Change meson test's build failure exit code to 125

man/meson.1

@@ -124,6 +124,18 @@ The default way of running tests is to invoke the default build command:
 .B meson test
 provides a richer set of tools for invoking tests.
 
+.B meson test
+automatically rebuilds the necessary targets to run tests when used with the Ninja backend.
+Upon build failure,
+.B meson test
+will return an exit code of 125.
+This return code tells
+.B git bisect run
+to skip the current commit.
+Thus bisecting using git can be done conveniently like this.
+
+.B git bisect run meson test -C build_dir
+
 .SS "options:"
 .TP
 \fB\-\-repeat\fR
@@ -214,6 +226,10 @@ Usage error, or an error parsing or executing meson.build.
 .B 2
 Internal error.
 .TP
+.B 125
+.B meson test
+could not rebuild the required targets.
+.TP
 
 .SH SEE ALSO
 

mesonbuild/mtest.py

@@ -1021,7 +1021,10 @@ def run(options: argparse.Namespace) -> int:
 
     if not options.list and not options.no_rebuild:
         if not rebuild_all(options.wd):
-            return 1
+            # We return 125 here in case the build failed.
+            # The reason is that exit code 125 tells `git bisect run` that the current commit should be skipped.
+            # Thus users can directly use `meson test` to bisect without needing to handle the does-not-build case separately in a wrapper script.
+            return 125
 
     with TestHarness(options) as th:
         try: