mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -54,7 +54,7 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         generalize p % 4 = m; decide!
       let ⟨k, hk⟩ := ZMod.exists_sq_eq_neg_one_iff.2 <| by rw [hp41] <;> exact by decide
       obtain ⟨k, k_lt_p, rfl⟩ : ∃ (k' : ℕ) (h : k' < p), (k' : ZMod p) = k := by
-        refine' ⟨k.val, k.val_lt, ZMod.nat_cast_zmod_val k⟩
+        refine' ⟨k.val, k.val_lt, ZMod.natCast_zmod_val k⟩
       have hpk : p ∣ k ^ 2 + 1 := by
         rw [pow_two, ← CharP.cast_eq_zero_iff (ZMod p) p, Nat.cast_add, Nat.cast_mul, Nat.cast_one,
           ← hk, add_left_neg]
@@ -102,7 +102,7 @@ theorem prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : Fact p.Prime] (h
     by_contradiction fun hpi =>
       let ⟨a, b, hab⟩ := sq_add_sq_of_nat_prime_of_not_irreducible p hpi
       have : ∀ a b : ZMod 4, a ^ 2 + b ^ 2 ≠ p := by
-        erw [← ZMod.nat_cast_mod p 4, hp3] <;> exact by decide
+        erw [← ZMod.natCast_mod p 4, hp3] <;> exact by decide
       this a b (hab ▸ by simp)
 #align gaussian_int.prime_of_nat_prime_of_mod_four_eq_three GaussianInt.prime_of_nat_prime_of_mod_four_eq_three
 -/

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -64,7 +64,7 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         calc
           1 + k * k ≤ k + k * k :=
             add_le_add_right
-              (Nat.pos_of_ne_zero fun hk0 => by clear_aux_decl <;> simp_all [pow_succ']) _
+              (Nat.pos_of_ne_zero fun hk0 => by clear_aux_decl <;> simp_all [pow_succ]) _
           _ = k * (k + 1) := by simp [add_comm, mul_add]
           _ < p * p := mul_lt_mul k_lt_p k_lt_p (Nat.succ_pos _) (Nat.zero_le _)
       have hpk₁ : ¬(p : ℤ[i]) ∣ ⟨k, -1⟩ := fun ⟨x, hx⟩ =>

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -41,14 +41,14 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         (mt irreducible_iff_prime.2 fun ⟨hu, h⟩ =>
           by
           have := h ⟨1, 1⟩ ⟨1, -1⟩ (hp2.symm ▸ rfl)
-          rw [← norm_eq_one_iff, ← norm_eq_one_iff] at this 
+          rw [← norm_eq_one_iff, ← norm_eq_one_iff] at this
           exact absurd this (by decide)))
     fun hp1 =>
     by_contradiction fun hp3 : p % 4 ≠ 3 =>
       by
       have hp41 : p % 4 = 1 :=
         by
-        rw [← Nat.mod_mul_left_mod p 2 2, show 2 * 2 = 4 from rfl] at hp1 
+        rw [← Nat.mod_mul_left_mod p 2 2, show 2 * 2 = 4 from rfl] at hp1
         have := Nat.mod_lt p (show 0 < 4 by decide)
         revert this hp3 hp1
         generalize p % 4 = m; decide!

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

@@ -58,7 +58,7 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
       have hpk : p ∣ k ^ 2 + 1 := by
         rw [pow_two, ← CharP.cast_eq_zero_iff (ZMod p) p, Nat.cast_add, Nat.cast_mul, Nat.cast_one,
           ← hk, add_left_neg]
-      have hkmul : (k ^ 2 + 1 : ℤ[i]) = ⟨k, 1⟩ * ⟨k, -1⟩ := by simp [sq, Zsqrtd.ext]
+      have hkmul : (k ^ 2 + 1 : ℤ[i]) = ⟨k, 1⟩ * ⟨k, -1⟩ := by simp [sq, Zsqrtd.ext_iff]
       have hpne1 : p ≠ 1 := ne_of_gt hp.1.one_lt
       have hkltp : 1 + k * k < p * p :=
         calc

mathlib commit https://github.com/leanprover-community/mathlib/commit/ce64cd319bb6b3e82f31c2d38e79080d377be451

