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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Workerd Maintainers <workers-dev@cloudflare.com>
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Date: Wed, 4 Mar 2026 12:37:49 -0800
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Subject: Remove V8 MODULE.bazel llvm toolchain and libcxx repo rules
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These reference third_party/ sources that are not present in the GitHub
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tarball. Workerd provides its own toolchain, so these are not needed.
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diff --git a/MODULE.bazel b/MODULE.bazel
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index 7d7ba53b579605a6f469fe01ddf699d1284110e3..7ddd8259e790ebbfce0bfbb08e08ed4130592f9b 100644
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--- a/MODULE.bazel
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+++ b/MODULE.bazel
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@@ -22,167 +22,7 @@ pip.parse(
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 )
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 use_repo(pip, "v8_python_deps")
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-# Define the local LLVM toolchain repository
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-llvm_toolchain_repository = use_repo_rule("//bazel/toolchain:llvm_repository.bzl", "llvm_toolchain_repository")
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-llvm_toolchain_repository(
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-    name = "llvm_toolchain",
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-    path = "third_party/llvm-build/Release+Asserts",
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-    config_file_content = """
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-load("@bazel_tools//tools/cpp:cc_toolchain_config_lib.bzl", "feature", "flag_group", "flag_set", "tool_path")
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-
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-def _impl(ctx):
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-    tool_paths = [
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-        tool_path(name = "gcc", path = "bin/clang"),
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-        tool_path(name = "ld", path = "bin/lld"),
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-        tool_path(name = "ar", path = "bin/llvm-ar"),
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-        tool_path(name = "cpp", path = "bin/clang++"),
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-        tool_path(name = "gcov", path = "/bin/false"),
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-        tool_path(name = "nm", path = "bin/llvm-nm"),
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-        tool_path(name = "objdump", path = "bin/llvm-objdump"),
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-        tool_path(name = "strip", path = "bin/llvm-strip"),
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-    ]
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-
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-    features = [
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-        feature(
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-            name = "default_compile_flags",
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-            enabled = True,
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-            flag_sets = [
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-                flag_set(
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-                    actions = [
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-                        "c-compile",
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-                        "c++-compile",
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-                        "c++-header-parsing",
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-                        "c++-module-compile",
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-                        "c++-module-codegen",
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-                        "linkstamp-compile",
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-                        "assemble",
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-                        "preprocess-assemble",
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-                    ],
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-                    flag_groups = [
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-                        flag_group(
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-                            flags = [
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-                                "--sysroot={WORKSPACE_ROOT}/build/linux/debian_bullseye_amd64-sysroot",
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-                                "-nostdinc++",
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-                                "-isystem",
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-                                "{WORKSPACE_ROOT}/buildtools/third_party/libc++",
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-                                "-isystem",
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-                                "{WORKSPACE_ROOT}/third_party/libc++/src/include",
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-                                "-isystem",
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-                                "{WORKSPACE_ROOT}/third_party/libc++abi/src/include",
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-                                "-isystem",
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-                                "{WORKSPACE_ROOT}/third_party/libc++/src/src",
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-                                "-isystem",
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-                                "{WORKSPACE_ROOT}/third_party/llvm-libc/src",
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-                                "-D_LIBCPP_HARDENING_MODE_DEFAULT=_LIBCPP_HARDENING_MODE_NONE",
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-                                "-DLIBC_NAMESPACE=__llvm_libc_cr",
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-                            ],
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-                        ),
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-                    ],
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-                ),
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-            ],
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-        ),
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-        feature(
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-            name = "default_linker_flags",
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-            enabled = True,
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-            flag_sets = [
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-                flag_set(
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-                    actions = [
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-                        "c++-link-executable",
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-                        "c++-link-dynamic-library",
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-                        "c++-link-nodeps-dynamic-library",
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-                    ],
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-                    flag_groups = [
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-                        flag_group(
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-                            flags = [
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-                                "--sysroot={WORKSPACE_ROOT}/build/linux/debian_bullseye_amd64-sysroot",
