Re: [PATCH 2/4 REVIEW] libtool.m4: fix nm BSD flag detection
On 21 Jul 2021, Alan Modra uttered the following: > On Wed, Jul 07, 2021 at 08:03:45PM +0100, Nick Alcock via Gcc-patches wrote: >> >>> PR libctf/27482 >> >>> * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided >> > >> > Changes to libtool need to be posted to the libtool project: >> > >> > https://www.gnu.org/software/libtool/ >> >> I considered this, but there is *serious* divergence between the >> libtool.m4 in our tree and upstream. Fixing this divergence looks to be >> a fairly major project in and of itself :( the last real sync looked >> like being all the way back in 2008. > > Yes, I looked at doing a sync myself a few years ago.. > I'll OK the two libtool changes for binutils. Finally getting back to this -- sorry for the delay! (July and August were fairly fraught for me). I'll bring them up to date (mostly affecting the sim/ regenerations as far as I can see) then retest. I'm happy to backport this stuff as far back as people have reported problems, insofar as those branches are even open (that would be back to 2.34 for all the PR27967 stuff, some of which I mislabelled in the changelog as 27482: will fix). Is that OK? (It doesn't look like any of the release branches are currently frozen.) I'll repost the lot (including one new patch which is just under libctf/ and has a testcase, so is probably uncontroversial) and wait a bit before pushing, because it's been so long. (I've got a forward-port to libtool trunk too: I'll repost that as well, and chase up for reviews.) -- NULL && (void)
Re: [PATCH 2/4 REVIEW] libtool.m4: fix nm BSD flag detection
On Wed, Jul 07, 2021 at 08:03:45PM +0100, Nick Alcock via Gcc-patches wrote: > On 7 Jul 2021, Nick Clifton told this: > > > Hi Nick, > > > >> Ping? > > > > Oops. > > I sent a bunch of pings out at the same time, to a bunch of different > projects. You are the only person to respond, so thank you! > > >>> PR libctf/27482 > >>> * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided > > > > Changes to libtool need to be posted to the libtool project: > > > > https://www.gnu.org/software/libtool/ > > I considered this, but there is *serious* divergence between the > libtool.m4 in our tree and upstream. Fixing this divergence looks to be > a fairly major project in and of itself :( the last real sync looked > like being all the way back in 2008. Yes, I looked at doing a sync myself a few years ago.. I'll OK the two libtool changes for binutils. -- Alan Modra Australia Development Lab, IBM
Re: [PATCH 2/4 REVIEW] libtool.m4: fix nm BSD flag detection
On 7 Jul 2021, Nick Clifton told this: > Hi Nick, > >> Ping? > > Oops. I sent a bunch of pings out at the same time, to a bunch of different projects. You are the only person to respond, so thank you! >>> PR libctf/27482 >>> * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided > > Changes to libtool need to be posted to the libtool project: > > https://www.gnu.org/software/libtool/ I considered this, but there is *serious* divergence between the libtool.m4 in our tree and upstream. Fixing this divergence looks to be a fairly major project in and of itself :( the last real sync looked like being all the way back in 2008. > They have mailing lists for bug reports and patch submissions. > > Once the patch has been accepted there it can be backported to the gcc and > gdb/binutils repositories... AIUI, libtool has no maintainer currently, and the divergence is such that the patch might need a near-complete rewrite anyway :( (there were changes to this function upstream in 2012 and 2013, long after our last sync.) (However, I'm going to try in any case. I may have found a sucker, er, I mean coworker willing to take this on.)
Re: [PATCH 2/4 REVIEW] libtool.m4: fix nm BSD flag detection
Hi Nick, Ping? Oops. PR libctf/27482 * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided Changes to libtool need to be posted to the libtool project: https://www.gnu.org/software/libtool/ They have mailing lists for bug reports and patch submissions. Once the patch has been accepted there it can be backported to the gcc and gdb/binutils repositories... Cheers Nick
Re: [PATCH 2/4 REVIEW] libtool.m4: fix nm BSD flag detection
Ping?