@@ -3,8 +3,8 @@ Copyright (c) 2019 Chris Hughes. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Chris Hughes
 -/
-import Mathbin.NumberTheory.Zsqrtd.GaussianInt
-import Mathbin.NumberTheory.LegendreSymbol.QuadraticReciprocity
+import NumberTheory.Zsqrtd.GaussianInt
+import NumberTheory.LegendreSymbol.QuadraticReciprocity
 
 #align_import number_theory.zsqrtd.quadratic_reciprocity from "leanprover-community/mathlib"@"08b63ab58a6ec1157ebeafcbbe6c7a3fb3c9f6d5"
 

mathlib commit https://github.com/leanprover-community/mathlib/commit/8ea5598db6caeddde6cb734aa179cc2408dbd345

@@ -2,15 +2,12 @@
 Copyright (c) 2019 Chris Hughes. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Chris Hughes
-
-! This file was ported from Lean 3 source module number_theory.zsqrtd.quadratic_reciprocity
-! leanprover-community/mathlib commit 08b63ab58a6ec1157ebeafcbbe6c7a3fb3c9f6d5
-! Please do not edit these lines, except to modify the commit id
-! if you have ported upstream changes.
 -/
 import Mathbin.NumberTheory.Zsqrtd.GaussianInt
 import Mathbin.NumberTheory.LegendreSymbol.QuadraticReciprocity
 
+#align_import number_theory.zsqrtd.quadratic_reciprocity from "leanprover-community/mathlib"@"08b63ab58a6ec1157ebeafcbbe6c7a3fb3c9f6d5"
+
 /-!
 # Facts about the gaussian integers relying on quadratic reciprocity.
 

mathlib commit https://github.com/leanprover-community/mathlib/commit/9240e8be927a0955b9a82c6c85ef499ee3a626b8

@@ -4,7 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Chris Hughes
 
 ! This file was ported from Lean 3 source module number_theory.zsqrtd.quadratic_reciprocity
-! leanprover-community/mathlib commit 5b2fe80501ff327b9109fb09b7cc8c325cd0d7d9
+! leanprover-community/mathlib commit 08b63ab58a6ec1157ebeafcbbe6c7a3fb3c9f6d5
 ! Please do not edit these lines, except to modify the commit id
 ! if you have ported upstream changes.
 -/
@@ -14,6 +14,9 @@ import Mathbin.NumberTheory.LegendreSymbol.QuadraticReciprocity
 /-!
 # Facts about the gaussian integers relying on quadratic reciprocity.
 
+> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
+> Any changes to this file require a corresponding PR to mathlib4.
+
 ## Main statements
 
 `prime_iff_mod_four_eq_three_of_nat_prime`

mathlib commit https://github.com/leanprover-community/mathlib/commit/fdc286cc6967a012f41b87f76dcd2797b53152af

@@ -32,6 +32,7 @@ namespace GaussianInt
 
 open PrincipalIdealRing
 
+#print GaussianInt.mod_four_eq_three_of_nat_prime_of_prime /-
 theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
     (hpi : Prime (p : ℤ[i])) : p % 4 = 3 :=
   hp.1.eq_two_or_odd.elim
@@ -92,7 +93,9 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
       clear_aux_decl
       tauto
 #align gaussian_int.mod_four_eq_three_of_nat_prime_of_prime GaussianInt.mod_four_eq_three_of_nat_prime_of_prime
+-/
 
+#print GaussianInt.prime_of_nat_prime_of_mod_four_eq_three /-
 theorem prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : Fact p.Prime] (hp3 : p % 4 = 3) :
     Prime (p : ℤ[i]) :=
   irreducible_iff_prime.1 <|
@@ -102,12 +105,15 @@ theorem prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : Fact p.Prime] (h
         erw [← ZMod.nat_cast_mod p 4, hp3] <;> exact by decide
       this a b (hab ▸ by simp)
 #align gaussian_int.prime_of_nat_prime_of_mod_four_eq_three GaussianInt.prime_of_nat_prime_of_mod_four_eq_three
+-/
 
