Hello automakers. I'll soon push a patch which works around a Zsh incompatibility in the handling of `$0'; this incompatibility currently prevents a successful run of the automake testsuite in parallel with Zsh as $(TEST_LOG_COMPILER).
Here is an in-depth description and analysis of the problem. I'm posting it in advance so that it will be possible to refer to it from the ChangeLog entry of the patch (thus avoiding excessive verbosity there). And JFTR, here is the original bug report & analysis: <http://lists.gnu.org/archive/html/bug-automake/2009-08/msg00013.html> and here is and older patch: <http://lists.gnu.org/archive/html/automake-patches/2010-01/msg00017.html> -*-*-*- The automake testcases are run each in its own temporary directory, whose name is computed (by code in `tests/defs') from the name of the testcase itself. For example, the test `foo.test' is expected to be executed in a temporary directory named `foo.dir'. The computing of the test name is done using the `$0' special shell variable. Unfortunately, an incompatibility in the way Zsh handles the `$0' variable in sourced scripts might cause serious problems with this scheme. By default, if Zsh is not running in Bourne compatibility mode, then in any script sourced with the `.' builtin it sets `$0' to the path of *that same sourced script*; more information about this behaviour can be found at: <http://zsh.sourceforge.net/Doc/Release/Parameters.html> Here is a simple demonstration: $ cat > foo.sh <<'END' echo 1. $0 . ./bar.sh END $ cat > bar.sh <<'END' echo 2. $0 END $ sh foo.sh 1. foo.sh 2. foo.sh $ zsh foo.sh 1. foo.sh 2. ./bar.sh Now, at a first glance, it seems that `tests/defs' (well, technically `tests/defs-static', but these details don't matter here) already takes care of the incompatibility, since it puts Zsh into Bourne compatibility mode with the command `emulate sh'. Unfortunately, such a command is issued too late to really work as expected. In fact, when a test, say `foo.test', includes `./defs', it isn't in Bourne compatibility mode yet, so that, when the execution of the code in `./defs' begins, the value of `$0' gets set to "./defs"; activating Bourne compatibility mode later (in either `defs' or `defs-static') cannot prevent or change this. Thus the `$me' variable is always set to "defs", and the temporary testcase directory is *always* set to "defs.dir". And here comes the problem. Apart from making debugging more difficult (since the temporary directories left behind by failed testcases are happily overridden by following, unrelated testcases), the issue above will also cause the testsuite to *utterly break* when run in parallel mode, since in that case many tests will use the *same* temporary directory *simultaneously*, and thus will stomp on each other feet. -*-*-*- The change I'm going to apply will work around the problems described above for modern-enough Zsh version, and will offer better error messages (instead of potential random failures) for older versions. Regards, Stefano
