This PR verifies the `String.dropWhile` and `String.takeWhile`
functions.
It also includes a refactor of the `PatternModel` class so that the
`not_matches_empty` condition is moved into a separate typeclass
`StrictPatternModel`. This allows string patterns to implement
`LawfulForwardPatternModel` unconditionally, which means that more of
the general theory about patterns directly applies to string patterns
without having to do a case distinction for empty strings.
This PR also includes a study of the `PatternModel` machinery given to
slices `s` and `t` such that `s.copy = t.copy`. From these results, we
deduce statements like `s.copy.startsWith pat = s.startsWith pat` (which
is far from obvious!).
This PR changes the counter-example accumulator in the match compiler
from
a `List` (built with cons, producing reverse order) to an `Array` (built
with push, preserving declaration order). Missing cases are now reported
in
the order constructors appear in the inductive type definition.
For example, given `inductive Enum | a | b | c | d`, missing cases `c`
and
`d` were previously shown as `d, c` and are now shown as `c, d`.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
privateConstantMap capacity was inflated by IR extraConstNames that are
only inserted into const2ModIdx. const2ModIdx capacity included
numPublicConsts even though public constants are never inserted into it.
This PR adds a `match.maxCounterExamples` option (default 5) to bound
the
number of "missing cases" counter-examples the match compiler generates.
When the match compiler runs out of alternatives for a variable, it
case-splits to explore missing cases. Previously, this would recursively
split all inductive-typed fields of each constructor, leading to
O(K^fields)
counter-examples for types with K constructors per field. For nested
incomplete matches on types like `Op w` (20 constructors with `Operand
w`
fields having 8 constructors each), this produced thousands of
counter-examples and took several seconds.
The fix checks the counter-example count in `isConstructorTransition`:
once
the limit is reached and there are no remaining alternatives, the match
compiler stops exploring further case splits. The error message notes
when
output has been truncated and names the option. The existing protection
against infinite recursion on recursive types is preserved.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR adds a `Core.checkInterrupted` call in `checkInferTypeCache` on
cache miss, allowing cancellation to be detected during large type
inference traversals. Previously, `inferTypeImp` could run for >100ms
without any interruption check when processing large expressions (e.g.
BVDecide proof terms), making IDE cancellation unresponsive.
The check is only on cache miss (actual computation), so cache hits have
zero overhead. `checkInterrupted` is used instead of the heavier
`checkSystem` to minimize performance impact — local benchmarks show no
measurable regression on `tests/elab/5664.lean`.
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR changes elaboration of structure instance notation when used in
patterns (e.g. `s matches { x := 1, y := [] }`) so that the structure's
default values are not used to elaborate the pattern. The motivation is
that default values frequently lead to surprisingly over-specific
patterns. It will now report "field missing" errors. The error can be
suppressed using `{ x := 1, .. }` ellipsis notation, which has the same
behavior as before. The pretty printer is also modified to stay in sync
with this feature. **Breaking change:** patterns using structure
instance notation may need missing fields or a `..` added, as
appropriate.
The rationale for the previous behavior is that with `..` you could
opt-in to not using default values, and now with this PR's behavior you
cannot opt-in. However, default values in structure instance patterns
are very likely to silently cause bugs. There are a couple examples in
this PR of unintentional default values in patterns in core Lean
(luckily these were not triggering bugs). With the new behavior, you can
now tell for sure whether every explicit field in a structure is being
matched explicitly or not, by the absence or presence of `..`.
Closes#10753
This PR adds support for marking options as deprecated. When a
deprecated option is used via `set_option`, a warning is emitted
(controlled by `linter.deprecated.options`).
An `OptionDeprecation` structure with a required `since` field and an
optional `text?` field is added to `OptionDecl`. Each `set_option`
elaborator (command, term, tactic, grind) calls `checkDeprecatedOption`
to emit warnings. The C++ `register_option` is updated to account for
the new field.
As a first use, `backward.eqns.nonrecursive` and
`backward.eqns.deepRecursiveSplit` are marked deprecated. Continues
earlier work done in #11096.
This PR adds test infrastructure and tests for tactic completion in
empty `by` blocks.
**Test runner improvements (`src/Lean/Server/Test/Runner.lean`):**
- Add `--⬑` marker variant that targets the column of `--` itself,
enabling column 0 tests (which `--^` cannot reach since `^` is always at
column 2+).
**New test file (`tests/server_interactive/completionEmptyBy.lean`):**
- Tests tactic completion in empty `by` blocks for both top-level `by`
and nested `by` (inside `id <| have := by`).
- Tests at various column positions on the line below `by`: indented
past `by`, at column 2, and at column 0.
- Tests on the `by` token itself (no completions expected).
