v4.12.0

v4.12.0

Language features, tactics, and metaprograms

• bv_decide tactic. This release introduces a new tactic for proving goals involving BitVec and Bool. It reduces the goal to a SAT instance that is refuted by an external solver, and the resulting LRAT proof is checked in Lean. This is used to synthesize a proof of the goal by reflection. As this process uses verified algorithms, proofs generated by this tactic use Lean.ofReduceBool, so this tactic includes the Lean compiler as part of the trusted code base. The external solver CaDiCaL is included with Lean and does not need to be installed separately to make use of bv_decide.

  For example, we can use bv_decide to verify that a bit twiddling formula leaves at most one bit set:

  def popcount (x : BitVec 64) : BitVec 64 :=
    let rec go (x pop : BitVec 64) : Nat → BitVec 64
      | 0 => pop
      | n + 1 => go (x >>> 2) (pop + (x &&& 1)) n
    go x 0 64
  
  example (x : BitVec 64) : popcount ((x &&& (x - 1)) ^^^ x) ≤ 1 := by
    simp only [popcount, popcount.go]
    bv_decide

  When the external solver fails to refute the SAT instance generated by bv_decide, it can report a counterexample:

  /--
  error: The prover found a counterexample, consider the following assignment:
  x = 0xffffffffffffffff#64
  -/
  #guard_msgs in
  example (x : BitVec 64) : x < x + 1 := by
    bv_decide

  See Lean.Elab.Tactic.BVDecide for a more detailed overview, and look in tests/lean/run/bv_* for examples.

  #5013, #5074, #5100, #5113, #5137, #5203, #5212, #5220.

• simp tactic

  • #4988 fixes a panic in the reducePow simproc.
  • #5071 exposes the index option to the dsimp tactic, introduced to simp in #4202.
  • #5159 fixes a panic at Fin.isValue simproc.
  • #5167 and #5175 rename the simpCtorEq simproc to reduceCtorEq and makes it optional. (See breaking changes.)
  • #5187 ensures reduceCtorEq is enabled in the norm_cast tactic.
  • #5073 modifies the simp debug trace messages to tag with "dpre" and "dpost" instead of "pre" and "post" when in definitional rewrite mode. #5054 explains the reduce steps for trace.Debug.Meta.Tactic.simp trace messages.

• ext tactic

  • #4996 reduces default maximum iteration depth from 1000000 to 100.

• induction tactic

  • #5117 fixes a bug where let bindings in minor premises wouldn't be counted correctly.

• omega tactic

  • #5157 fixes a panic.

• conv tactic

  • #5149 improves arg n to handle subsingleton instance arguments.

• #5044 upstreams the #time command.

• #5079 makes #check and #reduce typecheck the elaborated terms.

• Incrementality

  • #4974 fixes regression where we would not interrupt elaboration of previous document versions.
  • #5004 fixes a performance regression.
  • #5001 disables incremental body elaboration in presence of where clauses in declarations.
  • #5018 enables infotrees on the command line for ilean generation.
  • #5040 and #5056 improve performance of info trees.
  • #5090 disables incrementality in the case .. | .. tactic.
  • #5312 fixes a bug where changing whitespace after the module header could break subsequent commands.

• Definitions

  • #5016 and #5066 add clean_wf tactic to clean up tactic state in decreasing_by. This can be disabled with set_option debug.rawDecreasingByGoal false.
  • #5055 unifies equational theorems between structural and well-founded recursion.
  • #5041 allows mutually recursive functions to use different parameter names among the “fixed parameter prefix”
  • #4154 and #5109 add fine-grained equational lemmas for non-recursive functions. See breaking changes.
  • #5129 unifies equation lemmas for recursive and non-recursive definitions. The backward.eqns.deepRecursiveSplit option can be set to false to get the old behavior. See breaking changes.
  • #5141 adds f.eq_unfold lemmas. Now Lean produces the following zoo of rewrite rules:

    Option.map.eq_1      : Option.map f none = none
    Option.map.eq_2      : Option.map f (some x) = some (f x)
    Option.map.eq_def    : Option.map f p = match o with | none => none | (some x) => some (f x)
    Option.map.eq_unfold : Option.map = fun f p => match o with | none => none | (some x) => some (f x)
    

    The f.eq_unfold variant is especially useful to rewrite with rw under binders.
  • #5136 fixes bugs in recursion over predicates.

• Variable inclusion

  • #5206 documents that include currently only applies to theorems.

