rewriter: Accept UnknownValue() in more places

Fixes #14840

Author: Volker-Weissmann

mesonbuild/ast/interpreter.py

@@ -692,8 +692,11 @@ def func_set_variable(self, node: BaseNode, args: T.List[TYPE_var], kwargs: T.Di
     def func_get_variable(self, node: BaseNode, args: T.List[TYPE_var], kwargs: T.Dict[str, TYPE_var]) -> T.Any:
         assert isinstance(node, FunctionNode)
         var_name = args[0]
-        assert isinstance(var_name, str)
-        val = self.get_cur_value(var_name)
+        if isinstance(var_name, UnknownValue):
+            val: T.Union[UnknownValue, BaseNode] = UnknownValue()
+        else:
+            assert isinstance(var_name, str)
+            val = self.get_cur_value(var_name)
         self.dataflow_dag.add_edge(val, node)
         return val
 

mesonbuild/ast/introspection.py

@@ -203,9 +203,11 @@ def func_dependency(self, node: BaseNode, args: T.List[TYPE_var], kwargs: T.Dict
         has_fallback = 'fallback' in kwargs
         required = kwargs.get('required', True)
         version = kwargs.get('version', [])
-        if not isinstance(version, UnknownValue):
-            if not isinstance(version, list):
-                version = [version]
+        if not isinstance(version, list):
+            version = [version]
+        if any(isinstance(el, UnknownValue) for el in version):
+            version = UnknownValue()
+        else:
             assert all(isinstance(el, str) for el in version)
             version = T.cast(T.List[str], version)
         assert isinstance(required, (bool, UnknownValue))

test cases/unit/56 introspection/meson.build

@@ -58,6 +58,21 @@ test('test case 1', t1)
 test('test case 2', t2, depends: t3)
 benchmark('benchmark 1', t3, args: [cus1, cus2, cus3])
 
+### BEGIN: Stuff to test the handling of `UnknownValue`
+var_1 = 1
+var_2 = 2
+unknown_var = 'var_1'
+if host_machine.system() == 'windows'
+    unknown_var = 'var_2'
+endif
+# The IntrospectionInterpreter can't know the value of unknown_var and use the `UnknownValue` class.
+
+message(get_variable(unknown_var))
+
+dependency(unknown_var, version: [unknown_var], required: false)
+dependency(unknown_var, version: unknown_var, required: false)
+### END: Stuff to test the handling of `UnknownValue`
+
 ### Stuff to test the AST JSON printer
 foreach x : ['a', 'b', 'c']
   if x == 'a'

unittests/allplatformstests.py

@@ -3834,7 +3834,21 @@ def test_introspect_dependencies_from_source(self):
                 'version': ['>=1.0.0', '<=99.9.9'],
                 'has_fallback': True,
                 'conditional': True
-            }
+            },
+            {
+                'conditional': False,
+                'has_fallback': False,
+                'name': 'unknown',
+                'required': False,
+                'version': 'unknown'
+            },
+            {
+                'conditional': False,
+                'has_fallback': False,
+                'name': 'unknown',
+                'required': False,
+                'version': 'unknown'
+            },
         ]
         self.maxDiff = None
         self.assertListEqual(res_nb, expected)