Re: Question about a fix for PR 58925

[Andrew MacLeod <amacleod at redhat dot com>]

On 10/31/2013 01:02 PM, Andrew MacLeod wrote:
> On 10/31/2013 12:13 PM, Andrew MacLeod wrote:
>
> There isnt much difference in the log or status files...  nothing real 
> obvious. ie, no fails or anything...   still looking... I *hate* 
> configuration crud. sigh.
> Andrew
OK, hacking around with configure, I find that in the libcilk.rts 
configure, it tests for the c++ compiler to find the default extenstion, 
and builds a.out.  Then around line 3106 where it checks
   "checking whether the C++ compiler works...",
it executes the binary via:

ac_try='./$ac_file'

If I do all this by hand and build the c++ conftest.c file, the command 
line looks like:

/gcc/2013-10-31/build/./gcc/xg++ -B/gcc/2013-10-31/build/./gcc/ 
-nostdinc++ -nostdinc++ 
-I/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/include/x86_64-unknown-linux-gnu 
-I/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/include 
-I/gcc/2013-10-31/gcc/libstdc++-v3/libsupc++ 
-I/gcc/2013-10-31/gcc/libstdc++-v3/include/backward 
-I/gcc/2013-10-31/gcc/libstdc++-v3/testsuite/util 
-L/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/src 
-L/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/src/.libs 
-L/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/libsupc++/.libs 
-B/gcc/2013-10-31/install/x86_64-unknown-linux-gnu/bin/ 
-B/gcc/2013-10-31/install/x86_64-unknown-linux-gnu/lib/ -isystem 
/gcc/2013-10-31/install/x86_64-unknown-linux-gnu/include -isystem 
/gcc/2013-10-31/install/x86_64-unknown-linux-gnu/sys-include  -m32 -g 
-O2 -D_GNU_SOURCE  conftest.c

if I try to run a.out generated by hand, I get:
./a.out: error while loading shared libraries: libstdc++.so.6: cannot 
open shared object file: No such file or directory

So it thinks my c++ compiler doesn't work....

If I change that compile command to NOT use -m32 and the 32bit 
subdirectories, then it works fine.

so the problem seems to be related to the 32 bit side of things.

ldd indicates that the a.out executable does not have
    libstdc++.so.6 => not found


but the file is in the correct directory:
/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/src/.libs/libstdc++.so 
-> libstdc++.so.6.0.19
/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/src/.libs/libstdc++.so.6 
-> libstdc++.so.6.0.19
/gcc/2013-10-31/build/x86_64-unknown-linux-gnu/32/libstdc++-v3/src/.libs/libstdc++.so.6.0.19


Im still poking around at it.  very odd.

Andrew...