unix: templatize per version Makefile variables and targets

This refactor allows targets for each major Python version to be
defined simultaneously. This opens the door to a single `make`
invocation building multiple versions in parallel.

Author: indygreg

cpython-unix/Makefile

@@ -6,6 +6,8 @@ BUILD := $(HERE)/build.py
 NULL :=
 SPACE := $(subst ,, )
 
+ALL_PYTHON_VERSIONS := 3.9 3.10 3.11 3.12 3.13
+
 ifndef PYBUILD_TARGET_TRIPLE
     $(error PYBUILD_TARGET_TRIPLE not defined)
 endif
@@ -68,7 +70,7 @@ PYTHON_DEP_DEPENDS := \
     $(TOOLCHAIN_DEPENDS) \
     $(NULL)
 
-default: $(OUTDIR)/cpython-$(PYBUILD_PYTHON_VERSION)-$(PACKAGE_SUFFIX).tar
+default: $(OUTDIR)/cpython-$(CPYTHON_$(PYTHON_MAJOR_VERSION)_VERSION)-$(PACKAGE_SUFFIX).tar
 
 ifndef PYBUILD_NO_DOCKER
 $(OUTDIR)/image-%.tar: $(OUTDIR)/%.Dockerfile
@@ -254,26 +256,15 @@ PYTHON_HOST_DEPENDS := \
   $(OUTDIR)/m4-$(M4_VERSION)-$(PACKAGE_SUFFIX).tar \
   $(NULL)
 
-$(OUTDIR)/cpython-3.9-$(CPYTHON_3.9_VERSION)-$(HOST_PLATFORM).tar: $(PYTHON_HOST_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.9-host
-
-$(OUTDIR)/cpython-3.10-$(CPYTHON_3.10_VERSION)-$(HOST_PLATFORM).tar: $(PYTHON_HOST_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.10-host
-
-$(OUTDIR)/cpython-3.11-$(CPYTHON_3.11_VERSION)-$(HOST_PLATFORM).tar: $(PYTHON_HOST_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.11-host
-
-$(OUTDIR)/cpython-3.12-$(CPYTHON_3.12_VERSION)-$(HOST_PLATFORM).tar: $(PYTHON_HOST_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.12-host
-
-$(OUTDIR)/cpython-3.13-$(CPYTHON_3.13_VERSION)-$(HOST_PLATFORM).tar: $(PYTHON_HOST_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.13-host
-
-PYTHON_DEPENDS := \
+# Each X.Y Python version has its own set of variables and targets. This independent
+# definition allows multiple Python versions to be built using the same Makefile
+# invocation.
+define python_version_template =
+PYTHON_DEPENDS_$(1) := \
     $(PYTHON_SUPPORT_FILES) \
     $(OUTDIR)/versions/VERSION.pip \
     $(OUTDIR)/versions/VERSION.setuptools \
-    $(OUTDIR)/cpython-$(PYTHON_MAJOR_VERSION)-$(PYBUILD_PYTHON_VERSION)-$(HOST_PLATFORM).tar \
+    $(OUTDIR)/cpython-$(1)-$$(CPYTHON_$(1)_VERSION)-$(HOST_PLATFORM).tar \
     $(if $(NEED_AUTOCONF),$(OUTDIR)/autoconf-$(AUTOCONF_VERSION)-$(PACKAGE_SUFFIX).tar) \
     $(if $(NEED_BDB),$(OUTDIR)/bdb-$(BDB_VERSION)-$(PACKAGE_SUFFIX).tar) \
     $(if $(NEED_BZIP2),$(OUTDIR)/bzip2-$(BZIP2_VERSION)-$(PACKAGE_SUFFIX).tar) \
@@ -296,23 +287,17 @@ PYTHON_DEPENDS := \
     $(if $(NEED_ZLIB),$(OUTDIR)/zlib-$(ZLIB_VERSION)-$(PACKAGE_SUFFIX).tar) \
     $(NULL)
 
-ALL_PYTHON_DEPENDS = \
-    $(PYTHON_DEP_DEPENDS) \
-    $(HERE)/build-cpython.sh \
-    $(PYTHON_DEPENDS) \
-    $(NULL)
-
-$(OUTDIR)/cpython-$(CPYTHON_3.9_VERSION)-$(PACKAGE_SUFFIX).tar: $(ALL_PYTHON_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.9
-
-$(OUTDIR)/cpython-$(CPYTHON_3.10_VERSION)-$(PACKAGE_SUFFIX).tar: $(ALL_PYTHON_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.10
+ALL_PYTHON_DEPENDS_$(1) = \
+    $$(PYTHON_DEP_DEPENDS) \
+    $$(HERE)/build-cpython.sh \
+    $$(PYTHON_DEPENDS_$(1)) \
+    $$(NULL)
 
-$(OUTDIR)/cpython-$(CPYTHON_3.11_VERSION)-$(PACKAGE_SUFFIX).tar: $(ALL_PYTHON_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.11
+$$(OUTDIR)/cpython-$(1)-$$(CPYTHON_$(1)_VERSION)-$$(HOST_PLATFORM).tar: $$(PYTHON_HOST_DEPENDS)
+	$$(RUN_BUILD) --docker-image $$(DOCKER_IMAGE_BUILD) cpython-$(1)-host
 
-$(OUTDIR)/cpython-$(CPYTHON_3.12_VERSION)-$(PACKAGE_SUFFIX).tar: $(ALL_PYTHON_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.12
+$$(OUTDIR)/cpython-$$(CPYTHON_$(1)_VERSION)-$$(PACKAGE_SUFFIX).tar: $$(ALL_PYTHON_DEPENDS_$(1))
+	$$(RUN_BUILD) --docker-image $$(DOCKER_IMAGE_BUILD) cpython-$(1)
+endef
 
-$(OUTDIR)/cpython-$(CPYTHON_3.13_VERSION)-$(PACKAGE_SUFFIX).tar: $(ALL_PYTHON_DEPENDS)
-	$(RUN_BUILD) --docker-image $(DOCKER_IMAGE_BUILD) cpython-3.13
+$(foreach local_version,$(ALL_PYTHON_VERSIONS),$(eval $(call python_version_template,$(local_version))))

pythonbuild/utils.py

@@ -141,6 +141,12 @@ def write_triples_makefiles(
 
     for triple, settings in targets.items():
         for host_platform in settings["host_platforms"]:
+            # IMPORTANT: if we ever vary the content of these Makefiles by
+            # Python versions, the variable names will need add the Python
+            # version and the Makefile references updated to point to specific
+            # versions. If we don't do that, multi-version builds will fail
+            # to work correctly.
+
             makefile_path = dest_dir / ("Makefile.%s.%s" % (host_platform, triple))
 
             lines = []