• Elaboration

  • #4926 fixes a bug where autoparam errors were associated to an incorrect source position.
  • #4833 fixes an issue where cdot anonymous functions (e.g. (· + ·)) would not handle ambiguous notation correctly. Numbers the parameters, making this example expand as fun x1 x2 => x1 + x2 rather than fun x x_1 => x + x_1.
  • #5037 improves strength of the tactic that proves array indexing is in bounds.
  • #5119 fixes a bug in the tactic that proves indexing is in bounds where it could loop in the presence of mvars.
  • #5072 makes the structure type clickable in "not a field of structure" errors for structure instance notation.
  • #4717 fixes a bug where mutual inductive commands could create terms that the kernel rejects.
  • #5142 fixes a bug where variable could fail when mixing binder updates and declarations.

• Other fixes or improvements

  • #5118 changes the definition of the syntheticHole parser so that hovering over _ in ?_ gives the docstring for synthetic holes.
  • #5173 uses the emoji variant selector for ✅️,❌️,💥️ in messages, improving fonts selection.
  • #5183 fixes a bug in rename_i where implementation detail hypotheses could be renamed.

Language server, widgets, and IDE extensions

• #4821 resolves two language server bugs that especially affect Windows users. (1) Editing the header could result in the watchdog not correctly restarting the file worker, which would lead to the file seemingly being processed forever. (2) On an especially slow Windows machine, we found that starting the language server would sometimes not succeed at all. This PR also resolves an issue where we would not correctly emit messages that we received while the file worker is being restarted to the corresponding file worker after the restart.
• #5006 updates the user widget manual.
• #5193 updates the quickstart guide with the new display name for the Lean 4 extension ("Lean 4").
• #5185 fixes a bug where over time "import out of date" messages would accumulate.
• #4900 improves ilean loading performance by about a factor of two. Optimizes the JSON parser and the conversion from JSON to Lean data structures; see PR description for details.
• Other fixes or improvements
  • #5031 localizes an instance in Lsp.Diagnostics.

Pretty printing

• #4976 introduces @[app_delab], a macro for creating delaborators for particular constants. The @[app_delab ident] syntax resolves ident to its constant name name and th...

v4.12.0-rc1

chore: use `Expr.numObjs` instead of `lean_expr_size_shared` (#5239)

Remark: declarations like `sizeWithSharing` must be in `IO` since they
are not functions.

The commit also uses the more efficient `ShareCommon.shareCommon'`.

v4.11.0

Language features, tactics, and metaprograms

• The variable inclusion mechanism has been changed. Like before, when a definition mentions a variable, Lean will add it as an argument of the definition, but now in theorem bodies, variables are not included based on usage in order to ensure that changes to the proof cannot change the statement of the overall theorem. Instead, variables are only available to the proof if they have been mentioned in the theorem header or in an include command or are instance implicit and depend only on such variables. The omit command can be used to omit included variables.

  See breaking changes below.

  PRs: #4883, 1242ff, #5000, #5036, #5138, 0edf1b.

• Recursive definitions

  • Structural recursion can now be explicitly requested using

    termination_by structural x
    

    in analogy to the existing termination_by x syntax that causes well-founded recursion to be used.
    #4542

  • #4672 fixes a bug that could lead to ill-typed terms.

  • The termination_by? syntax no longer forces the use of well-founded recursion, and when structural
    recursion is inferred, it will print the result using the termination_by structural syntax.

  • Mutual structural recursion is now supported. This feature supports both mutual recursion over a non-mutual
    data type, as well as recursion over mutual or nested data types:

    mutual
    def Even : Nat → Prop
      | 0 => True
      | n+1 => Odd n
    
    def Odd : Nat → Prop
      | 0 => False
      | n+1 => Even n
    end
    
    mutual
    inductive A
    | other : B → A
    | empty
    inductive B
    | other : A → B
    | empty
    end
    
    mutual
    def A.size : A → Nat
    | .other b => b.size + 1
    | .empty => 0
    
    def B.size : B → Nat
    | .other a => a.size + 1
    | .empty => 0
    end
    
    inductive Tree where | node : List Tree → Tree
    
    mutual
    def Tree.size : Tree → Nat
    | node ts => Tree.list_size ts
    
    def Tree.list_size : List Tree → Nat
    | [] => 0
    | t::ts => Tree.size t + Tree.list_size ts
    end

    Functional induction principles are generated for these functions as well (A.size.induct, A.size.mutual_induct).

