[m-rev.] for review: configure.in improvements

[Fergus Henderson]

Hi Simon,

The following is an extract from configure.log from logs/test-0.11-hg-asm.out.

 | checking whether to enable the GCC back-end interface... configure: error: --enable-gcc-back-end requires an already installed Mercury compiler.
 | + mmake --target asm depend
 | /tmp/mmake.9VRhaL:765: scripts/Mmake.vars: No such file or directory
 | /tmp/mmake.9VRhaL:770: Mmake.common: No such file or directory
 | touch Mercury.options
 | if [ -f ./config.status ]; then \
 |         ./config.status --recheck; \
 | else \
 |         echo "======> You need to run configure!"; \
 |         exit 1; \
 | fi
 | ======> You need to run configure!
 | gmake: *** [config.status] Error 1                                              
As you can see, configure detects that an already installed Mercury compiler
is required but not present, and issues an error message.
(The error message would be clearer if it started on a new line.)

However, after doing this, it goes on and runs `mmake --target asm depend' --
a dangerous step since `mmake' might not be in the PATH.
This step doesn't work for a different reason: the files that `mmake depend'
needs have not yet been created.  I'm not sure if this is a consequence
of the earlier error or whether the files won't get created yet even if
AC_MSG_ERROR() wasn't called.
This then leads to some spurious flow-on errors.

Several points:
	- Could you please add a newline to the error message?
	- `mmake depend' should not be invoked in cases like the one above.
	  Could you please fix this?

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
--------------------------------------------------------------------------
mercury-reviews mailing list
post:  mercury-reviews at cs.mu.oz.au
administrative address: owner-mercury-reviews at cs.mu.oz.au
unsubscribe: Address: mercury-reviews-request at cs.mu.oz.au Message: unsubscribe
subscribe:   Address: mercury-reviews-request at cs.mu.oz.au Message: subscribe
--------------------------------------------------------------------------