- All positions below `by` currently offer tactic completions.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR adds support for let configuration options (`(eq := h)`,
`+nondep`, `+usedOnly`, `+zeta`) in `do` block `let` and `have`
declarations, matching the behavior available in term-level
`let`/`have`. Configuration options are rejected with `let mut` since
they are incompatible with mutable bindings. `+postponeValue` and
`+generalize` are also rejected in `do` blocks.
Follow-up to #13250 which added the parser support. Now that stage0 is
updated, this PR replaces the backward-compat index helpers with proper
quotation patterns and implements the actual `letConfig` elaboration.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR extends the `doLet`, `doLetElse`, `doLetArrow`, and `doHave`
parsers to accept `letConfig` (e.g. `(eq := h)`, `+nondep`, `+usedOnly`,
`+zeta`), matching the syntax of term-level `let`/`have`. The
elaborators are adjusted to handle the shifted syntax indices but do not
yet process the configuration; that will be done in a follow-up PR after
stage0 is updated, allowing the use of proper quotation patterns.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR removes a FIXME in Sym-based mvcgen' concerning a hardcoded step
limit for grind simplification. I tested that this is no longer
necessary even at highest setting for the GetThrowSetGrind benchmark.
This PR extends Lean syntax for dotted function notation (`.f`) to add
support for explicit mode (`@.f`), explicit universes (`.f.{u,v}`), and
both simultaneously (`@.f.{u,v}`). This also includes a fix for a bug
involving overloaded functions, where it used to give erroneous
deprecation warnings about declarations that the function did not
elaborate to.
Closes#10984
This PR improves pretty printing of level metavariables: they now print
with a per-definition index rather than their per-module internal
identifiers. Furthermore, `+` is printed uniformly in level expressions
with surrounding spaces. **Breaking metaprogramming change:** level
pretty printing should use `delabLevel` or `MessageData.ofLevel`;
functions such as `format` or `toString` do not have access to the
indices, since they are stored in the current metacontext. Absent index
information, metavariables print with the raw internal identifier as
`?_mvar.nnn`. **Note:** The heartbeat counter also increases quicker due
to counting allocations that record level metavariable indices. In some
tests we needed to increase `maxHeartbeats` by 20–50% to compensate,
without a corresponding slowdown.
This PR fixes a panic when compiling mutually recursive definitions that
use `casesOn` on indexed inductive types (e.g. `Vect`). The
`splitMatchOrCasesOn` function in `WF.Unfold` asserted
`matcherInfo.numDiscrs = 1`, but for indexed types the casesOn recursor
has multiple discriminants (indices + major premise). The fix uses the
last discriminant (the major premise) and lets the `cases` tactic handle
index discriminants automatically.
Closes#13015
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR adds a `deprecated_module` command that marks the current module
as deprecated. When another module imports a deprecated module, a
warning is emitted during elaboration suggesting replacement imports.
Example usage:
```lean
deprecated_module "use NewModule instead" (since := "2026-03-30")
```
The warning message is optional but recommended. The `since` parameter
is required. Warnings can be disabled, by setting
`linter.deprecated.module` option to false in the command line. Because
the check happens when importing , using `set_option
linter.deprecated.module` in the source file won't affect the warnings.
Instead, a whole file can be marked not to display depreciation
warnings, by putting a comment `deprecated_module: ignore` next to
`module` keyword. Similarly, individual keywords can be silenced.
A `#show_deprecated_modules` command is also provided for inspecting
which modules in the current environment are deprecated.
`linter.deprecated.module` has no effect on this command, and hence one
can view deprecated modules, even when having warnings silenced.
This PR fixes `FirstTokens.seq (.optTokens s) .unknown` to return
`.unknown`. This occurs e.g. when an optional (with first tokens
`.optTokens s`) is followed by a parser category (with first tokens
`.unknown`). Previously `FirstTokens.seq` returned `.optTokens s`,
ignoring the fact that the optional may be empty and then the parser
category may have any first token. The correct behavior here is to
return `.unknown`, which indicates that the first token may be anything.
Closes#13203
This PR adds `checkSystem` calls to several code paths that can run for
extended periods without checking for cancellation, heartbeat limits, or
stack overflow. This improves responsiveness of the cancellation
mechanism
in the language server.
Affected paths:
- `simpLoop` step loop (`Simp/Main.lean`)
- `simp` rewrite candidate loops (`Rewrite.lean`)
- `simpAppUsingCongr` argument traversal (`Types.lean`)
- `synthesizeSyntheticMVarsStep` mvar loop (`SyntheticMVars.lean`)
- `abstractNestedProofs` visitor (`AbstractNestedProofs.lean`)
- `transform`/`transformWithCache` visitors (`Transform.lean`)
- LCNF compiler pass runner loop (`LCNF/Main.lean`)
- LCNF checker recursive traversal (`LCNF/Check.lean`)
- `whnfImp` top-level reduction (`WHNF.lean`)
Intentionally *not* instrumented (too hot, measurable regression):
- `whnfCore.go` inner recursion
- `simpImpl` entry point (redundant with `simpLoop`)
- LCNF `simp` inner recursion (0.4% regression on `big_do`)
Also adds a docstring to `checkInterrupted` clarifying its relationship
to
`checkSystem`.
