First (uncontroversial) part of issue 9807.

* Expose the build flags to Python as sys.abiflags
* Shared library libpythonX.Y<abiflags>.so
* python-config --abiflags
* Make two distutils tests that failed with --enable-shared (even before this
  patch) succeed.
* Fix a few small style issues.

Doc/library/sys.rst

@@ -955,6 +955,11 @@ always available.
    module for informational purposes; modifying this value has no effect on the
    registry keys used by Python. Availability: Windows.
 
+.. data:: abiflags
+
+   On POSIX systems where Python is build with the standard ``configure``
+   script, this contains the ABI flags as specified by :pep:`3149`.
+
 .. rubric:: Citations
 
 .. [C99] ISO/IEC 9899:1999.  "Programming languages -- C."  A public draft of this standard is available at http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf .

Lib/distutils/command/build_ext.py

@@ -754,9 +754,9 @@ def get_libraries(self, ext):
         else:
             from distutils import sysconfig
             if sysconfig.get_config_var('Py_ENABLE_SHARED'):
-                template = "python%d.%d"
-                pythonlib = (template %
-                             (sys.hexversion >> 24, (sys.hexversion >> 16) & 0xff))
+                pythonlib = 'python{}.{}{}'.format(
+                    sys.hexversion >> 24, (sys.hexversion >> 16) & 0xff,
+                    sys.abiflags)
                 return ext.libraries + [pythonlib]
             else:
                 return ext.libraries

Lib/distutils/tests/test_build_ext.py

@@ -1,17 +1,16 @@
 import sys
 import os
-import tempfile
 import shutil
 from io import StringIO
 
-from distutils.core import Extension, Distribution
+from distutils.core import Distribution
 from distutils.command.build_ext import build_ext
 from distutils import sysconfig
 from distutils.tests.support import TempdirManager
 from distutils.tests.support import LoggingSilencer
 from distutils.extension import Extension
-from distutils.errors import (UnknownFileError, DistutilsSetupError,
-                              CompileError)
+from distutils.errors import (
+    CompileError, DistutilsSetupError, UnknownFileError)
 
 import unittest
 from test import support
@@ -42,6 +41,20 @@ def setUp(self):
             from distutils.command import build_ext
             build_ext.USER_BASE = site.USER_BASE
 
+    def _fixup_command(self, cmd):
+        # When Python was build with --enable-shared, -L. is not good enough
+        # to find the libpython<blah>.so.  This is because regrtest runs it
+        # under a tempdir, not in the top level where the .so lives.  By the
+        # time we've gotten here, Python's already been chdir'd to the
+        # tempdir.
+        #
+        # To further add to the fun, we can't just add library_dirs to the
+        # Extension() instance because that doesn't get plumbed through to the
+        # final compiler command.
+        if not sys.platform.startswith('win'):
+            library_dir = sysconfig.get_config_var('srcdir')
+            cmd.library_dirs = [('.' if library_dir is None else library_dir)]
+
     def test_build_ext(self):
         global ALREADY_TESTED
         xx_c = os.path.join(self.tmp_dir, 'xxmodule.c')
@@ -49,6 +62,7 @@ def test_build_ext(self):
         dist = Distribution({'name': 'xx', 'ext_modules': [xx_ext]})
         dist.package_dir = self.tmp_dir
         cmd = build_ext(dist)
+        self._fixup_command(cmd)
         if os.name == "nt":
             # On Windows, we must build a debug version iff running
             # a debug build of Python
@@ -235,7 +249,8 @@ def test_check_extensions_list(self):
         cmd.finalize_options()
 
         #'extensions' option must be a list of Extension instances
-        self.assertRaises(DistutilsSetupError, cmd.check_extensions_list, 'foo')
+        self.assertRaises(DistutilsSetupError,
+                          cmd.check_extensions_list, 'foo')
 
