mesonbuild: allow multiple --cross-file options

Just like --native-file, allow multiple --cross-file options.  This is mostly
unifying the logic between cross_files and config_files.

Upstream-Status: Backport [will be in 0.50.1]
Signed-off-by: Ross Burton <ross.burton@intel.com>

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 40402513..4b9bcb59 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -726,8 +726,7 @@ class Backend:
         deps = [os.path.join(self.build_to_src, df)
                 for df in self.interpreter.get_build_def_files()]
         if self.environment.is_cross_build():
-            deps.append(os.path.join(self.build_to_src,
-                                     self.environment.coredata.cross_file))
+            deps.extend(self.environment.coredata.cross_files)
         deps.append('meson-private/coredata.dat')
         if os.path.exists(os.path.join(self.environment.get_source_dir(), 'meson_options.txt')):
             deps.append(os.path.join(self.build_to_src, 'meson_options.txt'))
diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index c3f5a745..ff810683 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -201,8 +201,8 @@ class UserFeatureOption(UserComboOption):
         return self.value == 'auto'
 
 
-def load_configs(filenames):
-    """Load native files."""
+def load_configs(filenames, subdir):
+    """Load configuration files from a named subdirectory."""
     def gen():
         for f in filenames:
             f = os.path.expanduser(os.path.expandvars(f))
@@ -215,7 +215,7 @@ def load_configs(filenames):
                     os.environ.get('XDG_DATA_HOME', os.path.expanduser('~/.local/share')),
                 ] + os.environ.get('XDG_DATA_DIRS', '/usr/local/share:/usr/share').split(':')
                 for path in paths:
-                    path_to_try = os.path.join(path, 'meson', 'native', f)
+                    path_to_try = os.path.join(path, 'meson', subdir, f)
                     if os.path.isfile(path_to_try):
                         yield path_to_try
                         break
@@ -291,7 +291,7 @@ class CoreData:
         self.compiler_options = {}
         self.base_options = {}
         self.external_preprocess_args = {} # CPPFLAGS only
-        self.cross_file = self.__load_cross_file(options.cross_file)
+        self.cross_files = self.__load_config_files(options.cross_file)
         self.compilers = OrderedDict()
         self.cross_compilers = OrderedDict()
         self.deps = OrderedDict()
@@ -301,52 +301,14 @@ class CoreData:
 
     @staticmethod
     def __load_config_files(filenames):
+        # Need to try and make the passed filenames absolute because when the
+        # files are parsed later we'll have chdir()d.
         if not filenames:
             return []
         filenames = [os.path.abspath(os.path.expanduser(os.path.expanduser(f)))
                      for f in filenames]
         return filenames
 
-    @staticmethod
-    def __load_cross_file(filename):
-        """Try to load the cross file.
-
-        If the filename is None return None. If the filename is an absolute
-        (after resolving variables and ~), return that absolute path. Next,
-        check if the file is relative to the current source dir. If the path
-        still isn't resolved do the following:
-            Windows:
-                - Error
-            *:
-                - $XDG_DATA_HOME/meson/cross (or ~/.local/share/meson/cross if
-                  undefined)
-                - $XDG_DATA_DIRS/meson/cross (or
-                  /usr/local/share/meson/cross:/usr/share/meson/cross if undefined)
-                - Error
-
-        Non-Windows follows the Linux path and will honor XDG_* if set. This
-        simplifies the implementation somewhat.
-        """
-        if filename is None:
-            return None
-        filename = os.path.expanduser(os.path.expandvars(filename))
-        if os.path.isabs(filename):
-            return filename
-        path_to_try = os.path.abspath(filename)
-        if os.path.isfile(path_to_try):
-            return path_to_try
-        if sys.platform != 'win32':
-            paths = [
-                os.environ.get('XDG_DATA_HOME', os.path.expanduser('~/.local/share')),
-            ] + os.environ.get('XDG_DATA_DIRS', '/usr/local/share:/usr/share').split(':')
-            for path in paths:
-                path_to_try = os.path.join(path, 'meson', 'cross', filename)
-                if os.path.isfile(path_to_try):
-                    return path_to_try
-            raise MesonException('Cannot find specified cross file: ' + filename)
-
-        raise MesonException('Cannot find specified cross file: ' + filename)
-
     def sanitize_prefix(self, prefix):
         if not os.path.isabs(prefix):
             raise MesonException('prefix value {!r} must be an absolute path'
@@ -558,8 +520,8 @@ def read_cmd_line_file(build_dir, options):
     options.cmd_line_options = d
 
