Fixes 9716 [backport] (#9790)

* reuse temporary variable
* fixes #9716 [backport]
* Declare local vars in safer place

compiler/ccgstmts.nim

@@ -307,11 +307,13 @@ proc genSingleVar(p: BProc, a: PNode) =
 
 proc genClosureVar(p: BProc, a: PNode) =
   var immediateAsgn = a.sons[2].kind != nkEmpty
-  if immediateAsgn:
   var v: TLoc
   initLocExpr(p, a.sons[0], v)
   genLineDir(p, a)
+  if immediateAsgn:
     loadInto(p, a.sons[0], a.sons[2], v)
+  else:
+    constructLoc(p, v)
 
 proc genVarStmt(p: BProc, n: PNode) =
   for it in n.sons:

compiler/closureiters.nim

@@ -1009,7 +1009,7 @@ proc stateFromGotoState(n: PNode): int =
   assert(n.kind == nkGotoState)
   result = n[0].intVal.int
 
-proc tranformStateAssignments(ctx: var Ctx, n: PNode): PNode =
+proc transformStateAssignments(ctx: var Ctx, n: PNode): PNode =
   # This transforms 3 patterns:
   ########################## 1
   # yield e
@@ -1051,7 +1051,7 @@ proc tranformStateAssignments(ctx: var Ctx, n: PNode): PNode =
       result.add(retStmt)
     else:
       for i in 0 ..< n.len:
-        n[i] = ctx.tranformStateAssignments(n[i])
+        n[i] = ctx.transformStateAssignments(n[i])
 
   of nkSkip:
     discard
@@ -1071,7 +1071,7 @@ proc tranformStateAssignments(ctx: var Ctx, n: PNode): PNode =
 
   else:
     for i in 0 ..< n.len:
-      n[i] = ctx.tranformStateAssignments(n[i])
+      n[i] = ctx.transformStateAssignments(n[i])
 
 proc skipStmtList(ctx: Ctx; n: PNode): PNode =
   result = n
@@ -1220,18 +1220,20 @@ proc wrapIntoStateLoop(ctx: var Ctx, n: PNode): PNode =
   # while true:
   #   block :stateLoop:
   #     gotoState :state
+  #     local vars decl (if needed)
   #     body # Might get wrapped in try-except
   let loopBody = newNodeI(nkStmtList, n.info)
   result = newTree(nkWhileStmt, newSymNode(ctx.g.getSysSym(n.info, "true")), loopBody)
   result.info = n.info
 
+  let localVars = newNodeI(nkStmtList, n.info)
   if not ctx.stateVarSym.isNil:
     let varSect = newNodeI(nkVarSection, n.info)
     addVar(varSect, newSymNode(ctx.stateVarSym))
-    loopBody.add(varSect)
+    localVars.add(varSect)
 
     if not ctx.tempVars.isNil:
-      loopBody.add(ctx.tempVars)
+      localVars.add(ctx.tempVars)
 
   let blockStmt = newNodeI(nkBlockStmt, n.info)
   blockStmt.add(newSymNode(ctx.stateLoopLabel))
@@ -1240,7 +1242,7 @@ proc wrapIntoStateLoop(ctx: var Ctx, n: PNode): PNode =
   gs.add(ctx.newStateAccess())
   gs.add(ctx.g.newIntLit(n.info, ctx.states.len - 1))
 
-  var blockBody = newTree(nkStmtList, gs, n)
+  var blockBody = newTree(nkStmtList, gs, localVars, n)
   if ctx.hasExceptions:
     blockBody = ctx.wrapIntoTryExcept(blockBody)
 
@@ -1292,7 +1294,6 @@ proc transformClosureIterator*(g: ModuleGraph; fn: PSym, n: PNode): PNode =
     # should folllow the same logic.
     ctx.stateVarSym = newSym(skVar, getIdent(ctx.g.cache, ":state"), fn, fn.info)
     ctx.stateVarSym.typ = g.createClosureIterStateType(fn)
-
   ctx.stateLoopLabel = newSym(skLabel, getIdent(ctx.g.cache, ":stateLoop"), fn, fn.info)
   var n = n.toStmtList
 
@@ -1320,7 +1321,7 @@ proc transformClosureIterator*(g: ModuleGraph; fn: PSym, n: PNode): PNode =
     result.add(s)
     result.add(body)
 
-  result = ctx.tranformStateAssignments(result)
+  result = ctx.transformStateAssignments(result)
   result = ctx.wrapIntoStateLoop(result)
 
   # echo "TRANSFORM TO STATES: "

lib/pure/asyncnet.nim

@@ -218,7 +218,7 @@ when defineSsl:
       var data = await recv(socket.fd.AsyncFD, BufferSize, flags)
       let length = len(data)
       if length > 0:
-        let ret = bioWrite(socket.bioIn, addr data[0], data.len.cint)
+        let ret = bioWrite(socket.bioIn, addr data[0], length.cint)
         if ret < 0:
           raiseSSLError()
       elif length == 0:

tests/iter/tyieldintry.nim

@@ -454,5 +454,18 @@ block: #9694 - yield in ObjConstr
 
   test(it, 1, 2)
 
+block: #9716
+  iterator it(): int {.closure.} =
+    var a = 0
+    for i in 1 .. 3:
+      var a: int # Make sure the "local" var is reset
+      var b: string # ditto
+      yield 1
+      a += 5
+      b &= "hello"
+      doAssert(a == 5)
+      doAssert(b == "hello")
+  test(it, 1, 1, 1)
+
 echo "ok"