Re: [patch] Try to use python-config to get python include and lib parameters.

[Doug Evans <dje@google.com>]

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On Fri, May 21, 2010 at 9:25 AM, Tom Tromey <tromey@redhat.com> wrote:
>>>>>> "Doug" == Doug Evans <dje@google.com> writes:
>
> Doug> 2010-05-20  Doug Evans  <dje@google.com>
> Doug>         * configure.ac: For non-canadian-cross builds (build == host),
> Doug>         try to use python-config to get python include and lib parameters.
> Doug>         * configure: Regenerate.
>
> It seems reasonable to me.

I've learned that "python-config", which is a python script, can be
pretty much used with any recent python version.
I've also learned that it's not always spelled "python-config" when installed.

This version of the patch provides our own copy in python/python-config.py.
[NOTE: I didn't name it py-config.py on purpose.  It doesn't violate
the 8.3 file name rule, and since there already is python-internal.h
spelled the way it is, I wanted to keep the spelling close to the
public name.]

This version runs python-config.py with the specified copy of python.
Note that it can also work in a cross-compilation environment if the
user provides his/her own script that mimics what `python
python-config.py --includes|--ldflags' does.

I will let it soak until tomorrow.

2010-05-24  Doug Evans  <dje@google.com>

        * configure.ac: Try to use python's distutils to fetch compilation
        parameters.
        * configure: Regenerate.
        * python/python-config.py: New file.

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2010-05-24  Doug Evans  <dje@google.com>

	* configure.ac: Try to use python's distutils to fetch compilation
	parameters.
	* configure: Regenerate.
	* python/python-config.py: New file.

Index: configure.ac
===================================================================
RCS file: /cvs/src/src/gdb/configure.ac,v
retrieving revision 1.117
diff -u -p -r1.117 configure.ac
--- configure.ac	23 Apr 2010 18:07:26 -0000	1.117
+++ configure.ac	24 May 2010 22:43:44 -0000
@@ -589,22 +589,31 @@ else
 fi
 
 dnl Utility to simplify finding libpython.
+dnl $1 = pythonX.Y
+dnl $2 = the shell variable to assign the result to
+dnl      If libpython is found we store $version here.
+dnl $3 = additional flags to add to CPPFLAGS
+dnl $4 = additional flags to add to LIBS
+
 AC_DEFUN([AC_TRY_LIBPYTHON],
 [
   version=$1
   define([have_libpython_var],$2)
-  define([VERSION],[translit([$1],[abcdefghijklmnopqrstuvwxyz./-],
-                                  [ABCDEFGHIJKLMNOPQRSTUVWXYZ___])])
-  [HAVE_LIB]VERSION=no
+  new_CPPFLAGS=$3
+  new_LIBS=$4
   AC_MSG_CHECKING([for ${version}])
+  save_CPPFLAGS=$CPPFLAGS
   save_LIBS=$LIBS
-  LIBS="$LIBS -l${version}"
+  CPPFLAGS="$CPPFLAGS $new_CPPFLAGS"
+  LIBS="$LIBS $new_LIBS"
+  found_usable_python=no
   AC_LINK_IFELSE(AC_LANG_PROGRAM([[#include "${version}/Python.h"]],
                                  [[Py_Initialize ();]]),
-                 [[HAVE_LIB]VERSION=yes
-                  have_libpython_var=yes],
-                 [LIBS=$save_LIBS])
-  AC_MSG_RESULT([$[HAVE_LIB]VERSION])
+                 [have_libpython_var=${version}
+                  found_usable_python=yes],
+                 [CPPFLAGS=$save_CPPFLAGS
+                  LIBS=$save_LIBS])
+  AC_MSG_RESULT([${found_usable_python}])
 ])
 