    Nested structural recursion is still not supported.

    PRs: #4639, #4715, #4642, #4656, #4684, #4715, #4728, #4575, #4731, #4658, #4734, #4738, #4718, #4733, #4787, #4788, #4789, #4807, #4772

  • #4809 makes unnecessary termination_by clauses cause warnings, not errors.

  • #4831 improves handling of nested structural recursion through non-recursive types.

  • #4839 improves support for structural recursive over inductive predicates when there are reflexive arguments.

• simp tactic

  • #4784 sets configuration Simp.Config.implicitDefEqProofs to true by default.

• omega tactic

  • #4612 normalizes the order that constraints appear in error messages.
  • #4695 prevents pushing casts into multiplications unless it produces a non-trivial linear combination.
  • #4989 fixes a regression.

• decide tactic

  • #4711 switches from using default transparency to at least default transparency when reducing the Decidable instance.
  • #4674 adds detailed feedback on decide tactic failure. It tells you which Decidable instances it unfolded, if it get stuck on Eq.rec it gives a hint about avoiding tactics when defining Decidable instances, and if it gets stuck on Classical.choice it gives hints about classical instances being in scope. During this process, it processes Decidable.recs and matches to pin blame on a non-reducing instance.

• @[ext] attribute

  • #4543 and #4762 make @[ext] realize ext_iff theorems from user ext theorems. Fixes the attribute so that @[local ext] and @[scoped ext] are usable. The @[ext (iff := false)] option can be used to turn off ext_iff realization.
  • #4694 makes "go to definition" work for the generated lemmas. Also adjusts the core library to make use of ext_iff generation.
  • #4710 makes ext_iff theorem preserve inst implicit binder types, rather than making all binder types implicit.

• #eval command

  • #4810 introduces a safer #eval command that prevents evaluation of terms that contain sorry. The motivation is that failing tactics, in conjunction with operations such as array accesses, can lead to the Lean process crashing. Users can use the new #eval! command to use the previous unsafe behavior. (#4829 adjusts a test.)

• #4447 adds #discr_tree_key and #discr_tree_simp_key commands, for helping debug discrimination tree failures. The #discr_tree_key t command prints the discrimination tree keys for a term t (or, if it is a single identifier, the type of that constant). It uses the default configuration for generating keys. The #discr_tree_simp_key command is similar to #discr_tree_key, but treats the underlying type as one of a simp lemma, that is it transforms it into an equality and produces the key of the left-hand side.

  For example,

  #discr_tree_key (∀ {a n : Nat}, bar a (OfNat.ofNat n))
  -- bar _ (@OfNat.ofNat Nat _ _)
  
  #discr_tree_simp_key Nat.add_assoc
  -- @HAdd.hAdd Nat Nat Nat _ (@HAdd.hAdd Nat Nat Nat _ _ _) _
  

• #4741 changes option parsing to allow user-defined options from the command line. Initial options are now re-parsed and validated after importing. Command line option assignments prefixed with weak. are silently discarded if the option name without the prefix does not exist.

• Deriving handlers

  • 7253ef and a04f3c improve the construction of the BEq deriving handler.
  • 86af04 makes BEq deriving handler work when there are dependently typed fields.
  • #4826 refactors the DecidableEq deriving handle to use termination_by structural.

• Metaprogramming

  • #4593 adds unresolveNameGlobalAvoidingLocals.
  • #4618 deletes deprecated functions from 2022.
  • #4642 adds Meta.lambdaBoundedTelescope.
  • #4731 adds Meta.withErasedFVars, to enter a context with some fvars erased from the local context.
  • #4777 adds assignment validation at closeMainGoal, preventing users from circumventing the occurs check for tactics such as exact.
  • #4807 introduces Lean.Meta.PProdN module for packing and projecting nested PProds.
  • #5170 fixes Syntax.unsetTrailing. A consequence of this is that "go to definition" now works on the last module name in an import block (issue #4958).

