I am done

rl/Lib/site-packages/sympy/utilities/_compilation/__init__.py

@@ -0,0 +1,22 @@
+""" This sub-module is private, i.e. external code should not depend on it.
+
+These functions are used by tests run as part of continuous integration.
+Once the implementation is mature (it should support the major
+platforms: Windows, OS X & Linux) it may become official API which
+ may be relied upon by downstream libraries. Until then API may break
+without prior notice.
+
+TODO:
+- (optionally) clean up after tempfile.mkdtemp()
+- cross-platform testing
+- caching of compiler choice and intermediate files
+
+"""
+
+from .compilation import compile_link_import_strings, compile_run_strings
+from .availability import has_fortran, has_c, has_cxx
+
+__all__ = [
+    'compile_link_import_strings', 'compile_run_strings',
+    'has_fortran', 'has_c', 'has_cxx',
+]

rl/Lib/site-packages/sympy/utilities/_compilation/availability.py

@@ -0,0 +1,77 @@
+import os
+from .compilation import compile_run_strings
+from .util import CompilerNotFoundError
+
+def has_fortran():
+    if not hasattr(has_fortran, 'result'):
+        try:
+            (stdout, stderr), info = compile_run_strings(
+                [('main.f90', (
+                    'program foo\n'
+                    'print *, "hello world"\n'
+                    'end program'
+                ))], clean=True
+            )
+        except CompilerNotFoundError:
+            has_fortran.result = False
+            if os.environ.get('SYMPY_STRICT_COMPILER_CHECKS', '0') == '1':
+                raise
+        else:
+            if info['exit_status'] != os.EX_OK or 'hello world' not in stdout:
+                if os.environ.get('SYMPY_STRICT_COMPILER_CHECKS', '0') == '1':
+                    raise ValueError("Failed to compile test program:\n%s\n%s\n" % (stdout, stderr))
+                has_fortran.result = False
+            else:
+                has_fortran.result = True
+    return has_fortran.result
+
+
+def has_c():
+    if not hasattr(has_c, 'result'):
+        try:
+            (stdout, stderr), info = compile_run_strings(
+                [('main.c', (
+                    '#include <stdio.h>\n'
+                    'int main(){\n'
+                    'printf("hello world\\n");\n'
+                    'return 0;\n'
+                    '}'
+                ))], clean=True
+            )
+        except CompilerNotFoundError:
+            has_c.result = False
+            if os.environ.get('SYMPY_STRICT_COMPILER_CHECKS', '0') == '1':
+                raise
+        else:
+            if info['exit_status'] != os.EX_OK or 'hello world' not in stdout:
+                if os.environ.get('SYMPY_STRICT_COMPILER_CHECKS', '0') == '1':
+                    raise ValueError("Failed to compile test program:\n%s\n%s\n" % (stdout, stderr))
+                has_c.result = False
+            else:
+                has_c.result = True
+    return has_c.result
+
+
+def has_cxx():
+    if not hasattr(has_cxx, 'result'):
+        try:
+            (stdout, stderr), info = compile_run_strings(
+                [('main.cxx', (
+                    '#include <iostream>\n'
+                    'int main(){\n'
+                    'std::cout << "hello world" << std::endl;\n'
+                    '}'
+                ))], clean=True
+            )
+        except CompilerNotFoundError:
+            has_cxx.result = False
+            if os.environ.get('SYMPY_STRICT_COMPILER_CHECKS', '0') == '1':
+                raise
+        else:
+            if info['exit_status'] != os.EX_OK or 'hello world' not in stdout:
+                if os.environ.get('SYMPY_STRICT_COMPILER_CHECKS', '0') == '1':
+                    raise ValueError("Failed to compile test program:\n%s\n%s\n" % (stdout, stderr))
+                has_cxx.result = False
+            else:
+                has_cxx.result = True
+    return has_cxx.result

rl/Lib/site-packages/sympy/utilities/_compilation/compilation.py

@@ -0,0 +1,657 @@
+import glob
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+import warnings
+from sysconfig import get_config_var, get_config_vars, get_path
+
+from .runners import (
+    CCompilerRunner,
+    CppCompilerRunner,
+    FortranCompilerRunner
+)
+from .util import (
+    get_abspath, make_dirs, copy, Glob, ArbitraryDepthGlob,
+    glob_at_depth, import_module_from_file, pyx_is_cplus,
+    sha256_of_string, sha256_of_file, CompileError
+)
+
+if os.name == 'posix':
+    objext = '.o'
+elif os.name == 'nt':
+    objext = '.obj'
+else:
+    warnings.warn("Unknown os.name: {}".format(os.name))
+    objext = '.o'
+
+
+def compile_sources(files, Runner=None, destdir=None, cwd=None, keep_dir_struct=False,
+                    per_file_kwargs=None, **kwargs):
+    """ Compile source code files to object files.
+
+    Parameters
+    ==========
+
+    files : iterable of str
+        Paths to source files, if ``cwd`` is given, the paths are taken as relative.
+    Runner: CompilerRunner subclass (optional)
+        Could be e.g. ``FortranCompilerRunner``. Will be inferred from filename
+        extensions if missing.
+    destdir: str
+        Output directory, if cwd is given, the path is taken as relative.
+    cwd: str
+        Working directory. Specify to have compiler run in other directory.
+        also used as root of relative paths.
+    keep_dir_struct: bool
+        Reproduce directory structure in `destdir`. default: ``False``
+    per_file_kwargs: dict
+        Dict mapping instances in ``files`` to keyword arguments.
+    \\*\\*kwargs: dict
+        Default keyword arguments to pass to ``Runner``.
+
+    Returns
+    =======
+    List of strings (paths of object files).
+    """
+    _per_file_kwargs = {}
+
+    if per_file_kwargs is not None:
+        for k, v in per_file_kwargs.items():
+            if isinstance(k, Glob):
+                for path in glob.glob(k.pathname):
+                    _per_file_kwargs[path] = v
+            elif isinstance(k, ArbitraryDepthGlob):
+                for path in glob_at_depth(k.filename, cwd):
+                    _per_file_kwargs[path] = v
+            else:
+                _per_file_kwargs[k] = v
+
+    # Set up destination directory
+    destdir = destdir or '.'
+    if not os.path.isdir(destdir):
+        if os.path.exists(destdir):
+            raise OSError("{} is not a directory".format(destdir))
+        else:
+            make_dirs(destdir)
+    if cwd is None:
+        cwd = '.'
