Dear All, I have a question which is almost 'theological'.
Consider a case, where your --host system (on which the code will run) and the --build system (where you compile) have the same canonical name, but yet you still don't want AC_PROG_CC to produce a test executable and run it. How do you stop AC_PROC_CC from attempting to run the test executable?
"Why would you want to do this?" you may ask. "It is after all a native build."
In my case the answer is that I am trying to compile a parallel program, which needs a special compiler (mpcc). However in order to run the output of mpcc, I need to be in a batch queue. Outwith the batch queue I cannot run executables compiled with the parallel environment.
so CC=mpcc ./configure breaks.
If I configure with:
CC=mpcc ./configure --host=powerpc-ibm-aix5.1.0.0
the configuration enters cross compilation mode. However this is flagged as an obsolete feature in the autoconf documentation:
In section 15.6.3:
"To ease the transition between 2.13 and its successors, a more complicated scheme is implemented. Do not rely on the following, as it will be removed in the near future.
If you specify `--host', but not `--build', when configure performs the first compiler test it will try to run an executable produced by the compiler. If the execution fails, it will enter cross-compilation mode. This is fragile. Moreover, by the time the compiler test is performed, it may be too late to modify the build-system type: other tests may have already been performed. Therefore, whenever you specify --host, be sure to specify --build too."
Hence I am not supposed to rely on this. However when I do specify build as in:
CC=mpcc ./configure --host=powerpc-ibm-aix5.1.0.0 --build=powerpc-ibm-aix5.1.0.0
the configuration breaks (because host and build are the same):
bash-2.05a$ CC=mpcc ./configure --host=powerpc-ibm-aix5.1.0.0 --build=powerpc-ib m-aix5.1.0.0 checking build system type... powerpc-ibm-aix5.1.0.0 checking host system type... powerpc-ibm-aix5.1.0.0 checking for a BSD-compatible install... ./config/install-sh -c checking whether build environment is sane... yes checking for gawk... no checking for mawk... no checking for nawk... nawk checking whether make sets $(MAKE)... yes checking whether make sets $(MAKE)... (cached) yes checking for powerpc-ibm-aix5.1.0.0-gcc... mpcc checking for C compiler default output... a.out checking whether the C compiler works... configure: error: cannot run C compiled programs.
While the now obsoleted method of specifying --host but no --build works now, it is likely to go away in the future. How else can I stop the test from trying to execute the executable but not use an obsolete constructs?
Your thoughts would be much appreciated,
Balint
PS: The solution is not to claim that mpcc is just a wrapper and I should give its -I and -L flags in the CXXFLAGS, LDFLAGS etc. This doesn't work because the executable still won't run in interactive mode. Ciao, B -- ------------------------------------------------------------------- Dr Balint Joo Post Doctoral Research Fellow School of Physics University of Edinburgh Mayfield Road, Edinburgh EH9 3JZ Scotland UK Tel: 0131 650 6469 (from UK) +44-131-650-6469 (from outwith UK) Fax: 0131 650 5902 (from UK) +44-131-650-5902 (from outwith UK) email: bj@xxxxxxxxxxx bj@xxxxxxxxxxxxxxxxx WWW : http://www.ph.ed.ac.uk/~bj -------------------------------------------------------------------
