From e0a7844e2cd9b1700f362752985a2ba3e15a638b Mon Sep 17 00:00:00 2001
From: Michael Podtserkovskii <michaelpo@meta.com>
Date: Wed, 14 Aug 2024 15:51:31 -0700
Subject: [PATCH] New rule go_bootstrap_binary for making Go tools for buck

Summary:
> Produces a Go binary for use in prelude. Similar to `python_bootstrap_binary`. It doesn't depend on other Go rules and uses `go build` under the hood. CGo is disabled minimise dependencies.

The main purpose is to build tools for Go toolchain, e.q. test-main-gen or embedcfg-gen.

However it can be used for other rules as Go wrappers are faster than Python

It also may be used for building third-party Go binaries

Reviewed By: leoleovich

Differential Revision: D59154803

fbshipit-source-id: c3cf5accfb671bd37db7175c553f4ed4a7dd3c66
---
 prelude/decls/go_rules.bzl         |  9 ++++++
 prelude/go/go_bootstrap_binary.bzl | 45 ++++++++++++++++++++++++++++++
 prelude/go/tools/BUCK.v2           |  5 +++-
 prelude/rules_impl.bzl             |  8 +++++-
 4 files changed, 65 insertions(+), 2 deletions(-)
 create mode 100644 prelude/go/go_bootstrap_binary.bzl

diff --git a/prelude/decls/go_rules.bzl b/prelude/decls/go_rules.bzl
index d7100f5d9923..8f9c1a11caa1 100644
--- a/prelude/decls/go_rules.bzl
+++ b/prelude/decls/go_rules.bzl
@@ -521,9 +521,18 @@ prebuilt_go_library = prelude_rule(
     ),
 )
 
+go_bootstrap_binary = prelude_rule(
+    name = "go_bootstrap_binary",
+    attrs = (
+        go_common.srcs_arg() |
+        {"entrypoints": attrs.list(attrs.string(), default = [], doc = """Package name or file names""")}
+    ),
+)
+
 go_rules = struct(
     cgo_library = cgo_library,
     go_binary = go_binary,
+    go_bootstrap_binary = go_bootstrap_binary,
     go_exported_library = go_exported_library,
     go_library = go_library,
     go_test = go_test,
diff --git a/prelude/go/go_bootstrap_binary.bzl b/prelude/go/go_bootstrap_binary.bzl
new file mode 100644
index 000000000000..64e46cd31cf3
--- /dev/null
+++ b/prelude/go/go_bootstrap_binary.bzl
@@ -0,0 +1,45 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under both the MIT license found in the
+# LICENSE-MIT file in the root directory of this source tree and the Apache
+# License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+# of this source tree.
+
+load(":toolchain.bzl", "GoToolchainInfo", "get_toolchain_env_vars")
+
+def go_bootstrap_binary_impl(ctx: AnalysisContext) -> list[Provider]:
+    """
+    Produces a Go binary for use in prelude. Similar to `python_bootstrap_binary`
+    It doesn't depend on other Go rules and uses `go build` under the hood.
+    CGo is disabled minimise dependencies.
+    """
+    go_toolchain = ctx.attrs._go_toolchain[GoToolchainInfo]
+
+    target_is_win = go_toolchain.env_go_os == "windows"
+    exe_suffix = ".exe" if target_is_win else ""
+    output = ctx.actions.declare_output(ctx.label.name + exe_suffix)
+
+    # Copy files, becode go:embed doesn't work with symlinks
+    srcs_dir = ctx.actions.copied_dir(
+        "__srcs_dir__",
+        {src.short_path: src for src in ctx.attrs.srcs},
+    )
+
+    cmd = cmd_args([
+        go_toolchain.go_wrapper,
+        go_toolchain.go,
+        ["--workdir", srcs_dir],
+        "build",
+        ["-o", cmd_args(output.as_output(), relative_to = srcs_dir)],
+        ctx.attrs.entrypoints,
+    ])
+
+    env = get_toolchain_env_vars(go_toolchain)
+    env["CGO_ENABLED"] = "0"
+
+    ctx.actions.run(cmd, env = env, category = "go_bootstrap_binary")
+
+    return [
+        DefaultInfo(default_output = output),
+        RunInfo(args = [output]),
+    ]
diff --git a/prelude/go/tools/BUCK.v2 b/prelude/go/tools/BUCK.v2
index 4c31770f4811..7c7eeced6e86 100644
--- a/prelude/go/tools/BUCK.v2
+++ b/prelude/go/tools/BUCK.v2
@@ -30,11 +30,14 @@ prelude.python_bootstrap_binary(
     visibility = ["PUBLIC"],
 )
 
-prelude.go_binary(
+prelude.go_bootstrap_binary(
     name = "testmaingen",
     srcs = [
         "testmaingen.go",
     ],
+    entrypoints = [
+        "testmaingen.go",
+    ],
     visibility = [
         "PUBLIC",
     ],
diff --git a/prelude/rules_impl.bzl b/prelude/rules_impl.bzl
index de7173126bd1..7178542ba1c3 100644
--- a/prelude/rules_impl.bzl
+++ b/prelude/rules_impl.bzl
@@ -23,6 +23,7 @@ load("@prelude//git:git_fetch.bzl", "git_fetch_impl")
 load("@prelude//go:cgo_library.bzl", "cgo_library_impl")
 load("@prelude//go:coverage.bzl", "GoCoverageMode")
 load("@prelude//go:go_binary.bzl", "go_binary_impl")
+load("@prelude//go:go_bootstrap_binary.bzl", "go_bootstrap_binary_impl")
 load("@prelude//go:go_exported_library.bzl", "go_exported_library_impl")
 load("@prelude//go:go_library.bzl", "go_library_impl")
 load("@prelude//go:go_stdlib.bzl", "go_stdlib_impl")
@@ -174,6 +175,7 @@ extra_implemented_rules = struct(
     #go
     cgo_library = cgo_library_impl,
     go_binary = go_binary_impl,
+    go_bootstrap_binary = go_bootstrap_binary_impl,
     go_exported_library = go_exported_library_impl,
     go_library = go_library_impl,
     go_test = go_test_impl,
@@ -473,6 +475,10 @@ inlined_extra_attributes = {
         "_race": race_attr,
         "_tags": tags_attr,
     },
+    "go_bootstrap_binary": {
+        "_exec_os_type": buck.exec_os_type_arg(),
+        "_go_toolchain": toolchains_common.go(),
+    },
     "go_exported_library": {
         "embedcfg": attrs.option(attrs.source(allow_directory = False), default = None),
         "_asan": asan_attr,
@@ -513,7 +519,7 @@ inlined_extra_attributes = {
         "_go_toolchain": toolchains_common.go(),
         "_race": race_attr,
         "_tags": tags_attr,
-        "_testmaingen": attrs.default_only(attrs.exec_dep(default = "prelude//go/tools:testmaingen")),
+        "_testmaingen": attrs.default_only(attrs.exec_dep(providers = [RunInfo], default = "prelude//go/tools:testmaingen")),
     },
 
     # groovy