hghave: add "absimport" feature to check "absolute_import" in __future__

This patch adds "absimport" feature to check whether "absolute_import"
exists in __future__, which means supporting module loading by
absolute name.

This check is needed for portability of test code using
"absolute_import", because Python earlier than 2.5 doesn't support it.

tests/hghave.py

@@ -1,321 +1,327
 import os, stat, socket
 import re
 import sys
 import tempfile
 
 tempprefix = 'hg-hghave-'
 
 def matchoutput(cmd, regexp, ignorestatus=False):
     """Return True if cmd executes successfully and its output
     is matched by the supplied regular expression.
     """
     r = re.compile(regexp)
     fh = os.popen(cmd)
     s = fh.read()
     try:
         ret = fh.close()
     except IOError:
         # Happen in Windows test environment
         ret = 1
     return (ignorestatus or ret is None) and r.search(s)
 
 def has_baz():
     return matchoutput('baz --version 2>&1', r'baz Bazaar version')
 
 def has_bzr():
     try:
         import bzrlib
         return bzrlib.__doc__ is not None
     except ImportError:
         return False
 
 def has_bzr114():
     try:
         import bzrlib
         return (bzrlib.__doc__ is not None
                 and bzrlib.version_info[:2] >= (1, 14))
     except ImportError:
         return False
 
 def has_cvs():
     re = r'Concurrent Versions System.*?server'
     return matchoutput('cvs --version 2>&1', re) and not has_msys()
 
 def has_cvs112():
     re = r'Concurrent Versions System \(CVS\) 1.12.*?server'
     return matchoutput('cvs --version 2>&1', re) and not has_msys()
 
 def has_darcs():
     return matchoutput('darcs --version', r'2\.[2-9]', True)
 
 def has_mtn():
     return matchoutput('mtn --version', r'monotone', True) and not matchoutput(
         'mtn --version', r'monotone 0\.', True)
 
 def has_eol_in_paths():
     try:
         fd, path = tempfile.mkstemp(dir='.', prefix=tempprefix, suffix='\n\r')
         os.close(fd)
         os.remove(path)
         return True
     except (IOError, OSError):
         return False
 
 def has_executablebit():
     try:
         EXECFLAGS = stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH
         fh, fn = tempfile.mkstemp(dir='.', prefix=tempprefix)
         try:
             os.close(fh)
             m = os.stat(fn).st_mode & 0777
             new_file_has_exec = m & EXECFLAGS
             os.chmod(fn, m ^ EXECFLAGS)
             exec_flags_cannot_flip = ((os.stat(fn).st_mode & 0777) == m)
         finally:
             os.unlink(fn)
     except (IOError, OSError):
         # we don't care, the user probably won't be able to commit anyway
         return False
     return not (new_file_has_exec or exec_flags_cannot_flip)
 
 def has_icasefs():
     # Stolen from mercurial.util
     fd, path = tempfile.mkstemp(dir='.', prefix=tempprefix)
     os.close(fd)
     try:
         s1 = os.stat(path)
         d, b = os.path.split(path)
         p2 = os.path.join(d, b.upper())
         if path == p2:
             p2 = os.path.join(d, b.lower())
         try:
             s2 = os.stat(p2)
             return s2 == s1
         except OSError:
             return False
     finally:
         os.remove(path)
 
 def has_inotify():
     try:
         import hgext.inotify.linux.watcher
     except ImportError:
         return False
     name = tempfile.mktemp(dir='.', prefix=tempprefix)
     sock = socket.socket(socket.AF_UNIX)
     try:
         sock.bind(name)
     except socket.error:
         return False
     sock.close()
     os.unlink(name)
     return True
 
 def has_fifo():
     if getattr(os, "mkfifo", None) is None:
         return False
     name = tempfile.mktemp(dir='.', prefix=tempprefix)
     try:
         os.mkfifo(name)
         os.unlink(name)
         return True
     except OSError:
         return False
 
 def has_killdaemons():
     return True
 
 def has_cacheable_fs():
     from mercurial import util
 
     fd, path = tempfile.mkstemp(dir='.', prefix=tempprefix)
     os.close(fd)
     try:
         return util.cachestat(path).cacheable()
     finally:
         os.remove(path)
 
 def has_lsprof():
     try:
         import _lsprof
         return True
     except ImportError:
         return False
 
 def has_gettext():
     return matchoutput('msgfmt --version', 'GNU gettext-tools')
 
 def has_git():
     return matchoutput('git --version 2>&1', r'^git version')
 
 def has_docutils():
     try:
         from docutils.core import publish_cmdline
         return True
     except ImportError:
         return False
 
 def getsvnversion():
     m = matchoutput('svn --version --quiet 2>&1', r'^(\d+)\.(\d+)')
     if not m:
         return (0, 0)
     return (int(m.group(1)), int(m.group(2)))
 
 def has_svn15():
     return getsvnversion() >= (1, 5)
 
 def has_svn13():
     return getsvnversion() >= (1, 3)
 
 def has_svn():
     return matchoutput('svn --version 2>&1', r'^svn, version') and \
         matchoutput('svnadmin --version 2>&1', r'^svnadmin, version')
 
 def has_svn_bindings():
     try:
         import svn.core
         version = svn.core.SVN_VER_MAJOR, svn.core.SVN_VER_MINOR
         if version < (1, 4):
             return False
         return True
     except ImportError:
         return False
 
