jt_cursor = ri_1_cursor
 -- end of expandArc ------------------------'''
 """