Hacktoberfest 2026:メンテナが10月に向けて印を付けた、オープンで初心者向けの issue。 Hacktoberfest の issue を見る

A brace inside an f-string interpolation comment silently changes the resulting value

クローズ
#1,252 コメント 0 件 リアクション 0 件 担当者 0 名 GitHub で見る

メンテナーはふだん 1 日以内に返信

まだ誰も着手していません。

評価

難易度
3/5
見積もり時間
1〜2日
初心者へのやさしさ
76/100
issue の種類
バグ
明瞭さ
明確に書かれている
活発さ
活発
技術スタック
c
領域
compilers

調査の方向性

Start in src/lexer.c at the interpolation boundary scanner around lines 399 and 422, then read the comment and f-string rules in docs/SPEC.md. Reproduce the issue and compare it with the existing #334/#344 quoted-character cases. Add regression coverage for braces in comments, preserving nested braces and quoted # or braces, and verify the evaluated output is exactly 3\n.

索引モデルが issue の本文から書いたものです。

説明

area:runtime-vm bug found-by:code-review kind:silent-wrong

A closing brace inside an f-string interpolation's comment terminates interpolation before the comment ends. The program succeeds but treats the remaining expression as literal text, changing its value.

Reproduce

Save and run this exact two-line program:

print of f"{1 # }
 + 2}"

Actual: exit 0, empty stderr, stdout shown as an escaped string:

"1\n + 2}\n"

Expected: 3\n. The } after # belongs to the comment; the actual expression is 1 + 2.

Paired control: change only the comment text from } to comment:

print of f"{1 # comment
 + 2}"

This exits 0 and prints 3\n. The ordinary parenthesized-expression control also handles the same brace-containing comment correctly:

print of (1 # }
 + 2)

It exits 0 and prints 3\n. This is not a request to introduce multiline expressions: the paired f-string control already accepts and evaluates one.

Cause and contract

The interpolation boundary scanner extracts the expression before recursively tokenizing it. It skips quoted string literals but has no comment state, and counts every exposed {/}. A } in the comment ends extraction; the following newline and + 2} become f-string literal text. The inner tokenizer recognizes the comment only after the boundary was chosen incorrectly.

The lexical contract says comments extend from # to end of line, and f-strings interpolate expressions. Boundary recognition must honor those lexical states.

Regression acceptance

  • The reproducer prints exactly 3\n, matching both controls.
  • Test opening and closing braces within comments, including multiple brace characters.
  • Retain genuine nested-expression brace handling and quoted #/brace characters; # inside a string must not start a comment.
  • Assert exact output after evaluation, not parse success alone: the current defective program exits successfully.

The existing #334/#344 cases cover braces inside quoted strings, not braces inside comments. No matching open or closed report was found.

Verification

Confirmed on a fresh default release build of b91768e23c5a874a64e76e4af9ab291e6aa49983, with inherited EIGS_* variables cleared. Each reproducer and paired control was executed; no runtime or test source was changed. This is a current correctness defect, not a proposed v1 language restriction.

主要言語
C
スター
3
フォーク
7
平均マージ
3時間 56分
マージ済み PR(30日)
102

環境構築

Codespaces で開く

このプロジェクトの開発コンテナを、あなたの GitHub アカウントでブラウザ上に起動します。

はじめの一歩

  1. issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
  2. 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
  3. リポジトリをフォークし、ブランチを切って変更します。
  4. issue 番号を参照したプルリクエストを送ります。

InauguralSystems/EigenScript のほかの issue

InauguralSystems/EigenScript の issue をすべて見る

似ている issue

C の issue をもっと見る

新しい issue をメールで受け取る

初心者向けの GitHub issue を短くまとめたダイジェスト。