+        for f in files:
+            copy(f, destdir, only_update=True, dest_is_dir=True)
+
+    # Compile files and return list of paths to the objects
+    dstpaths = []
+    for f in files:
+        if keep_dir_struct:
+            name, ext = os.path.splitext(f)
+        else:
+            name, ext = os.path.splitext(os.path.basename(f))
+        file_kwargs = kwargs.copy()
+        file_kwargs.update(_per_file_kwargs.get(f, {}))
+        dstpaths.append(src2obj(f, Runner, cwd=cwd, **file_kwargs))
+    return dstpaths
+
+
+def get_mixed_fort_c_linker(vendor=None, cplus=False, cwd=None):
+    vendor = vendor or os.environ.get('SYMPY_COMPILER_VENDOR', 'gnu')
+
+    if vendor.lower() == 'intel':
+        if cplus:
+            return (FortranCompilerRunner,
+                    {'flags': ['-nofor_main', '-cxxlib']}, vendor)
+        else:
+            return (FortranCompilerRunner,
+                    {'flags': ['-nofor_main']}, vendor)
+    elif vendor.lower() == 'gnu' or 'llvm':
+        if cplus:
+            return (CppCompilerRunner,
+                    {'lib_options': ['fortran']}, vendor)
+        else:
+            return (FortranCompilerRunner,
+                    {}, vendor)
+    else:
+        raise ValueError("No vendor found.")
+
+
+def link(obj_files, out_file=None, shared=False, Runner=None,
+         cwd=None, cplus=False, fort=False, extra_objs=None, **kwargs):
+    """ Link object files.
+
+    Parameters
+    ==========
+
+    obj_files: iterable of str
+        Paths to object files.
+    out_file: str (optional)
+        Path to executable/shared library, if ``None`` it will be
+        deduced from the last item in obj_files.
+    shared: bool
+        Generate a shared library?
+    Runner: CompilerRunner subclass (optional)
+        If not given the ``cplus`` and ``fort`` flags will be inspected
+        (fallback is the C compiler).
+    cwd: str
+        Path to the root of relative paths and working directory for compiler.
+    cplus: bool
+        C++ objects? default: ``False``.
+    fort: bool
+        Fortran objects? default: ``False``.
+    extra_objs: list
+        List of paths to extra object files / static libraries.
+    \\*\\*kwargs: dict
+        Keyword arguments passed to ``Runner``.
+
+    Returns
+    =======
+
+    The absolute path to the generated shared object / executable.
+
+    """
+    if out_file is None:
+        out_file, ext = os.path.splitext(os.path.basename(obj_files[-1]))
+        if shared:
+            out_file += get_config_var('EXT_SUFFIX')
+
+    if not Runner:
+        if fort:
+            Runner, extra_kwargs, vendor = \
+                get_mixed_fort_c_linker(
+                    vendor=kwargs.get('vendor', None),
+                    cplus=cplus,
+                    cwd=cwd,
+                )
+            for k, v in extra_kwargs.items():
+                if k in kwargs:
+                    kwargs[k].expand(v)
+                else:
+                    kwargs[k] = v
+        else:
+            if cplus:
+                Runner = CppCompilerRunner
+            else:
+                Runner = CCompilerRunner
+
+    flags = kwargs.pop('flags', [])
+    if shared:
+        if '-shared' not in flags:
+            flags.append('-shared')
+    run_linker = kwargs.pop('run_linker', True)
+    if not run_linker:
+        raise ValueError("run_linker was set to False (nonsensical).")
+
+    out_file = get_abspath(out_file, cwd=cwd)
+    runner = Runner(obj_files+(extra_objs or []), out_file, flags, cwd=cwd, **kwargs)
+    runner.run()
+    return out_file
+
+
+def link_py_so(obj_files, so_file=None, cwd=None, libraries=None,
+               cplus=False, fort=False, extra_objs=None, **kwargs):
+    """ Link Python extension module (shared object) for importing
+
+    Parameters
+    ==========
+
+    obj_files: iterable of str
+        Paths to object files to be linked.
+    so_file: str
+        Name (path) of shared object file to create. If not specified it will
+        have the basname of the last object file in `obj_files` but with the
+        extension '.so' (Unix).
+    cwd: path string
+        Root of relative paths and working directory of linker.
+    libraries: iterable of strings
+        Libraries to link against, e.g. ['m'].
+    cplus: bool
+        Any C++ objects? default: ``False``.
+    fort: bool
+        Any Fortran objects? default: ``False``.
+    extra_objs: list
+        List of paths of extra object files / static libraries to link against.
+    kwargs**: dict
+        Keyword arguments passed to ``link(...)``.
+
+    Returns
+    =======
+
+    Absolute path to the generate shared object.
+    """
+    libraries = libraries or []
+
+    include_dirs = kwargs.pop('include_dirs', [])
+    library_dirs = kwargs.pop('library_dirs', [])
+
+    # Add Python include and library directories
+    # PY_LDFLAGS does not available on all python implementations
+    # e.g. when with pypy, so it's LDFLAGS we need to use
+    if sys.platform == "win32":
+        warnings.warn("Windows not yet supported.")
+    elif sys.platform == 'darwin':
+        cfgDict = get_config_vars()
+        kwargs['linkline'] = kwargs.get('linkline', []) + [cfgDict['LDFLAGS']]
+        library_dirs += [cfgDict['LIBDIR']]
+
+        # In macOS, linker needs to compile frameworks
+        # e.g. "-framework CoreFoundation"
+        is_framework = False
+        for opt in cfgDict['LIBS'].split():
+            if is_framework:
+                kwargs['linkline'] = kwargs.get('linkline', []) + ['-framework', opt]
+                is_framework = False
+            elif opt.startswith('-l'):
+                libraries.append(opt[2:])
+            elif opt.startswith('-framework'):
+                is_framework = True
+        # The python library is not included in LIBS
+        libfile = cfgDict['LIBRARY']
+        libname = ".".join(libfile.split('.')[:-1])[3:]
+        libraries.append(libname)
+
+    elif sys.platform[:3] == 'aix':
+        # Don't use the default code below
+        pass
+    else:
+        if get_config_var('Py_ENABLE_SHARED'):
+            cfgDict = get_config_vars()
+            kwargs['linkline'] = kwargs.get('linkline', []) + [cfgDict['LDFLAGS']]
+            library_dirs += [cfgDict['LIBDIR']]
+            for opt in cfgDict['BLDLIBRARY'].split():
+                if opt.startswith('-l'):
+                    libraries += [opt[2:]]
+        else:
+            pass
+
+    flags = kwargs.pop('flags', [])
+    needed_flags = ('-pthread',)
+    for flag in needed_flags:
+        if flag not in flags:
+            flags.append(flag)
+
+    return link(obj_files, shared=True, flags=flags, cwd=cwd, cplus=cplus, fort=fort,
+                include_dirs=include_dirs, libraries=libraries,
+                library_dirs=library_dirs, extra_objs=extra_objs, **kwargs)
+
+
+def simple_cythonize(src, destdir=None, cwd=None, **cy_kwargs):
+    """ Generates a C file from a Cython source file.