Language server, widgets, and IDE extensions

• #4727 makes it so that responses to info view requests come as soon as the relevant tactic has finished execution.
• #4580 makes it so that whitespace changes do not invalidate imports, and so starting to type the first declaration after imports should no longer cause them to reload.
• [#4780](https://github.com/leanprover/lean4/pull...

v4.11.0-rc3

This is v4.11.0-rc2, plus cherry-picked commits from #5000, #5036, #5138, and #5170.

v4.11.0-rc2

chore: adapt stdlib to new `variable` behavior

v4.11.0-rc1

What's Changed

• feat: upstream List.attach and Array.attach from Batteries by @llllvvuu in #4586
• fix: typo hearbeats -> heartbeats by @kmill in #4590
• feat: total ByteArray.toList/findIdx? by @Vtec234 in #4582
• chore: release triggers update of release.lean-lang.org by @nomeata in #4531
• chore: begin development cycle for v4.11.0 by @semorrison in #4594
• chore: pr-release: adjust to new lakefile.lean syntax by @nomeata in #4598
• fix: adapt kernel interruption to new cancellation system by @Kha in #4584
• feat: omega error message: normalize constraint order by @nomeata in #4612
• fix: diagnostics: show kernel diags even if it is the only section by @nomeata in #4611
• feat: termination_by structural by @nomeata in #4542
• feat: mul recurrence theorems for LeanSAT by @bollu in #4568
• fix: unresolve name avoiding locals by @digama0 in #4593
• feat: Nat.and_le_(left|right) by @TwoFX in #4597
• feat: additional lemmas for Option by @TwoFX in #4599
• feat: additional lemmas for lists by @TwoFX in #4602
• feat: getElem_congr by @TwoFX in #4603
• feat: additional lemmas for cond by @TwoFX in #4604
• feat: additional lemmas for bounded integers by @TwoFX in #4605
• chore: defs that should be theorems by @semorrison in #4619
• chore: delete deprecations from 2022 by @semorrison in #4618
• chore: satisfy duplicate namespace linter by @semorrison in #4616
• chore: follow simpNF linter's advice by @semorrison in #4620
• chore: add 'since' dates to deprecated by @semorrison in #4617
• chore: make constructor-as-variable test more robust by @TwoFX in #4625
• fix: enforce isDefEqStuckEx at unstuckMVar procedure by @leodemoura in #4596
• fix: Windows build by @Kha in #4628
• chore: pr-release: use right tag name by @nomeata in #4632
• fix: set default value of pp.instantiateMVars to true and make the option be effective by @kmill in #4558
• feat: USize.and_toNat by @TwoFX in #4629
• feat: Option.or by @TwoFX in #4600
• chore: typo by @alok in #4635
• feat: safe exponentiation by @leodemoura in #4637
• fix: make sure syntax nodes always run their formatters by @kmill in #4631
• chore: manual nightly trigger by @Kha in #4638
• chore: CI: restart-on-label: view run more often by @nomeata in #4640
• refactor: include declNames in Structural.EqnInfo by @nomeata in #4639
• fix: snapshot subtree was not restored on reuse by @Kha in #4643
• refactor: lambdaBoundedTelescope by @nomeata in #4642
• fix: improve synthAppInstances by @leodemoura in #4646
• feat: EquivBEq and LawfulHashable classes by @TwoFX in #4607
• feat: additional lemmas for arrays by @TwoFX in #4627
• fix: universe level in .below and .brecOn construction by @nomeata in #4651
• refactor: Split Constructions module by @nomeata in #4656
• feat: Std.HashMap by @TwoFX in #4583
• chore: restart-on-label: wait for 30s by @nomeata in #4663
• fix: don't set pp.tagAppFns when pretty printing signatures by @kmill in #4665
• fix: move Std from libleanshared to much smaller libInit_shared by @Kha in #4661
• fix: explicitly initialize Std in lean_initialize by @Kha in #4668
• chore: make Antisymm a Prop by @semorrison in #4666
• fix: hasBadParamDep? to look at term, not type by @nomeata in #4672
• chore: bump actions/checkout and actions/upload-artifacts by @nomeata in #4664
• chore: cleanup unused arguments (from linter) by @semorrison in #4621
• fix: unorphan modules in Init by @TwoFX in #4680
• fix: unorphan modules in Std.Data by @TwoFX in #4679
• chore: update codeowners by @TwoFX in #4681
• chore: Inhabited instances for Std.HashMap by @TwoFX in #4682
• chore: fix "max dynamic symbols" metric by @Kha in #4669
• fix: calculate error suppression per snapshot by @Kha in #4657
• chore: update comments in kernel/declaration.h by @nomeata in #4683
• feat: structural mutual recursion by @nomeata in #4575
• feat: Process.tryWait by @hargoniX in #4660
• chore: adjust List.replicate simp lemmas by @semorrison in #4687
• chore: upstream ToExpr FilePath and compile_time_search_path% by @semorrison in #4453
• chore: forward and backward directions of not_exists by @semorrison in #4688
• chore: upstream SMap.foldM by @semorrison in #4690
• chore: improve compatibility of tests/list_simp with Mathlib by @semorrison in #4691
• chore: add step to release checklist by @semorrison in #4693
• refactor: InductiveVal.numNested instead of .isNested by @nomeata in #4684
• feat: make @[ext] derive ext_iff theorems from user ext theorems by @kmill in #4543
• chore: upstream eq_iff_true_of_subsingleton by @semorrison in #4689
• chore: make use of ext_iff realization now that stage0 is updated by @kmill in #4694
• feat: lake: require @ git by @tydeu in #4692
• feat: omega doesn't push coercion over multiplication unnecessarily by @semorrison in #4695
• feat: chore upstream List.Sublist and API from Batteries by @semorrison in #4697
• fix: prefer original module in const2ModIdx by @digama0 in #4652
• feat: characterisations of List.Sublist by @semorrison in #4704
• feat: basic material on List.Pairwise and Nodup by @semorrison in #4706
• doc: update release checklist for new release notes workflow by @kmill in #4458
• feat: lemmas for List.head and List.getLast by @semorrison in #4678
• feat: simp normal form tests for Pairwise and Nodup by @semorrison in #4707
• chore: reorganise lemmas on list getters by @semorrison in #4708
• fix: Repr instances for Int and Float by @leodemoura in #4709
• fix: decide tactic transparency by @leodemoura in #4711
• fix: make iff theorem generated by @[ext] preserve inst implicits by @kmill in #4710
• fix: deprecated warnings for overloaded symbols by @leodemoura in #4713
• fix: mutual structural recursion: check that datatype parameters agree by @nomeata in #4715
• feat: upstream more erase API by @semorrison in #4720
• chore: fix typo in doc-string by @grunweg in #4719
• feat: further theorems for List.erase by @semorrison in #4723
• fix: make matcher pretty printer sensitive to pp.explicit by @kmill in #4724
• fix: nested structural recursion over reflexive data type by @nomeata in #4728
• feat: detailed feedback on decide tactic failure by @kmill in #4674
• feat: Meta.withErasedFVars by @no...

