File: libtool.info,  Node: Stripped link flags,  Up: FAQ

13.1 Why does libtool strip link flags when creating a library?
===============================================================

When creating a shared library, but not when compiling or creating a
program, ‘libtool’ drops some flags from the command line provided by
the user.  This is done because flags unknown to ‘libtool’ may interfere
with library creation or require additional support from ‘libtool’, and
because omitting flags is usually the conservative choice for a
successful build.

   If you encounter flags that you think are useful to pass, as a
work-around you can prepend flags with ‘-Wc,’ or ‘-Xcompiler ’ to allow
them to be passed through to the compiler driver (*note Link mode::).
Another possibility is to add flags already to the compiler command at
‘configure’ run time:

     ./configure CC='gcc -m64'

   If you think ‘libtool’ should let some flag through by default,
here's how you can test such an inclusion: grab the Libtool development
tree, edit the ‘ltmain.in’ file in the ‘libltdl/config’ subdirectory to
pass through the flag (search for ‘Flags to be passed through’),
re-bootstrap and build with the flags in question added to ‘LDFLAGS’,
‘CFLAGS’, ‘CXXFLAGS’, etc.  on the ‘configure’ command line as
appropriate.  Run the testsuite as described in the ‘README’ file and
report results to the Libtool bug reporting address
.