+
+    Parameters
+    ==========
+
+    src: str
+        Path to Cython source.
+    destdir: str (optional)
+        Path to output directory (default: '.').
+    cwd: path string (optional)
+        Root of relative paths (default: '.').
+    **cy_kwargs:
+        Second argument passed to cy_compile. Generates a .cpp file if ``cplus=True`` in ``cy_kwargs``,
+        else a .c file.
+    """
+    from Cython.Compiler.Main import (
+        default_options, CompilationOptions
+    )
+    from Cython.Compiler.Main import compile as cy_compile
+
+    assert src.lower().endswith('.pyx') or src.lower().endswith('.py')
+    cwd = cwd or '.'
+    destdir = destdir or '.'
+
+    ext = '.cpp' if cy_kwargs.get('cplus', False) else '.c'
+    c_name = os.path.splitext(os.path.basename(src))[0] + ext
+
+    dstfile = os.path.join(destdir, c_name)
+
+    if cwd:
+        ori_dir = os.getcwd()
+    else:
+        ori_dir = '.'
+    os.chdir(cwd)
+    try:
+        cy_options = CompilationOptions(default_options)
+        cy_options.__dict__.update(cy_kwargs)
+        # Set language_level if not set by cy_kwargs
+        # as not setting it is deprecated
+        if 'language_level' not in cy_kwargs:
+            cy_options.__dict__['language_level'] = 3
+        cy_result = cy_compile([src], cy_options)
+        if cy_result.num_errors > 0:
+            raise ValueError("Cython compilation failed.")
+
+        # Move generated C file to destination
+        # In macOS, the generated C file is in the same directory as the source
+        # but the /var is a symlink to /private/var, so we need to use realpath
+        if os.path.realpath(os.path.dirname(src)) != os.path.realpath(destdir):
+            if os.path.exists(dstfile):
+                os.unlink(dstfile)
+            shutil.move(os.path.join(os.path.dirname(src), c_name), destdir)
+    finally:
+        os.chdir(ori_dir)
+    return dstfile
+
+
+extension_mapping = {
+    '.c': (CCompilerRunner, None),
+    '.cpp': (CppCompilerRunner, None),
+    '.cxx': (CppCompilerRunner, None),
+    '.f': (FortranCompilerRunner, None),
+    '.for': (FortranCompilerRunner, None),
+    '.ftn': (FortranCompilerRunner, None),
+    '.f90': (FortranCompilerRunner, None),  # ifort only knows about .f90
+    '.f95': (FortranCompilerRunner, 'f95'),
+    '.f03': (FortranCompilerRunner, 'f2003'),
+    '.f08': (FortranCompilerRunner, 'f2008'),
+}
+
+
+def src2obj(srcpath, Runner=None, objpath=None, cwd=None, inc_py=False, **kwargs):
+    """ Compiles a source code file to an object file.
+
+    Files ending with '.pyx' assumed to be cython files and
+    are dispatched to pyx2obj.
+
+    Parameters
+    ==========
+
+    srcpath: str
+        Path to source file.
+    Runner: CompilerRunner subclass (optional)
+        If ``None``: deduced from extension of srcpath.
+    objpath : str (optional)
+        Path to generated object. If ``None``: deduced from ``srcpath``.
+    cwd: str (optional)
+        Working directory and root of relative paths. If ``None``: current dir.
+    inc_py: bool
+        Add Python include path to kwarg "include_dirs". Default: False
+    \\*\\*kwargs: dict
+        keyword arguments passed to Runner or pyx2obj
+
+    """
+    name, ext = os.path.splitext(os.path.basename(srcpath))
+    if objpath is None:
+        if os.path.isabs(srcpath):
+            objpath = '.'
+        else:
+            objpath = os.path.dirname(srcpath)
+            objpath = objpath or '.'  # avoid objpath == ''
+
+    if os.path.isdir(objpath):
+        objpath = os.path.join(objpath, name + objext)
+
+    include_dirs = kwargs.pop('include_dirs', [])
+    if inc_py:
+        py_inc_dir = get_path('include')
+        if py_inc_dir not in include_dirs:
+            include_dirs.append(py_inc_dir)
+
+    if ext.lower() == '.pyx':
+        return pyx2obj(srcpath, objpath=objpath, include_dirs=include_dirs, cwd=cwd,
+                       **kwargs)
+
+    if Runner is None:
+        Runner, std = extension_mapping[ext.lower()]
+        if 'std' not in kwargs:
+            kwargs['std'] = std
+
+    flags = kwargs.pop('flags', [])
+    needed_flags = ('-fPIC',)
+    for flag in needed_flags:
+        if flag not in flags:
+            flags.append(flag)
+
+    # src2obj implies not running the linker...
+    run_linker = kwargs.pop('run_linker', False)
+    if run_linker:
+        raise CompileError("src2obj called with run_linker=True")
+
+    runner = Runner([srcpath], objpath, include_dirs=include_dirs,
+                    run_linker=run_linker, cwd=cwd, flags=flags, **kwargs)
+    runner.run()
+    return objpath
+
+
+def pyx2obj(pyxpath, objpath=None, destdir=None, cwd=None,
+            include_dirs=None, cy_kwargs=None, cplus=None, **kwargs):
+    """
+    Convenience function
+
+    If cwd is specified, pyxpath and dst are taken to be relative
+    If only_update is set to `True` the modification time is checked
+    and compilation is only run if the source is newer than the
+    destination
+
+    Parameters
+    ==========
+
+    pyxpath: str
+        Path to Cython source file.