v4.10.0

Language features, tactics, and metaprograms

• split tactic:

  • #4401 improves the strategy split uses to generalize discriminants of matches and adds trace.split.failure trace class for diagnosing issues.

• rw tactic:

  • #4385 prevents the tactic from claiming pre-existing goals are new subgoals.
  • dac1da adds configuration for ordering new goals, like for apply.

• simp tactic:

  • #4430 adds dsimprocs for if expressions (ite and dite).
  • #4434 improves heuristics for unfolding. Equational lemmas now have priorities where more-specific equationals lemmas are tried first before a possible catch-all.
  • #4481 fixes an issue where function-valued OfNat numeric literals would become denormalized.
  • #4467 fixes an issue where dsimp theorems might not apply to literals.
  • #4484 fixes the source position for the warning for deprecated simp arguments.
  • #4258 adds docstrings for dsimp configuration.
  • #4567 improves the accuracy of used simp lemmas reported by simp?.
  • fb9727 adds (but does not implement) the simp configuration option implicitDefEqProofs, which will enable including rfl-theorems in proof terms.

• omega tactic:

  • #4360 makes the tactic generate error messages lazily, improving its performance when used in tactic combinators.

• bv_omega tactic:

  • #4579 works around changes to the definition of Fin.sub in this release.

• #4490 sets up groundwork for a tactic index in generated documentation, as there was in Lean 3. See PR description for details.

• Commands

  • #4370 makes the variable command fully elaborate binders during validation, fixing an issue where some errors would be reported only at the next declaration.
  • #4408 fixes a discrepency in universe parameter order between theorem and def declarations.
  • #4493 and #4482 fix a discrepancy in the elaborators for theorem, def, and example,
    making Prop-valued examples and other definition commands elaborate like theorems.
  • 8f023b, 3c4d6b and 0783d0 change the #reduce command to be able to control what gets reduced.
    For example, #reduce (proofs := true) (types := false) e reduces both proofs and types in the expression e.
    By default, neither proofs or types are reduced.
  • #4489 fixes an elaboration bug in #check_tactic.
  • #4505 adds support for open _root_.<namespace>.

