Tools: run_coverage.py: cope with lcov 2.x fatal error classes

lcov 2.x, as shipped in the Ubuntu 24.04 CI containers, promotes two
conditions the weekly coverage run always hits from warnings to fatal
errors:

 - "mismatched end line": two functions starting on the same source
   line with different end lines.  Every gtest TEST() body trips this,
   as the macro also defines the fixture constructor and destructor on
   the TEST() line, so both lcov --capture invocations abort.
 - "unused": a --remove pattern which matched nothing; ".waf*" never
   matches, so the pattern-removal step aborts.

Pass --ignore-errors for those classes on the affected invocations.
lcov 1.x rejects unknown error classes, so the arguments are only
emitted when lcov reports version 2 or later.

Tools/scripts/run_coverage.py

@@ -7,6 +7,7 @@ Runs tests with gcov coverage support.
 """
 import argparse
 import os
+import re
 import shutil
 import subprocess
 import sys
@@ -38,6 +39,30 @@ class CoverageRunner(object):
         self.failed_suites = []
         self.start_time = time.time()
 
+    def lcov_ignore_errors(self, *classes):
+        """Return --ignore-errors arguments for the given lcov error classes.
+
+        lcov 2.x promotes several conditions to fatal errors which 1.x
+        merely warned about (or did not check at all):
+
+         - "mismatch": two functions defined on the same source line
+           with different end lines.  Every gtest TEST() body trips
+           this, as the macro also defines the fixture's constructor and
+           destructor on that line.
+         - "unused": an --exclude/--remove pattern which matched nothing.
+
+        lcov 1.x rejects unknown error classes outright, so the
+        arguments are only emitted for 2.x and later.
+        """
+        try:
+            output = subprocess.run(["lcov", "--version"], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True).stdout
+        except OSError:
+            return []
+        match = re.search(r"version (\d+)", output)
+        if match is None or int(match.group(1)) < 2:
+            return []
+        return ["--ignore-errors", ",".join(classes)]
+
     def progress(self, text) -> None:
         """Pretty printer."""
         delta_time = time.time() - self.start_time
@@ -81,6 +106,7 @@ class CoverageRunner(object):
         self.progress("Initializing Coverage with current build")
         try:
             result = subprocess.run(["lcov",
+                                     *self.lcov_ignore_errors("mismatch"),
                                      "--no-external",
                                      "--initial",
                                      "--capture",
@@ -210,6 +236,7 @@ class CoverageRunner(object):
                 try:
                     self.progress("Capturing Coverage statistics")
                     subprocess.run(["lcov",
+                                    *self.lcov_ignore_errors("mismatch"),
                                     "--no-external",
                                     "--capture",
                                     "--directory", root_dir,
@@ -236,6 +263,7 @@ class CoverageRunner(object):
                     # remove files we do not intentionally test:
                     self.progress("Removing unwanted coverage statistics")
                     subprocess.run(["lcov",
+                                    *self.lcov_ignore_errors("unused"),
                                     "--remove", self.INFO_FILE,
                                     ".waf*",
                                     root_dir + "/modules/*",