Revert "bazel: delete bazel build system"

This reverts commit 6d3f9b2.

.bazelrc

@@ -0,0 +1,51 @@
+# Enable configurations specific to the host platform.
+common --enable_platform_specific_config
+
+# Disallow empty `glob()`s.
+build --incompatible_disallow_empty_glob
+
+# Don't auto-detect the C/C++ toolchain.
+build --action_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
+
+# Use platforms to select toolchains.
+# See https://bazel.build/concepts/platforms#cxx and
+# https://github.com/bazelbuild/bazel/issues/7260.
+build --incompatible_enable_cc_toolchain_resolution
+
+# Disable transitions.
+# See https://github.com/bazelbuild/rules_docker/issues/2052.
+build --@io_bazel_rules_docker//transitions:enable=false
+
+# Add aliases for compiler version build settings.
+build --flag_alias=clang_version=//:clang_version
+build --flag_alias=gcc_version=//:gcc_version
+
+# Use optimized build by default. According to the bazel documentation, this
+# corresponds to -O2 -DNDEBUG, but these are overriden in
+# //bazel/common_settings.bzl:vere_library.
+# https://bazel.build/docs/user-manual#build-semantics
+build --compilation_mode=opt
+
+# Don't include source level debug info on macOS. See
+# https://github.com/urbit/urbit/issues/5561 and
+# https://github.com/urbit/vere/issues/131.
+build:linux --host_copt='-g'
+build --strip=never
+
+# Turn on optimization, CPU and memory debug for exec config, which we only use
+# to run the fake ship tests.  Also turn on extra snapshot validation.
+build --host_copt='-O3'
+build --host_copt='-DU3_CPU_DEBUG'
+build --host_copt='-DU3_MEMORY_DEBUG'
+build --host_copt='-DC3DBG'
+build --host_copt='-DU3_SNAPSHOT_VALIDATION'
+
+# Set as per-file copts as a plain --copt gets passed to third party
+# dependencies which forces recompilation (slow) if you are switching between
+# including/excluding a symbol define.
+build:mem_dbg --per_file_copt='pkg/.*@-DU3_MEMORY_DEBUG'
+build:cpu_dbg --per_file_copt='pkg/.*@-DU3_CPU_DEBUG'
+build:snp_dbg --per_file_copt='pkg/.*@-DU3_SNAPSHOT_VALIDATION'
+
+# Any personal configuration should go in .user.bazelrc.
+try-import %workspace%/.user.bazelrc

BUILD.bazel

@@ -0,0 +1,214 @@
+load("//bazel:common_settings.bzl", "string_flag")
+exports_files(["PACE"])
+
+#
+# OS-CPU CONFIG SETTINGS
+#
+
+config_setting(
+    name = "linux_aarch64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:aarch64",
+    ],
+)
+
+config_setting(
+    name = "linux_x86_64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+config_setting(
+    name = "macos_aarch64",
+    constraint_values = [
+        "@platforms//os:macos",
+        "@platforms//cpu:aarch64",
+    ],
+)
+
+config_setting(
+    name = "macos_x86_64",
+    constraint_values = [
+        "@platforms//os:macos",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+#
+# CONFIGS DETAILING WHEN TO ENABLE CERTAIN FEATURES BY DEFAULT.
+# CHANGES BEHAVIOR OF //bazel/common_settings.bzl:vere_library.
+#
+
+config_setting(
+    name = "thinlto",
+    constraint_values = [
+        "@platforms//os:macos",
+    ],
+    values = {
+        "compilation_mode": "opt"
+    }
+)
+
+config_setting(
+    name = "lto",
+    constraint_values = [
+        "@platforms//os:linux",
+    ],
+    values = {
+        "compilation_mode": "opt"
+    }
+)
+
+config_setting(
+    name = "debug",
+    values = {
+        "compilation_mode": "dbg"
+    }
+)
+
+#
+# COMPILERS
+#
+
+# Version flag for clang.
+string_flag(
+    name = "clang_version",
+    # macOS uses `clang-15.0.0` by default.
+    build_setting_default = "15.0.0",
+    visibility = ["//visibility:public"],
+)
+
+# Version flag for gcc.
+string_flag(
+    name = "gcc_version",
+    # musl-cross-make uses `gcc-11.4.0` by default.
+    build_setting_default = "11.4.0",
+    visibility = ["//visibility:public"],
+)
+
+#
+# PLATFORMS
+#
+# A platform takes one of two formats: `<compiler>-<os>-<cpu>` or `<os>-<cpu>`
+# if the compiler is unspecified.
+
+# Linux aarch64 platform with unspecified compiler.
+platform(
+    name = "linux-aarch64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:aarch64",
+    ],
+)
+
+# Linux x86_64 platform with unspecified compiler.
+platform(
+    name = "linux-x86_64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+# Linux x86_64 platform with gcc.
+platform(
+    name = "gcc-linux-x86_64",
+    constraint_values = [
+        ":gcc",
+        "@platforms//os:linux",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+platform(
+    name = "macos-aarch64",
+    constraint_values = [
+        "@platforms//os:macos",
+        "@platforms//cpu:aarch64",
+    ],
+)
+
+platform(
+    name = "clang-macos-aarch64",
+    constraint_values = [
+        ":clang",
+        "@platforms//os:macos",
+        "@platforms//cpu:aarch64",
+    ],
+)
+
+platform(
+    name = "macos-x86_64",
+    constraint_values = [
+        "@platforms//os:macos",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+platform(
+    name = "clang-macos-x86_64",
+    constraint_values = [
+        ":clang",
+        "@platforms//os:macos",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+# Produce the `U3_VERE_PACE` macro.
+genrule(
+    name = "pace_hdr",
+    srcs = ["PACE"],
+    outs = ["pace.h"],
+    cmd = """
+    echo '#ifndef URBIT_PACE_H' > $@
+    echo '#define URBIT_PACE_H' >> $@
+    printf '#define U3_VERE_PACE "%s"\n' $$(cat $< | tr -d '\n') >> $@
+    echo '#endif' >> $@
+    """,
+    visibility = ["//:__subpackages__"],
+)
+
+genrule(
+    name = "version_str",
+    srcs = [
+        # Bazel warns dependency checking directories is unsound, but there's no
+        # apparent way around depending on .git if we want to run git commands.
+        ".git",
+        "PACE",
+        "VERSION",
+    ],
+    outs = ["version"],
+    cmd = """
+    version_num=$$(cat $(execpath VERSION) | tr -d '\n')
+    commit_sha=$$(git rev-parse --short HEAD)
+    if [ $$(tr -d '\n' < $(execpath PACE)) == "live" ]; then
+        version="$$version_num"
+    else
+        version="$$version_num-$$commit_sha"
+    fi
+    echo -n $$version > $@
+    """,
+    visibility = ["//:__subpackages__"],
+)
+
+# Produce the `URBIT_VERSION` macro.
+genrule(
+    name = "version_hdr",
+    srcs = [":version_str"],
+    outs = ["version.h"],
+    cmd = """
+    echo '#ifndef URBIT_VERSION_H' > $@
+    echo '#define URBIT_VERSION_H' >> $@
+    printf '#define URBIT_VERSION "%s"\n' $$(cat $< | tr -d '\n') >> $@
+    echo '#endif' >> $@
+    """,
+    visibility = ["//:__subpackages__"],
+)
+
+alias(
+    name = "urbit",
+    actual = "//pkg/vere:urbit",
+)

PACE

@@ -0,0 +1 @@
+once

VERSION

@@ -0,0 +1 @@
+3.1