I decided this feature was too impacting to make the permanent default
behavior. This set of changes makes the default behavior of make the
old behavior (no second expansion). If you want second expansion, you
must define the .SECONDEXPANSION: special target before the first target
that needs it.
This set of changes ONLY fixes explicit and static pattern rules to work
like this. Implicit rules still have second expansion enabled all the
time: I'll work on that next.
Note that there is still a backward-incompatibility: now to get the old
SysV behavior using $$@ etc. in the prerequisites list you need to set
.SECONDEXPANSION: as well.
follow POSIX backslash/newline conventions.
Use a different method for testing the SHELL variable, which hopefully
will work better on non-UNIX systems.
Solaris system with an EMC NFS storage solution. Still get some odd
errors here unfortunately related to sub-second timestamps that I just
can't figure out. It all works if we run the tests in /tmp instead
though :-/.
check for this and exit with an error.
The closeout.c version from gnulib pulls in too much other stuff, and
gnulib requires an ANSI C 89 compliant compiler, while GNU make (so far)
still wants to work on K&R.
cleanups.
If we find a make error (invalid makefile syntax or something like that)
write back any tokens we have before we exit.
If we have waiting jobs (using -j + -l) set an alarm before we sleep on
the read() system call, so we can wake up to check the load and start
waiting jobs, if there are long-running jobs we would otherwise be
waiting for. Suggested by Grant Taylor.
Taylor. There are two forms of this: first, it was possible to lose
tokens when using -j and -l at the same time, because waiting jobs were
not checked when determining whether any jobs were outstanding. Second,
if you had an exported recursive variable that contained a $(shell ...)
function there is a possibility to lose tokens, since a token was taken
but the child list was not updated until after the shell function was
complete.
To resolve this I introduced a new variable that counted the number of
tokens we have obtained, rather than checking whether there were any
children on the list. I also added some sanity checks to make sure we
weren't writing back too many or not enough tokens. And, the master
make will drain the token pipe before exiting and compare the count of
tokens at the end to what was written there at the beginning.
Also:
* Ensure a bug in the environment (missing "=") doesn't cause make to core.
* Rename the .DEFAULT_TARGET variable to .DEFAULT_GOAL, to match the
terminology in the documentation and other variables like MAKECMDGOALS.
* Add documentation of the .DEFAULT_GOAL special variable.
Still need to document the secondary expansion stuff...
I did this by adding intelligence into the algorithm such that the
second expansion was only actually performed when the prerequisite list
contained at least one "$", so we knew it is actually needed.
Without this we were using up a LOT more memory, since every single
target (even ones never used by make) had their file variables
initialized. This also used a lot more CPU, since we needed to create
and populate a new variable hash table for every target.
There is one issue remaining with this feature: it leaks memory. In
pattern_search() we now initialize the file variables for every pattern
target, which allocates a hash table, etc. However, sometimes we
recursively invoke pattern_search() (for intermediate files) with an
automatic variable (alloca() I believe) as the file. When that function
returns, obviously, the file variable hash memory is lost.
