POC: Add a relocatable build flag

cpython-unix/build-cpython.sh

@@ -58,6 +58,14 @@ cat Makefile.extra
 
 pushd Python-${PYTHON_VERSION}
 
+
+if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_15}" ]; then
+    # add `--enable-relocatable`
+    patch -p1 -i ${ROOT}/patch-relocatable-flag.patch
+    # add native support for rpath
+    patch -p1 -i ${ROOT}/patch-relocatable-link.patch
+fi
+
 # configure doesn't support cross-compiling on Apple. Teach it.
 if [[ "${PYBUILD_PLATFORM}" = macos* ]]; then
     if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_13}" ]; then
@@ -157,10 +165,12 @@ fi
 
 # The default build rule for the macOS dylib doesn't pick up libraries
 # from modules / makesetup. So patch it accordingly.
-if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_13}" ]; then
-    patch -p1 -i ${ROOT}/patch-macos-link-extension-modules-13.patch
-else
-    patch -p1 -i ${ROOT}/patch-macos-link-extension-modules.patch
+if [ -n "${PYTHON_MEETS_MAXIMUM_VERSION_3_14}" ]; then
+    if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_13}" ]; then
+        patch -p1 -i ${ROOT}/patch-macos-link-extension-modules-13.patch
+    else
+        patch -p1 -i ${ROOT}/patch-macos-link-extension-modules.patch
+    fi
 fi
 
 # Also on macOS, the `python` executable is linked against libraries defined by statically
@@ -369,6 +379,11 @@ if [[ "${PYBUILD_PLATFORM}" = macos* ]]; then
     LDFLAGS="${LDFLAGS} -Wl,-headerpad,40"
 fi
 
+
+if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_15}" ]; then
+    EXTRA_CONFIGURE_FLAGS="${EXTRA_CONFIGURE_FLAGS} --enable-relocatable"
+fi
+
 CPPFLAGS=$CFLAGS
 
 CONFIGURE_FLAGS="
@@ -676,7 +691,8 @@ fi
 # If we're building a shared library hack some binaries so rpath is set.
 # This ensures we can run the binary in any location without
 # LD_LIBRARY_PATH pointing to the directory containing libpython.
-if [ "${PYBUILD_SHARED}" = "1" ]; then
+# In 3.15+, we've upstreamed this behavior
+if [[ "${PYBUILD_SHARED}" = "1"  && -n "${PYTHON_MEETS_MAXIMUM_VERSION_3_14}" ]]; then
     if [[ "${PYBUILD_PLATFORM}" = macos* ]]; then
         # There's only 1 dylib produced on macOS and it has the binary suffix.
         LIBPYTHON_SHARED_LIBRARY_BASENAME=libpython${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}.dylib
@@ -816,6 +832,12 @@ if [ "${PYBUILD_SHARED}" = "1" ]; then
             fi
         fi
     fi
+else
+    # For Python 3.15+ on Linux, we still need to define LIBPYTHON_SHARED_LIBRARY for glibc version detection
+    if [[ "${PYBUILD_PLATFORM}" != macos* ]]; then
+        LIBPYTHON_SHARED_LIBRARY_BASENAME=libpython${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}.so.1.0
+        LIBPYTHON_SHARED_LIBRARY=${ROOT}/out/python/install/lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}
+    fi
 fi
 