 def has_p4():
     return (matchoutput('p4 -V', r'Rev\. P4/') and
             matchoutput('p4d -V', r'Rev\. P4D/'))
 
 def has_symlink():
     if getattr(os, "symlink", None) is None:
         return False
     name = tempfile.mktemp(dir='.', prefix=tempprefix)
     try:
         os.symlink(".", name)
         os.unlink(name)
         return True
     except (OSError, AttributeError):
         return False
 
 def has_hardlink():
     from mercurial import util
     fh, fn = tempfile.mkstemp(dir='.', prefix=tempprefix)
     os.close(fh)
     name = tempfile.mktemp(dir='.', prefix=tempprefix)
     try:
         try:
             util.oslink(fn, name)
             os.unlink(name)
             return True
         except OSError:
             return False
     finally:
         os.unlink(fn)
 
 def has_tla():
     return matchoutput('tla --version 2>&1', r'The GNU Arch Revision')
 
 def has_gpg():
     return matchoutput('gpg --version 2>&1', r'GnuPG')
 
 def has_unix_permissions():
     d = tempfile.mkdtemp(dir='.', prefix=tempprefix)
     try:
         fname = os.path.join(d, 'foo')
         for umask in (077, 007, 022):
             os.umask(umask)
             f = open(fname, 'w')
             f.close()
             mode = os.stat(fname).st_mode
             os.unlink(fname)
             if mode & 0777 != ~umask & 0666:
                 return False
         return True
     finally:
         os.rmdir(d)
 
 def has_pyflakes():
     return matchoutput("sh -c \"echo 'import re' 2>&1 | pyflakes\"",
                        r"<stdin>:1: 're' imported but unused",
                        True)
 
 def has_pygments():
     try:
         import pygments
         return True
     except ImportError:
         return False
 
 def has_outer_repo():
     # failing for other reasons than 'no repo' imply that there is a repo
     return not matchoutput('hg root 2>&1',
                            r'abort: no repository found', True)
 
 def has_ssl():
     try:
         import ssl
         import OpenSSL
         OpenSSL.SSL.Context
         return True
     except ImportError:
         return False
 
 def has_windows():
     return os.name == 'nt'
 
 def has_system_sh():
     return os.name != 'nt'
 
 def has_serve():
     return os.name != 'nt' # gross approximation
 
 def has_tic():
     return matchoutput('test -x "`which tic`"', '')
 
 def has_msys():
     return os.getenv('MSYSTEM')
 
 def has_aix():
     return sys.platform.startswith("aix")
 
+def has_absimport():
+    import __future__
+    from mercurial import util
+    return util.safehasattr(__future__, "absolute_import")
+
 checks = {
     "true": (lambda: True, "yak shaving"),
     "false": (lambda: False, "nail clipper"),
     "baz": (has_baz, "GNU Arch baz client"),
     "bzr": (has_bzr, "Canonical's Bazaar client"),
     "bzr114": (has_bzr114, "Canonical's Bazaar client >= 1.14"),
     "cacheable": (has_cacheable_fs, "cacheable filesystem"),
     "cvs": (has_cvs, "cvs client/server"),
     "cvs112": (has_cvs112, "cvs client/server >= 1.12"),
     "darcs": (has_darcs, "darcs client"),
     "docutils": (has_docutils, "Docutils text processing library"),
     "eol-in-paths": (has_eol_in_paths, "end-of-lines in paths"),
     "execbit": (has_executablebit, "executable bit"),
     "fifo": (has_fifo, "named pipes"),
     "gettext": (has_gettext, "GNU Gettext (msgfmt)"),
     "git": (has_git, "git command line client"),
     "gpg": (has_gpg, "gpg client"),
     "hardlink": (has_hardlink, "hardlinks"),
     "icasefs": (has_icasefs, "case insensitive file system"),
     "inotify": (has_inotify, "inotify extension support"),
     "killdaemons": (has_killdaemons, 'killdaemons.py support'),
     "lsprof": (has_lsprof, "python lsprof module"),
     "mtn": (has_mtn, "monotone client (>= 1.0)"),
     "outer-repo": (has_outer_repo, "outer repo"),
     "p4": (has_p4, "Perforce server and client"),
     "pyflakes": (has_pyflakes, "Pyflakes python linter"),
     "pygments": (has_pygments, "Pygments source highlighting library"),
     "serve": (has_serve, "platform and python can manage 'hg serve -d'"),
     "ssl": (has_ssl, "python >= 2.6 ssl module and python OpenSSL"),
     "svn": (has_svn, "subversion client and admin tools"),
     "svn13": (has_svn13, "subversion client and admin tools >= 1.3"),
     "svn15": (has_svn15, "subversion client and admin tools >= 1.5"),
     "svn-bindings": (has_svn_bindings, "subversion python bindings"),
     "symlink": (has_symlink, "symbolic links"),
     "system-sh": (has_system_sh, "system() uses sh"),
     "tic": (has_tic, "terminfo compiler"),
     "tla": (has_tla, "GNU Arch tla client"),
     "unix-permissions": (has_unix_permissions, "unix-style permissions"),
     "windows": (has_windows, "Windows"),
     "msys": (has_msys, "Windows with MSYS"),
     "aix": (has_aix, "AIX"),
+    "absimport": (has_absimport, "absolute_import in __future__"),
 }