On 25 Jun 2021, Nick Alcock via Binutils said this:
> 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 $NM, a path might have been
>provided: so we use the user-specified path if there was one, and
>otherwise do the path search as usual. (If the nm specified doesn't
>work, this might lead to a few extra pointless path searches -- but
>the test is going to fail anyway, so that's not a problem.)
>
> (Tested with NM unset, and set to nm, /usr/bin/nm, my-nm where my-nm is a
> symlink to /usr/bin/nm on the PATH, and /not-on-the-path/my-nm where
> *that* is a symlink to /usr/bin/nm.)
>
> Cc: gcc-patches@gcc.gnu.org
>
> ChangeLog
> 2021-06-22 Nick Alcock
>
> PR libctf/27482
> * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided
> NM, if there is one. Run nm on itself, not on /dev/null, to avoid
> errors from nms that refuse to work on non-regular files. Remove
> other workarounds for this problem. Strip out blank lines from the
> nm output.
> ---
> libtool.m4 | 88 --
> 1 file changed, 45 insertions(+), 43 deletions(-)
>
> diff --git a/libtool.m4 b/libtool.m4
> index b0a56917497..29dce1f8239 100644
> --- a/libtool.m4
> +++ b/libtool.m4
> @@ -3200,53 +3200,55 @@ _LT_DECL([], [file_magic_cmd], [1],
>
> # LT_PATH_NM
> # --
> -# find the pathname to a BSD- or MS-compatible name lister
> +# find the pathname to a BSD- or MS-compatible name lister, and any flags
> +# needed to make it compatible
> AC_DEFUN([LT_PATH_NM],
> [AC_REQUIRE([AC_PROG_CC])dnl
> AC_CACHE_CHECK([for BSD- or MS-compatible name lister (nm)], lt_cv_path_NM,
> [if test -n "$NM"; then
> - # Let the user override the test.
> - lt_cv_path_NM="$NM"
> -else
> - lt_nm_to_check="${ac_tool_prefix}nm"
> - if test -n "$ac_tool_prefix" && test "$build" = "$host"; then
> -lt_nm_to_check="$lt_nm_to_check nm"
> - fi
> - for lt_tmp_nm in $lt_nm_to_check; do
> -lt_save_ifs="$IFS"; IFS=$PATH_SEPARATOR
> -for ac_dir in $PATH /usr/ccs/bin/elf /usr/ccs/bin /usr/ucb /bin; do
> - IFS="$lt_save_ifs"
> - test -z "$ac_dir" && ac_dir=.
> - tmp_nm="$ac_dir/$lt_tmp_nm"
> - if test -f "$tmp_nm" || test -f "$tmp_nm$ac_exeext" ; then
> - # Check to see if the nm accepts a BSD-compat flag.
> - # Adding the `sed 1q' prevents false positives on HP-UX, which says:
> - # nm: unknown option "B" ignored
> - # Tru64's nm complains that /dev/null is an invalid object file
> - case `"$tmp_nm" -B /dev/null 2>&1 | sed '1q'` in
> - */dev/null* | *'Invalid file or object type'*)
> - lt_cv_path_NM="$tmp_nm -B"
> - break
> - ;;
> - *)
> - case `"$tmp_nm" -p /dev/null 2>&1 | sed '1q'` in
> - */dev/null*)
> - lt_cv_path_NM="$tmp_nm -p"
> - break
> - ;;
> - *)
> - lt_cv_path_NM=${lt_cv_path_NM="$tmp_nm"} # keep the first match, but
> - continue # so that we can try to find one that supports BSD flags
> - ;;
> - esac
> - ;;
> - esac
> - fi
> -done
> -IFS="$lt_save_ifs"
> - done
> - : ${lt_cv_path_NM=no}
> -fi])
> + # Let the user override the nm to test.
