This PR adjusts the results of `inferInstanceAs` and the `def` `deriving` handler to conform to recently strengthened restrictions on reducibility. This change ensures that when deriving or inferring an instance for a semireducible type definition, the definition's RHS is not leaked when the instance is reduced at lower than semireducible transparency.
More specifically, given the "source type" and "target type" (the given and expected type for `inferInstanceAs`, the right-hand side and applied left-hand side of the `def` for `deriving`), we synthesize an instance for the source type and then unfold and rewrap its components (fields, nested instances) as necessary to make them compatible with the target type. The individual steps are represented by the following options, which all default to enabled and can be disabled to help with porting:
- `backward.inferInstanceAs.wrap`: master switch for instance adjustment in both `inferInstanceAs` and the default `deriving` handler
- `backward.inferInstanceAs.wrap.reuseSubInstances`: reuse existing instances for the target type for sub-instance fields to avoid non-defeq instance diamonds
- `backward.inferInstanceAs.wrap.instances`: wrap non-reducible instances in auxiliary definitions
- `backward.inferInstanceAs.wrap.data`: wrap data fields in auxiliary definitions (proof fields are always wrapped)
This PR is an extension and rewrite of prior work in Mathlib: https://github.com/leanprover-community/mathlib4/pull/36420
Last(?) part of fix for #9077🤖 Prepared with Claude Code
# Breaking changes
Proofs that relied on the prior "defeq abuse" of these instance or that depended on their specific structure may need adjustments. As `inferInstanceAs A` now needs to know the source and target types exactly before it can continue, it cannot be used anymore as a synonym for `(inferInstance : A)`, use the latter instead when source and target type are identical.
The tests need to run with certain environment variables set that only
cmake really knows and that differ between stages. Cmake could just set
the variables directly when running the tests and benchmarks, but that
would leave no good way to manually run a single benchmark. So cmake
generates some stage-specific scripts instead that set the required
environment variables.
Previously, those scripts were sourced directly by the individual
`run_*` scripts, so the env scripts of different stages would overwrite
each other. This PR changes the setup so they can instead be generated
next to each other. This also simplifies the `run_*` scripts themselves
a bit, and makes `tests/bench/build` less of a hack.
This PR migrates most remaining tests to the new test suite. It also
completes the migration of directories like `tests/lean/run`, meaning
that PRs trying to add tests to those old directories will now fail.
This adds the ancillary materials for the IJCAR 2026 grind paper to
`doc/examples/IJCAR2026/`.
- `examples.lean`: interactive examples from the paper
- `analyze_grind_loc.py`: script used for the evaluation section
(analyzing grind adoption LoC changes in mathlib)
🤖 Prepared with Claude Code
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This PR eliminates uses of `intros x y z` (with arguments) and updates
the `intros` docstring to suggest that `intro x y z` should be used
instead. The `intros` tactic is historical, and can be traced all the
way back to Lean 2, when `intro` could only introduce a single
hypothesis. Since 2020, the `intro` tactic has superceded it. The
`intros` tactic (without arguments) is currently still useful.
This PR removes the old documentation overview site, as its content has
moved to the main Lean website infrastructure.
This should be merged when the new website section is deployed, after
installing appropriate redirects.
Developer documentation is remaining in Markdown form, but it will no
longer be part of the documentation hosted on the Lean website. Example
code stays here for CI, but it is now rendered via a Verso plugin.
This PR replaces `List.lt` with `List.Lex`, from Mathlib, and adds the
new `Bool` valued lexicographic comparatory function `List.lex`. This
subtly changes the definition of `<` on Lists in some situations.
`List.lt` was a weaker relation: in particular if `l₁ < l₂`, then
`a :: l₁ < b :: l₂` may hold according to `List.lt` even if `a` and `b`
are merely incomparable
(either neither `a < b` nor `b < a`), whereas according to `List.Lex`
this would require `a = b`.
When `<` is total, in the sense that `¬ · < ·` is antisymmetric, then
the two relations coincide.
