chore: adaptations for nightly-2025-06-20 (#26209)

* Trigger CI for leanprover-community/batteries#1220

* Merge master into nightly-testing

* chore: bump to nightly-2025-06-05

* Kick CI

* Bump lean4-cli

* Bump import-graph

* Kick CI

* update lakefile

* chore: use more robust syntax quotation in Shake

* Trigger CI for leanprover/lean4#8419

* Revert "chore: use more robust syntax quotation in Shake"

This reverts commit cd87328.

* fix(Shake): fix import syntax

@Kha this is deliberately using this approach because syntax quotations
are also not robust but for a different reason: they fail to parse the
new versions of the syntax (and do so at run time). And using all the
optional doohickeys will not be future proof. The current setup is
explicitly meant to ping me when there is a syntax change so I can
evaluate the right way to handle it. In this case we want all the
module options to be ignored (treated the same as a regular import
for the purpose of dependency tracking), we don't want to fail.

* cleanup lakefile

* chore: bump to nightly-2025-06-06

* Update lean-toolchain for testing leanprover/lean4#8653

* fix

* how did this get dropped?!?!

* chore: bump to nightly-2025-06-07

* chore: bump to nightly-2025-06-08

* chore: bump to nightly-2025-06-09

* fix lakefile

* fix lint-style for new Lean.Options API

* chore: bump to nightly-2025-06-10

* chore: bump to nightly-2025-06-09

* merge lean-pr-testing-4

* chore: bump to nightly-2025-06-11

* chore: adaptations for nightly-2025-06-11

* Update Shake/Main.lean

Co-authored-by: Johan Commelin <[email protected]>

* Apply suggestions from code review

* revert

* chore: adaptations for nightly-2025-06-11

* cleanup grind tests

* chore: bump to nightly-2025-06-12

* merge lean-pr-testing-8419

* chore: bump to nightly-2025-06-12

* merge lean-pr-testing-8653

* adaptation note

* oops

* chore: adaptations for nightly-2025-06-12

* remove nolint simpNF

* remove spurious file

* Update lean-toolchain for testing leanprover/lean4#8751

* fix

* chore: bump to nightly-2025-06-13

* Merge master into nightly-testing

* fix

* remove upstreamed

* drop no-op `show`

* chore: bump to nightly-2025-06-14

* chore: bump to nightly-2025-06-15

* intentionally left blank

* fix tests

* chore: bump to nightly-2025-06-16

* fix upstream

* fix

* fix

* fixes

* chore: adaptations for nightly-2025-06-16

* chore: bump to nightly-2025-06-17

* fixes

* more fixes

* fixes!

* more fixes!

* hmm

* chore: adaptations for nightly-2025-06-17

* chore: adaptations for nightly-2025-06-17

* chore: lint `show` (adaptation for leanprover/lean4#7395) (#25749)

Adds `show` as an exception to the unused tactic linter and adds a separate linter for `show`s that should be replaced by `change`.
Context: https://leanprover.zulipchat.com/#narrow/channel/287929-mathlib4/topic/unused.20tactic.20linter.20for.20.60show.60/with/523701633

Co-authored-by: Christian Merten <[email protected]>
Co-authored-by: Kenny Lau <[email protected]>
Co-authored-by: Fabrizio Barroero <[email protected]>
Co-authored-by: Rob23oba <[email protected]>
Co-authored-by: leanprover-community-mathlib4-bot <[email protected]>
Co-authored-by: Rob23oba <[email protected]>
Co-authored-by: Kim Morrison <[email protected]>

* chore: bump to nightly-2025-06-18

* chore: adaptations for nightly-2025-06-18

* Merge master into nightly-testing

* chore: bump to nightly-2025-06-19

* fix

* remove mul_hmul

* linter

* chore: bump to nightly-2025-06-20

* chore: adaptations for nightly-2025-06-20

---------

Co-authored-by: leanprover-community-mathlib4-bot <[email protected]>
Co-authored-by: github-actions <[email protected]>
Co-authored-by: Joachim Breitner <[email protected]>
Co-authored-by: Kim Morrison <[email protected]>
Co-authored-by: Sebastian Ullrich <[email protected]>
Co-authored-by: mathlib4-bot <[email protected]>
Co-authored-by: Mario Carneiro <[email protected]>
Co-authored-by: Johan Commelin <[email protected]>
Co-authored-by: sgouezel <[email protected]>
Co-authored-by: Kyle Miller <[email protected]>
Co-authored-by: Rob23oba <[email protected]>
Co-authored-by: Rob23oba <[email protected]>
Co-authored-by: Christian Merten <[email protected]>
Co-authored-by: Kenny Lau <[email protected]>
Co-authored-by: Fabrizio Barroero <[email protected]>
Co-authored-by: Rob23oba <[email protected]>