+    objpath: str (optional)
+        Path to object file to generate.
+    destdir: str (optional)
+        Directory to put generated C file. When ``None``: directory of ``objpath``.
+    cwd: str (optional)
+        Working directory and root of relative paths.
+    include_dirs: iterable of path strings (optional)
+        Passed onto src2obj and via cy_kwargs['include_path']
+        to simple_cythonize.
+    cy_kwargs: dict (optional)
+        Keyword arguments passed onto `simple_cythonize`
+    cplus: bool (optional)
+        Indicate whether C++ is used. default: auto-detect using ``.util.pyx_is_cplus``.
+    compile_kwargs: dict
+        keyword arguments passed onto src2obj
+
+    Returns
+    =======
+
+    Absolute path of generated object file.
+
+    """
+    assert pyxpath.endswith('.pyx')
+    cwd = cwd or '.'
+    objpath = objpath or '.'
+    destdir = destdir or os.path.dirname(objpath)
+
+    abs_objpath = get_abspath(objpath, cwd=cwd)
+
+    if os.path.isdir(abs_objpath):
+        pyx_fname = os.path.basename(pyxpath)
+        name, ext = os.path.splitext(pyx_fname)
+        objpath = os.path.join(objpath, name + objext)
+
+    cy_kwargs = cy_kwargs or {}
+    cy_kwargs['output_dir'] = cwd
+    if cplus is None:
+        cplus = pyx_is_cplus(pyxpath)
+    cy_kwargs['cplus'] = cplus
+
+    interm_c_file = simple_cythonize(pyxpath, destdir=destdir, cwd=cwd, **cy_kwargs)
+
+    include_dirs = include_dirs or []
+    flags = kwargs.pop('flags', [])
+    needed_flags = ('-fwrapv', '-pthread', '-fPIC')
+    for flag in needed_flags:
+        if flag not in flags:
+            flags.append(flag)
+
+    options = kwargs.pop('options', [])
+
+    if kwargs.pop('strict_aliasing', False):
+        raise CompileError("Cython requires strict aliasing to be disabled.")
+
+    # Let's be explicit about standard
+    if cplus:
+        std = kwargs.pop('std', 'c++98')
+    else:
+        std = kwargs.pop('std', 'c99')
+
+    return src2obj(interm_c_file, objpath=objpath, cwd=cwd,
+                   include_dirs=include_dirs, flags=flags, std=std,
+                   options=options, inc_py=True, strict_aliasing=False,
+                   **kwargs)
+
+
+def _any_X(srcs, cls):
+    for src in srcs:
+        name, ext = os.path.splitext(src)
+        key = ext.lower()
+        if key in extension_mapping:
+            if extension_mapping[key][0] == cls:
+                return True
+    return False
+
+
+def any_fortran_src(srcs):
+    return _any_X(srcs, FortranCompilerRunner)
+
+
+def any_cplus_src(srcs):
+    return _any_X(srcs, CppCompilerRunner)
+
+
+def compile_link_import_py_ext(sources, extname=None, build_dir='.', compile_kwargs=None,
+                               link_kwargs=None, extra_objs=None):
+    """ Compiles sources to a shared object (Python extension) and imports it
+
+    Sources in ``sources`` which is imported. If shared object is newer than the sources, they
+    are not recompiled but instead it is imported.
+
+    Parameters
+    ==========
+
+    sources : list of strings
+        List of paths to sources.
+    extname : string
+        Name of extension (default: ``None``).
+        If ``None``: taken from the last file in ``sources`` without extension.
+    build_dir: str
+        Path to directory in which objects files etc. are generated.
+    compile_kwargs: dict
+        keyword arguments passed to ``compile_sources``
+    link_kwargs: dict
+        keyword arguments passed to ``link_py_so``
+    extra_objs: list
+        List of paths to (prebuilt) object files / static libraries to link against.
+
+    Returns
+    =======
+
+    The imported module from of the Python extension.
+    """
+    if extname is None:
+        extname = os.path.splitext(os.path.basename(sources[-1]))[0]
+
+    compile_kwargs = compile_kwargs or {}
+    link_kwargs = link_kwargs or {}
+
+    try:
+        mod = import_module_from_file(os.path.join(build_dir, extname), sources)
+    except ImportError:
+        objs = compile_sources(list(map(get_abspath, sources)), destdir=build_dir,
+                               cwd=build_dir, **compile_kwargs)
+        so = link_py_so(objs, cwd=build_dir, fort=any_fortran_src(sources),
+                        cplus=any_cplus_src(sources), extra_objs=extra_objs, **link_kwargs)
+        mod = import_module_from_file(so)
+    return mod
+
+
+def _write_sources_to_build_dir(sources, build_dir):
+    build_dir = build_dir or tempfile.mkdtemp()
+    if not os.path.isdir(build_dir):
+        raise OSError("Non-existent directory: ", build_dir)
+
+    source_files = []
+    for name, src in sources:
+        dest = os.path.join(build_dir, name)
+        differs = True
+        sha256_in_mem = sha256_of_string(src.encode('utf-8')).hexdigest()
+        if os.path.exists(dest):
+            if os.path.exists(dest + '.sha256'):
+                with open(dest + '.sha256') as fh:
+                    sha256_on_disk = fh.read()
+            else:
+                sha256_on_disk = sha256_of_file(dest).hexdigest()
+
+            differs = sha256_on_disk != sha256_in_mem
+        if differs:
+            with open(dest, 'wt') as fh:
+                fh.write(src)
+            with open(dest + '.sha256', 'wt') as fh:
+                fh.write(sha256_in_mem)
+        source_files.append(dest)
+    return source_files, build_dir
+
+
+def compile_link_import_strings(sources, build_dir=None, **kwargs):
+    """ Compiles, links and imports extension module from source.
+
+    Parameters
+    ==========
+
+    sources : iterable of name/source pair tuples
+    build_dir : string (default: None)
+        Path. ``None`` implies use a temporary directory.
+    **kwargs:
+        Keyword arguments passed onto `compile_link_import_py_ext`.
+
+    Returns
+    =======
+
+    mod : module
+        The compiled and imported extension module.
+    info : dict
+        Containing ``build_dir`` as 'build_dir'.
