[antlir2][toolchain] reorganize third-party deps to match expectations

Summary:
Reorganize deps to match the expectations of the standard fbsource machinery
(see the following diff)

Test Plan:
```
❯ buck2 test fbcode//antlir/distro/toolchain/cxx/tests: fbcode//antlir/distro/toolchain/rust/tests:
Buck UI: https://www.internalfb.com/buck2/868bffa6-ae4a-4a6a-93dd-0b15a29605ad
Test UI: https://www.internalfb.com/intern/testinfra/testrun/5066549837190240
Network: Up: 19MiB  Down: 531MiB  (reSessionID-c31c7c23-abf7-4d35-a50b-619a335301a8)
Jobs completed: 324844. Time elapsed: 1:20.6s.
Cache hits: 0%. Commands: 97 (cached: 0, remote: 0, local: 97)
Tests finished: Pass 20. Fail 0. Fatal 0. Skip 0. Build failure 0
```

Reviewed By: naveedgol

Differential Revision: D66893437

fbshipit-source-id: ba61b20f4f2c29a1e518a488a0719b4084b47996

antlir/distro/deps/BUCK

@@ -2,12 +2,9 @@ load("//antlir/antlir2/bzl/feature:defs.bzl", "feature")
 load("//antlir/antlir2/bzl/image:defs.bzl", "image")
 load("//antlir/antlir2/bzl/package:defs.bzl", "package")
 load("//antlir/antlir2/image_command_alias:image_command_alias.bzl", "image_command_alias")
-load(":pkgconfig.bzl", "image_pkgconfig_library")
 
 oncall("antlir")
 
-prelude = native
-
 image.layer(
     name = "sysroot-layer",
     features = [
@@ -16,6 +13,10 @@ image.layer(
             # toolchains/cxx:layer, but installing it here gives us all the deps
             # that clang will expect to find in `--sysroot`
             "clang",
+            # Install some other core dependencies that we will always need
+            "libgcc",
+            "glibc-devel",
+            "libatomic",
         ]),
     ],
     rootless = True,
@@ -30,16 +31,6 @@ package.unprivileged_dir(
     visibility = ["PUBLIC"],
 )
 
-prelude.prebuilt_cxx_library(
-    name = "libstdc++",
-    exported_linker_flags = [
-        "-std=c++20",
-        "-lstdc++",
-    ],
-    exported_preprocessor_flags = ["-std=c++20"],
-    visibility = ["PUBLIC"],
-)
-
 image.layer(
     name = "base",
     features = [
@@ -73,13 +64,3 @@ image_command_alias(
     rootless = True,
     visibility = ["PUBLIC"],
 )
-
-image_pkgconfig_library(
-    name = "rpm",
-    visibility = ["PUBLIC"],
-)
-
-image_pkgconfig_library(
-    name = "jsoncpp",
-    visibility = ["PUBLIC"],
-)

antlir/distro/deps/glibc/BUCK

@@ -0,0 +1,19 @@
+load("//antlir/distro/deps:sysroot.bzl", "sysroot_dep")
+
+oncall("antlir")
+
+sysroot_dep(
+    name = "c",
+)
+
+sysroot_dep(
+    name = "m",
+)
+
+sysroot_dep(
+    name = "dl",
+)
+
+sysroot_dep(
+    name = "pthread",
+)

antlir/distro/deps/jsoncpp/BUCK

@@ -0,0 +1,8 @@
+load("//antlir/distro/deps:pkgconfig.bzl", "image_pkgconfig_library")
+
+oncall("antlir")
+
+image_pkgconfig_library(
+    name = "jsoncpp",
+    visibility = ["PUBLIC"],
+)

antlir/distro/deps/libgcc/BUCK

@@ -0,0 +1,29 @@
+load("//antlir/distro/deps:sysroot.bzl", "sysroot_dep")
+
+oncall("antlir")
+
+prelude = native
+
+prelude.prebuilt_cxx_library(
+    name = "stdc++",
+    exported_linker_flags = [
+        "-std=c++20",
+        "-lstdc++",
+    ],
+    exported_preprocessor_flags = ["-std=c++20"],
+    visibility = ["PUBLIC"],
+)
+
+prelude.prebuilt_cxx_library(
+    name = "stdc++-legacy",
+    exported_preprocessor_flags = ["-I$(location //antlir/distro/deps:sysroot)/usr/include/c++/11/backward"],
+    visibility = ["PUBLIC"],
+)
+
+sysroot_dep(
+    name = "gcc_s",
+)
+
+sysroot_dep(
+    name = "atomic",
+)

antlir/distro/deps/openmp/BUCK

@@ -0,0 +1,11 @@
+oncall("antlir")
+
+prelude = native
+
+# This exists only because it's an implicit dep added on every cxx target. If it
+# becomes needed by any binaries using the antlir toolchain, someone will need
+# to figure out how to present it.
+prelude.prebuilt_cxx_library(
+    name = "headers",
+    visibility = ["PUBLIC"],
+)

antlir/distro/deps/pkgconfig.bzl

@@ -76,13 +76,12 @@ _pkgconfig = rule(
 def image_pkgconfig_library(
         *,
         name: str,
+        pkgconfig_name: str | None = None,
         visibility: list[str] = ["PUBLIC"],
         deps: list[str] = [],
         exported_preprocessor_flags: list[str] = [],
         compatible_with_os: list[str] = []):
-    # clearly separate out the pkg-config name from the target name in case they
-    # ever need to differ (but hopefully they don't)
-    pkgconfig_name = name
+    pkgconfig_name = pkgconfig_name or name
 
     target_compatible_with = select({
         "DEFAULT": ["antlir//antlir/distro:incompatible"],

antlir/distro/deps/rpm/BUCK

@@ -0,0 +1,11 @@
+load("//antlir/distro/deps:pkgconfig.bzl", "image_pkgconfig_library")
+
+oncall("antlir")
+
+image_pkgconfig_library(
+    # Existing third-party copies of rpm are named 'librpm', so to be consistent
+    # we use 'pkgconfig(rpm)' but name it 'librpm'
+    name = "librpm",
+    pkgconfig_name = "rpm",
+    visibility = ["PUBLIC"],
+)

antlir/distro/deps/sysroot.bzl

@@ -0,0 +1,21 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+def sysroot_dep(
+        *,
+        name: str,
+        link: str | None = None,
+        visibility: list[str] = ["PUBLIC"]):
+    """
+    A cxx_library target that links against a library that exists in the
+    sysroot, but does not have any pkg-config definition, just a linker flag.
+    """
+    native.prebuilt_cxx_library(
+        name = name,
+        exported_linker_flags = [
+            "-l" + (link or name),
+        ],
+        visibility = visibility,
+    )

antlir/distro/toolchain/cxx/tests/BUCK

@@ -23,8 +23,8 @@ prelude.cxx_binary(
     default_target_platform = default_image_platform("centos9"),
     deps = [
         ":dep",
-        "//antlir/distro/deps:jsoncpp",
-        "//antlir/distro/deps:libstdc++",
+        "//antlir/distro/deps/jsoncpp:jsoncpp",
+        "//antlir/distro/deps/libgcc:stdc++",
     ],
 )
 
@@ -36,7 +36,7 @@ cpp_library(
     _cxx_toolchain = "//antlir/distro/toolchain/cxx:toolchain",
     default_target_platform = default_image_platform("centos9"),
     deps = [
-        "//antlir/distro/deps:rpm",
+        "//antlir/distro/deps/rpm:librpm",
     ],
 )