Mathlib was already overriding the order instances for `List α`,
so this change should not be noticed by anyone already using Mathlib.
We simultaneously add the boolean valued `List.lex` function,
parameterised by a `BEq` typeclass
and an arbitrary `lt` function. This will support the flexibility
previously provided for `List.lt`,
via a `==` function which is weaker than strict equality.
Updates the user widget manual to account for more recent changes. One
issue is that the samples no longer work on https://live.lean-lang.org/
because it uses an outdated version of the `@leanprover/infoview` NPM
package. They work on https://lean.math.hhu.de/ and in recent versions
of the VSCode extension.
previously, `#eval` would happily evaluate expressions that contain
`sorry`, either explicitly or because of failing tactics. In conjunction
with operations like array access this can lead to the lean process
crashing, which isn't particularly great.
So how `#eval` will refuse to run code that (transitively) depends on
the `sorry` axiom (using the same code as `#print axioms`).
If the user really wants to run it, they can use `#eval!`.
Closes#1697
This is from a ~~pair~~triple programming session with @tydeu and
@mhuisi.
If stage 1 is built with `-DUSE_LAKE=ON`, the CMake run will generate
`lakefile.toml` files for the root, `src`, and `tests`. These Lake
configuration files can then be used to build core oleans. While they do
not yet allow Lake to be used to build the Lean binaries. they do allow
Lake to be used for working interactively with the Lean source. In our
preliminary experiments, this allowed updates to `Init.Data.Nat` to be
noticed automatically when reloading downstream files, rather than
requiring a full manual compiler rebuild. This will make it easier to
work on the system.
As part of this change, Lake is added to stage 0. This allows Lake to
function in `src`, which uses the stage 0 toolchain.
---------
Co-authored-by: Mac Malone <tydeu@hatpress.net>
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
Extends Lean's incremental reporting and reuse between commands into
various steps inside declarations:
* headers and bodies of each (mutual) definition/theorem
* `theorem ... := by` for each contained tactic step, including
recursively inside supported combinators currently consisting of
* `·` (cdot), `case`, `next`
* `induction`, `cases`
* macros such as `next` unfolding to the above
*Incremental reuse* means not recomputing any such steps if they are not
affected by a document change. *Incremental reporting* includes the
parts seen in the recording above: the progress bar and messages. Other
language server features such as hover etc. are *not yet* supported
incrementally, i.e. they are shown only when the declaration has been
fully processed as before.
---------
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
Complement to #3967 , adds a `(since := "<date>")` field to
`@[deprecated]` so that metaprogramming code has access to the
deprecation date for e.g. bulk removals. Also adds `@[deprecated
"deprecation message"]` to optionally replace the default text
"`{declName}` has been deprecated, use `{newName}` instead".
This adds a number of lemmas for simplification of `Bool` and `Prop`
terms. It pulls lemmas from Mathlib and adds additional lemmas where
confluence or consistency suggested they are needed.
It has been tested against Mathlib using some automated test
infrastructure.
That testing module is not yet included in this PR, but will be included
as part of this.
Note. There are currently some comments saying the origin of the simp
rule. These will be removed prior to merging, but are added to clarify
where the rule came from during review.
---------
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
This will collect definitions from Std.Logic
---------
Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
This change
* moves `termination_by` and `decreasing_by` next to the function they
apply to
* simplify the syntax of `termination_by`
* apply the `decreasing_by` goal to all goals at once, for better
interactive use.
See the section in `RELEASES.md` for more details and migration advise.
This is a hard breaking change, requiring developers to touch every
`termination_by` in their code base. We decided to still do it as a
hard-breaking change, because supporting both old and new syntax at the
same time would be non-trivial, and not save that much. Moreover, this
requires changes to some metaprograms that developers might have
written, and supporting both syntaxes at the same time would make
_their_ migration harder.
- ignore unused variables in dep arrows
- avoid negated options
- make syntax stack generation more performant
- make ignore functions more extensible
- change message severity to `warning`