+
+    """
+    source_files, build_dir = _write_sources_to_build_dir(sources, build_dir)
+    mod = compile_link_import_py_ext(source_files, build_dir=build_dir, **kwargs)
+    info = {"build_dir": build_dir}
+    return mod, info
+
+
+def compile_run_strings(sources, build_dir=None, clean=False, compile_kwargs=None, link_kwargs=None):
+    """ Compiles, links and runs a program built from sources.
+
+    Parameters
+    ==========
+
+    sources : iterable of name/source pair tuples
+    build_dir : string (default: None)
+        Path. ``None`` implies use a temporary directory.
+    clean : bool
+        Whether to remove build_dir after use. This will only have an
+        effect if ``build_dir`` is ``None`` (which creates a temporary directory).
+        Passing ``clean == True`` and ``build_dir != None`` raises a ``ValueError``.
+        This will also set ``build_dir`` in returned info dictionary to ``None``.
+    compile_kwargs: dict
+        Keyword arguments passed onto ``compile_sources``
+    link_kwargs: dict
+        Keyword arguments passed onto ``link``
+
+    Returns
+    =======
+
+    (stdout, stderr): pair of strings
+    info: dict
+        Containing exit status as 'exit_status' and ``build_dir`` as 'build_dir'
+
+    """
+    if clean and build_dir is not None:
+        raise ValueError("Automatic removal of build_dir is only available for temporary directory.")
+    try:
+        source_files, build_dir = _write_sources_to_build_dir(sources, build_dir)
+        objs = compile_sources(list(map(get_abspath, source_files)), destdir=build_dir,
+                               cwd=build_dir, **(compile_kwargs or {}))
+        prog = link(objs, cwd=build_dir,
+                    fort=any_fortran_src(source_files),
+                    cplus=any_cplus_src(source_files), **(link_kwargs or {}))
+        p = subprocess.Popen([prog], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        exit_status = p.wait()
+        stdout, stderr = [txt.decode('utf-8') for txt in p.communicate()]
+    finally:
+        if clean and os.path.isdir(build_dir):
+            shutil.rmtree(build_dir)
+            build_dir = None
+    info = {"exit_status": exit_status, "build_dir": build_dir}
+    return (stdout, stderr), info

rl/Lib/site-packages/sympy/utilities/_compilation/runners.py

@@ -0,0 +1,301 @@
+from __future__ import annotations
+from typing import Callable, Optional
+
+from collections import OrderedDict
+import os
+import re
+import subprocess
+import warnings
+
+from .util import (
+    find_binary_of_command, unique_list, CompileError
+)
+
+
+class CompilerRunner:
+    """ CompilerRunner base class.
+
+    Parameters
+    ==========
+
+    sources : list of str
+        Paths to sources.
+    out : str
+    flags : iterable of str
+        Compiler flags.
+    run_linker : bool
+    compiler_name_exe : (str, str) tuple
+        Tuple of compiler name &  command to call.
+    cwd : str
+        Path of root of relative paths.
+    include_dirs : list of str
+        Include directories.
+    libraries : list of str
+        Libraries to link against.
+    library_dirs : list of str
+        Paths to search for shared libraries.
+    std : str
+        Standard string, e.g. ``'c++11'``, ``'c99'``, ``'f2003'``.
+    define: iterable of strings
+        macros to define
+    undef : iterable of strings
+        macros to undefine
+    preferred_vendor : string
+        name of preferred vendor e.g. 'gnu' or 'intel'
+
+    Methods
+    =======
+
+    run():
+        Invoke compilation as a subprocess.
+
+    """
+
+    environ_key_compiler: str  # e.g. 'CC', 'CXX', ...
+    environ_key_flags: str  # e.g. 'CFLAGS', 'CXXFLAGS', ...
+    environ_key_ldflags: str = "LDFLAGS"  # typically 'LDFLAGS'
+
+    # Subclass to vendor/binary dict
+    compiler_dict: dict[str, str]
+
+    # Standards should be a tuple of supported standards
+    # (first one will be the default)
+    standards: tuple[None | str, ...]
+
+    # Subclass to dict of binary/formater-callback
+    std_formater: dict[str, Callable[[Optional[str]], str]]
+
+    # subclass to be e.g. {'gcc': 'gnu', ...}
+    compiler_name_vendor_mapping: dict[str, str]
+
+    def __init__(self, sources, out, flags=None, run_linker=True, compiler=None, cwd='.',
+                 include_dirs=None, libraries=None, library_dirs=None, std=None, define=None,
+                 undef=None, strict_aliasing=None, preferred_vendor=None, linkline=None, **kwargs):
+        if isinstance(sources, str):
+            raise ValueError("Expected argument sources to be a list of strings.")