     properties = config['properties']
-    if options.cross_file is None:
-        options.cross_file = properties.get('cross_file', None)
+    if not options.cross_file:
+        options.cross_file = ast.literal_eval(properties.get('cross_file', '[]'))
     if not options.native_file:
         # This will be a string in the form: "['first', 'second', ...]", use
         # literal_eval to get it into the list of strings.
@@ -570,7 +532,7 @@ def write_cmd_line_file(build_dir, options):
     config = CmdLineFileParser()
 
     properties = {}
-    if options.cross_file is not None:
+    if options.cross_file:
         properties['cross_file'] = options.cross_file
     if options.native_file:
         properties['native_file'] = options.native_file
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index 6d86daf9..406ab8b8 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -355,8 +355,8 @@ class Environment:
         self.machines = MachineInfos()
         # Will be fully initialized later using compilers later.
         self.machines.detect_build()
-        if self.coredata.cross_file:
-            self.cross_info = CrossBuildInfo(self.coredata.cross_file)
+        if self.coredata.cross_files:
+            self.cross_info = CrossBuildInfo(self.coredata.cross_files)
             if 'exe_wrapper' in self.cross_info.config['binaries']:
                 from .dependencies import ExternalProgram
                 self.exe_wrapper = ExternalProgram.from_bin_list(
@@ -373,7 +373,7 @@ class Environment:
 
         if self.coredata.config_files:
             self.config_info = coredata.ConfigData(
-                coredata.load_configs(self.coredata.config_files))
+                coredata.load_configs(self.coredata.config_files, 'native'))
         else:
             self.config_info = coredata.ConfigData()
 
@@ -1113,13 +1113,8 @@ class CrossBuildInfo:
     def ok_type(self, i):
         return isinstance(i, (str, int, bool))
 
-    def parse_datafile(self, filename):
-        config = configparser.ConfigParser()
-        try:
-            with open(filename, 'r') as f:
-                config.read_file(f, filename)
-        except FileNotFoundError:
-            raise EnvironmentException('File not found: %s.' % filename)
+    def parse_datafile(self, filenames):
+        config = coredata.load_configs(filenames, 'cross')
         # This is a bit hackish at the moment.
         for s in config.sections():
             self.config[s] = {}
diff --git a/mesonbuild/msetup.py b/mesonbuild/msetup.py
index 56a0e9a7..f0a1ae19 100644
--- a/mesonbuild/msetup.py
+++ b/mesonbuild/msetup.py
@@ -27,7 +27,9 @@ from .mesonlib import MesonException
 
 def add_arguments(parser):
     coredata.register_builtin_arguments(parser)
-    parser.add_argument('--cross-file', default=None,
+    parser.add_argument('--cross-file',
+                        default=[],
+                        action='append',
                         help='File describing cross compilation environment.')
     parser.add_argument('--native-file',
                         default=[],
diff --git a/run_unittests.py b/run_unittests.py
index e6874b25..1d247291 100755
--- a/run_unittests.py
+++ b/run_unittests.py
@@ -529,7 +529,7 @@ class InternalTests(unittest.TestCase):
         config.write(configfile)
         configfile.flush()
         configfile.close()
-        detected_value = mesonbuild.environment.CrossBuildInfo(configfile.name).need_exe_wrapper()
+        detected_value = mesonbuild.environment.CrossBuildInfo((configfile.name,)).need_exe_wrapper()
         os.unlink(configfilename)
 
         desired_value = not detected_value
@@ -541,7 +541,7 @@ class InternalTests(unittest.TestCase):
         configfilename = configfile.name
         config.write(configfile)
         configfile.close()
-        forced_value = mesonbuild.environment.CrossBuildInfo(configfile.name).need_exe_wrapper()
+        forced_value = mesonbuild.environment.CrossBuildInfo((configfile.name,)).need_exe_wrapper()
         os.unlink(configfilename)
 
         self.assertEqual(forced_value, desired_value)