id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
5514	Erroneous return value propagation in Boost.Build	Jason Kovacs	Vladimir Prus	"Hello,

I would like to report a problem I have noticed using Boost.Build combined with the Boost Unit Testing Framework. The problem manifests when using the '''run''' rule to execute unit tests, in a fashion similar to what is shown on this [http://www.alittlemadness.com/2009/12/10/boost-test-xml-reports-with-boost-build/ tutorial].

The problem is that, on Windows platforms, when one or more tests fail, the bjam return code is 0, while it is 1 on Linux. The propagation of this erroneous return value has been traced to the following code snippet, from ''tools/build/v2/tools/testing.jam'':


{{{
actions capture-output bind INPUT_FILES output-file
{
    $(PATH_SETUP)
    $(LAUNCHER) ""$(>)"" $(ARGS) ""$(INPUT_FILES)"" > ""$(output-file)"" 2>&1
    $(.SET_STATUS)
    $(.RUN_OUTPUT_NL) >> ""$(output-file)""
    echo EXIT STATUS: $(.STATUS) >> ""$(output-file)""
    if $(.STATUS_0)
        $(.CP) ""$(output-file)"" ""$(<)""
    $(.ENDIF)
    $(.SHELL_SET)verbose=$(.VERBOSE_TEST)
    if $(.STATUS_NOT_0)
        $(.SHELL_SET)verbose=1
    $(.ENDIF)
    if $(.VERBOSE)
        echo ====== BEGIN OUTPUT ======
        $(.CATENATE) ""$(output-file)""
        echo ====== END OUTPUT ======
    $(.ENDIF)
    exit $(.STATUS)
}
}}}

The problem comes from the exit command, which, called from a Windows batch file, closes the whole shell instead of the batch file, causing '''%ERRORLEVEL%''' to be reset to 0.
The proper way to call ''exit'' from a batch file is the following:

{{{
exit /B $(.STATUS)
}}}

For more information, type ''exit /?'' in a Windows command shell.
For now, the error level propagated is always zero, which is not consistent with the Linux implementation. A diff attempting at correcting this particular problem was submitted with this post.

----

Also, this is a good opportunity to discuss what return value bjam should return when the build is over.
It makes sense to return 0 for a successful build, and 1 if some targets could not be built.

But, on the other hand, it may not be desirable to have a non-zero return value because an executable launched by the '''run''' rule has exited with a non-null return value.
Some continuous integration tools such as [http://zutubi.com/ Pulse] use bjam's return value to determine whether the build was successful or not.
In test-driven development conditions, unit tests are meant to fail until issues are resolved. The fact that the unit tests have a non-zero return value does not indicate a build failure - the build may actually have succeeded.

Therefore, would it be possible to have bjam return 0 even though one of the programs called through the '''run''' rule has a non-zero exit code? Or could this feature at least be switched on with a flag?

Thanks in advance."	Bugs	closed	To Be Determined	build	Boost 1.46.1	Problem	worksforme	return value run bjam