+#print GaussianInt.prime_iff_mod_four_eq_three_of_nat_prime /-
 /-- A prime natural number is prime in `ℤ[i]` if and only if it is `3` mod `4` -/
 theorem prime_iff_mod_four_eq_three_of_nat_prime (p : ℕ) [hp : Fact p.Prime] :
     Prime (p : ℤ[i]) ↔ p % 4 = 3 :=
   ⟨mod_four_eq_three_of_nat_prime_of_prime p, prime_of_nat_prime_of_mod_four_eq_three p⟩
 #align gaussian_int.prime_iff_mod_four_eq_three_of_nat_prime GaussianInt.prime_iff_mod_four_eq_three_of_nat_prime
+-/
 
 end GaussianInt
 

mathlib commit https://github.com/leanprover-community/mathlib/commit/893964fc28cefbcffc7cb784ed00a2895b4e65cf

Now that I am defining NNRat.cast, I want a definitive answer to this naming issue. Plenty of lemmas in mathlib already use natCast/intCast/ratCast over nat_cast/int_cast/rat_cast, and this matches with the general expectation that underscore-separated name parts correspond to a single declaration.

@@ -49,7 +49,7 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         intros; interval_cases m <;> simp_all -- Porting note (#11043): was `decide!`
       let ⟨k, hk⟩ := (ZMod.exists_sq_eq_neg_one_iff (p := p)).2 <| by rw [hp41]; decide
       obtain ⟨k, k_lt_p, rfl⟩ : ∃ (k' : ℕ) (_ : k' < p), (k' : ZMod p) = k := by
-        exact ⟨k.val, k.val_lt, ZMod.nat_cast_zmod_val k⟩
+        exact ⟨k.val, k.val_lt, ZMod.natCast_zmod_val k⟩
       have hpk : p ∣ k ^ 2 + 1 := by
         rw [pow_two, ← CharP.cast_eq_zero_iff (ZMod p) p, Nat.cast_add, Nat.cast_mul, Nat.cast_one,
           ← hk, add_left_neg]
@@ -89,7 +89,7 @@ theorem prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : Fact p.Prime] (h
     by_contradiction fun hpi =>
       let ⟨a, b, hab⟩ := sq_add_sq_of_nat_prime_of_not_irreducible p hpi
       have : ∀ a b : ZMod 4, a ^ 2 + b ^ 2 ≠ ↑p := by
-        erw [← ZMod.nat_cast_mod p 4, hp3]; decide
+        erw [← ZMod.natCast_mod p 4, hp3]; decide
       this a b (hab ▸ by simp)
 #align gaussian_int.prime_of_nat_prime_of_mod_four_eq_three GaussianInt.prime_of_nat_prime_of_mod_four_eq_three
 

Co-authored-by: Mario Carneiro <di.gama@gmail.com>

@@ -89,7 +89,7 @@ theorem prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : Fact p.Prime] (h
     by_contradiction fun hpi =>
       let ⟨a, b, hab⟩ := sq_add_sq_of_nat_prime_of_not_irreducible p hpi
       have : ∀ a b : ZMod 4, a ^ 2 + b ^ 2 ≠ ↑p := by
-        erw [← ZMod.nat_cast_mod p 4, hp3]; exact by decide
+        erw [← ZMod.nat_cast_mod p 4, hp3]; decide
       this a b (hab ▸ by simp)
 #align gaussian_int.prime_of_nat_prime_of_mod_four_eq_three GaussianInt.prime_of_nat_prime_of_mod_four_eq_three
 

Classifies by adding issue number #11043 to porting notes claiming:

was decide!

@@ -46,7 +46,7 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         have := Nat.mod_lt p (show 0 < 4 by decide)
         revert this hp3 hp1
         generalize p % 4 = m
-        intros; interval_cases m <;> simp_all -- Porting note: was `decide!`
+        intros; interval_cases m <;> simp_all -- Porting note (#11043): was `decide!`
       let ⟨k, hk⟩ := (ZMod.exists_sq_eq_neg_one_iff (p := p)).2 <| by rw [hp41]; decide
       obtain ⟨k, k_lt_p, rfl⟩ : ∃ (k' : ℕ) (_ : k' < p), (k' : ZMod p) = k := by
         exact ⟨k.val, k.val_lt, ZMod.nat_cast_zmod_val k⟩

I replaced a few "terminal" refine/refine's with exact.

The strategy was very simple-minded: essentially any refine whose following line had smaller indentation got replaced by exact and then I cleaned up the mess.

