build: introduce custom prelude to improve Cargo compatibility

Signed-off-by: jl.jiang <[email protected]>

Author: jjl9807

.buckconfig

@@ -3,6 +3,7 @@
   prelude = prelude
   toolchains = toolchains
   none = none
+  buckal = buckal
 
 [cell_aliases]
   config = prelude

PACKAGE

@@ -0,0 +1,19 @@
+# @generated by `cargo buckal`
+
+load("@prelude//cfg/modifier:set_cfg_modifiers.bzl", "set_cfg_modifiers")
+load("@prelude//rust:with_workspace.bzl", "with_rust_workspace")
+load("@buckal//config:set_cfg_constructor.bzl", "set_cfg_constructor")
+
+ALIASES = {
+    "debug": "buckal//config/mode:debug",
+    "release": "buckal//config/mode:release",
+}
+set_cfg_constructor(aliases = ALIASES)
+
+set_cfg_modifiers(
+    cfg_modifiers = [
+        # default is debug mode.
+        # override with -m release
+        "buckal//config/mode:debug",
+    ],
+)

buckal/cargo_buildscript.bzl

@@ -0,0 +1,263 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is dual-licensed under either the MIT license found in the
+# LICENSE-MIT file in the root directory of this source tree or the Apache
+# License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+# of this source tree. You may select, at your option, one of the
+# above-listed licenses.
+
+# Cargo build script runner compatible with Reindeer-generated targets.
+#
+# Use this reindeer.toml configuration to refer to this rule:
+#
+#     [buck]
+#     buckfile_imports = """
+#     load("@prelude//rust:cargo_buildscript.bzl", "buildscript_run")
+#     """
+#
+#     # optional (this matches the default rule name):
+#     buildscript_genrule = "buildscript_run"
+#
+
+load("@prelude//decls:common.bzl", "buck")
+load("@prelude//decls:toolchains_common.bzl", "toolchains_common")
+load("@prelude//os_lookup:defs.bzl", "Os", "OsLookup")
+load("@prelude//rust:rust_toolchain.bzl", "RustToolchainInfo")
+load("@prelude//rust:targets.bzl", "targets")
+load(
+    "@prelude//rust/tools:buildscript_platform.bzl",
+    "buildscript_platform_constraints",
+    "transition_alias",
+)
+load("@prelude//utils:cmd_script.bzl", "cmd_script")
+load("@prelude//utils:selects.bzl", "selects")
+load("@prelude//rust:build.bzl", "dependency_args")
+load("@prelude//rust:build_params.bzl", "MetadataKind")
+load(
+    "@prelude//rust:cargo_package.bzl",
+    "apply_platform_attrs",
+    "get_reindeer_platform_names",
+    "get_reindeer_platforms",
+)
+load("@prelude//rust:context.bzl", "DepCollectionContext")
+load(
+    "@prelude//rust:link_info.bzl",
+    "DEFAULT_STATIC_LINK_STRATEGY",
+    "RustProcMacroPlugin",
+    "gather_explicit_sysroot_deps",
+    "resolve_rust_deps_inner",
+)
+load("@prelude//rust:rust_toolchain.bzl", "PanicRuntime")
+
+def _make_rustc_shim(ctx: AnalysisContext, cwd: Artifact) -> cmd_args:
+    # Build scripts expect to receive a `rustc` which "just works." However,
+    # our rustc sometimes has no sysroot available, so we need to make a shim
+    # which supplies the sysroot deps if necessary
+    toolchain_info = ctx.attrs._rust_toolchain[RustToolchainInfo]
+    explicit_sysroot_deps = toolchain_info.explicit_sysroot_deps
+    if explicit_sysroot_deps:
+        dep_ctx = DepCollectionContext(
+            advanced_unstable_linking = False,
+            include_doc_deps = False,
+            is_proc_macro = False,
+            explicit_sysroot_deps = explicit_sysroot_deps,
+            panic_runtime = PanicRuntime("unwind"),  # not actually used
+        )
+        deps = gather_explicit_sysroot_deps(dep_ctx)
+        deps = resolve_rust_deps_inner(ctx, deps)
+        dep_args, _ = dependency_args(
+            ctx = ctx,
+            compile_ctx = None,
+            toolchain_info = toolchain_info,
+            deps = deps,
+            subdir = "any",
+            dep_link_strategy = DEFAULT_STATIC_LINK_STRATEGY,
+            dep_metadata_kind = MetadataKind("full"),
+            is_rustdoc_test = False,
+        )
+