 # Install setuptools and pip as they are common tools that should be in any

cpython-unix/patch-relocatable-flag.patch

@@ -0,0 +1,121 @@
+commit 6187c3916ac1e7e6eb2bff7ca5f976c99cbe273b
+Author: Zanie Blue <[email protected]>
+Date:   Sat Nov 15 08:47:20 2025 -0600
+
+    Add an `--enable-relocatable` configure flag
+
+diff --git a/Makefile.pre.in b/Makefile.pre.in
+index 19423c11545..6c9cba59e27 100644
+--- a/Makefile.pre.in
++++ b/Makefile.pre.in
+@@ -60,6 +60,7 @@ DSYMUTIL=       @DSYMUTIL@
+ DSYMUTIL_PATH=  @DSYMUTIL_PATH@
+
+ GNULD=		@GNULD@
++RELOCATABLE=	@RELOCATABLE@
+
+ # Shell used by make (some versions default to the login shell, which is bad)
+ SHELL=		/bin/sh -e
+diff --git a/configure b/configure
+index 9757b3419d3..38f2d4dfbf2 100755
+--- a/configure
++++ b/configure
+@@ -949,6 +949,7 @@ LINK_PYTHON_DEPS
+ LIBRARY_DEPS
+ HOSTRUNNER
+ NODE
++RELOCATABLE
+ STATIC_LIBPYTHON
+ GNULD
+ EXPORTSFROM
+@@ -1091,6 +1092,7 @@ with_suffix
+ enable_shared
+ with_static_libpython
+ enable_profiling
++enable_relocatable
+ enable_gil
+ with_pydebug
+ with_trace_refs
+@@ -1826,6 +1828,8 @@ Optional Features:
+                           no)
+   --enable-profiling      enable C-level code profiling with gprof (default is
+                           no)
++  --enable-relocatable    enable build of a relocatable Python distribution
++                          (default is no)
+   --disable-gil           enable support for running without the GIL (default
+                           is no)
+   --enable-pystats        enable internal statistics gathering (default is no)
+@@ -7673,6 +7677,31 @@ if test "x$enable_profiling" = xyes; then
+   LDFLAGS="-pg $LDFLAGS"
+ fi
+
++{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for --enable-relocatable" >&5
++printf %s "checking for --enable-relocatable... " >&6; }
++# Check whether --enable-relocatable was given.
++if test ${enable_relocatable+y}
++then :
++  enableval=$enable_relocatable;
++fi
++
++if test -z "$enable_relocatable"
++then
++  enable_relocatable="no"
++fi
++{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $enable_relocatable" >&5
++printf "%s\n" "$enable_relocatable" >&6; }
++
++if test "x$enable_relocatable" = xyes; then
++
++printf "%s\n" "#define Py_ENABLE_RELOCATABLE 1" >>confdefs.h
++
++  RELOCATABLE=yes
++else
++  RELOCATABLE=no
++fi
++
++
+ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking LDLIBRARY" >&5
+ printf %s "checking LDLIBRARY... " >&6; }
+
+diff --git a/configure.ac b/configure.ac
+index f244e0b71a6..b1c859071f4 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -1523,6 +1523,23 @@ if test "x$enable_profiling" = xyes; then
+   LDFLAGS="-pg $LDFLAGS"
+ fi
+
++AC_MSG_CHECKING([for --enable-relocatable])
++AC_ARG_ENABLE([relocatable],
++              AS_HELP_STRING([--enable-relocatable], [enable build of a relocatable Python distribution (default is no)]))
++if test -z "$enable_relocatable"
++then
++  enable_relocatable="no"
++fi
++AC_MSG_RESULT([$enable_relocatable])
++
++if test "x$enable_relocatable" = xyes; then
++  AC_DEFINE([Py_ENABLE_RELOCATABLE], [1], [Define if --enable-relocatable is used])
++  RELOCATABLE=yes
++else
++  RELOCATABLE=no
++fi
++AC_SUBST([RELOCATABLE])
++
+ AC_MSG_CHECKING([LDLIBRARY])
+
+ # Apple framework builds need more magic. LDLIBRARY is the dynamic
+diff --git a/pyconfig.h.in b/pyconfig.h.in
+index 72870411bc0..76fe6a9b52c 100644
+--- a/pyconfig.h.in
++++ b/pyconfig.h.in
+@@ -1733,6 +1733,9 @@
+ /* Define if you want to build an interpreter with many run-time checks. */
+ #undef Py_DEBUG
+
++/* Define if --enable-relocatable is used */
++#undef Py_ENABLE_RELOCATABLE
++
+ /* Defined if Python is built as a shared library. */
+ #undef Py_ENABLE_SHARED
+

