blst: Change from blst from http_archive to go_repository (#15709)

changelog/pvl-blst-go-repo.md

@@ -0,0 +1,3 @@
+### Changed
+
+- Changed blst dependency from `http_archive` to `go_repository` so that gazelle can keep it in sync with go.mod.

deps.bzl

@@ -3312,6 +3312,15 @@ def prysm_deps():
         sum = "h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=",
         version = "v1.10.0",
     )
+    go_repository(
+        name = "com_github_supranational_blst",
+        build_file_generation = "off",
+        importpath = "github.com/supranational/blst",
+        patch_args = ["-p1"],
+        patches = ["//third_party:com_github_supranational_blst.patch"],
+        sum = "h1:xNMoHRJOTwMn63ip6qoWJ2Ymgvj7E2b9jY2FAwY+qRo=",
+        version = "v0.3.14",
+    )
     go_repository(
         name = "com_github_syndtr_goleveldb",
         importpath = "github.com/syndtr/goleveldb",
@@ -4939,13 +4948,3 @@ def prysm_deps():
         sum = "h1:aJMhYGrd5QSmlpLMr2MftRKl7t8J8PTZPA732ud/XR8=",
         version = "v1.27.0",
     )
-
-    http_archive(
-        name = "com_github_supranational_blst",
-        urls = [
-            "https://github.com/supranational/blst/archive/8c7db7fe8d2ce6e76dc398ebd4d475c0ec564355.tar.gz",
-        ],
-        strip_prefix = "blst-8c7db7fe8d2ce6e76dc398ebd4d475c0ec564355",
-        build_file = "//third_party:blst/blst.BUILD",
-        sha256 = "e9041d03594271c9739d22d9f013ea8b5c28403285a2e8938f6e41a2437c6ff8",
-    )

third_party/blst/README.md

@@ -0,0 +1,25 @@
+# blst BUILD file
+
+Due to the project structure of [blst](https://github.com/supranational/blst) having go bindings 
+and cdeps in different directories, [gazelle](https://github.com/bazel-contrib/bazel-gazelle) 
+is unable to appropriately generate the BUILD.bazel files for this repository. We have hand written
+the BUILD.bazel file here by the name `blst.BUILD`. PR [#6539](https://github.com/OffchainLabs/prysm/pull/6539)
+added build support for blst, but relied on an [http_archive](https://bazel.build/rules/lib/repo/http#http_archive)
+repository rule to provide blst as a dependency. This pattern worked, but gazelle would not keep the 
+dependency in sync with go.mod. There was a risk that go and bazel builds would include different versions
+of blst. 
+
+Now, we can switch to a [go_repository](https://github.com/bazel-contrib/bazel-gazelle/blob/master/reference.md#go_repository)
+model which gazelle understand how to sync with go.mod. However, we still have to tell gazelle how generate a BUILD.bazel file.
+Our solution is to tell gazelle not to generate any build file, then we provide blst.BUILD as a patch. 
+
+Generating the patch is relatively straight forward:
+
+```
+mkdir /tmp/a
+mkdir /tmp/b
+cp ./third_party/blst/blst.BUILD /tmp/b/BUILD.bazel
+(cd /tmp && diff -urN a b) > ./third_party/com_github_supranational_blst.patch
+```
+
+If future edits are needed, edit the ./third_party/blst/blst.BUILD and regenerate the patch.

third_party/com_github_supranational_blst.patch

@@ -0,0 +1,132 @@
+diff --color -urN a/BUILD.bazel b/BUILD.bazel
+--- a/BUILD.bazel	1969-12-31 18:00:00.000000000 -0600
++++ b/BUILD.bazel	2025-09-17 10:29:51.159884226 -0500
+@@ -0,0 +1,128 @@
++load("@prysm//tools/go:def.bzl", "go_library")
++load("@io_bazel_rules_go//go:def.bzl", "go_test")
++
++config_setting(
++    name = "blst_modern",
++    constraint_values = [
++        "@platforms//os:linux",
++        "@platforms//cpu:x86_64",
++    ],
++    values = {
++        "define": "blst_modern=true",
++    },
++)
++
++go_library(
++    name = "go_default_library",
++    srcs = [
++        "bindings/go/blst.go",
++        "bindings/go/cgo_server.c",
++    ],
++    cgo = True,
++    copts = [
++        "-D__BLST_CGO__",
++        "-Ibindings",
++        "-Isrc",
++        "-O2",
++    ] + select({
++        "@io_bazel_rules_go//go/platform:amd64": [
++            "-mno-avx",
++            "-D__ADX__",
++        ],
++        "//conditions:default": [],
++    }) + select({
++        "//conditions:default": [
++            "-D__BLST_PORTABLE__",
++        ],
++        ":blst_modern": [],
++    }),
++    cdeps = [":blst"],
++    importpath = "github.com/supranational/blst/bindings/go",
++    visibility = ["//visibility:public"],
++)
++
++go_test(
++    name = "go_default_test",
++    srcs = [
++        "bindings/go/blst_htoc_test.go",
++        "bindings/go/blst_minpk_test.go",
++        "bindings/go/blst_minsig_test.go",
++    ],
++    embed = [":go_default_library"],
++    data = glob([
++        "bindings/go/hash_to_curve/*.json",
++    ]),
++)
++
++cc_library(
++    name = "blst",
++    srcs = [
++        "bindings/blst.h",
++        "bindings/blst_aux.h",
++    ],
++    hdrs = [
++        "bindings/blst.h",
++        "bindings/blst_aux.h",
++    ],
++    deps = [
++        ":src",
++        ":asm",
++    ],
++    strip_include_prefix = "bindings",
++    visibility = ["//visibility:public"],
++)
++
++cc_library(
++    name = "asm_hdrs",
++    hdrs = glob([
++        "build/**/*.s",
++        "build/**/*.S",
++    ], exclude = ["build/assembly.s"]),
++)
++
++cc_library(
++    name = "asm",
++    srcs = [
++        "build/assembly.S",
++    ],
++    copts = [
++            "-O2",
++    ] + select({
++        "@io_bazel_rules_go//go/platform:amd64": [
++            "-mno-avx",
++            "-D__ADX__",
++        ],
++        "//conditions:default": [],
++    }) + select({
++        "//conditions:default": [
++            "-D__BLST_PORTABLE__",
++        ],
++        ":blst_modern": [],
++    }),
++    deps = [":asm_hdrs"],
++    linkstatic = True,
++)
++
++cc_library(
++    name = "hdrs",
++    hdrs = glob(
++        [
++            "src/*.c",
++            "src/*.h",
++        ],
++        exclude = [
++            "src/client_*.c",
++        ],
++    ),
++    strip_include_prefix = "src",
++)
++
++cc_library(
++    name = "src",
++    srcs = [
++        "src/server.c",
++    ],
++    deps = [
++        ":hdrs",
++    ],
++)