         # each element of 'ext_modules' option must be an
         # Extension instance or 2-tuple
@@ -302,6 +317,7 @@ def test_get_outputs(self):
         dist = Distribution({'name': 'xx',
                              'ext_modules': [ext]})
         cmd = build_ext(dist)
+        self._fixup_command(cmd)
         cmd.ensure_finalized()
         self.assertEquals(len(cmd.get_outputs()), 1)
 

Lib/test/test_sys.py

@@ -468,6 +468,8 @@ def test_attributes(self):
         self.assertTrue(vi > (1,0,0))
         self.assertIsInstance(sys.float_repr_style, str)
         self.assertIn(sys.float_repr_style, ('short', 'legacy'))
+        if not sys.platform.startswith('win'):
+            self.assertIsInstance(sys.abiflags, str)
 
     def test_43581(self):
         # Can't use sys.stdout, as this is a StringIO object when

Makefile.pre.in

@@ -36,6 +36,7 @@ AR=		@AR@
 RANLIB=		@RANLIB@
 SVNVERSION=	@SVNVERSION@
 SOABI=		@SOABI@
+LDVERSION=	@LDVERSION@
 
 GNULD=		@GNULD@
 
@@ -102,6 +103,7 @@ MANDIR=		@mandir@
 INCLUDEDIR=	@includedir@
 CONFINCLUDEDIR=	$(exec_prefix)/include
 SCRIPTDIR=	$(prefix)/lib
+ABIFLAGS=	@ABIFLAGS@
 
 # Detailed destination directories
 BINLIBDEST=	$(LIBDIR)/python$(VERSION)
@@ -445,7 +447,7 @@ $(LIBRARY): $(LIBRARY_OBJS)
 	$(AR) $(ARFLAGS) $@ $(MODOBJS)
 	$(RANLIB) $@
 
-libpython$(VERSION).so: $(LIBRARY_OBJS)
+libpython$(LDVERSION).so: $(LIBRARY_OBJS)
 	if test $(INSTSONAME) != $(LDLIBRARY); then \
 		$(BLDSHARED) -Wl,-h$(INSTSONAME) -o $(INSTSONAME) $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM) $(LDLAST); \
 		$(LN) -f $(INSTSONAME) $@; \
@@ -566,6 +568,11 @@ Python/dynload_shlib.o: $(srcdir)/Python/dynload_shlib.c Makefile
 		-DSOABI='"$(SOABI)"' \
 		-o $@ $(srcdir)/Python/dynload_shlib.c
 
+Python/sysmodule.o: $(srcdir)/Python/sysmodule.c Makefile
+	$(CC) -c $(PY_CORE_CFLAGS) \
+		-DABIFLAGS='"$(ABIFLAGS)"' \
+		-o $@ $(srcdir)/Python/sysmodule.c
+
 $(IO_OBJS): $(IO_H)
 
 # Use a stamp file to prevent make -j invoking pgen twice

Misc/python-config.in

@@ -6,7 +6,7 @@ import sys
 import sysconfig
 
 valid_opts = ['prefix', 'exec-prefix', 'includes', 'libs', 'cflags',
-              'ldflags', 'extension-suffix', 'help']
+              'ldflags', 'extension-suffix', 'help', 'abiflags']
 
 def exit_with_usage(code=1):
     print("Usage: {0} [{1}]".format(
@@ -56,3 +56,6 @@ for opt in opt_flags:
 
     elif opt == '--extension-suffix':
         print(sysconfig.get_config_var('SO'))
+
+    elif opt == '--abiflags':
+        print(sys.abiflags)

