fix: block difficulty calc frontier

[souradeep-das]

What was wrong?

Frontier block difficulty calculation was broken

How was it fixed?

Type conversion

Cute Animal Picture

[SamWilsn]

Huh, is this broken all the way up to the merge?

[SamWilsn]

num_bomb_periods = (block_number // Uint(100000)) - Uint(2)
if num_bomb_periods >= 0:
    difficulty += Uint(2) ** num_bomb_periods

Kinda just thinking out loud, but would it be better in your opinion to do the math as Uint, or do the conversion at the end?

[souradeep-das]

yeah was thinking the same! that would make it consistent with the other forks. Also do you think in that case converting difficulty to int for doing the calculations is better to be consistent?

[souradeep-das]

difficulty = int(difficulty)
num_bomb_periods = (int(block_number) // 100000) - 2
if num_bomb_periods >= 0:
    difficulty += 2**num_bomb_periods

return max(Uint(difficulty), MINIMUM_DIFFICULTY)

is this better?

[SamWilsn]

Does Frontier have a minimum difficulty?

[souradeep-das]

seems like it - https://github.com/ethereum/execution-specs/blob/forks/osaka/src/ethereum/frontier/fork.py#L776C28-L776C46

[souradeep-das]

the other forks seems to be okay with the calculation - looks like only a problem with frontier

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.94%. Comparing base (6b0f795) to head (e68bc58).
⚠️ Report is 1 commits behind head on forks/osaka.

Files with missing lines	Patch %	Lines
src/ethereum/frontier/fork.py	0.00%	1 Missing ⚠️
❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@             Coverage Diff              @@
##           forks/osaka    #1409   +/-   ##
============================================
  Coverage        94.94%   94.94%           
============================================
  Files              583      583           
  Lines            34665    34665           
  Branches          3070     3070           
============================================
  Hits             32914    32914           
  Misses            1198     1198           
  Partials           553      553           

Flag	Coverage Δ
unittests	94.94% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[SamWilsn]

What you had is fine, now that I've looked a bit more deeply at it. Post-Frontier forks convert everything to int before doing the math, so if we want to fix this, we should do it for all the forks.