Use host CPython as Python dependency; remove xcb image

The `xcb` Dockerfile / image existed to provide a host build of CPython,
which was required to build libxcb, xcb-proto, and tk. The existence of this
image predated our building a host CPython in order to build CPython itself.

With PBS now unconditionally building a host CPython, we can use our host
CPython during the builds of these packages, eliminating the need for the
xcb image.

This commit makes that transition.

Author: indygreg

.github/workflows/linux.yml

@@ -60,9 +60,6 @@ jobs:
           - build.cross
           - build.cross-riscv64
           - gcc
-          - xcb
-          - xcb.cross
-          - xcb.cross-riscv64
     name: ${{ matrix.image }}
     runs-on: depot-ubuntu-22.04
     permissions:

cpython-unix/Makefile

@@ -70,6 +70,8 @@ PYTHON_DEP_DEPENDS := \
     $(TOOLCHAIN_DEPENDS) \
     $(NULL)
 
+HOST_PYTHON_DEPENDS := $(OUTDIR)/cpython-$(PYTHON_MAJOR_VERSION)-$(CPYTHON_$(PYTHON_MAJOR_VERSION)_VERSION)-$(HOST_PLATFORM).tar
+
 default: $(OUTDIR)/cpython-$(CPYTHON_$(PYTHON_MAJOR_VERSION)_VERSION)-$(PACKAGE_SUFFIX).tar
 
 ifndef PYBUILD_NO_DOCKER
@@ -149,16 +151,16 @@ $(OUTDIR)/libXau-$(LIBXAU_VERSION)-$(PACKAGE_SUFFIX).tar: $(LIBXAU_DEPENDS)
 
 LIBXCB_DEPENDS = \
     $(PYTHON_DEP_DEPENDS) \
+    $(HOST_PYTHON_DEPENDS) \
     $(HERE)/build-libxcb.sh \
-    $(OUTDIR)/image-$(DOCKER_IMAGE_XCB).tar \
     $(OUTDIR)/xcb-proto-$(XCB_PROTO_VERSION)-$(PACKAGE_SUFFIX).tar \
     $(OUTDIR)/libXau-$(LIBXAU_VERSION)-$(PACKAGE_SUFFIX).tar \
     $(OUTDIR)/xorgproto-$(XORGPROTO_VERSION)-$(PACKAGE_SUFFIX).tar \
     $(OUTDIR)/libpthread-stubs-$(LIBPTHREAD_STUBS_VERSION)-$(PACKAGE_SUFFIX).tar \
     $(NULL)
 
 $(OUTDIR)/libxcb-$(LIBXCB_VERSION)-$(PACKAGE_SUFFIX).tar: $(LIBXCB_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_XCB) libxcb
+	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) --python-host-version $(PYBUILD_PYTHON_VERSION) libxcb
 
 $(OUTDIR)/m4-$(M4_VERSION)-$(PACKAGE_SUFFIX).tar: $(PYTHON_DEP_DEPENDS) $(HERE)/build-m4.sh
 	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) m4
@@ -204,22 +206,23 @@ $(OUTDIR)/tix-$(TIX_VERSION)-$(PACKAGE_SUFFIX).tar: $(TIX_DEPENDS)
 	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) tix
 
 TK_DEPENDS = \
+    $(HOST_PYTHON_DEPENDS) \
     $(HERE)/build-tk.sh \
     $(OUTDIR)/tcl-$(TCL_VERSION)-$(PACKAGE_SUFFIX).tar \
     $(if $(NEED_LIBX11),$(OUTDIR)/libX11-$(LIBX11_VERSION)-$(PACKAGE_SUFFIX).tar) \
     $(NULL)
 
 $(OUTDIR)/tk-$(TK_VERSION)-$(PACKAGE_SUFFIX).tar: $(TK_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_XCB) tk
+	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) --python-host-version $(PYBUILD_PYTHON_VERSION) tk
 
 $(OUTDIR)/uuid-$(UUID_VERSION)-$(PACKAGE_SUFFIX).tar: $(PYTHON_DEP_DEPENDS) $(HERE)/build-uuid.sh
 	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) uuid
 