This PR certainly leaves some further terminal refines, but maybe the current change is beneficial.

@@ -49,7 +49,7 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         intros; interval_cases m <;> simp_all -- Porting note: was `decide!`
       let ⟨k, hk⟩ := (ZMod.exists_sq_eq_neg_one_iff (p := p)).2 <| by rw [hp41]; decide
       obtain ⟨k, k_lt_p, rfl⟩ : ∃ (k' : ℕ) (_ : k' < p), (k' : ZMod p) = k := by
-        refine' ⟨k.val, k.val_lt, ZMod.nat_cast_zmod_val k⟩
+        exact ⟨k.val, k.val_lt, ZMod.nat_cast_zmod_val k⟩
       have hpk : p ∣ k ^ 2 + 1 := by
         rw [pow_two, ← CharP.cast_eq_zero_iff (ZMod p) p, Nat.cast_add, Nat.cast_mul, Nat.cast_one,
           ← hk, add_left_neg]

This uses the improved shake script from #9772 to reduce imports across mathlib. The corresponding noshake.json file has been added to #9772.

Co-authored-by: Mario Carneiro <di.gama@gmail.com>

@@ -4,7 +4,8 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Chris Hughes
 -/
 import Mathlib.NumberTheory.Zsqrtd.GaussianInt
-import Mathlib.NumberTheory.LegendreSymbol.QuadraticReciprocity
+import Mathlib.NumberTheory.LegendreSymbol.Basic
+import Mathlib.Analysis.Normed.Field.Basic
 
 #align_import number_theory.zsqrtd.quadratic_reciprocity from "leanprover-community/mathlib"@"5b2fe80501ff327b9109fb09b7cc8c325cd0d7d9"
 

Added @[ext] to definition structure Zsqrtd (d : ℤ). (also added lemma sub_re, sub_im)

@@ -46,13 +46,13 @@ theorem mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : Fact p.Prime]
         revert this hp3 hp1
         generalize p % 4 = m
         intros; interval_cases m <;> simp_all -- Porting note: was `decide!`
-      let ⟨k, hk⟩ := (ZMod.exists_sq_eq_neg_one_iff (p := p)).2 <| by rw [hp41]; exact by decide
+      let ⟨k, hk⟩ := (ZMod.exists_sq_eq_neg_one_iff (p := p)).2 <| by rw [hp41]; decide
       obtain ⟨k, k_lt_p, rfl⟩ : ∃ (k' : ℕ) (_ : k' < p), (k' : ZMod p) = k := by
         refine' ⟨k.val, k.val_lt, ZMod.nat_cast_zmod_val k⟩
       have hpk : p ∣ k ^ 2 + 1 := by
         rw [pow_two, ← CharP.cast_eq_zero_iff (ZMod p) p, Nat.cast_add, Nat.cast_mul, Nat.cast_one,
           ← hk, add_left_neg]
-      have hkmul : (k ^ 2 + 1 : ℤ[i]) = ⟨k, 1⟩ * ⟨k, -1⟩ := by simp [sq, Zsqrtd.ext]
+      have hkmul : (k ^ 2 + 1 : ℤ[i]) = ⟨k, 1⟩ * ⟨k, -1⟩ := by ext <;> simp [sq]
       have hkltp : 1 + k * k < p * p :=
         calc
           1 + k * k ≤ k + k * k := by

PR contents

This is the supremum of

• #8284
• #8056
• #8023
• #8332
• #8226 (already approved)
• #7834 (already approved)

along with some minor fixes from failures on nightly-testing as Mathlib master is merged into it.

Note that some PRs for changes that are already compatible with the current toolchain and will be necessary have already been split out: #8380.

I am hopeful that in future we will be able to progressively merge adaptation PRs into a bump/v4.X.0 branch, so we never end up with a "big merge" like this. However one of these adaptation PRs (#8056) predates my new scheme for combined CI, and it wasn't possible to keep that PR viable in the meantime.