+        null_path = "nul" if ctx.attrs._exec_os_type[OsLookup].os == Os("windows") else "/dev/null"
+        dep_args = cmd_args("--sysroot=" + null_path, dep_args, relative_to = cwd)
+        dep_file, _ = ctx.actions.write("rustc_dep_file", dep_args, allow_args = True)
+        sysroot_args = cmd_args("@", dep_file, delimiter = "", hidden = dep_args)
+    else:
+        sysroot_args = cmd_args()
+
+    shim = cmd_script(
+        ctx = ctx,
+        name = "__rustc_shim",
+        cmd = cmd_args(toolchain_info.compiler, sysroot_args, relative_to = cwd),
+        language = ctx.attrs._exec_os_type[OsLookup].script,
+    )
+
+    return cmd_args(shim, relative_to = cwd)
+
+def _cargo_buildscript_impl(ctx: AnalysisContext) -> list[Provider]:
+    toolchain_info = ctx.attrs._rust_toolchain[RustToolchainInfo]
+
+    cwd = ctx.actions.declare_output("cwd", dir = True)
+    out_dir = ctx.actions.declare_output("OUT_DIR", dir = True)
+    rustc_flags = ctx.actions.declare_output("rustc_flags")
+    # *BUCKAL-ONLY* metadata environment variables for *dependent* buildscript runners to consume
+    metadata = ctx.actions.declare_output("METADATA")
+
+    if ctx.attrs.manifest_dir != None:
+        manifest_dir = ctx.attrs.manifest_dir[DefaultInfo].default_outputs[0]
+    else:
+        manifest_dir = ctx.actions.symlinked_dir("manifest_dir", ctx.attrs.filegroup_for_manifest_dir)
+        
+    cmd = [
+        ctx.attrs.runner[RunInfo],
+        cmd_args("--buildscript=", ctx.attrs.buildscript[RunInfo], delimiter = ""),
+        cmd_args("--rustc-cfg=", ctx.attrs.rustc_cfg[DefaultInfo].default_outputs[0], delimiter = ""),
+        cmd_args("--manifest-dir=", manifest_dir, delimiter = ""),
+        cmd_args("--create-cwd=", cwd.as_output(), delimiter = ""),
+        cmd_args("--outfile=", rustc_flags.as_output(), delimiter = ""),
+        cmd_args("--outenv=", metadata.as_output(), delimiter = ""),
+    ]
+
+    # *BUCKAL-ONLY* read environment variable source files and set them for buildscript runner
+    for env_src in ctx.attrs.env_srcs:
+        cmd.append(cmd_args("--extra-env=", env_src[DefaultInfo].default_outputs[0], delimiter = ""))
+
+    # See https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts
+
+    env = {}
+    env["CARGO"] = "/bin/false"
+    env["CARGO_PKG_NAME"] = ctx.attrs.package_name
+    env["CARGO_PKG_VERSION"] = ctx.attrs.version
+    env["OUT_DIR"] = out_dir.as_output()
+    env["RUSTC"] = _make_rustc_shim(ctx, cwd)
+    env["RUSTC_LINKER"] = "/bin/false"
+    env["RUST_BACKTRACE"] = "1"
+
+    if toolchain_info.rustc_target_triple:
+        env["TARGET"] = toolchain_info.rustc_target_triple
+    else:
+        cmd.append(cmd_args("--rustc-host-tuple=", ctx.attrs.rustc_host_tuple[DefaultInfo].default_outputs[0], delimiter = ""))
+
+    # \037 == \x1f == the magic delimiter specified in the environment variable
+    # reference above.
+    env["CARGO_ENCODED_RUSTFLAGS"] = cmd_args(toolchain_info.rustc_flags, delimiter = "\037")
+
+    host_triple = targets.exec_triple(ctx)
+    if host_triple:
+        env["HOST"] = host_triple
+
+    for feature in ctx.attrs.features:
+        upper_feature = feature.upper().replace("-", "_")
+        env["CARGO_FEATURE_{}".format(upper_feature)] = "1"
+
+    # Environment variables specified in the target's attributes get priority
+    # over all the above.
+    for k, v in ctx.attrs.env.items():
+        env[k] = cmd_args(v, relative_to = cwd)
+
+    ctx.actions.run(
+        cmd,
+        env = env,
+        category = "buildscript",
+    )
+
+    return [DefaultInfo(
+        default_output = None,
+        sub_targets = {
+            "out_dir": [DefaultInfo(default_output = out_dir)],
+            "rustc_flags": [DefaultInfo(default_output = rustc_flags)],
+            "metadata": [DefaultInfo(default_output = metadata)],
+        },
+    )]
+
+_cargo_buildscript_rule = rule(
+    impl = _cargo_buildscript_impl,
+    attrs = {
