build: enable custom toolchain use in crlib

We set up a patch to enable the crdb-specific code in crlib/crsync. We
add a test in syncutil which verifies that the correct path is being
used.

Epic: none
Release note: None

Author: RaduBerinde

DEPS.bzl

@@ -1750,10 +1750,14 @@ def go_deps():
         name = "com_github_cockroachdb_crlib",
         build_file_proto_mode = "disable_global",
         importpath = "github.com/cockroachdb/crlib",
-        sha256 = "4e2aad9df48f99411a51186fdf92041c881adc642c87106776734e8a64578077",
-        strip_prefix = "github.com/cockroachdb/crlib@v0.0.0-20250916151006-1094cb39adac",
+        patch_args = ["-p1"],
+        patches = [
+            "@com_github_cockroachdb_cockroach//build/patches:com_github_cockroachdb_crlib.patch",
+        ],
+        sha256 = "539dd737ca1da53ee5c296ea0f3aad92f6d59f577e0d169dffb5a4ad706e1728",
+        strip_prefix = "github.com/cockroachdb/crlib@v0.0.0-20251001180057-2a49e1873587",
         urls = [
-            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20250916151006-1094cb39adac.zip",
+            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20251001180057-2a49e1873587.zip",
         ],
     )
     go_repository(

build/bazelutil/distdir_files.bzl

@@ -346,7 +346,7 @@ DISTDIR_FILES = {
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/cmux/com_github_cockroachdb_cmux-v0.0.0-20250514152509-914d3bf9ec58.zip": "c1cf4cd99a1ad6a00f2ccd4188cbcf004cb0d56895670b2c171061ce564cd791",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/cockroach-go/v2/com_github_cockroachdb_cockroach_go_v2-v2.4.1.zip": "ba646db91152f3121a6812c7b74d12d8c0e126f7b4d3b927618b159692ceb424",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlfmt/com_github_cockroachdb_crlfmt-v0.0.0-20221214225007-b2fc5c302548.zip": "fedc01bdd6d964da0425d5eaac8efadc951e78e13f102292cc0774197f09ab63",
-    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20250916151006-1094cb39adac.zip": "4e2aad9df48f99411a51186fdf92041c881adc642c87106776734e8a64578077",
+    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20251001180057-2a49e1873587.zip": "539dd737ca1da53ee5c296ea0f3aad92f6d59f577e0d169dffb5a4ad706e1728",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/datadriven/com_github_cockroachdb_datadriven-v1.0.3-0.20250911232732-d959cf14706c.zip": "417027b5ff27774000129768f79e9ae62021b95d3ac9d3181e132dbe46b44da3",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/drpc/com_github_cockroachdb_drpc-v0.0.0-20250924114114-78d4e121902a.zip": "98b44a51f82873f93f77da80230212ab40f35044e8d38645cb1392ae03462f0b",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/errors/com_github_cockroachdb_errors-v1.12.0.zip": "f73d8a5f4d8fcbc4ed61db2b47f17e2601d8b32e9a49c0665667489d9d9d6e7c",

build/patches/com_github_cockroachdb_crlib.patch

@@ -0,0 +1,28 @@
+diff --git a/crsync/BUILD.bazel b/crsync/BUILD.bazel
+index e787597..0c25863 100644
+--- a/crsync/BUILD.bazel
++++ b/crsync/BUILD.bazel
+@@ -4,13 +4,22 @@ go_library(
+     name = "crsync",
+     srcs = [
+         "counters.go",
+-        "sharding_vanilla.go",
++        ":gen-sharding_crdb",
+         "typed_atomic.go",
+     ],
+     importpath = "github.com/cockroachdb/crlib/crsync",
+     visibility = ["//visibility:public"],
+ )
+ 
++REMOVE_GO_BUILD_CONSTRAINTS = "cat $< | grep -v '//go:build' | grep -v '// +build' > $@"
++
++genrule(
++    name = "gen-sharding_crdb",
++    srcs = ["sharding_crdb.go"],
++    outs = ["gen-sharding_crdb.go"],
++    cmd = REMOVE_GO_BUILD_CONSTRAINTS,
++)
++
+ alias(
+     name = "go_default_library",
+     actual = ":crsync",

build/scripts/patch-apply.sh

@@ -49,6 +49,9 @@ echo ""
 
 if patch -p1 < "$PATCH_FILE"; then
   echo "Patch applied successfully."
+  echo ""
+  echo "If you get an error applying the patch when building: comment out the patch in DEPS.bzl,"
+  echo "build cockroach, then inspect the relevant files in _bazel/cockroach/external/<repo>".
 else
   echo "Failed to apply patch."
   echo "Make sure the repository is at the proper commit."

