scripts: ci: check_compliance: add a no-modules Kconfig check

Add a variation of the basic Kconfig check that runs with no modules,
catches symbols that are used in the main repository but are defined
only in modules, which are potentially problematic if a downstream
project is not using the specific module.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

.gitignore

@@ -75,6 +75,7 @@ Identity.txt
 ImageSize.txt
 Kconfig.txt
 KconfigBasic.txt
+KconfigBasicNoModules.txt
 MaintainersFormat.txt
 Nits.txt
 Pylint.txt

scripts/ci/check_compliance.py

@@ -268,7 +268,9 @@ class KconfigCheck(ComplianceTest):
     doc = "See https://docs.zephyrproject.org/latest/guides/kconfig/index.html for more details."
     path_hint = "<zephyr-base>"
 
-    def run(self, full=True):
+    def run(self, full=True, no_modules=False):
+        self.no_modules = no_modules
+
         kconf = self.parse_kconfig()
 
         self.check_top_menu_not_too_long(kconf)
@@ -287,6 +289,11 @@ class KconfigCheck(ComplianceTest):
         This is needed to complete Kconfig sanity tests.
 
         """
+        if self.no_modules:
+            with open(modules_file, 'w') as fp_module_file:
+                fp_module_file.write("# Empty\n")
+            return
+
         # Invoke the script directly using the Python executable since this is
         # not a module nor a pip-installed Python utility
         zephyr_module_path = os.path.join(ZEPHYR_BASE, "scripts",
@@ -711,6 +718,18 @@ class KconfigBasicCheck(KconfigCheck):
     def run(self):
         super().run(full=False)
 
+class KconfigBasicNoModulesCheck(KconfigCheck):
+    """
+    Checks if we are introducing any new warnings/errors with Kconfig when no
+    modules are available. Catches symbols used in the main repository but
+    defined only in a module.
+    """
+    name = "KconfigBasicNoModules"
+    doc = "See https://docs.zephyrproject.org/latest/guides/kconfig/index.html for more details."
+    path_hint = "<zephyr-base>"
+    def run(self):
+        super().run(full=False, no_modules=True)
+
 
 class Nits(ComplianceTest):
     """