• Options

  • #4576 adds the debug.byAsSorry option. Setting set_option debug.byAsSorry true causes all by ... terms to elaborate as sorry.
  • 7b56eb and d8e719 add the debug.skipKernelTC option. Setting set_option debug.skipKernelTC true turns off kernel typechecking. This is meant for temporarily working around kernel performance issues, and it compromises soundness since buggy tactics may produce invalid proofs, which will not be caught if this option is set to true.

• #4301 adds a linter to flag situations where a local variable's name is one of
  the argumentless constructors of its type. This can arise when a user either
  doesn't open a namespace or doesn't add a dot or leading qualifier, as
  in the following:

  inductive Tree (α : Type) where
    | leaf
    | branch (left : Tree α) (val : α) (right : Tree α)
  
  def depth : Tree α → Nat
    | leaf => 0

  With this linter, the leaf pattern is highlighted as a local
  variable whose name overlaps with the constructor Tree.leaf.

  The linter can be disabled with set_option linter.constructorNameAsVariable false.

  Additionally, the error message that occurs when a name in a pattern that takes arguments isn't valid now suggests similar names that would be valid. This means that the following definition:

  def length (list : List α) : Nat :=
    match list with
    | nil => 0
    | cons x xs => length xs + 1

  now results in the following warning:

  warning: Local variable 'nil' resembles constructor 'List.nil' - write '.nil' (with a dot) or 'List.nil' to use the constructor.
  note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
  

  and error:

  invalid pattern, constructor or constant marked with '[match_pattern]' expected
  
  Suggestion: 'List.cons' is similar
  

• Metaprogramming

  • #4454 adds public Name.isInternalDetail function for filtering declarations using naming conventions for internal names.

• Other fixes or improvements

  • #4416 sorts the ouput of #print axioms for determinism.
  • #4528 fixes error message range for the cdot focusing tactic.

Language server, widgets, and IDE extensions

• #4443 makes the watchdog be more resilient against badly behaving clients.

Pretty printing

• #4433 restores fallback pretty printers when context is not available, and documents addMessageContext.
• #4556 introduces pp.maxSteps option and sets the default value of pp.deepTerms to false. Together, these keep excessively large or deep terms from overwhelming the Infoview.

Library

• #4560 splits GetElem class into GetElem and GetElem?.
  This enables removing Decidable instance arguments from GetElem.getElem? and GetElem.getElem!, improving their rewritability.
  See the docstrings for these classes for more information.
• Array
  • #4389 makes Array.toArrayAux_eq be a simp lemma.
  • #4399 improves robustness of the proof for Array.reverse_data.
• List
  • #4469 and #4475 improve the organization of the List API.
  • #4470 improves the List.set and List.concat API.
  • #4472 upstreams lemmas about List.filter from Batteries.
  • #4473 adjusts @[simp] attributes.
  • #4488 makes List.getElem?_eq_getElem be a simp lemma.
  • #4487 adds missing List.replicate API.
  • #4521 adds lemmas about List.map.
  • #4500 changes List.length_cons to use as.length + 1 instead of as.length.succ.
  • #4524 fixes the statement of List.filter_congr.
  • #4525 changes binder explicitness in List.bind_map.
  • #4550 adds maximum?_eq_some_iff' and minimum?_eq_some_iff?.
• #4400 switches the normal forms for indexing List and Array to xs[n] and xs[n]?.
• HashMap
  • #4372 fixes linearity in HashMap.insert and HashMap.erase, leading to a 40% speedup in a replace-heavy workload.
• Option
  • #4403 generalizes type of Option.forM from Unit to PUnit.
  • #4504 remove simp attribute from Option.elim and instead adds it to individal reduction lemmas, making unfolding less aggressive.
• Nat
  • #4242 adds missing theorems for n + 1 and n - 1 normal forms.
  • #4486 makes Nat.min_assoc be a simp lemma.
  • #4522 moves @[simp] from Nat.pred_le to Nat.sub_one_le.
  • #4532 changes various Nat.succ n to n + 1.
• Int
  • #3850 adds complete div/mod simprocs for Int.
    *...

v4.10.0-rc2

fix: calculate error suppression per snapshot (#4657)

Generalizes #3556 to not suppressing errors in tactic steps either when
the parse error is in a later step, as otherwise changes to the end of a
proof would affect (correctness or effectiveness of) incrementality of
preceding steps.

Fixes #4623, in combination with #4643

v4.9.1

Bugfixes for incremental compilation. Otherwise identical to v4.9.0.

v4.10.0-rc1

update RELEASES.md and CMakeLists.txt for release branch