specify aarch64-linux toolchain for Yggdrasil build

deps/ReactantExtra/BUILD

@@ -13,9 +13,10 @@ cc_toolchain_suite(
         "k8": ":ygg_x86_toolchain",
         "darwin": ":ygg_x86_toolchain",
         "darwin_arm64": ":ygg_x86_toolchain",
-        "linux_arm64": ":ygg_x86_toolchain",
+        "aarch64": ":ygg_aarch64_toolchain",
     },
 )
+
 cc_toolchain_suite(
     name = "beast_toolchain_suite",
     toolchains = {
@@ -38,6 +39,19 @@ cc_toolchain(
     toolchain_identifier = "ygg_x86_toolchain",
 )
 
+cc_toolchain(
+    name = "ygg_aarch64_toolchain",
+    all_files = ":empty",
+    compiler_files = ":empty",
+    dwp_files = ":empty",
+    linker_files = ":empty",
+    objcopy_files = ":empty",
+    strip_files = ":empty",
+    supports_param_files = 1,
+    toolchain_config = ":ygg_aarch64_toolchain_config",
+    toolchain_identifier = "ygg_aarch64_toolchain",
+)
+
 cc_toolchain_config(
     name = "ygg_x86_toolchain_config",
     abi_libc_version = "local",
@@ -120,6 +134,103 @@ cc_toolchain_config(
     ],
 )
 
+# TODO distinguish between clang and gcc toolchains
+cc_toolchain_config(
+    name = "ygg_aarch64_toolchain_config",
+    cpu = "aarch64",
+    compiler = "compiler",
+    toolchain_identifier = "ygg_aarch64",
+    target_system_name = "aarch64-unknown-linux-gnu",
+    target_libc = "",
+    abi_libc_version = "local",
+    abi_version = "local",
+    cxx_builtin_include_directories = [
+        "/opt/aarch64-linux-gnu/lib/gcc/aarch64-linux-gnu/10.2.0/include",
+        "/opt/aarch64-linux-gnu/lib/gcc/aarch64-linux-gnu/10.2.0/include-fixed",
+        "/opt/aarch64-linux-gnu/aarch64-linux-gnu/include",
+        "/opt/aarch64-linux-gnu/aarch64-linux-gnu/sys-root/usr/include",
+        "/opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0",
+        "/opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0/aarch64-linux-gnu",
+        "/opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0/backward",
+        "/opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0/parallel"
+    ],
+    tool_paths = {
+        "ar": "/opt/bin/aarch64-linux-gnu-*/ar",
+        "as": "/opt/bin/aarch64-linux-gnu-*/as",
+        "c++": "/opt/bin/aarch64-linux-gnu-*/c++",
+        "c++filt": "/opt/bin/aarch64-linux-gnu-*/c++filt",
+        "cc": "/opt/bin/aarch64-linux-gnu-*/cc",
+        "clang": "/opt/bin/aarch64-linux-gnu-*/clang",
+        "clang++": "/opt/bin/aarch64-linux-gnu-*/clang++",
+        "cpp": "/opt/bin/aarch64-linux-gnu-*/cpp",
+        "f77": "/opt/bin/aarch64-linux-gnu-*/f77",
+        "g++": "/opt/bin/aarch64-linux-gnu-*/g++",
+        "gcc": "/opt/bin/aarch64-linux-gnu-*/gcc",
+        "gfortran": "/opt/bin/aarch64-linux-gnu-*/gfortran",
+        "ld": "/opt/bin/aarch64-linux-gnu-*/ld",
+        "ld.lld": "/opt/bin/aarch64-linux-gnu-*/ld.lld",
+        "libtool": "/opt/bin/aarch64-linux-gnu-*/libtool",
+        "lld": "/opt/bin/aarch64-linux-gnu-*/lld",
+        "nm": "/opt/bin/aarch64-linux-gnu-*/nm",
+        "objcopy": "/opt/bin/aarch64-linux-gnu-*/objcopy",
+        "patchelf": "/opt/bin/aarch64-linux-gnu-*/patchelf",
+        "ranlib": "/opt/bin/aarch64-linux-gnu-*/ranlib",
+        "readelf": "/opt/bin/aarch64-linux-gnu-*/readelf",
+        "strip": "/opt/bin/aarch64-linux-gnu-*/strip",
+        # from host
+        "llvm-cov": "/opt/x86_64-linux-musl/bin/llvm-cov",
+        "llvm-profdata": "/opt/x86_64-linux-musl/bin/llvm-profdata",
+        "objdump": "/usr/bin/objdump",
+    },
+    compile_flags = [
+        "-fstack-protector",
+        "-Wall",
+        "-Wunused-but-set-parameter",
+        "-Wno-free-nonheap-object",
+        "-fno-omit-frame-pointer",
+        # TODO cxx_builtin_include_directories doesn't seem to be working, so we add the INCLUDE_PATHs manually
+        "-isystem /opt/aarch64-linux-gnu/lib/gcc/aarch64-linux-gnu/10.2.0/include",
+        "-isystem /opt/aarch64-linux-gnu/lib/gcc/aarch64-linux-gnu/10.2.0/include-fixed",
+        "-isystem /opt/aarch64-linux-gnu/aarch64-linux-gnu/include",
+        "-isystem /opt/aarch64-linux-gnu/aarch64-linux-gnu/sys-root/usr/include",
+        "-isystem /opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0",
+        "-isystem /opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0/aarch64-linux-gnu",
+        "-isystem /opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0/backward",
+        "-isystem /opt/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/10.2.0/parallel",
+    ],
+    opt_compile_flags = [
+        "-g0",
+        "-O2",
+        "-D_FORTIFY_SOURCE=1",
+        "-DNDEBUG",
+        "-ffunction-sections",
+        "-fdata-sections",
+        # "-stdlib=libstdc++",
+    ],
+    dbg_compile_flags = ["-g"],
+    link_flags = [],
+    link_libs = [
+        "-lstdc++",
+        "-lm",
+    ],
+    opt_link_flags = ["-Wl,--gc-sections"],
+    unfiltered_compile_flags = [
+        "-no-canonical-prefixes",
+        "-Wno-builtin-macro-redefined",
+        "-D__DATE__=\"redacted\"",
+        "-D__TIMESTAMP__=\"redacted\"",
+        "-D__TIME__=\"redacted\"",
+        "-Wno-unused-command-line-argument",
+        "-Wno-gnu-offsetof-extensions",
+    ],
+    builtin_sysroot = "/opt/aarch64-linux-gnu/aarch64-linux-gnu/sys-root/",
+    coverage_compile_flags = ["--coverage"],
+    coverage_link_flags = ["--coverage"],
+    host_system_name = "linux",
+    # TODO gcc doesn't support it, only put it on clang (maybe even only for clang on aarch64-darwin?)
+    supports_start_end_lib = False,
+)
+
 cc_toolchain(
     name = "beast_x86_toolchain",
     all_files = ":empty",