Python/sysmodule.c

@@ -1520,6 +1520,10 @@ _PySys_Init(void)
                         PyLong_FromVoidPtr(PyWin_DLLhModule));
     SET_SYS_FROM_STRING("winver",
                         PyUnicode_FromString(PyWin_DLLVersionString));
+#endif
+#ifdef ABIFLAGS
+    SET_SYS_FROM_STRING("abiflags",
+                        PyUnicode_FromString(ABIFLAGS));
 #endif
     if (warnoptions == NULL) {
         warnoptions = PyList_New(0);

configure.in

@@ -602,18 +602,23 @@ AC_MSG_RESULT($LIBRARY)
 #
 # INSTSONAME is the name of the shared library that will be use to install
 # on the system - some systems like version suffix, others don't
+#
+# LDVERSION is the shared library version number, normally the Python version
+# with the ABI build flags appended.
 AC_SUBST(LDLIBRARY)
 AC_SUBST(DLLLIBRARY)
 AC_SUBST(BLDLIBRARY)
 AC_SUBST(LDLIBRARYDIR)
 AC_SUBST(INSTSONAME)
 AC_SUBST(RUNSHARED)
+AC_SUBST(LDVERSION)
 LDLIBRARY="$LIBRARY"
 BLDLIBRARY='$(LDLIBRARY)'
 INSTSONAME='$(LDLIBRARY)'
 DLLLIBRARY=''
 LDLIBRARYDIR=''
 RUNSHARED=''
+LDVERSION="$(VERSION)"
 
 # LINKCC is the command that links the python executable -- default is $(CC).
 # If CXX is set, and if it is needed to link a main function that was
@@ -724,18 +729,18 @@ if test $enable_shared = "yes"; then
   AC_DEFINE(Py_ENABLE_SHARED, 1, [Defined if Python is built as a shared library.])
   case $ac_sys_system in
     CYGWIN*)
-          LDLIBRARY='libpython$(VERSION).dll.a'
-          DLLLIBRARY='libpython$(VERSION).dll'
+          LDLIBRARY='libpython$(LDVERSION).dll.a'
+          DLLLIBRARY='libpython$(LDVERSION).dll'
           ;;
     SunOS*)
-	  LDLIBRARY='libpython$(VERSION).so'
-	  BLDLIBRARY='-Wl,-R,$(LIBDIR) -L. -lpython$(VERSION)'
+	  LDLIBRARY='libpython$(LDVERSION).so'
+	  BLDLIBRARY='-Wl,-R,$(LIBDIR) -L. -lpython$(LDVERSION)'
 	  RUNSHARED=LD_LIBRARY_PATH=`pwd`:${LD_LIBRARY_PATH}
 	  INSTSONAME="$LDLIBRARY".$SOVERSION
           ;;
     Linux*|GNU*|NetBSD*|FreeBSD*|DragonFly*)
-	  LDLIBRARY='libpython$(VERSION).so'
-	  BLDLIBRARY='-L. -lpython$(VERSION)'
+	  LDLIBRARY='libpython$(LDVERSION).so'
+	  BLDLIBRARY='-L. -lpython$(LDVERSION)'
 	  RUNSHARED=LD_LIBRARY_PATH=`pwd`:${LD_LIBRARY_PATH}
 	  case $ac_sys_system in
 	      FreeBSD*)
@@ -747,27 +752,27 @@ if test $enable_shared = "yes"; then
     hp*|HP*)
 	  case `uname -m` in
 		ia64)
-			LDLIBRARY='libpython$(VERSION).so'
+			LDLIBRARY='libpython$(LDVERSION).so'
 			;;
 		*)
-			LDLIBRARY='libpython$(VERSION).sl'
+			LDLIBRARY='libpython$(LDVERSION).sl'
 			;;
 	  esac
-	  BLDLIBRARY='-Wl,+b,$(LIBDIR) -L. -lpython$(VERSION)'
+	  BLDLIBRARY='-Wl,+b,$(LIBDIR) -L. -lpython$(LDVERSION)'
 	  RUNSHARED=SHLIB_PATH=`pwd`:${SHLIB_PATH}
 	  ;;
     OSF*)
-	  LDLIBRARY='libpython$(VERSION).so'
-	  BLDLIBRARY='-rpath $(LIBDIR) -L. -lpython$(VERSION)'
+	  LDLIBRARY='libpython$(LDVERSION).so'
+	  BLDLIBRARY='-rpath $(LIBDIR) -L. -lpython$(LDVERSION)'
 	  RUNSHARED=LD_LIBRARY_PATH=`pwd`:${LD_LIBRARY_PATH}
 	  ;;
     Darwin*)
-    	LDLIBRARY='libpython$(VERSION).dylib'
-	BLDLIBRARY='-L. -lpython$(VERSION)'
+    	LDLIBRARY='libpython$(LDVERSION).dylib'
+	BLDLIBRARY='-L. -lpython$(LDVERSION)'
 	RUNSHARED='DYLD_LIBRARY_PATH=`pwd`:${DYLD_LIBRARY_PATH}'
 	;;
     AIX*)
-	LDLIBRARY='libpython$(VERSION).so'
+	LDLIBRARY='libpython$(LDVERSION).so'
 	RUNSHARED=LIBPATH=`pwd`:${LIBPATH}
 	;;
 
