This looks like memory corruption. Have you tried running your program under the race detector? See https://blog.golang.org/race-detector .

If a compiler is using undeclared variable ,the bug does not fall in category of memory corruption. In this case compiler is using undeclared variable and thus the code should not even compile.

Can you please provide small self contained example of the compiler using an undeclared variable. Thanks.

I would have already submitted here but Its not easy to create a simple test case for this case. Have documented sufficiently here https://github.com/deroproject/derosuite/blob/995d27eec249c7b3d908ebcf28af1449184c6cbf/crypto/ringct/mlsag.go#L159

I don’t understand what you mean by an undeclared variable. Could you possibly write a small program in the playground to show this, it doesn’t need to reproduce the bug your demonstrated here.

Can you also try passing -gcflags=“-l -N” to disable optimisations and see if that affects the outcome.

The race detector barks at your project. I'm using $ go run -race main.go at derosuite/cmd/derod.

WARNING: DATA RACE
Read at 0x00c42017a250 by goroutine 17:
  main.main.func1()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/blockchain/blockchain.go:181 +0xe9

Previous write at 0x00c42017a250 by goroutine 13:
  github.com/deroproject/derosuite/blockchain.(*Blockchain).Add_Complete_Block()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/blockchain/blockchain.go:469 +0xd9c
  github.com/deroproject/derosuite/p2p.Handle_BC_Notify_Response_GetObjects()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/p2p/bc_notify_response_get_objects.go:146 +0xd9a
  github.com/deroproject/derosuite/p2p.Handle_Connection()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/p2p/levin.go:245 +0x1099
  github.com/deroproject/derosuite/p2p.P2P_engine()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/p2p/controller.go:95 +0x737

Goroutine 17 (running) created at:
  main.main()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/cmd/derod/main.go:118 +0xb9a

Goroutine 13 (running) created at:
  github.com/deroproject/derosuite/p2p.P2P_Init()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/p2p/controller.go:38 +0x1db
  main.main()
      /home/adonizetti/gocode/src/github.com/deroproject/derosuite/cmd/derod/main.go:113 +0xb4a
==================

and several others.

It is also not true that the compiler is using undeclared variables. You wrote in the comment you linked:

if the variables are declared within first loop, second loop is able to access them without declaring them

If you comment line 179 here, the code in the second loop, at line 195, will start using variable L as declared in const.go, line 25. The L declaration outside the loops is shadowing the already-declared L in const.go.

Thanks for pointing out the mistake.