meson: handle nested disabler

Fixes #5659

mesonbuild/interpreterbase.py

@@ -337,20 +337,25 @@ class Disabler(InterpreterObject):
     def found_method(self, args, kwargs):
         return False
 
-def is_disabler(i):
+def is_disabler(i) -> bool:
     return isinstance(i, Disabler)
 
-def is_disabled(args, kwargs):
+def is_arg_disabled(arg) -> bool:
+    if is_disabler(arg):
+        return True
+    if isinstance(arg, list):
+        for i in arg:
+            if is_arg_disabled(i):
+                return True
+    return False
+
+def is_disabled(args, kwargs) -> bool:
     for i in args:
-        if isinstance(i, Disabler):
+        if is_arg_disabled(i):
             return True
     for i in kwargs.values():
-        if isinstance(i, Disabler):
+        if is_arg_disabled(i):
             return True
-        if isinstance(i, list):
-            for j in i:
-                if isinstance(j, Disabler):
-                    return True
     return False
 
 class InterpreterBase:

test cases/common/164 disabler/meson.build

@@ -33,6 +33,7 @@ assert(number == 2, 'If found handled incorrectly, value should be 2 but is @0@'
 
 dep = dependency('notfounddep', required : false, disabler : true)
 app = executable('myapp', 'notfound.c', dependencies : [dep])
+app = executable('myapp', 'notfound.c', dependencies : [[dep]])
 
 cc = meson.get_compiler('c')
 dep = cc.find_library('notfounddep', required : false, disabler : true)