Author: 15 people

Mathlib/Algebra/CharP/Basic.lean

@@ -207,9 +207,10 @@ end AddMonoidWithOne
 
 section CommRing
 
-instance (α : Type*) [Ring α] (n : ℕ) [CharP α n] : Lean.Grind.IsCharP α n where
-  ofNat_eq_zero_iff m := by
-    rw [Semiring.toGrindSemiring_ofNat]
-    simpa [← Nat.dvd_iff_mod_eq_zero] using CharP.cast_eq_zero_iff α n m
+instance (α : Type*) [Semiring α] [IsLeftCancelAdd α] (n : ℕ) [CharP α n] :
+    Lean.Grind.IsCharP α n where
+  ofNat_ext_iff {a b} := by
+    rw [Lean.Grind.Semiring.ofNat_eq_natCast, Lean.Grind.Semiring.ofNat_eq_natCast]
+    exact CharP.cast_eq_iff_mod_eq α n
 
 end CommRing

Mathlib/Algebra/CharP/Defs.lean

@@ -57,6 +57,25 @@ lemma congr {q : ℕ} (h : p = q) : CharP R q := h ▸ ‹CharP R p›
 
 @[simp] lemma cast_eq_zero : (p : R) = 0 := (cast_eq_zero_iff R p p).2 dvd_rfl
 
+lemma cast_eq_mod (k : ℕ) : (k : R) = (k % p : ℕ) :=
+  have (a : ℕ) : ((p * a : ℕ) : R) = 0 := by
+    rw [CharP.cast_eq_zero_iff R p]
+    exact Nat.dvd_mul_right p a
+  calc
+    (k : R) = ↑(k % p + p * (k / p)) := by rw [Nat.mod_add_div]
+    _ = ↑(k % p) := by simp [cast_eq_zero, this]
+
+lemma cast_eq_iff_mod_eq [IsLeftCancelAdd R] : (a:R) = (b:R) ↔ a % p = b % p := by
+  wlog hle : a ≤ b
+  · simpa only [eq_comm] using (this _ _ (lt_of_not_ge hle).le)
+  obtain ⟨c, rfl⟩ := Nat.le.dest hle
+  rw [Nat.cast_add, left_eq_add, CharP.cast_eq_zero_iff R p]
+  constructor
+  · simp +contextual [Nat.add_mod, Nat.dvd_iff_mod_eq_zero]
+  intro h
+  have := Nat.sub_mod_eq_zero_of_mod_eq h.symm
+  simpa [Nat.dvd_iff_mod_eq_zero] using this
+
 -- TODO: This lemma needs to be `@[simp]` for confluence in the presence of `CharP.cast_eq_zero` and
 -- `Nat.cast_ofNat`, but with `no_index` on its entire LHS, it matches literally every expression so
 -- is too expensive. If https://github.com/leanprover/lean4/issues/2867 is fixed in a performant way, this can be made `@[simp]`.
@@ -178,11 +197,6 @@ section
 
 variable [NonAssocRing R]
 
-lemma cast_eq_mod (p : ℕ) [CharP R p] (k : ℕ) : (k : R) = (k % p : ℕ) :=
-  calc
-    (k : R) = ↑(k % p + p * (k / p)) := by rw [Nat.mod_add_div]
-    _ = ↑(k % p) := by simp [cast_eq_zero]
-
 lemma ringChar_zero_iff_CharZero : ringChar R = 0 ↔ CharZero R := by
   rw [ringChar.eq_iff, charP_zero_iff_charZero]
 

Mathlib/Algebra/Group/Basic.lean

@@ -1079,8 +1079,7 @@ instance AddCommMonoid.toGrindNatModule [s : AddCommMonoid α] :
     one_hmul := one_nsmul
     add_hmul n m a := add_nsmul a n m
     hmul_zero := nsmul_zero
-    hmul_add n a b := nsmul_add a b n
-    mul_hmul n m a := mul_nsmul' a n m }
+    hmul_add n a b := nsmul_add a b n }
 
 instance AddCommGroup.toGrindIntModule [s : AddCommGroup α] :
     Grind.IntModule α :=
@@ -1090,5 +1089,4 @@ instance AddCommGroup.toGrindIntModule [s : AddCommGroup α] :
     one_hmul := one_zsmul
     add_hmul n m a := add_zsmul a n m
     hmul_zero := zsmul_zero
-    hmul_add n a b := zsmul_add a b n
-    mul_hmul n m a := mul_zsmul a n m }
+    hmul_add n a b := zsmul_add a b n }

lean-toolchain

@@ -1 +1 @@
-leanprover/lean4:nightly-2025-06-18
+leanprover/lean4:nightly-2025-06-20