@@ -776,7 +781,7 @@ else # shared is disabled
   case $ac_sys_system in
     CYGWIN*)
           BLDLIBRARY='$(LIBRARY)'
-          LDLIBRARY='libpython$(VERSION).dll.a'
+          LDLIBRARY='libpython$(LDVERSION).dll.a'
           ;;
   esac
 fi
@@ -823,7 +828,8 @@ if test -z "$LN" ; then
 fi
 
 # For calculating the .so ABI tag.
-SOABI_QUALIFIERS=""
+AC_SUBST(ABIFLAGS)
+ABIFLAGS=""
 
 # Check for --with-pydebug
 AC_MSG_CHECKING(for --with-pydebug)
@@ -836,7 +842,7 @@ then
   [Define if you want to build an interpreter with many run-time checks.]) 
   AC_MSG_RESULT(yes); 
   Py_DEBUG='true'
-  SOABI_QUALIFIERS="${SOABI_QUALIFIERS}d"
+  ABIFLAGS="${ABIFLAGS}d"
 else AC_MSG_RESULT(no); Py_DEBUG='false'
 fi],
 [AC_MSG_RESULT(no)])
@@ -2473,7 +2479,7 @@ AC_ARG_WITH(pymalloc,
 if test -z "$with_pymalloc"
 then
     with_pymalloc="yes"
-    SOABI_QUALIFIERS="${SOABI_QUALIFIERS}m"
+    ABIFLAGS="${ABIFLAGS}m"
 fi
 if test "$with_pymalloc" != "no"
 then
@@ -3586,7 +3592,7 @@ AH_TEMPLATE(Py_UNICODE_SIZE,
 case "$unicode_size" in
   4)
      AC_DEFINE(Py_UNICODE_SIZE, 4)
-     SOABI_QUALIFIERS="${SOABI_QUALIFIERS}u"
+     ABIFLAGS="${ABIFLAGS}u"
      ;;
   *) AC_DEFINE(Py_UNICODE_SIZE, 2) ;;
 esac
@@ -3635,10 +3641,16 @@ AC_C_BIGENDIAN
 # would get a shared library ABI version tag of 'cpython-32dmu' and shared
 # libraries would be named 'foo.cpython-32dmu.so'.
 AC_SUBST(SOABI)
+AC_MSG_CHECKING(ABIFLAGS)
+AC_MSG_RESULT($ABIFLAGS)
 AC_MSG_CHECKING(SOABI)
-SOABI='cpython-'`echo $VERSION | tr -d .`${SOABI_QUALIFIERS}
+SOABI='cpython-'`echo $VERSION | tr -d .`${ABIFLAGS}
 AC_MSG_RESULT($SOABI)
 
+AC_MSG_CHECKING(LDVERSION)
+LDVERSION='$(VERSION)$(ABIFLAGS)'
+AC_MSG_RESULT($LDVERSION)
+
 # SO is the extension of shared libraries `(including the dot!)
 # -- usually .so, .sl on HP-UX, .dll on Cygwin
 AC_MSG_CHECKING(SO)