experiment: use PersistentArray for Environment.extensions

[Kha]

No description provided.

[Kha]

!bench

[leanprover-radar]

Benchmark results for 1e4f9e1 against 87180a0 are in. Significant changes detected! @Kha

• 🟥 build//instructions: +159.3G (+1.31%)

Large changes (2🟥)

• 🟥 compiled/parser//instructions: +235.7M (+0.62%)
• 🟥 elab/grind_bitvec2//instructions: +2.7G (+1.34%)

Medium changes (26🟥)

Too many entries to display here. View the full report on radar instead.

Small changes (1382🟥)

Too many entries to display here. View the full report on radar instead.

[Kha]

!bench mathlib

[leanprover-radar]

Benchmark results for leanprover-community/mathlib4-nightly-testing@f4a03c8 against leanprover-community/mathlib4-nightly-testing@c715495 are in. Significant changes detected! @Kha

• 🟥 build//instructions: +2.1T (+1.18%)

Large changes (1🟥)

• 🟥 build/profile/C code generation//wall-clock: +567ms (+4.89%)

Medium changes (2🟥)

• 🟥 build//instructions: +2.1T (+1.18%)
• 🟥 lint//wall-clock: +32s (+26.86%)

and 1 hidden

Small changes (1✅, 255🟥)

Too many entries to display here. View the full report on radar instead.

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI can not be attempted yet, as the nightly-testing-2026-03-19 tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto nightly-with-manual, reference manual CI should run now. You can force reference manual CI using the force-manual-ci label. (2026-03-21 22:51:11)

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ✅ Mathlib branch lean-pr-testing-13010 has successfully built against this PR. (2026-03-21 23:45:38) View Log