+        self.sources = list(sources)
+        self.out = out
+        self.flags = flags or []
+        if os.environ.get(self.environ_key_flags):
+            self.flags += os.environ[self.environ_key_flags].split()
+        self.cwd = cwd
+        if compiler:
+            self.compiler_name, self.compiler_binary = compiler
+        elif os.environ.get(self.environ_key_compiler):
+            self.compiler_binary = os.environ[self.environ_key_compiler]
+            for k, v in self.compiler_dict.items():
+                if k in self.compiler_binary:
+                    self.compiler_vendor = k
+                    self.compiler_name = v
+                    break
+            else:
+                self.compiler_vendor, self.compiler_name = list(self.compiler_dict.items())[0]
+                warnings.warn("failed to determine what kind of compiler %s is, assuming %s" %
+                              (self.compiler_binary, self.compiler_name))
+        else:
+            # Find a compiler
+            if preferred_vendor is None:
+                preferred_vendor = os.environ.get('SYMPY_COMPILER_VENDOR', None)
+            self.compiler_name, self.compiler_binary, self.compiler_vendor = self.find_compiler(preferred_vendor)
+            if self.compiler_binary is None:
+                raise ValueError("No compiler found (searched: {})".format(', '.join(self.compiler_dict.values())))
+        self.define = define or []
+        self.undef = undef or []
+        self.include_dirs = include_dirs or []
+        self.libraries = libraries or []
+        self.library_dirs = library_dirs or []
+        self.std = std or self.standards[0]
+        self.run_linker = run_linker
+        if self.run_linker:
+            # both gnu and intel compilers use '-c' for disabling linker
+            self.flags = list(filter(lambda x: x != '-c', self.flags))
+        else:
+            if '-c' not in self.flags:
+                self.flags.append('-c')
+
+        if self.std:
+            self.flags.append(self.std_formater[
+                self.compiler_name](self.std))
+
+        self.linkline = (linkline or []) + [lf for lf in map(
+            str.strip, os.environ.get(self.environ_key_ldflags, "").split()
+        ) if lf != ""]
+
+        if strict_aliasing is not None:
+            nsa_re = re.compile("no-strict-aliasing$")
+            sa_re = re.compile("strict-aliasing$")
+            if strict_aliasing is True:
+                if any(map(nsa_re.match, flags)):
+                    raise CompileError("Strict aliasing cannot be both enforced and disabled")
+                elif any(map(sa_re.match, flags)):
+                    pass  # already enforced
+                else:
+                    flags.append('-fstrict-aliasing')
+            elif strict_aliasing is False:
+                if any(map(nsa_re.match, flags)):
+                    pass  # already disabled
+                else:
+                    if any(map(sa_re.match, flags)):
+                        raise CompileError("Strict aliasing cannot be both enforced and disabled")
+                    else:
+                        flags.append('-fno-strict-aliasing')
+            else:
+                msg = "Expected argument strict_aliasing to be True/False, got {}"
+                raise ValueError(msg.format(strict_aliasing))
+
+    @classmethod
+    def find_compiler(cls, preferred_vendor=None):
+        """ Identify a suitable C/fortran/other compiler. """
+        candidates = list(cls.compiler_dict.keys())
+        if preferred_vendor:
+            if preferred_vendor in candidates:
+                candidates = [preferred_vendor]+candidates
+            else:
+                raise ValueError("Unknown vendor {}".format(preferred_vendor))
+        name, path = find_binary_of_command([cls.compiler_dict[x] for x in candidates])
+        return name, path, cls.compiler_name_vendor_mapping[name]
+
+    def cmd(self):
+        """ List of arguments (str) to be passed to e.g. ``subprocess.Popen``. """
+        cmd = (
+            [self.compiler_binary] +
+            self.flags +
+            ['-U'+x for x in self.undef] +
+            ['-D'+x for x in self.define] +
+            ['-I'+x for x in self.include_dirs] +
+            self.sources
+        )
+        if self.run_linker:
+            cmd += (['-L'+x for x in self.library_dirs] +
+                    ['-l'+x for x in self.libraries] +
+                    self.linkline)
+        counted = []
+        for envvar in re.findall(r'\$\{(\w+)\}', ' '.join(cmd)):
+            if os.getenv(envvar) is None:
+                if envvar not in counted:
+                    counted.append(envvar)
+                    msg = "Environment variable '{}' undefined.".format(envvar)
+                    raise CompileError(msg)
+        return cmd
+
+    def run(self):
+        self.flags = unique_list(self.flags)
+
+        # Append output flag and name to tail of flags
+        self.flags.extend(['-o', self.out])
+        env = os.environ.copy()
+        env['PWD'] = self.cwd
+
+        # NOTE: intel compilers seems to need shell=True
+        p = subprocess.Popen(' '.join(self.cmd()),
+                             shell=True,
+                             cwd=self.cwd,
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.STDOUT,
+                             env=env)
+        comm = p.communicate()
+        try:
+            self.cmd_outerr = comm[0].decode('utf-8')
+        except UnicodeDecodeError:
+            self.cmd_outerr = comm[0].decode('iso-8859-1')  # win32
+        self.cmd_returncode = p.returncode
+
+        # Error handling
+        if self.cmd_returncode != 0:
+            msg = "Error executing '{}' in {} (exited status {}):\n {}\n".format(
+                ' '.join(self.cmd()), self.cwd, str(self.cmd_returncode), self.cmd_outerr
+            )
+            raise CompileError(msg)
+
+        return self.cmd_outerr, self.cmd_returncode
+
+
+class CCompilerRunner(CompilerRunner):
+
+    environ_key_compiler = 'CC'
+    environ_key_flags = 'CFLAGS'
+
+    compiler_dict = OrderedDict([
+        ('gnu', 'gcc'),
+        ('intel', 'icc'),
+        ('llvm', 'clang'),
+    ])
+
+    standards = ('c89', 'c90', 'c99', 'c11')  # First is default
+
+    std_formater = {
+        'gcc': '-std={}'.format,
+        'icc': '-std={}'.format,
+        'clang': '-std={}'.format,
+    }
+
+    compiler_name_vendor_mapping = {
+        'gcc': 'gnu',
+        'icc': 'intel',
+        'clang': 'llvm'
+    }
+
+
+def _mk_flag_filter(cmplr_name):  # helper for class initialization
+    not_welcome = {'g++': ("Wimplicit-interface",)}  # "Wstrict-prototypes",)}
+    if cmplr_name in not_welcome:
+        def fltr(x):
+            for nw in not_welcome[cmplr_name]:
+                if nw in x:
+                    return False
+            return True
+    else:
+        def fltr(x):
+            return True
+    return fltr
+
+
+class CppCompilerRunner(CompilerRunner):
+
+    environ_key_compiler = 'CXX'
+    environ_key_flags = 'CXXFLAGS'
+
+    compiler_dict = OrderedDict([
+        ('gnu', 'g++'),
+        ('intel', 'icpc'),
+        ('llvm', 'clang++'),
+    ])
+
+    # First is the default, c++0x == c++11
+    standards = ('c++98', 'c++0x')
+
+    std_formater = {
+        'g++': '-std={}'.format,
+        'icpc': '-std={}'.format,
+        'clang++': '-std={}'.format,
+    }
+
+    compiler_name_vendor_mapping = {
+        'g++': 'gnu',
+        'icpc': 'intel',
+        'clang++': 'llvm'
+    }
+
+
+class FortranCompilerRunner(CompilerRunner):
+
+    environ_key_compiler = 'FC'
+    environ_key_flags = 'FFLAGS'
+
+    standards = (None, 'f77', 'f95', 'f2003', 'f2008')
+
+    std_formater = {
+        'gfortran': lambda x: '-std=gnu' if x is None else '-std=legacy' if x == 'f77' else '-std={}'.format(x),
+        'ifort': lambda x: '-stand f08' if x is None else '-stand f{}'.format(x[-2:]),  # f2008 => f08
+    }
+
+    compiler_dict = OrderedDict([
+        ('gnu', 'gfortran'),
+        ('intel', 'ifort'),
+    ])
+
+    compiler_name_vendor_mapping = {
+        'gfortran': 'gnu',
+        'ifort': 'intel',
+    }

rl/Lib/site-packages/sympy/utilities/_compilation/tests/test_compilation.py

@@ -0,0 +1,101 @@
+import shutil
+import os
+import subprocess
+import tempfile
+from sympy.external import import_module
+from sympy.testing.pytest import skip
+
+from sympy.utilities._compilation.compilation import compile_link_import_py_ext, compile_link_import_strings, compile_sources, get_abspath
+
+numpy = import_module('numpy')
+cython = import_module('cython')
+
+_sources1 = [
+    ('sigmoid.c', r"""
+#include <math.h>
+
+void sigmoid(int n, const double * const restrict in,
+             double * const restrict out, double lim){
+    for (int i=0; i<n; ++i){
+        const double x = in[i];
+        out[i] = x*pow(pow(x/lim, 8)+1, -1./8.);
+    }
+}
+"""),
+    ('_sigmoid.pyx', r"""
+import numpy as np
+cimport numpy as cnp
+
+cdef extern void c_sigmoid "sigmoid" (int, const double * const,
+                                      double * const, double)
+
+def sigmoid(double [:] inp, double lim=350.0):
+    cdef cnp.ndarray[cnp.float64_t, ndim=1] out = np.empty(
+        inp.size, dtype=np.float64)
+    c_sigmoid(inp.size, &inp[0], &out[0], lim)
+    return out
+""")
+]
+
+
+def npy(data, lim=350.0):
+    return data/((data/lim)**8+1)**(1/8.)