Lean PRs involved in this bump

In particular this includes adjustments for the Lean PRs

• leanprover/lean4#2778
• leanprover/lean4#2790
• leanprover/lean4#2783
• leanprover/lean4#2825
• leanprover/lean4#2722

leanprover/lean4#2778

We can get rid of all the

local macro_rules | `($x ^ $y) => `(HPow.hPow $x $y) -- Porting note: See issue [lean4#2220](https://github.com/leanprover/lean4/pull/2220)

macros across Mathlib (and in any projects that want to write natural number powers of reals).

leanprover/lean4#2722

Changes the default behaviour of simp to (config := {decide := false}). This makes simp (and consequentially norm_num) less powerful, but also more consistent, and less likely to blow up in long failures. This requires a variety of changes: changing some previously by simp or norm_num to decide or rfl, or adding (config := {decide := true}).

leanprover/lean4#2783

This changed the behaviour of simp so that simp [f] will only unfold "fully applied" occurrences of f. The old behaviour can be recovered with simp (config := { unfoldPartialApp := true }). We may in future add a syntax for this, e.g. simp [!f]; please provide feedback! In the meantime, we have made the following changes:

• switching to using explicit lemmas that have the intended level of application
• (config := { unfoldPartialApp := true }) in some places, to recover the old behaviour
• Using @[eqns] to manually adjust the equation lemmas for a particular definition, recovering the old behaviour just for that definition. See #8371, where we do this for Function.comp and Function.flip.

This change in Lean may require further changes down the line (e.g. adding the !f syntax, and/or upstreaming the special treatment for Function.comp and Function.flip, and/or removing this special treatment). Please keep an open and skeptical mind about these changes!

Co-authored-by: leanprover-community-mathlib4-bot <leanprover-community-mathlib4-bot@users.noreply.github.com> Co-authored-by: Scott Morrison <scott.morrison@gmail.com> Co-authored-by: Eric Wieser <wieser.eric@gmail.com> Co-authored-by: Mauricio Collares <mauricio@collares.org>

@@ -23,8 +23,6 @@ open Zsqrtd Complex
 
 open scoped ComplexConjugate
 
-local macro_rules | `($x ^ $y) => `(HPow.hPow $x $y) -- Porting note: See issue lean4#2220
-
 local notation "ℤ[i]" => GaussianInt
 
 namespace GaussianInt
@@ -89,7 +87,7 @@ theorem prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : Fact p.Prime] (h
   irreducible_iff_prime.1 <|
     by_contradiction fun hpi =>
       let ⟨a, b, hab⟩ := sq_add_sq_of_nat_prime_of_not_irreducible p hpi
-      have : ∀ a b : ZMod 4, a ^ 2 + b ^ 2 ≠ p := by
+      have : ∀ a b : ZMod 4, a ^ 2 + b ^ 2 ≠ ↑p := by
         erw [← ZMod.nat_cast_mod p 4, hp3]; exact by decide
       this a b (hab ▸ by simp)
 #align gaussian_int.prime_of_nat_prime_of_mod_four_eq_three GaussianInt.prime_of_nat_prime_of_mod_four_eq_three

@@ -23,7 +23,7 @@ open Zsqrtd Complex
 
 open scoped ComplexConjugate
 
-local macro_rules | `($x ^ $y) => `(HPow.hPow $x $y) -- Porting note: See issue #2220
+local macro_rules | `($x ^ $y) => `(HPow.hPow $x $y) -- Porting note: See issue lean4#2220
 
 local notation "ℤ[i]" => GaussianInt
 

• depends on: #5966

Co-authored-by: Eric Wieser <wieser.eric@gmail.com> Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

@@ -2,15 +2,12 @@
 Copyright (c) 2019 Chris Hughes. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Chris Hughes
-
-! This file was ported from Lean 3 source module number_theory.zsqrtd.quadratic_reciprocity
-! leanprover-community/mathlib commit 5b2fe80501ff327b9109fb09b7cc8c325cd0d7d9
-! Please do not edit these lines, except to modify the commit id
-! if you have ported upstream changes.
 -/
 import Mathlib.NumberTheory.Zsqrtd.GaussianInt
 import Mathlib.NumberTheory.LegendreSymbol.QuadraticReciprocity
 
+#align_import number_theory.zsqrtd.quadratic_reciprocity from "leanprover-community/mathlib"@"5b2fe80501ff327b9109fb09b7cc8c325cd0d7d9"
+
 /-!
 # Facts about the gaussian integers relying on quadratic reciprocity.