Issues

• lean --deps panics in HeaderSyntax.imports on a header that does not parse

  leanprover/lean4#16464 · Filter by author rinarakaki opened on Nov 14, 2026

• IO.Process.spawn with stdio .null silently inherits the parent's stdio when opening /dev/null fails

  leanprover/lean4#16463 · Filter by author Marti2203 opened on Nov 14, 2026

• throw IO.Error.unexpectedEof from main segfaults instead of printing the error

  leanprover/lean4#16462 · Filter by author Robertboy18 opened on Nov 14, 2026

• IO.asTask with a pure body silently runs the work on the spawning thread

  code-generator
  leanprover/lean4#16459 · Filter by author cpehle opened on Nov 13, 2026

• Missing order instances for Bool

  bug
  leanprover/lean4#16450 · Filter by author gasparattila opened on Nov 13, 2026

• An ST function can use its world token twice, so two equal ST.Prim.Ref.swap terms return different values

  leanprover/lean4#16437 · Filter by author ethanyiwu opened on Nov 13, 2026

• joinTypes? erases a join point parameter that carries data when another branch returns a type

  code-generator
  leanprover/lean4#16434 · Filter by author ethanyiwu opened on Nov 13, 2026

• recall? doesn't resolve names

  bug
  leanprover/lean4#16433 · Filter by author frangio opened on Nov 12, 2026
  1

• VCGen reduceHead? loops on a projection function applied to a variable

  leanprover/lean4#16416 · Filter by author rish-agent opened on Nov 12, 2026

• getStarLemmas lists the current module's star-indexed lemmas once more after each library search

  leanprover/lean4#16415 · Filter by author rinarakaki opened on Nov 12, 2026

• Lake: restoring a module from a cached .ltar leaves stale .olean.hash sidecars, so importers reuse artifacts built against the old module

  leanprover/lean4#16407 · Filter by author kim-em opened on Nov 11, 2026
  1

• New do elaborator accepts mut reassignment in finally and drops it (regression in v4.32.0-rc1)

  leanprover/lean4#16399 · Filter by author empath-nirvana opened on Nov 11, 2026

• [Windows] Lean server worker thread spike and stack-overflow abort during Mathlib import

  leanprover/lean4#16398 · Filter by author vinbo opened on Nov 11, 2026

• vcgen cannot handle early returns from while loops properly

  bug
  leanprover/lean4#16377 · Filter by author dipeshkaphle opened on Nov 11, 2026

• RFC: Performance improvement in lean_mark_persistent and lean_mark_mt

  leanprover/lean4#16374 · Filter by author zgrannan opened on Nov 10, 2026
  1

• vcgen +jp: join-point discharge is still exponential when the state is a structure

  bug
  leanprover/lean4#16364 · Filter by author govereau opened on Nov 9, 2026
  1

• IO.Process.spawn: .null stdio setup is unchecked, so a child may inherit stray fds or the parent's stream

  leanprover/lean4#16350 · Filter by author nomeata opened on Nov 8, 2026

• lake comparator: the sandboxed lake build and export drop LEAN_NUM_THREADS

  bug
  leanprover/lean4#16347 · Filter by author marleymcwilliams opened on Nov 8, 2026

• Generalized field notation incorrectly sets type information

  leanprover/lean4#16345 · Filter by author user202729 opened on Nov 8, 2026

• Cache invalidation bug in the LSP with following unexpected token

  bug
  leanprover/lean4#16344 · Filter by author user202729 opened on Nov 8, 2026

• More readable Repr for Rat

  leanprover/lean4#16327 · Filter by author FeldrinH opened on Nov 6, 2026

• Every inductive type gets an unsafe declaration T.ctorIdx._impl

  leanprover/lean4#16323 · Filter by author vincentqb opened on Nov 6, 2026

• RFC: compile and run new syntax definitions without waiting for all preceding proofs

  leanprover/lean4#16318 · Filter by author xukp20 opened on Nov 6, 2026

• structure, inductive and class wait for all preceding proofs in the file

  leanprover/lean4#16317 · Filter by author xukp20 opened on Nov 6, 2026

• ASCII forall and exists fail to parse with binder predicates

  leanprover/lean4#16315 · Filter by author cjen1-msft opened on Nov 6, 2026