Found using `LEAN_CHECK_SYSTEM_INTERVAL_MS` monitoring from #13218.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR adds a `deprecated_syntax` command that marks syntax kinds as
deprecated. When deprecated syntax is elaborated (in terms, tactics, or
commands), a linter warning is emitted. The warning is also emitted
during quotation precheck when a macro definition uses deprecated syntax
in its expansion.
The `deprecated_syntax` command takes a syntax node kind, an optional
message, and a `(since := "...")` clause. Deprecation warnings correctly
attribute the warning to macro call sites when the deprecated syntax is
produced by macro expansion, including through nested macro chains.
---------
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
This PR adds an `unlock_limits` command that sets `maxHeartbeats`,
`maxRecDepth`, and `synthInstance.maxHeartbeats` to 0, disabling all
core resource limits. Also makes `maxRecDepth 0` mean "no limit"
(matching the existing behavior of `maxHeartbeats 0`).
This PR updates `release_checklist.py` to handle the `CACHE STRING ""`
suffix on CMake version variables. The `CACHE STRING` format was
introduced in the `releases/v4.30.0` branch, but the script's parsing
wasn't updated to match, causing false failures.
🤖 Prepared with Claude Code
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR adds two safety notes to the Claude Code release command:
- Mathlib bump branches live on `mathlib4-nightly-testing`, not the main
`mathlib4` repo
- Never force-update remote refs without explicit user confirmation
🤖 Prepared with Claude Code
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This PR moves `hasAssignableMVar`, `hasAssignableLevelMVar`, and
`isLevelMVarAssignable` from `MetavarContext.lean` to a new
`Lean.Meta.HasAssignableMVar` module, changing them from generic `[Monad
m] [MonadMCtx m]` functions to `MetaM` functions. This enables adding
`checkSystem` calls in the recursive traversal, which ensures
cancellation and heartbeat checks happen during what can be a very
expensive computation.
All callers of these functions were already in `MetaM`, so this change
is safe. The motivating case is the `4595_slowdown.lean` test, where
`hasAssignableMVar` (with `PersistentHashMap.find?` lookups on
`mctx.lDepth`) was the dominant CPU cost during elaboration of category
theory definitions. Without `checkSystem` calls, cancellation requests
could be delayed by over 2 seconds.
The test file `4595_slowdown.lean` gets a slightly increased
`maxHeartbeats` limit because `checkSystem` now detects heartbeat
exhaustion mid-traversal rather than after the function returns.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This commit ensures binaries are only stripped in the `release` build
preset, not in any of the other presets.
Since `release` is used for development, the commit adds a non-stripping
copy called `dev` that can be used via `cmake --preset dev`.
This PR fixes the Windows dev build by using
`CMAKE_RELATIVE_LIBRARY_OUTPUT_DIRECTORY` instead of the hardcoded
`lib/lean` path for the Lake plugin. On Windows, DLLs must be placed
next to executables in `bin/`, but the plugin path was hardcoded to
`lib/lean`, causing stage0 DLLs to not be found.
The `CMAKE_RELATIVE_LIBRARY_OUTPUT_DIRECTORY` variable was introduced
precisely for this purpose — it resolves to `bin` on Windows and
`lib/lean` elsewhere.
Closes#13126🤖 Prepared with Claude Code
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
This PR replaces eager let-expression zeta-reduction in the sym-based
mvcgen with on-demand unfolding that mirrors the production mvcgen's
behavior.
Previously, all let-expressions in the program head were immediately
zeta-reduced. Now, let-expressions are hoisted to the top of the goal
target, and the value is only inlined if it is duplicable (literals,
fvars, consts, `OfNat.ofNat`). Complex values are introduced into the
local context via `introsSimp`, preserving SymM's maximal sharing
invariants, and unfolded on demand when the fvar later appears as the
program head.
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR fixes several issues in `Init.Data.String`, most of them typos.
We also move the remaining material out of `Init.Data.String.Lemmas` to
`Init.Data.String.Lemmas.StringOrder`, which shortens the pole.
This PR extends the `missingDocs` linter to detect and warn about empty
doc strings (e.g. `/---/` or `/-- -/`), in addition to missing doc
strings. Previously, an empty doc comment would silence the linter even
though it provides no documentation value. Now empty doc strings produce
a distinct "empty doc string for ..." warning, while `@[inherit_doc]`
still suppresses warnings as before.