go.mod

@@ -136,7 +136,7 @@ require (
 	github.com/cockroachdb/cmux v0.0.0-20250514152509-914d3bf9ec58
 	github.com/cockroachdb/cockroach-go/v2 v2.4.1
 	github.com/cockroachdb/crlfmt v0.0.0-20221214225007-b2fc5c302548
-	github.com/cockroachdb/crlib v0.0.0-20250916151006-1094cb39adac
+	github.com/cockroachdb/crlib v0.0.0-20251001180057-2a49e1873587
 	github.com/cockroachdb/datadriven v1.0.3-0.20250911232732-d959cf14706c
 	github.com/cockroachdb/errors v1.12.0
 	github.com/cockroachdb/go-test-teamcity v0.0.0-20191211140407-cff980ad0a55

go.sum

@@ -555,8 +555,8 @@ github.com/cockroachdb/cockroach-go/v2 v2.4.1 h1:ACVT/zXsuK6waRPVYtDQpsM8pPA7IA/
 github.com/cockroachdb/cockroach-go/v2 v2.4.1/go.mod h1:9U179XbCx4qFWtNhc7BiWLPfuyMVQ7qdAhfrwLz1vH0=
 github.com/cockroachdb/crlfmt v0.0.0-20221214225007-b2fc5c302548 h1:i0bnjanlWAvM50wHMT7EFyxlt5HQusznWrkwl+HBIsU=
 github.com/cockroachdb/crlfmt v0.0.0-20221214225007-b2fc5c302548/go.mod h1:qtkxNlt5i3rrdirfJE/bQeW/IeLajKexErv7jEIV+Uc=
-github.com/cockroachdb/crlib v0.0.0-20250916151006-1094cb39adac h1:L+7nhSrQ9WzW91AJHP0LmjwMHEed2nl5b7PvN9eIw58=
-github.com/cockroachdb/crlib v0.0.0-20250916151006-1094cb39adac/go.mod h1:Gq51ZeKaFCXk6QwuGM0w1dnaOqc/F5zKT2zA9D6Xeac=
+github.com/cockroachdb/crlib v0.0.0-20251001180057-2a49e1873587 h1:qjG2TrBrPbGRVYp5obcAi8OSsuFJ8s1AElDImHLV9tY=
+github.com/cockroachdb/crlib v0.0.0-20251001180057-2a49e1873587/go.mod h1:ae57yNis2F1FThSNdPdoXfiPOVi8G1TLreCBQYPOdqo=
 github.com/cockroachdb/datadriven v0.0.0-20190809214429-80d97fb3cbaa/go.mod h1:zn76sxSg3SzpJ0PPJaLDCu+Bu0Lg3sKTORVIj19EIF8=
 github.com/cockroachdb/datadriven v1.0.2/go.mod h1:a9RdTaap04u637JoCzcUoIcDmvwSUtcUFtT/C3kJlTU=
 github.com/cockroachdb/datadriven v1.0.3-0.20250911232732-d959cf14706c h1:a0m7gmtv2mzJQ4wP9BkxCmJAnjZ7fsvCi2IORGD1als=

pkg/util/syncutil/BUILD.bazel

@@ -23,6 +23,7 @@ go_test(
     size = "small",
     srcs = [
         "atomic_test.go",
+        "crsync_test.go",
         "map_bench_test.go",
         "map_reference_test.go",
         "map_test.go",
@@ -31,5 +32,8 @@ go_test(
         "set_test.go",
     ],
     embed = [":syncutil"],
-    deps = ["@com_github_stretchr_testify//require"],
+    deps = [
+        "@com_github_cockroachdb_crlib//crsync",
+        "@com_github_stretchr_testify//require",
+    ],
 )

pkg/util/syncutil/crsync_test.go

@@ -0,0 +1,23 @@
+// Copyright 2026 The Cockroach Authors.
+//
+// Use of this software is governed by the CockroachDB Software License
+// included in the /LICENSE file.
+
+// This file verifies that crlib is set up to use the CRDB Go toolchain when
+// built with bazel.
+//
+//go:build bazel
+
+package syncutil
+
+import (
+	"testing"
+
+	"github.com/cockroachdb/crlib/crsync"
+)
+
+func TestCRSync(t *testing.T) {
+	if !crsync.UsingCockroachGo {
+		t.Fatalf("expected crsync.UsingCockroachGo to be true")
+	}
+}