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-                                "-fuse-ld=lld",
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-                                "-lm",
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-                                "-lpthread",
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-                            ],
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-                        ),
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-                    ],
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-                ),
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-            ],
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-        ),
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-    ]
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-
102
-    return cc_common.create_cc_toolchain_config_info(
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-        ctx = ctx,
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-        features = features,
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-        cxx_builtin_include_directories = [
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-            "{WORKSPACE_ROOT}/buildtools/third_party/libc++",
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-            "{WORKSPACE_ROOT}/third_party/libc++/src/include",
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-            "{WORKSPACE_ROOT}/third_party/libc++abi/src/include",
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-            "{WORKSPACE_ROOT}/third_party/libc++/src/src",
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-            "{WORKSPACE_ROOT}/third_party/llvm-libc/src",
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-            "{WORKSPACE_ROOT}/third_party/llvm-build/Release+Asserts/lib/clang/22/include",
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-            "{WORKSPACE_ROOT}/third_party/llvm-build/Release+Asserts/lib/clang/23/include",
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-            "{WORKSPACE_ROOT}/build/linux/debian_bullseye_amd64-sysroot/usr/include",
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-            "{WORKSPACE_ROOT}/build/linux/debian_bullseye_amd64-sysroot/usr/local/include",
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-        ],
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-        toolchain_identifier = "local_clang",
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-        host_system_name = "local",
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-        target_system_name = "local",
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-        target_cpu = "k8",
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-        target_libc = "unknown",
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-        compiler = "clang",
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-        abi_version = "unknown",
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-        abi_libc_version = "unknown",
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-        tool_paths = tool_paths,
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-    )
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-
127
-cc_toolchain_config = rule(
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-    implementation = _impl,
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-    attrs = {},
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-    provides = [CcToolchainConfigInfo],
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-)
132
-""",
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-    build_file_content = """
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-load(":cc_toolchain_config.bzl", "cc_toolchain_config")
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-
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-package(default_visibility = ["//visibility:public"])
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-
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-filegroup(
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-    name = "all_files",
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-    srcs = glob(["**/*"]),
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-)
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-
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-filegroup(name = "empty")
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-
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-cc_toolchain_config(name = "k8_toolchain_config")
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-
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-cc_toolchain(
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-    name = "k8_toolchain",
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-    all_files = ":all_files",
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-    ar_files = ":all_files",
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-    compiler_files = ":all_files",
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-    dwp_files = ":empty",
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-    linker_files = ":all_files",
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-    objcopy_files = ":all_files",
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-    strip_files = ":all_files",
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-    supports_param_files = 0,
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-    toolchain_config = ":k8_toolchain_config",
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-    toolchain_identifier = "local_clang",
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-)
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-
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-toolchain(
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-    name = "cc_toolchain_k8",
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-    exec_compatible_with = [
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-        "@platforms//cpu:x86_64",
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-        "@platforms//os:linux",
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-    ],
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-    target_compatible_with = [
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-        "@platforms//cpu:x86_64",
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-        "@platforms//os:linux",
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-    ],
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-    toolchain = ":k8_toolchain",
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-    toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
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-)
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-""",
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-)
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-
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-register_toolchains("@llvm_toolchain//:cc_toolchain_k8")
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 # Define local repository for libc++ from third_party sources
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 libcxx_repository = use_repo_rule("//bazel/toolchain:libcxx_repository.bzl", "libcxx_repository")
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diff --git a/bazel/toolchain/libcxx_repository.bzl b/bazel/toolchain/libcxx_repository.bzl
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index a7d5f11053dd333c5bec614c27168a0effb7b4aa..ed367ef64871133867e9eccb07c6482a4de08ceb 100644
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--- a/bazel/toolchain/libcxx_repository.bzl
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+++ b/bazel/toolchain/libcxx_repository.bzl
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@@ -1,99 +1,17 @@
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-"""Repository rule for building libc++ from third_party sources."""
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+"""Stub repository rule: workerd uses the system/toolchain libc++, so @libcxx
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+is an empty shim that satisfies the dep in bazel/defs.bzl without pulling in
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+any third_party sources."""