+        "buildscript": attrs.exec_dep(providers = [RunInfo]),
+        "env": attrs.dict(key = attrs.string(), value = attrs.arg(), default = {}),
+        # *BUCKAL-ONLY* list of environment variable source files to set for the buildscript
+        "env_srcs": attrs.list(attrs.dep(), default = []),
+        "features": attrs.list(attrs.string(), default = []),
+        "filegroup_for_manifest_dir": attrs.option(attrs.dict(key = attrs.string(), value = attrs.source()), default = None),
+        "manifest_dir": attrs.option(attrs.dep(), default = None),
+        "package_name": attrs.string(),
+        "runner": attrs.default_only(attrs.exec_dep(providers = [RunInfo], default = "buckal//tool:buildscript_run")),
+        # *IMPORTANT* rustc_cfg must be a `dep` and not an `exec_dep` because
+        # we want the `rustc --cfg` for the target platform, not the exec platform.
+        "rustc_cfg": attrs.dep(default = "prelude//rust/tools:rustc_cfg"),
+        "rustc_host_tuple": attrs.dep(default = "prelude//rust/tools:rustc_host_tuple"),
+        "version": attrs.string(),
+        "_exec_os_type": buck.exec_os_type_arg(),
+        "_rust_toolchain": toolchains_common.rust(),
+    },
+    # Always empty, but needed to prevent errors
+    uses_plugins = [RustProcMacroPlugin],
+)
+
+def buildscript_run(
+        name,
+        buildscript_rule,
+        package_name,
+        version,
+        platform = {},
+        # path to crate's directory in source tree, e.g. "vendor/serde-1.0.100"
+        local_manifest_dir = None,
+        # target or subtarget containing crate, e.g. ":serde.git[serde]"
+        manifest_dir = None,
+        buildscript_compatible_with = None,
+        **kwargs):
+    kwargs = apply_platform_attrs(platform, kwargs)
+
+    if manifest_dir == None and local_manifest_dir == None:
+        existing_filegroup_name = "{}-{}.crate".format(package_name, version)
+        if rule_exists(existing_filegroup_name):
+            manifest_dir = ":{}".format(existing_filegroup_name)
+        else:
+            local_manifest_dir = "vendor/{}-{}".format(package_name, version)
+
+    filegroup_for_manifest_dir = None
+    if local_manifest_dir != None:
+        prefix_with_trailing_slash = "{}/".format(local_manifest_dir)
+        filegroup_for_manifest_dir = {
+            path.removeprefix(prefix_with_trailing_slash): path
+            for path in glob(["{}/**".format(local_manifest_dir)])
+        }
+
+    def platform_buildscript_build_name(plat):
+        if name.endswith("-build-script-run"):
+            # This is the expected case for Reindeer-generated targets, which
+            # come in pairs build-script-run and build-script-build.
+            return "{}-build-script-build-{}".format(
+                name.removesuffix("-build-script-run"),
+                plat,
+            )
+        else:
+            return "{}-{}".format(name, plat)
+
+    if not rule_exists("buildscript_for_platform="):
+        buildscript_platform_constraints(
+            name = "buildscript_for_platform=",
+            reindeer_platforms = get_reindeer_platform_names(),
+        )
+
+    for plat in get_reindeer_platform_names():
+        transition_alias(
+            name = platform_buildscript_build_name(plat),
+            actual = buildscript_rule,
+            incoming_transition = ":buildscript_for_platform=[{}]".format(plat),
+            target_compatible_with = buildscript_compatible_with,
+            visibility = [],
+        )
+
+    buildscript_rule = selects.apply(
+        get_reindeer_platforms(),
+        lambda plat: buildscript_rule if plat == None else ":{}".format(platform_buildscript_build_name(plat)),
+    )
+
+    _cargo_buildscript_rule(
+        name = name,
+        buildscript = buildscript_rule,
+        package_name = package_name,
+        version = version,
+        filegroup_for_manifest_dir = filegroup_for_manifest_dir,
+        manifest_dir = manifest_dir,
+        **kwargs
+    )