 AC_ARG_WITH(python,
@@ -617,45 +626,130 @@ if test "${with_python}" = no; then
   AC_MSG_WARN([python support disabled; some features may be unavailable.])
   have_libpython=no
 else
+  have_python_config=no
   case "${with_python}" in
-  yes | auto)
-    # Leave as empty, use defaults.
-    python_includes=
-    python_libs=
-    ;;
   /*)
-    python_includes="-I${with_python}/include"
-    python_libs="-L${with_python}/lib"
+    if test -d ${with_python}; then
+      # Assume the python binary is ${with_python}/bin/python.
+      python_prefix=${with_python}
+      python_prog="${with_python}/bin/python"
+      if test ! -x ${python_prog}; then
+        # Fall back to gdb 7.0/7.1 behaviour.
+        python_prog=missing
+      fi
+    elif test -x ${with_python}; then
+      # While we can't run python compiled for $host (unless host == build),
+      # the user could write a script that provides the needed information,
+      # so we support that.
+      python_prefix=
+      python_prog=${with_python}
+    else
+      AC_ERROR(invalid value for --with-python)
+    fi
     ;;
-  *)
+  */*)
+    # Disallow --with-python=foo/bar.
     AC_ERROR(invalid value for --with-python)
     ;;
+  *)
+    # The user has either specified auto, yes, or the name of the python
+    # program assumed to be in $PATH.
+    python_prefix=
+    case "${with_python}" in
+    yes | auto)
+      if test ${build} = ${host}; then
+        AC_PATH_PROG(python_prog_path, python, missing)
+        if test "${python_prog_path}" = missing; then
+          python_prog=missing
+        else
+          python_prog=${python_prog_path}
+        fi
+      else
+        # Not much we can do except assume the cross-compiler will find the
+        # right files.
+        python_prog=missing
+      fi
+      ;;
+    *)
+      # While we can't run python compiled for $host (unless host == build),
+      # the user could write a script that provides the needed information,
+      # so we support that.
+      python_prog="${with_python}"
+      AC_PATH_PROG(python_prog_path, ${python_prog}, missing)
+      if test "${python_prog_path}" = missing; then
+        AC_ERROR(unable to find python program ${python_prog})
+      fi
+      ;;
+    esac
   esac
 
-  save_CPPFLAGS=$CPPFLAGS
-  CPPFLAGS="$CPPFLAGS ${python_includes}"
-  save_LIBS=$LIBS
-  LIBS="$LIBS ${python_libs}"
-  have_libpython=no
-  if test "${have_libpython}" = no; then
-    AC_TRY_LIBPYTHON(python2.6, have_libpython)
-    if test "${HAVE_LIBPYTHON2_6}" = yes; then
-      AC_DEFINE(HAVE_LIBPYTHON2_6, 1, [Define if Python 2.6 is being used.])
+  if test "${python_prog}" != missing; then
+    python_includes=`${python_prog} ${srcdir}/python/python-config.py --includes`
+    if test $? != 0; then
+      AC_ERROR(failure running python-config --includes)
     fi
-  fi
-  if test ${have_libpython} = no; then
-    AC_TRY_LIBPYTHON(python2.5, have_libpython)
-    if test "${HAVE_LIBPYTHON2_5}" = yes; then
-      AC_DEFINE(HAVE_LIBPYTHON2_5, 1, [Define if Python 2.5 is being used.])
+    python_libs=`${python_prog} ${srcdir}/python/python-config.py --ldflags`
+    if test $? != 0; then
+      AC_ERROR(failure running python-config --ldflags)
+    fi
+    have_python_config=yes
+  else
+    # Fall back to gdb 7.0/7.1 behaviour.
+    if test -z ${python_prefix}; then
+      python_includes=
+      python_libs=
+    else
+      python_includes="-I${python_prefix}/include"
+      python_libs="-L${python_prefix}/lib"
     fi
   fi
-  if test ${have_libpython} = no; then
-    AC_TRY_LIBPYTHON(python2.4, have_libpython)
-    if test "${HAVE_LIBPYTHON2_4}" = yes; then
-      AC_DEFINE(HAVE_LIBPYTHON2_4, 1, [Define if Python 2.4 is being used.])
+
+  # Having "/pythonX.Y" in the include path is awkward.
+  # All those python headers get bubbled up to the top inviting lots
+  # of random collisions.  GDB originally didn't use python-config to
+  # find the compilation parameters and includes "pythonX.Y/" in the
+  # path of the, umm, include file.  So strip away this part of the
+  # output of python-config --includes.
+  python_includes=`echo "${python_includes} " \
+  			| sed -e 's,/python[[0-9]]*[[.]][[0-9]]* , ,g'`
+
+  # If we have python-config, only try the configuration it provides.
+  # Otherwise fallback on the old way of trying different versions of
+  # python in turn.
+
+  have_libpython=no
+  if test "${have_python_config}" = yes; then
+    python_version=`echo " ${python_libs} " \
+    			 | sed -e 's,^.* -l\(python[[0-9]]*[[.]][[0-9]]*\) .*$,\1,'`
+    if test "${python_version}" != ""; then
+      AC_TRY_LIBPYTHON(${python_version}, have_libpython,
+                       ${python_includes}, ${python_libs})
+    else
+      AC_MSG_ERROR([unable to determine python version from ${python_libs}])
+    fi
+  else
+    if test "${have_libpython}" = no; then
+      AC_TRY_LIBPYTHON(python2.6, have_libpython,
+                       ${python_includes}, "${python_libs} -lpython2.6")
+    fi
+    if test ${have_libpython} = no; then
+      AC_TRY_LIBPYTHON(python2.5, have_libpython,
+                       ${python_includes}, "${python_libs} -lpython2.5")
     fi
+    if test ${have_libpython} = no; then
+      AC_TRY_LIBPYTHON(python2.4, have_libpython,
+                       ${python_includes}, "${python_libs} -lpython2.4")
+    fi
+  fi
+  if test "${have_libpython}" = python2.6; then
+    AC_DEFINE(HAVE_LIBPYTHON2_6, 1, [Define if Python 2.6 is being used.])
+  elif test "${have_libpython}" = python2.5; then
+    AC_DEFINE(HAVE_LIBPYTHON2_5, 1, [Define if Python 2.5 is being used.])
+  elif test "${have_libpython}" = python2.4; then
+    AC_DEFINE(HAVE_LIBPYTHON2_4, 1, [Define if Python 2.4 is being used.])
   fi
-  if test ${have_libpython} = no; then
+
+  if test "${have_libpython}" = no; then
     case "${with_python}" in
     yes)
       AC_MSG_ERROR([python is missing or unusable])
@@ -667,12 +761,10 @@ else
       AC_MSG_ERROR([no usable python found at ${with_python}])
       ;;
     esac
-    CPPFLAGS=$save_CPPFLAGS
-    LIBS=$save_LIBS
   fi
 fi
 