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 def _libcxx_repository_impl(ctx):
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-    # Find the workspace root
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-    workspace_root = ctx.path(Label("@//:BUILD.bazel")).dirname
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-
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-    # Symlink the source directories
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-    ctx.symlink(workspace_root.get_child("third_party").get_child("libc++"), "libc++")
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-    ctx.symlink(workspace_root.get_child("third_party").get_child("libc++abi"), "libc++abi")
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-    ctx.symlink(workspace_root.get_child("third_party").get_child("llvm-libc"), "llvm-libc")
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-    ctx.symlink(workspace_root.get_child("buildtools").get_child("third_party").get_child("libc++"), "buildtools_libc++")
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-
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-    # Get the external repository path for include flags
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-    # In bzlmod, repo names may have prefixes, so we need to determine the actual path
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-    repo_path = "external/" + ctx.name
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-
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-    # Create the BUILD file
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-    # NOTE: We don't use 'includes' attribute here because it creates relative paths
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-    # that conflict with the toolchain's absolute paths, breaking #include_next.
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-    # The toolchain provides the libc++ include paths via -isystem flags.
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-    build_content = '''
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+    ctx.file("BUILD.bazel", """
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 package(default_visibility = ["//visibility:public"])
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-LIBCXX_COPTS = [
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-    "-std=c++23",
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-    "-fPIC",
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-    "-fstrict-aliasing",
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-    "-fexceptions",
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-    "-frtti",
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-    "-D_LIBCPP_BUILDING_LIBRARY",
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-    "-D_LIBCPP_HARDENING_MODE_DEFAULT=_LIBCPP_HARDENING_MODE_NONE",
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-    "-DLIBC_NAMESPACE=__llvm_libc_cr",
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-]
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-
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-cc_library(
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-    name = "libc++abi",
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-    srcs = glob([
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-        "libc++abi/src/src/*.cpp",
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-        "libc++abi/src/src/*.h",
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-        "libc++abi/src/src/demangle/*.h",
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-    ], exclude = [
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-        # Exclude files not needed for Linux build
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-        "libc++abi/src/src/cxa_noexception.cpp",
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-        "libc++abi/src/src/stdlib_new_delete.cpp",
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-    ]),
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-    hdrs = glob([
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-        "libc++abi/src/include/**/*.h",
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-        "libc++/src/include/**/*",
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-        "libc++/src/src/include/*.h",
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-        "libc++abi/src/src/demangle/*.def",
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-        "buildtools_libc++/__config_site",
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-        "buildtools_libc++/__assertion_handler",
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-        "llvm-libc/src/**/*.h",
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-    ]),
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-    copts = LIBCXX_COPTS + [
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-        "-DLIBCXXABI_SILENT_TERMINATE",
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-        "-iquote", "{REPO_PATH}/libc++abi/src/src",
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-        "-iquote", "{REPO_PATH}/libc++abi/src/src/demangle",
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-    ],
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-    linkstatic = True,
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-)
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-
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-cc_library(
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-    name = "libc++",
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-    srcs = glob([
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-        "libc++/src/src/*.cpp",
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-        "libc++/src/src/*.h",
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-        "libc++/src/src/filesystem/*.cpp",
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-        "libc++/src/src/filesystem/*.h",
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-        "libc++/src/src/ryu/*.cpp",
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-        "libc++/src/src/include/*.h",
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-        "libc++/src/src/include/ryu/*.h",
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-    ]) + glob(["libc++/src/src/support/**/*.ipp"], allow_empty = True),
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-    hdrs = glob([
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-        "libc++/src/include/**/*",
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-        "buildtools_libc++/__config_site",
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-        "buildtools_libc++/__assertion_handler",
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-        "llvm-libc/src/**/*.h",
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-    ]),
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-    copts = LIBCXX_COPTS + [
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-        "-DLIBCXX_BUILDING_LIBCXXABI",
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-        "-iquote", "{REPO_PATH}/libc++/src/src",
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-        "-iquote", "{REPO_PATH}/libc++/src/src/filesystem",
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-    ],
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-    linkopts = [
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-        "-lpthread",
276
-        "-lm",
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-    ],
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-    deps = [":libc++abi"],
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-    linkstatic = True,
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-)
281
-'''.format(REPO_PATH=repo_path)
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-    ctx.file("BUILD.bazel", build_content)
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+# Empty stub – the real libc++ is provided by the toolchain.
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+cc_library(name = "libc++")
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+cc_library(name = "libc++abi")
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+""")
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 libcxx_repository = repository_rule(
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     implementation = _libcxx_repository_impl,
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     local = True,
291
-    configure = True,
292
 )