Fix assertion raised with invalid option name

When option name contains more that one dot, it should be detected
earlier to prevent an assert to be raised.

Fixes #11904.

mesonbuild/interpreter/interpreter.py

@@ -37,6 +37,7 @@ from ..interpreterbase import FeatureNew, FeatureDeprecated, FeatureBroken, Feat
 from ..interpreterbase import ObjectHolder, ContextManagerObject
 from ..interpreterbase import stringifyUserArguments
 from ..modules import ExtensionModule, ModuleObject, MutableModuleObject, NewExtensionModule, NotFoundExtensionModule
+from ..optinterpreter import optname_regex
 
 from . import interpreterobjects as OBJ
 from . import compiler as compilerOBJ
@@ -1090,6 +1091,10 @@ class Interpreter(InterpreterBase, HoldableObject):
             raise InterpreterException('Having a colon in option name is forbidden, '
                                        'projects are not allowed to directly access '
                                        'options of other subprojects.')
+
+        if optname_regex.search(optname.split('.', maxsplit=1)[-1]) is not None:
+            raise InterpreterException(f'Invalid option name {optname!r}')
+
         opt = self.get_option_internal(optname)
         if isinstance(opt, coredata.UserFeatureOption):
             opt.name = optname

test cases/common/40 options/meson.build

@@ -46,3 +46,11 @@ assert(get_option('wrap_mode') == 'default', 'Wrap mode option is broken.')
 assert(get_option('boolean_string') == false)
 assert(get_option('boolean_string2') == true)
 assert(get_option('integer_string') == 42)
+
+testcase expect_error('Invalid option name \'..invalid\'')
+  get_option('..invalid')
+endtestcase
+
+testcase expect_error('Invalid option name \'this.is.also.invalid\'')
+  get_option('this.is.also.invalid')
+endtestcase