+
+
+def test_compile_link_import_strings():
+    if not numpy:
+        skip("numpy not installed.")
+    if not cython:
+        skip("cython not installed.")
+
+    from sympy.utilities._compilation import has_c
+    if not has_c():
+        skip("No C compiler found.")
+
+    compile_kw = {"std": 'c99', "include_dirs": [numpy.get_include()]}
+    info = None
+    try:
+        mod, info = compile_link_import_strings(_sources1, compile_kwargs=compile_kw)
+        data = numpy.random.random(1024*1024*8)  # 64 MB of RAM needed..
+        res_mod = mod.sigmoid(data)
+        res_npy = npy(data)
+        assert numpy.allclose(res_mod, res_npy)
+    finally:
+        if info and info['build_dir']:
+            shutil.rmtree(info['build_dir'])
+
+
+def test_compile_sources(tmpdir):
+    from sympy.utilities._compilation import has_c
+    if not has_c():
+        skip("No C compiler found.")
+
+    build_dir = str(tmpdir)
+    _handle, file_path = tempfile.mkstemp('.c', dir=build_dir)
+    with open(file_path, 'wt') as ofh:
+        ofh.write("""
+        int foo(int bar) {
+            return 2*bar;
+        }
+        """)
+    obj, = compile_sources([file_path], cwd=build_dir)
+    obj_path = get_abspath(obj, cwd=build_dir)
+    assert os.path.exists(obj_path)
+    try:
+        _ = subprocess.check_output(["nm", "--help"])
+    except subprocess.CalledProcessError:
+        pass  # we cannot test contents of object file
+    else:
+        nm_out = subprocess.check_output(["nm", obj_path])
+        assert 'foo' in nm_out.decode('utf-8')
+
+    if not cython:
+        return  # the final (optional) part of the test below requires Cython.
+
+    _handle, pyx_path = tempfile.mkstemp('.pyx', dir=build_dir)
+    with open(pyx_path, 'wt') as ofh:
+        ofh.write(("cdef extern int foo(int)\n"
+                   "def _foo(arg):\n"
+                   "    return foo(arg)"))
+    mod = compile_link_import_py_ext([pyx_path], extra_objs=[obj_path], build_dir=build_dir)
+    assert mod._foo(21) == 42

rl/Lib/site-packages/sympy/utilities/_compilation/util.py

@@ -0,0 +1,312 @@
+from collections import namedtuple
+from hashlib import sha256
+import os
+import shutil
+import sys
+import fnmatch
+
+from sympy.testing.pytest import XFAIL
+
+
+def may_xfail(func):
+    if sys.platform.lower() == 'darwin' or os.name == 'nt':
+        # sympy.utilities._compilation needs more testing on Windows and macOS
+        # once those two platforms are reliably supported this xfail decorator
+        # may be removed.
+        return XFAIL(func)
+    else:
+        return func
+
+
+class CompilerNotFoundError(FileNotFoundError):
+    pass
+
+
+class CompileError (Exception):
+    """Failure to compile one or more C/C++ source files."""
+
+
+def get_abspath(path, cwd='.'):
+    """ Returns the absolute path.
+
+    Parameters
+    ==========
+
+    path : str
+        (relative) path.
+    cwd : str
+        Path to root of relative path.
+    """
+    if os.path.isabs(path):
+        return path
+    else:
+        if not os.path.isabs(cwd):
+            cwd = os.path.abspath(cwd)
+        return os.path.abspath(
+            os.path.join(cwd, path)
+        )
+
+
+def make_dirs(path):
+    """ Create directories (equivalent of ``mkdir -p``). """
+    if path[-1] == '/':
+        parent = os.path.dirname(path[:-1])
+    else:
+        parent = os.path.dirname(path)
+
+    if len(parent) > 0:
+        if not os.path.exists(parent):
+            make_dirs(parent)
+
+    if not os.path.exists(path):
+        os.mkdir(path, 0o777)
+    else:
+        assert os.path.isdir(path)
+
+def missing_or_other_newer(path, other_path, cwd=None):
+    """
+    Investigate if path is non-existant or older than provided reference
+    path.
+
+    Parameters
+    ==========
+    path: string
+        path to path which might be missing or too old
+    other_path: string
+        reference path
+    cwd: string
+        working directory (root of relative paths)
+
+    Returns
+    =======
+    True if path is older or missing.
+    """
+    cwd = cwd or '.'
+    path = get_abspath(path, cwd=cwd)
+    other_path = get_abspath(other_path, cwd=cwd)
+    if not os.path.exists(path):
+        return True
+    if os.path.getmtime(other_path) - 1e-6 >= os.path.getmtime(path):
+        # 1e-6 is needed beacuse http://stackoverflow.com/questions/17086426/
+        return True
+    return False
+
+def copy(src, dst, only_update=False, copystat=True, cwd=None,
+         dest_is_dir=False, create_dest_dirs=False):
+    """ Variation of ``shutil.copy`` with extra options.
