From 8b0d700b4507f889abae28614026047ce42a98f4 Mon Sep 17 00:00:00 2001
From: jangko <jangko128@gmail.com>
Date: Tue, 24 May 2022 10:43:31 +0700
Subject: [PATCH] fix EVM stack.[] bug

---
 nimbus/vm/stack.nim   |  2 +-
 nimbus/vm2/stack.nim  |  2 +-
 tests/test_op_env.nim | 15 +++++++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/nimbus/vm/stack.nim b/nimbus/vm/stack.nim
index 2a9de72ea..d6641de05 100644
--- a/nimbus/vm/stack.nim
+++ b/nimbus/vm/stack.nim
@@ -124,7 +124,7 @@ proc `$`*(stack: Stack): string =
   &"Stack:\n{values}"
 
 proc `[]`*(stack: Stack, i: BackwardsIndex, T: typedesc): T =
-  # This should be used only for tracer/test/debugging
+  ensurePop(stack, int(i))
   fromStackElement(stack.values[i], result)
 
 proc peekInt*(stack: Stack): UInt256 =
diff --git a/nimbus/vm2/stack.nim b/nimbus/vm2/stack.nim
index 2a9de72ea..d6641de05 100644
--- a/nimbus/vm2/stack.nim
+++ b/nimbus/vm2/stack.nim
@@ -124,7 +124,7 @@ proc `$`*(stack: Stack): string =
   &"Stack:\n{values}"
 
 proc `[]`*(stack: Stack, i: BackwardsIndex, T: typedesc): T =
-  # This should be used only for tracer/test/debugging
+  ensurePop(stack, int(i))
   fromStackElement(stack.values[i], result)
 
 proc peekInt*(stack: Stack): UInt256 =
diff --git a/tests/test_op_env.nim b/tests/test_op_env.nim
index 0612141ea..368ba429b 100644
--- a/tests/test_op_env.nim
+++ b/tests/test_op_env.nim
@@ -8,6 +8,21 @@ proc opEnvMain*() =
   suite "Environmental Information Opcodes":
     let (vmState, chainDB) = initDatabase()
 
+    assembler: # EVM bug reported in discord
+      title: "stack's operator [] bug"
+      code:
+        PUSH1 "0x0A"
+        DUP1
+        RETURNDATASIZE
+        MSIZE
+        ADDRESS
+        GAS
+        STATICCALL
+        CALL
+      fork: london
+      success: false
+      memory: "0x0000000000000000000000000000000000000000000000000000000000000000"
+
     assembler: # CODECOPY OP
       title: "CODECOPY_1"
       code: