5ab7dd14e1
Libtool needs to get BSD-format (or MS-format) output out of the system nm, so that it can scan generated object files for symbol names for -export-symbols-regex support. Some nms need specific flags to turn on BSD-formatted output, so libtool checks for this in its AC_PATH_NM. Unfortunately the code to do this has a pair of interlocking flaws: - it runs the test by doing an nm of /dev/null. Some platforms reasonably refuse to do an nm on a device file, but before now this has only been worked around by assuming that the error message has a specific textual form emitted by Tru64 nm, and that getting this error means this is Tru64 nm and that nm -B would work to produce BSD-format output, even though the test never actually got anything but an error message out of nm -B. This is fixable by nm'ing *nm itself* (since we necessarily have a path to it). - the test is entirely skipped if NM is set in the environment, on the grounds that the user has overridden the test: but the user cannot reasonably be expected to know that libtool wants not only nm but also flags forcing BSD-format output. Worse yet, one such "user" is the top-level Cygnus configure script, which neither tests for nor specifies any BSD-format flags. So platforms needing BSD-format flags always fail to set them when run in a Cygnus tree, breaking -export-symbols-regex on such platforms. Libtool also needs to augment $LD on some platforms, but this is done unconditionally, augmenting whatever the user specified: the nm check should do the same. One wrinkle: if the user has overridden $NM, a path might have been provided: so we use the user-specified path if there was one, and otherwise do the path search as usual. (If the nm specified doesn't work, this might lead to a few extra pointless path searches -- but the test is going to fail anyway, so that's not a problem.) (Tested with NM unset, and set to nm, /usr/bin/nm, my-nm where my-nm is a symlink to /usr/bin/nm on the PATH, and /not-on-the-path/my-nm where *that* is a symlink to /usr/bin/nm.) ChangeLog 2021-09-27 Nick Alcock <nick.alcock@oracle.com> PR libctf/27967 * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided NM, if there is one. Run nm on itself, not on /dev/null, to avoid errors from nms that refuse to work on non-regular files. Remove other workarounds for this problem. Strip out blank lines from the nm output. |
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README
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.