+
+    Parameters
+    ==========
+
+    src : str
+        Path to source file.
+    dst : str
+        Path to destination.
+    only_update : bool
+        Only copy if source is newer than destination
+        (returns None if it was newer), default: ``False``.
+    copystat : bool
+        See ``shutil.copystat``. default: ``True``.
+    cwd : str
+        Path to working directory (root of relative paths).
+    dest_is_dir : bool
+        Ensures that dst is treated as a directory. default: ``False``
+    create_dest_dirs : bool
+        Creates directories if needed.
+
+    Returns
+    =======
+
+    Path to the copied file.
+
+    """
+    if cwd:  # Handle working directory
+        if not os.path.isabs(src):
+            src = os.path.join(cwd, src)
+        if not os.path.isabs(dst):
+            dst = os.path.join(cwd, dst)
+
+    if not os.path.exists(src):  # Make sure source file extists
+        raise FileNotFoundError("Source: `{}` does not exist".format(src))
+
+    # We accept both (re)naming destination file _or_
+    # passing a (possible non-existent) destination directory
+    if dest_is_dir:
+        if not dst[-1] == '/':
+            dst = dst+'/'
+    else:
+        if os.path.exists(dst) and os.path.isdir(dst):
+            dest_is_dir = True
+
+    if dest_is_dir:
+        dest_dir = dst
+        dest_fname = os.path.basename(src)
+        dst = os.path.join(dest_dir, dest_fname)
+    else:
+        dest_dir = os.path.dirname(dst)
+
+    if not os.path.exists(dest_dir):
+        if create_dest_dirs:
+            make_dirs(dest_dir)
+        else:
+            raise FileNotFoundError("You must create directory first.")
+
+    if only_update:
+        if not missing_or_other_newer(dst, src):
+            return
+
+    if os.path.islink(dst):
+        dst = os.path.abspath(os.path.realpath(dst), cwd=cwd)
+
+    shutil.copy(src, dst)
+    if copystat:
+        shutil.copystat(src, dst)
+
+    return dst
+
+Glob = namedtuple('Glob', 'pathname')
+ArbitraryDepthGlob = namedtuple('ArbitraryDepthGlob', 'filename')
+
+def glob_at_depth(filename_glob, cwd=None):
+    if cwd is not None:
+        cwd = '.'
+    globbed = []
+    for root, dirs, filenames in os.walk(cwd):
+        for fn in filenames:
+            # This is not tested:
+            if fnmatch.fnmatch(fn, filename_glob):
+                globbed.append(os.path.join(root, fn))
+    return globbed
+
+def sha256_of_file(path, nblocks=128):
+    """ Computes the SHA256 hash of a file.
+
+    Parameters
+    ==========
+
+    path : string
+        Path to file to compute hash of.
+    nblocks : int
+        Number of blocks to read per iteration.
+
+    Returns
+    =======
+
+    hashlib sha256 hash object. Use ``.digest()`` or ``.hexdigest()``
+    on returned object to get binary or hex encoded string.
+    """
+    sh = sha256()
+    with open(path, 'rb') as f:
+        for chunk in iter(lambda: f.read(nblocks*sh.block_size), b''):
+            sh.update(chunk)
+    return sh
+
+
+def sha256_of_string(string):
+    """ Computes the SHA256 hash of a string. """
+    sh = sha256()
+    sh.update(string)
+    return sh
+
+
+def pyx_is_cplus(path):
+    """
+    Inspect a Cython source file (.pyx) and look for comment line like:
+
+    # distutils: language = c++
+
+    Returns True if such a file is present in the file, else False.
+    """
+    with open(path) as fh:
+        for line in fh:
+            if line.startswith('#') and '=' in line:
+                splitted = line.split('=')
+                if len(splitted) != 2:
+                    continue
+                lhs, rhs = splitted
+                if lhs.strip().split()[-1].lower() == 'language' and \
+                       rhs.strip().split()[0].lower() == 'c++':
+                            return True
+    return False
+
+def import_module_from_file(filename, only_if_newer_than=None):
+    """ Imports Python extension (from shared object file)
+
+    Provide a list of paths in `only_if_newer_than` to check
+    timestamps of dependencies. import_ raises an ImportError
+    if any is newer.
+
+    Word of warning: The OS may cache shared objects which makes
+    reimporting same path of an shared object file very problematic.
+
+    It will not detect the new time stamp, nor new checksum, but will
+    instead silently use old module. Use unique names for this reason.
+
+    Parameters
+    ==========
+
+    filename : str
+        Path to shared object.
+    only_if_newer_than : iterable of strings
+        Paths to dependencies of the shared object.
+
+    Raises
+    ======
+
+    ``ImportError`` if any of the files specified in ``only_if_newer_than`` are newer
+    than the file given by filename.
+    """
+    path, name = os.path.split(filename)
+    name, ext = os.path.splitext(name)
+    name = name.split('.')[0]
+    if sys.version_info[0] == 2:
+        from imp import find_module, load_module
+        fobj, filename, data = find_module(name, [path])
+        if only_if_newer_than:
+            for dep in only_if_newer_than:
+                if os.path.getmtime(filename) < os.path.getmtime(dep):
+                    raise ImportError("{} is newer than {}".format(dep, filename))
+        mod = load_module(name, fobj, filename, data)
+    else:
+        import importlib.util
+        spec = importlib.util.spec_from_file_location(name, filename)
+        if spec is None:
+            raise ImportError("Failed to import: '%s'" % filename)
+        mod = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(mod)
+    return mod
+
+
+def find_binary_of_command(candidates):
+    """ Finds binary first matching name among candidates.
+
+    Calls ``which`` from shutils for provided candidates and returns
+    first hit.
+
+    Parameters
+    ==========
+
+    candidates : iterable of str
+        Names of candidate commands
+
+    Raises
+    ======
+
+    CompilerNotFoundError if no candidates match.
+    """
+    from shutil import which
+    for c in candidates:
+        binary_path = which(c)
+        if c and binary_path:
+            return c, binary_path
+
+    raise CompilerNotFoundError('No binary located for candidates: {}'.format(candidates))
+
+
+def unique_list(l):
+    """ Uniquify a list (skip duplicate items). """
+    result = []
+    for x in l:
+        if x not in result:
+            result.append(x)
+    return result