checks: kconfig: Check for references to undefined Kconfig symbols

Use 'git grep' to look for the pattern CONFIG_[A-Z0-9_]+ at word
boundaries in all files. For each match, check that the corresponding
Kconfig symbol is defined.

This check is broad enough that it will always need some whitelisting,
e.g. due to token pasting (CONFIG_FOO_#x) and non-existent symbols used
as examples. The message printed on failures points out where the
whitelist is.

There's a few stragglers in the whitelist for small issues that are
about to be fixed (the issue IDs are included).

Skip the samples/ and tests/ directories for now. They contain Kconfig
files that aren't part of the main Kconfig tree, which triggers false
positives. Maybe something fancier could be done later to include those.

Signed-off-by: Ulf Magnusson <[email protected]>

Author: ulfalizer

scripts/ci/check_compliance.py

@@ -4,6 +4,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+import collections
 import sys
 import subprocess
 import re
@@ -195,6 +196,7 @@ def run(self):
 
         self.check_no_undef_within_kconfig(kconf)
         self.check_top_menu_not_too_long(kconf)
+        self.check_no_undef_outside_kconfig(kconf)
 
     def get_modules(self, modules_file):
         """
@@ -295,6 +297,126 @@ def check_top_menu_not_too_long(self, kconf):
 entries, then bump the 'max_top_items' variable in {}.
 """.format(max_top_items, n_top_items, __file__))
 
+    def check_no_undef_outside_kconfig(self, kconf):
+        """
+        Checks that there are no references to undefined Kconfig symbols
+        outside Kconfig files (any CONFIG_FOO where no FOO symbol exists)
+        """
+        # Grep for symbol references.
+        #
+        # Example output line for a reference to CONFIG_BAZ at line 17 of
+        # foo/bar.c:
+        #
+        #   foo/bar.c<null>17<null>CONFIG_BAZ
+        #
+        # Skip the samples/ and tests/ directories for now. They often contain
+        # Kconfig files that are not part of the main Kconfig tree, which will
+        # trigger false positives until we do something fancier. Skip
+        # doc/releases too, which often references removed symbols.
+        grep_cmd = "git grep --only-matching --line-number -I --null " \
+                   "--extended-regexp --word-regexp CONFIG_[A-Z0-9_]+ " \
+                   "-- :!samples :!tests :!doc/releases"
+
+        grep_process = subprocess.Popen(grep_cmd.split(),
+                                        stdout=subprocess.PIPE,
+                                        stderr=subprocess.PIPE,
+                                        cwd=self.zephyr_base)
+
+        grep_stdout, grep_stderr = grep_process.communicate()
+        # Fail if there's anything on stderr too, so that it doesn't get missed
+        if grep_process.returncode or grep_stderr:
+            self.error("'{}' failed with exit code {} (while searching for "
+                       "Kconfig symbol references)\n\nstdout:\n{}\n\n"
+                       "stderr:\n{}"
+                       .format(grep_cmd, grep_process.returncode, grep_stdout,
+                               grep_stderr))
+
+        defined_syms = set(sym.name for sym in kconf.unique_defined_syms)
+        undef_to_locs = collections.defaultdict(list)
+
+        # splitlines() supports various line terminators
+        for line in grep_stdout.decode("utf-8").splitlines():
+            path, lineno, sym_name = line.split("\0")
+
+            # [7:] removes the "CONFIG_" prefix
+            if sym_name[7:] not in defined_syms and \
+               sym_name not in UNDEF_KCONFIG_WHITELIST:
+
+               undef_to_locs[sym_name].append("{}:{}".format(path, lineno))
+
+        if not undef_to_locs:
+            return
+
+        # String that describes all referenced but undefined Kconfig symbols,
+        # in alphabetical order, along with the locations where they're
+        # referenced. Example:
+        #
+        #   CONFIG_ALSO_MISSING    arch/xtensa/core/fatal.c:273
+        #   CONFIG_MISSING         arch/xtensa/core/fatal.c:264, subsys/fb/cfb.c:20
+        undef_desc = "\n".join(
+            "{:35} {}".format(sym_name, ", ".join(locs))
+            for sym_name, locs in sorted(undef_to_locs.items()))
+
+        self.add_failure("""
+Found references to undefined Kconfig symbols. If any of these are false
+positives, then add them to UNDEF_KCONFIG_WHITELIST in {} in the ci-tools
+repo.\n\n{}""".format(__file__, undef_desc))
+
+
+# Many of these are either symbols used as examples or due to token pasting
+# (CONFIG_FOO_#x, etc.). Note that the list is sorted alphabetically.
+UNDEF_KCONFIG_WHITELIST = {
+    "CONFIG_2ND_LVL_INTR_",
+    "CONFIG_3RD_LVL_INTR_",
+    "CONFIG_APP_LINK_WITH_",
+    "CONFIG_CDC_ACM_PORT_NAME_",
+    "CONFIG_CLOCK_STM32_PLL_SRC_",
+    "CONFIG_CLOCK_STM32_SYSCLK_SRC_",
+    "CONFIG_CMU",
+    "CONFIG_COUNTER_RTC",
+    "CONFIG_COUNTER_RTC_STM32_CLOCK_SRC",
+    "CONFIG_COUNTER_TIMER",
+    "CONFIG_DEEP_SLEEP",  # #defined by RV32M1 in ext/
+    "CONFIG_DESCRIPTION",
+    "CONFIG_ERR",
+    "CONFIG_ESP_DIF_LIBRARY",  # Referenced in CMake comment
+    "CONFIG_EXPERIMENTAL",
+    "CONFIG_FFT",  # Used as an example in cmake/extensions.cmake
+    "CONFIG_FLAG",  # Used as an example
+    "CONFIG_FOO",
+    "CONFIG_FOO_LOG_LEVEL",
+    "CONFIG_FOO_SETTING_1",
+    "CONFIG_FOO_SETTING_2",
+    "CONFIG_GPIO_SIFIVE_",
+    "CONFIG_I2C_GPIO_",
+    "CONFIG_I2S_CAVS_",
+    "CONFIG_LIS2DW12_INT_PIN",
+    "CONFIG_MODULES",
+    "CONFIG_MYFEATURE",
+    "CONFIG_MY_DRIVER_0",
+    "CONFIG_NORMAL_SLEEP",  # #defined by RV32M1 in ext/
+    "CONFIG_OPT",
+    "CONFIG_OPT_0",
+    "CONFIG_PWM_",
+    "CONFIG_REG1",
+    "CONFIG_REG2",
+    "CONFIG_SEL",
+    "CONFIG_SOC_SERIES_",
+    "CONFIG_SOC_WATCH",  # Issue 13749
+    "CONFIG_SOME_BOOL",
+    "CONFIG_SOME_INT",
+    "CONFIG_SOME_OTHER_BOOL",
+    "CONFIG_SOME_STRING",
+    "CONFIG_SPI_",
+    "CONFIG_STD_CPP",  # Referenced in CMake comment
+    "CONFIG_TEST1",
+    "CONFIG_TYPE_BOOLEAN",
+    "CONFIG_UART_",
+    "CONFIG_USB_CONSOLE",
+    "CONFIG_USB_HID_DEVICE_NAME_",
+    "CONFIG_WHATEVER",
+}
+
 
 class Codeowners(ComplianceTest):
     """