name: math/unbalanced-env default: true advisory: false fix: false since: 0.1.0

math/unbalanced-env

LaTeX \begin{env} with no matching \end{env} at the same nesting depth.

What it does

Flags TeX \begin{env} blocks that have no matching \end{env} (or vice versa), where env is one of the math environments mdwright tracks (equation, align, aligned, cases, matrix, pmatrix, bmatrix, vmatrix, Vmatrix, gather, multline, split, and their starred variants).

Why

\begin{align} … \end{align} and friends are math regions. Like \[ … \], they suspend prose lint rules and are passed through the formatter verbatim. An unmatched \begin leaves the parser unable to tell where math ends; an unmatched \end is almost always a copy-paste error that will silently break rendering in any math-aware renderer.

Example (bad)

\begin{align}
  a + b &= c \\
  d - e &= f

Example (good)

\begin{align}
  a + b &= c \\
  d - e &= f
\end{align}

Configuration

Disable inline: .
Disable in config: [lint] ignore = ["math/unbalanced-env"].
Severity: non-advisory.

References

mdwright's environment recogniser (src/stdlib/math_unbalanced_env.rs).
amsmath user's guide for the canonical environment list.