4 files changed, 11 insertions, 6 deletions
diff --git a/mesonbuild/interpreterbase/__init__.py b/mesonbuild/interpreterbase/__init__.py
index 298a034..8e45cdb 100644
--- a/mesonbuild/interpreterbase/__init__.py
+++ b/mesonbuild/interpreterbase/__init__.py
@@ -41,7 +41,7 @@ __all__ = [
     'stringArgs',
     'noArgsFlattening',
     'noSecondLevelHolderResolving',
-    'unholder_return',
+    'permissive_unholder_return',
     'disablerIfNotFound',
     'permittedKwargs',
     'typed_pos_args',
@@ -94,7 +94,7 @@ from .decorators import (
     stringArgs,
     noArgsFlattening,
     noSecondLevelHolderResolving,
-    unholder_return,
+    permissive_unholder_return,
     disablerIfNotFound,
     permittedKwargs,
     typed_pos_args,
diff --git a/mesonbuild/interpreterbase/_unholder.py b/mesonbuild/interpreterbase/_unholder.py
index b5663a5..7e95232 100644
--- a/mesonbuild/interpreterbase/_unholder.py
+++ b/mesonbuild/interpreterbase/_unholder.py
@@ -18,7 +18,7 @@ from ..mesonlib import HoldableObject, MesonBugException
 
 import typing as T
 
-def _unholder(obj: T.Union[TYPE_var, InterpreterObject]) -> TYPE_var:
+def _unholder(obj: T.Union[TYPE_var, InterpreterObject], *, permissive: bool = False) -> TYPE_var:
     if isinstance(obj, (int, bool, str)):
         return obj
     elif isinstance(obj, list):
@@ -30,6 +30,8 @@ def _unholder(obj: T.Union[TYPE_var, InterpreterObject]) -> TYPE_var:
         return obj.held_object
     elif isinstance(obj, MesonInterpreterObject):
         return obj
+    elif isinstance(obj, HoldableObject) and permissive:
+        return obj
     elif isinstance(obj, HoldableObject):
         raise MesonBugException(f'Argument {obj} of type {type(obj).__name__} is not held by an ObjectHolder.')
     elif isinstance(obj, InterpreterObject):
diff --git a/mesonbuild/interpreterbase/decorators.py b/mesonbuild/interpreterbase/decorators.py
index b91e9d5..eabc6d8 100644
--- a/mesonbuild/interpreterbase/decorators.py
+++ b/mesonbuild/interpreterbase/decorators.py
@@ -72,11 +72,11 @@ def noSecondLevelHolderResolving(f: TV_func) -> TV_func:
     setattr(f, 'no-second-level-holder-flattening', True)  # noqa: B010
     return f
 
-def unholder_return(f: TV_func) -> T.Callable[..., TYPE_var]:
+def permissive_unholder_return(f: TV_func) -> T.Callable[..., TYPE_var]:
     @wraps(f)
     def wrapped(*wrapped_args: T.Any, **wrapped_kwargs: T.Any) -> T.Any:
         res = f(*wrapped_args, **wrapped_kwargs)
-        return _unholder(res)
+        return _unholder(res, permissive=True)
     return T.cast(T.Callable[..., TYPE_var], wrapped)
 
 def disablerIfNotFound(f: TV_func) -> TV_func:
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index d66fb9c..91cb7aa 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -268,7 +268,7 @@ class InterpreterBase:
         return True
 
     def evaluate_in(self, val1: T.Any, val2: T.Any) -> bool:
-        if not isinstance(val1, (str, int, float, ObjectHolder)):
+        if not isinstance(val1, (str, int, float, mesonlib.HoldableObject)):
             raise InvalidArguments('lvalue of "in" operator must be a string, integer, float, or object')
         if not isinstance(val2, (list, dict)):
             raise InvalidArguments('rvalue of "in" operator must be an array or a dict')
@@ -281,6 +281,9 @@ class InterpreterBase:
         val2 = self.evaluate_statement(node.right)
         if isinstance(val2, Disabler):
             return val2
+        # Do not compare the ObjectHolders but the actual held objects
+        val1 = _unholder(val1)
+        val2 = _unholder(val2)
         if node.ctype == 'in':
             return self.evaluate_in(val1, val2)
         elif node.ctype == 'notin':