-if test "${have_libpython}" = yes; then
+if test "${have_libpython}" != no; then
   AC_DEFINE(HAVE_PYTHON, 1, [Define if Python interpreter is being linked in.])
   CONFIG_OBS="$CONFIG_OBS \$(SUBDIR_PYTHON_OBS)"
   CONFIG_DEPS="$CONFIG_DEPS \$(SUBDIR_PYTHON_DEPS)"
Index: python/python-config.py
===================================================================
RCS file: python/python-config.py
diff -N python/python-config.py
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ python/python-config.py	24 May 2010 22:43:44 -0000
@@ -0,0 +1,54 @@
+# Program to fetch python compilation parameters.
+# Copied from python-config of the 2.6.5 release.
+
+import sys
+import os
+import getopt
+from distutils import sysconfig
+
+valid_opts = ['prefix', 'exec-prefix', 'includes', 'libs', 'cflags', 
+              'ldflags', 'help']
+
+def exit_with_usage(code=1):
+    print >>sys.stderr, "Usage: %s [%s]" % (sys.argv[0], 
+                                            '|'.join('--'+opt for opt in valid_opts))
+    sys.exit(code)
+
+try:
+    opts, args = getopt.getopt(sys.argv[1:], '', valid_opts)
+except getopt.error:
+    exit_with_usage()
+
+if not opts:
+    exit_with_usage()
+
+opt = opts[0][0]
+
+pyver = sysconfig.get_config_var('VERSION')
+getvar = sysconfig.get_config_var
+
+if opt == '--help':
+    exit_with_usage(0)
+
+elif opt == '--prefix':
+    print sysconfig.PREFIX
+
+elif opt == '--exec-prefix':
+    print sysconfig.EXEC_PREFIX
+
+elif opt in ('--includes', '--cflags'):
+    flags = ['-I' + sysconfig.get_python_inc(),
+             '-I' + sysconfig.get_python_inc(plat_specific=True)]
+    if opt == '--cflags':
+        flags.extend(getvar('CFLAGS').split())
+    print ' '.join(flags)
+
+elif opt in ('--libs', '--ldflags'):
+    libs = getvar('LIBS').split() + getvar('SYSLIBS').split()
+    libs.append('-lpython'+pyver)
+    # add the prefix/lib/pythonX.Y/config dir, but only if there is no
+    # shared library in prefix/lib/.
+    if opt == '--ldflags' and not getvar('Py_ENABLE_SHARED'):
+        libs.insert(0, '-L' + getvar('LIBPL'))
+    print ' '.join(libs)
+