Using newer gcc in /opt/netapps: Difference between revisions
(The script is not generic, provide a version-specific one in the gcc/5.2 dir) |
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Please note: /opt is *NOT* in ld.so.conf, and should not be | Please note: /opt is *NOT* in ld.so.conf, and should not be | ||
The environment variables that are set in the sourceme snippet influence Make-like programs (GNU make, icmake). So projects using such utilities will automatically build your programs using the newer compiler. | |||
If you want to build by calling the compiler directly, you cannot just call 'g++'. Instead, call the newer compiler as $CXX, like this: | |||
${CXX} -o hello hello.cc | |||
NB: if you are reading this page as a participant (or attendee) of the C++ course, please ask your questions on the mailing list first, not through the Service Desk. | |||
== Later versions == | == Later versions == | ||
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GCCBASE="/opt/netapps/gnu/gcc/5.2" | GCCBASE="/opt/netapps/gnu/gcc/5.2" | ||
== Addendum == | |||
Programs built with this newer compiler and these newer libraries use a | |||
newer ABI than the regular compiler/libraries on the LWP. | |||
(See | |||
https://gcc.gnu.org/onlinedocs/libstdc%2B%2B/manual/using_dual_abi.html ) | |||
If you run such programs without the environment settings that were set | |||
in the shell snippet, the dynamic linker, at run/load time, will give | |||
you relocation errors. Of course it is undesirable to have to set the | |||
environment depending on which executables are going to run, even if you | |||
can predict that at all. | |||
Luckily, we can hardcode the new library paths into the executable | |||
during building: | |||
export LDFLAGS='-Wl,--rpath,/opt/netapps/gnu/gcc/5.2/lib64' | |||
The weird dual-comma syntax means to tell the compiler (-Wl) to tell the | |||
linker to use option "--rpath /opt/netapps/gnu/gcc/5.2/lib64". | |||
Such an export command, used just before calling Make, will cause Make | |||
to build an executable that '''will''' run without any special environment | |||
settings, albeit only on the LWP, where the paths mentioned actually exist. | |||
Revision as of 17:25, 12 December 2016
Gcc-5.2 is in /opt/netapps/gnu/gcc/5.2. In order for you to use it, this may have to be appended to your .profile:
GCCSNIPPET=/opt/netapps/gnu/gcc/5.2/sourceme
[ -r ${GCCSNIPPET} ] && . ${GCCSNIPPET}
Please note: /opt is *NOT* in ld.so.conf, and should not be
The environment variables that are set in the sourceme snippet influence Make-like programs (GNU make, icmake). So projects using such utilities will automatically build your programs using the newer compiler.
If you want to build by calling the compiler directly, you cannot just call 'g++'. Instead, call the newer compiler as $CXX, like this:
${CXX} -o hello hello.cc
NB: if you are reading this page as a participant (or attendee) of the C++ course, please ask your questions on the mailing list first, not through the Service Desk.
Later versions
You may find that still later versions are available. Check /opt/netapps/gnu/gcc, and alter the above script by adjusting the line
GCCBASE="/opt/netapps/gnu/gcc/5.2"
Addendum
Programs built with this newer compiler and these newer libraries use a newer ABI than the regular compiler/libraries on the LWP. (See https://gcc.gnu.org/onlinedocs/libstdc%2B%2B/manual/using_dual_abi.html )
If you run such programs without the environment settings that were set in the shell snippet, the dynamic linker, at run/load time, will give you relocation errors. Of course it is undesirable to have to set the environment depending on which executables are going to run, even if you can predict that at all.
Luckily, we can hardcode the new library paths into the executable during building:
export LDFLAGS='-Wl,--rpath,/opt/netapps/gnu/gcc/5.2/lib64'
The weird dual-comma syntax means to tell the compiler (-Wl) to tell the linker to use option "--rpath /opt/netapps/gnu/gcc/5.2/lib64".
Such an export command, used just before calling Make, will cause Make to build an executable that will run without any special environment settings, albeit only on the LWP, where the paths mentioned actually exist.