> + lt_nm_to_check="$NM"
> + else
> + lt_nm_to_check="${ac_tool_prefix}nm"
> + if test -n "$ac_tool_prefi
[PATCH 2/4 REVIEW] libtool.m4: fix nm BSD flag detection
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 $NM, a path might have been
provided: so we use the user-specified path if there was one, and
otherwise do the path search as usual. (If the nm specified doesn't
work, this might lead to a few extra pointless path searches -- but
the test is going to fail anyway, so that's not a problem.)
(Tested with NM unset, and set to nm, /usr/bin/nm, my-nm where my-nm is a
symlink to /usr/bin/nm on the PATH, and /not-on-the-path/my-nm where
*that* is a symlink to /usr/bin/nm.)
Cc: gcc-patches@gcc.gnu.org
ChangeLog
2021-06-22 Nick Alcock
PR libctf/27482
* libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided
NM, if there is one. Run nm on itself, not on /dev/null, to avoid
errors from nms that refuse to work on non-regular files. Remove
other workarounds for this problem. Strip out blank lines from the
nm output.
---
libtool.m4 | 88 --
1 file changed, 45 insertions(+), 43 deletions(-)
diff --git a/libtool.m4 b/libtool.m4
index b0a56917497..29dce1f8239 100644
--- a/libtool.m4
+++ b/libtool.m4
@@ -3200,53 +3200,55 @@ _LT_DECL([], [file_magic_cmd], [1],
# LT_PATH_NM
# --
-# find the pathname to a BSD- or MS-compatible name lister
+# find the pathname to a BSD- or MS-compatible name lister, and any flags
+# needed to make it compatible
AC_DEFUN([LT_PATH_NM],
[AC_REQUIRE([AC_PROG_CC])dnl
AC_CACHE_CHECK([for BSD- or MS-compatible name lister (nm)], lt_cv_path_NM,
[if test -n "$NM"; then
- # Let the user override the test.
- lt_cv_path_NM="$NM"
-else
- lt_nm_to_check="${ac_tool_prefix}nm"
- if test -n "$ac_tool_prefix" && test "$build" = "$host"; then
-lt_nm_to_check="$lt_nm_to_check nm"
- fi
- for lt_tmp_nm in $lt_nm_to_check; do
-lt_save_ifs="$IFS"; IFS=$PATH_SEPARATOR
-for ac_dir in $PATH /usr/ccs/bin/elf /usr/ccs/bin /usr/ucb /bin; do
- IFS="$lt_save_ifs"
- test -z "$ac_dir" && ac_dir=.
- tmp_nm="$ac_dir/$lt_tmp_nm"
- if test -f "$tmp_nm" || test -f "$tmp_nm$ac_exeext" ; then
- # Check to see if the nm accepts a BSD-compat flag.
- # Adding the `sed 1q' prevents false positives on HP-UX, which says:
- # nm: unknown option "B" ignored
- # Tru64's nm complains that /dev/null is an invalid object file
- case `"$tmp_nm" -B /dev/null 2>&1 | sed '1q'` in
- */dev/null* | *'Invalid file or object type'*)
- lt_cv_path_NM="$tmp_nm -B"
- break
- ;;
- *)
- case `"$tmp_nm" -p /dev/null 2>&1 | sed '1q'` in
- */dev/null*)
- lt_cv_path_NM="$tmp_nm -p"
- break
- ;;
- *)
- lt_cv_path_NM=${lt_cv_path_NM="$tmp_nm"} # keep the first match, but
- continue # so that we can try to find one that supports BSD flags
- ;;
- esac
- ;;
- esac
- fi
-done
-IFS="$lt_save_ifs"
- done
- : ${lt_cv_path_NM=no}
-fi])
+ # Let the user override the nm to test.
+ lt_nm_to_check="$NM"
+ else
+ lt_nm_to_check="${ac_tool_prefix}nm"
+ if test -n "$ac_tool_prefix" && test "$build" = "$host"; then
+ lt_nm_to_check="$lt_nm_to_check nm"
+ fi
+ fi
+ for lt_tmp_nm in $lt_nm_to_check; do
+ lt_save_ifs="$IFS"; IFS=$PATH_SEPARATOR
+ for ac_dir in $PATH /usr/ccs/bin/elf /usr/ccs/b