 $(OUTDIR)/x11-util-macros-$(X11_UTIL_MACROS_VERSION)-$(PACKAGE_SUFFIX).tar: $(PYTHON_DEP_DEPENDS) $(HERE)/build-x11-util-macros.sh
 	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) x11-util-macros
 
-$(OUTDIR)/xcb-proto-$(XCB_PROTO_VERSION)-$(PACKAGE_SUFFIX).tar: $(PYTHON_DEP_DEPENDS) $(HERE)/build-xcb-proto.sh
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_XCB) xcb-proto
+$(OUTDIR)/xcb-proto-$(XCB_PROTO_VERSION)-$(PACKAGE_SUFFIX).tar: $(PYTHON_DEP_DEPENDS) $(HOST_PYTHON_DEPENDS) $(HERE)/build-xcb-proto.sh
+	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) --python-host-version $(PYBUILD_PYTHON_VERSION) xcb-proto
 
 $(OUTDIR)/xorgproto-$(XORGPROTO_VERSION)-$(PACKAGE_SUFFIX).tar: $(PYTHON_DEP_DEPENDS) $(HERE)/build-xorgproto.sh
 	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) xorgproto

cpython-unix/build.py

@@ -246,6 +246,7 @@ def simple_build(
     dest_archive,
     extra_archives=None,
     tools_path="deps",
+    python_host_version=None,
 ):
     archive = download_entry(entry, DOWNLOADS_PATH)
 
@@ -264,6 +265,12 @@ def simple_build(
         for a in extra_archives or []:
             build_env.install_artifact_archive(BUILD, a, target_triple, build_options)
 
+        if python_host_version:
+            majmin = ".".join(python_host_version.split(".")[0:2])
+            build_env.install_toolchain_archive(
+                BUILD, f"cpython-{majmin}", host_platform, version=python_host_version,
+            )
+
         build_env.copy_file(archive)
         build_env.copy_file(SUPPORT / ("build-%s.sh" % entry))
 
@@ -796,6 +803,7 @@ def build_cpython(
         for p in sorted(packages):
             build_env.install_artifact_archive(BUILD, p, target_triple, build_options)
 
+        # Install the host CPython.
         build_env.install_toolchain_archive(
             BUILD, entry_name, host_platform, version=python_version
         )
@@ -1032,6 +1040,11 @@ def main():
         default=None,
         help="A custom path to CPython source files to use",
     )
+    parser.add_argument(
+        "--python-host-version",
+        default=None,
+        help="Python X.Y version for host Python installation",
+    )
     parser.add_argument("action")
 
     args = parser.parse_args()
@@ -1047,6 +1060,8 @@ def main():
     dest_archive = pathlib.Path(args.dest_archive)
     docker_image = args.docker_image
 
+    python_host_version = args.python_host_version
+
     settings = get_target_settings(TARGETS_CONFIG, target_triple)
 
     if args.action == "dockerfiles":
@@ -1213,6 +1228,7 @@ def main():
                 target_triple=target_triple,
                 build_options=build_options,
                 dest_archive=dest_archive,
+                python_host_version=python_host_version,
             )
 
         elif action == "libxcb":
@@ -1226,6 +1242,7 @@ def main():
                 build_options=build_options,
                 dest_archive=dest_archive,
                 extra_archives={"libpthread-stubs", "libXau", "xcb-proto", "xorgproto"},
+                python_host_version=python_host_version,
             )
 
         elif action == "tix":
@@ -1260,6 +1277,7 @@ def main():
                 build_options=build_options,
                 dest_archive=dest_archive,
                 extra_archives=extra_archives,
+                python_host_version=python_host_version,
             )
 
         elif action.startswith("cpython-") and action.endswith("-host"):

cpython-unix/xcb.Dockerfile

@@ -195,7 +195,6 @@ def write_triples_makefiles(
             image_suffix = settings.get("docker_image_suffix", "")
 
             lines.append("DOCKER_IMAGE_BUILD := build%s\n" % image_suffix)
-            lines.append("DOCKER_IMAGE_XCB := xcb%s\n" % image_suffix)
 
             entry = clang_toolchain(host_platform, triple)
             lines.append(