buckal/cargo_manifest.bzl

@@ -0,0 +1,33 @@
+# @generated by `cargo buckal`
+
+def _cargo_manifest_impl(ctx: AnalysisContext) -> list[Provider]:
+    env_dict = ctx.actions.declare_output("ENV_DICT")
+    env_flags = ctx.actions.declare_output("ENV_FLAGS")
+
+    cmd = [
+        ctx.attrs.executor[RunInfo],
+        cmd_args("--vendor=", ctx.attrs.vendor[DefaultInfo].default_outputs[0], delimiter = ""),
+        cmd_args("--out-dict=", env_dict.as_output(), delimiter = ""),
+        cmd_args("--out-flags=", env_flags.as_output(), delimiter = ""),
+    ]
+
+    ctx.actions.run(
+        cmd,
+        category = "cargo_manifest",
+    )
+
+    return [DefaultInfo(
+        default_output = None,
+        sub_targets = {
+            "env_dict": [DefaultInfo(default_output = env_dict)],
+            "env_flags": [DefaultInfo(default_output = env_flags)],
+        },
+    )]
+
+cargo_manifest = rule(
+    impl = _cargo_manifest_impl,
+    attrs = {
+        "vendor": attrs.dep(),
+        "executor": attrs.default_only(attrs.exec_dep(providers = [RunInfo], default = "buckal//tool:manifest_parse")),
+    },
+)

buckal/config/mode/BUCK

@@ -0,0 +1,17 @@
+# @generated by `cargo buckal`
+
+config_setting(
+    name = "debug",
+    constraint_values = [
+        "buckal//config/mode/constraints:debug",
+    ],
+    visibility = ["PUBLIC"],
+)
+
+config_setting(
+    name = "release",
+    constraint_values = [
+        "buckal//config/mode/constraints:release",
+    ],
+    visibility = ["PUBLIC"],
+)

buckal/config/mode/constraints/BUCK

@@ -0,0 +1,18 @@
+# @generated by `cargo buckal`
+
+constraint_setting(
+    name = "mode",
+    visibility = ["PUBLIC"],
+)
+
+constraint_value(
+    name = "debug",
+    constraint_setting = ":mode",
+    visibility = ["PUBLIC"],
+)
+
+constraint_value(
+    name = "release",
+    constraint_setting = ":mode",
+    visibility = ["PUBLIC"],
+)

buckal/config/set_cfg_constructor.bzl

@@ -0,0 +1,16 @@
+# @generated by `cargo buckal`
+
+load("@prelude//cfg/modifier:cfg_constructor.bzl", "cfg_constructor_post_constraint_analysis", "cfg_constructor_pre_constraint_analysis")
+load("@prelude//cfg/modifier:common.bzl", "MODIFIER_METADATA_KEY")
+
+def set_cfg_constructor(aliases = dict()):
+    project_root_cell = read_root_config("cell_aliases", "root")
+    current_root_cell = read_config("cell_aliases", "root")
+    if project_root_cell == current_root_cell:
+        native.set_cfg_constructor(
+            stage0 = cfg_constructor_pre_constraint_analysis,
+            stage1 = cfg_constructor_post_constraint_analysis,
+            key = MODIFIER_METADATA_KEY,
+            aliases = struct(**aliases),
+            extra_data = struct(),
+        )

buckal/tool/BUCK

@@ -0,0 +1,13 @@
+# @generated by `cargo buckal`
+
+native.python_bootstrap_binary(
+    name = "manifest_parse",
+    main = "manifest_parse.py",
+    visibility = ["PUBLIC"],
+)
+
+native.python_bootstrap_binary(
+    name = "buildscript_run",
+    main = "buildscript_run.py",
+    visibility = ["PUBLIC"],
+)