msetup: Give a nice error message if cmd_line.txt cannot be read
As would happen if someone tried to manually call meson --wipe on a
directory configured with a version < 0.49.0
@@ -62,8 +62,13 @@ class MesonApp:
# restore that file if anything bad happens. For example if
# configuration fails we need to be able to wipe again.
filename = coredata.get_cmd_line_file(self.build_dir)
+ try:
with open(filename, 'r') as f:
content = f.read()
+ except FileNotFoundError:
+ raise MesonException(
+ 'Cannot find cmd_line.txt. This is probably because this '
+ 'build directory was configured with a meson version < 0.49.0.')
coredata.read_cmd_line_file(self.build_dir, options)