cpython-unix/patch-relocatable-link.patch

@@ -0,0 +1,70 @@
+commit 34915211b42a64082e0470ebb9a8c4f2ebb20512
+Author: Zanie Blue <[email protected]>
+Date:   Fri Nov 21 15:44:42 2025 -0600
+
+    Set linker arguments when `--enabled-relocatable` is used
+
+diff --git a/Makefile.pre.in b/Makefile.pre.in
+index 6c9cba59e27..6c89690c35e 100644
+--- a/Makefile.pre.in
++++ b/Makefile.pre.in
+@@ -1025,10 +1025,19 @@ libpython$(LDVERSION).so: $(LIBRARY_OBJS) $(DTRACE_OBJS)
+ 	fi
+
+ libpython3.so:	libpython$(LDVERSION).so
+-	$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^
++	if [ "$(RELOCATABLE)" = "yes" ]; then \
++		$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ -Wl,-rpath,'$$ORIGIN' $^; \
++	else \
++		$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^; \
++	fi
+
+ libpython$(LDVERSION).dylib: $(LIBRARY_OBJS)
+-	 $(CC) -dynamiclib $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(SHLIBS) $(LIBC) $(LIBM); \
++	if [ "$(RELOCATABLE)" = "yes" ]; then \
++		install_name="@executable_path/../lib/libpython$(LDVERSION).dylib"; \
++	else \
++		install_name="$(prefix)/lib/libpython$(LDVERSION).dylib"; \
++	fi; \
++	$(CC) -dynamiclib $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$$install_name -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM);
+
+
+ libpython$(VERSION).sl: $(LIBRARY_OBJS)
+diff --git a/configure b/configure
+index 38f2d4dfbf2..9991932680e 100755
+--- a/configure
++++ b/configure
+@@ -13749,7 +13749,13 @@ then
+ 	    LINKFORSHARED="-Wl,-E -Wl,+s";;
+ #	    LINKFORSHARED="-Wl,-E -Wl,+s -Wl,+b\$(BINLIBDEST)/lib-dynload";;
+ 	Linux-android*) LINKFORSHARED="-pie -Xlinker -export-dynamic";;
+-	Linux*|GNU*) LINKFORSHARED="-Xlinker -export-dynamic";;
++	Linux*|GNU*)
++		LINKFORSHARED="-Xlinker -export-dynamic"
++		# Add rpath for relocatable builds
++		if test "x$enable_relocatable" = xyes; then
++			LINKFORSHARED="$LINKFORSHARED -Wl,-rpath=\$ORIGIN/../lib"
++		fi
++		;;
+ 	# -u libsys_s pulls in all symbols in libsys
+ 	Darwin/*|iOS/*)
+ 		LINKFORSHARED="$extra_undefs -framework CoreFoundation"
+diff --git a/configure.ac b/configure.ac
+index b1c859071f4..f75f41441e2 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -3613,7 +3613,13 @@ then
+ 	    LINKFORSHARED="-Wl,-E -Wl,+s";;
+ #	    LINKFORSHARED="-Wl,-E -Wl,+s -Wl,+b\$(BINLIBDEST)/lib-dynload";;
+ 	Linux-android*) LINKFORSHARED="-pie -Xlinker -export-dynamic";;
+-	Linux*|GNU*) LINKFORSHARED="-Xlinker -export-dynamic";;
++	Linux*|GNU*)
++		LINKFORSHARED="-Xlinker -export-dynamic"
++		# Add rpath for relocatable builds
++		if test "x$enable_relocatable" = xyes; then
++			LINKFORSHARED="$LINKFORSHARED -Wl,-rpath=\$ORIGIN/../lib"
++		fi
++		;;
+ 	# -u libsys_s pulls in all symbols in libsys
+ 	Darwin/*|iOS/*)
+ 		LINKFORSHARED="$extra_undefs -framework CoreFoundation"