This PR switches the mvcgen worklist from BFS (queue) to DFS (stack)
ordering for subgoal processing.
With the new do elaborator, `if`-without-`else` generates asymmetric
bind depth between branches (`pure () >>= cont` is optimized to just
`cont` in the else branch). This caused BFS-based VC numbering to depend
on elaborator internals, swapping vc10/vc11 in test cases. DFS ordering
follows the syntactic program structure more naturally and is robust to
such bind-depth asymmetries.
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR fixes the handling of anonymous dependent `if` (`if _ : cond
then ... else ...`) inside `do` blocks when using the new do elaborator.
The `_%$tk` binder pattern was incorrectly quoted as `$(⟨tk⟩):hole` in
the generated `dite` syntax, causing "elaboration function for
`termDepIfThenElse` has not been implemented" errors. The fix quotes it
correctly as `_%$tk`.
A test case is added to verify both anonymous (`if _ : ...`) and named
(`if h : ...`) dependent `if` work in do blocks.
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
The stage0 tree hash used by Lake to invalidate stage 1 oleans was
computed via `git ls-tree HEAD`, which fails in jj workspaces (no .git
directory). Fall back to discovering the backing git repo via `jj git
root` and resolving the current workspace's commit via `jj log -r @`
(since git's HEAD points to the root jj workspace, not the current one).
This PR adds a `@[deprecated_arg]` attribute that marks individual
function parameters as deprecated. When a caller uses the old parameter
name, the elaborator emits a deprecation warning with a code action hint
to rename or delete the argument, and silently forwards the value to the
correct binder.
Supported forms:
- `@[deprecated_arg old new (since := "...")]` — renamed parameter,
warns and forwards
- `@[deprecated_arg old new "reason" (since := "...")]` — with custom
message
- `@[deprecated_arg removed (since := "...")]` — removed parameter,
errors with delete hint
- `@[deprecated_arg removed "reason" (since := "...")]` — removed with
custom message
A warning is emitted if `(since := "...")` is omitted.
When a parameter is deprecated without a replacement, the elaborator
treats it as no longer present: using it as a named argument produces an
error. Note that positional uses of deprecated arguments are not checked
— if a function's arity changed, the caller will simply get a "function
expected" error.
The `linter.deprecated.arg` option (default `true`) controls behavior:
when enabled, renamed args produce warnings and removed args produce
specific deprecation errors with code action hints; when disabled, both
fall through to the standard "invalid argument name" error. This lets
library authors phase out old parameter names without breaking
downstream code immediately.
Example (renamed parameter):
```lean
@[deprecated_arg old new (since := "2026-03-18")]
def f (new : Nat) : Nat := new
/--
warning: parameter `old` of `f` has been deprecated, use `new` instead
Hint: Rename this argument:
o̵l̵d̵n̲e̲w̲
---
info: f 42 : Nat
-/
#guard_msgs in
#check f (old := 42)
```
Example (removed parameter):
```lean
@[deprecated_arg removed (since := "2026-03-18")]
def g (x : Nat) : Nat := x
/--
error: parameter `removed` of `g` has been deprecated
Hint: Delete this argument:
(̵r̵e̵m̵o̵v̵e̵d̵ ̵:̵=̵ ̵4̵2̵)̵
-/
#guard_msgs in
#check g (removed := 42)
```
This PR adds `simplifying_assumptions [Nat.add_assoc]` to the
`vcgen_get_throw_set_grind` benchmark, recovering hypothesis
simplification lost in a54eafb ("refactor: decouple solve from grind").
That refactor introduced `PreTac.processHypotheses` which wraps
`simpNewHyps`, but the call sites in `work` and `main` call
`Grind.processHypotheses` directly, leaving `simpNewHyps` as dead code.
Without it, long `s + 1 + … + 1` chains are never collapsed, causing an
asymptotic slowdown visible by a factor of 2 at n=150 (largest radar
input size).
Benchmark results (VCGen time in ms):
| n | Before | After | Speedup |
|---|--------|-------|---------|
| 50 | 222 | 186 | 1.2× |
| 100 | 391 | 251 | 1.6× |
| 150 | 647 | 329 | 2.0× |
| 200 | 995 | 415 | 2.4× |
| 300 | 1894 | 589 | 3.2× |
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---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR adds `@[expose]` to `Lean.Grind.abstractFn` and
`Lean.Grind.simpMatchDiscrsOnly` so that the kernel can unfold them when
type-checking `grind`-produced proofs inside `module` blocks. Other
similar gadgets (`nestedDecidable`, `PreMatchCond`, `alreadyNorm`) were
already exposed; these two were simply missed.
Closes https://github.com/leanprover/lean4/issues/13167
