bug#25740: [PATCH] Swallow m4traces that have no file/line number

[Christophe de Dinechin]

On 7 Mar 2017, at 23:51, Eric Blake <address@hidden> wrote:

autom4te is maintained by autoconf, not automake; redirecting your patch
there.

On 03/07/2017 04:00 PM, Christophe de Dinechin wrote:

The symptoms are something like:

 Use of uninitialized value $msg in concatenation (.) or string at /usr/local/Cellar/autoconf/2.69/bin/autom4te line 1032.
 Use of uninitialized value $stacktrace in pattern match (m//) at /usr/local/Cellar/autoconf/2.69/bin/autom4te line 1032.
 unknown channel m4trace: -1- AS_VAR_APPEND(ac_configure_args, " '$ac_arg'")
  at /usr/local/Cellar/autoconf/2.69/share/autoconf/Autom4te/Channels.pm line 638.
     Autom4te::Channels::msg('m4trace: -1- AS_VAR_APPEND(ac_configure_args, " \'$ac_arg\'")\x{a}', undef, 'warning: ', 'partial', 0) called at /usr/local/Cellar/autoconf/2.69/bin/autom4te line 1032

The root cause is m4 traces without a file/line number shown.

So instead of something like:

  m4trace:configure.ac:48: -1- ...

you have something like:

 m4trace: -1- ...

In the scenarios I ran into, this is due to some error that throws m4 out.
Eliminating these messages from the temporary m4 file being generated
(which will not complete anyway) is sufficient for the rest of autoconf
to complete, until it prints errors.

In my case, the final error looks like:

 common/Makefile.am:20: error: Libtool library used but 'LIBTOOL' is undefined
 common/Makefile.am:20:   The usual way to define 'LIBTOOL' is to add 'LT_INIT'
 common/Makefile.am:20:   to 'configure.ac' and run 'aclocal' and 'autoconf' again.
 common/Makefile.am:20:   If 'LT_INIT' is in 'configure.ac', make sure
 common/Makefile.am:20:   its definition is in aclocal's search path.
 autoreconf: automake failed with exit status: 1

But I've seen various reports for other root causes that ran into the same
problem (see bug report)

Signed-off-by: Christophe de Dinechin <address@hidden>
---
bin/autom4te.in | 2 ++
1 file changed, 2 insertions(+)

diff --git a/bin/autom4te.in b/bin/autom4te.in
index 964ac1a..b3f3831 100644
--- a/bin/autom4te.in
+++ b/bin/autom4te.in
@@ -821,6 +821,8 @@ EOF
  my $traces = new Autom4te::XFile ($tcache . $req->id, "<");
  while ($_ = $traces->getline)
    {
+      # Traces without file/line
+      next if (m{^m4trace: -(\d+)- ([^(]+)\((.*)$});

Would it be better to keep the error message, but set the file and line
to placeholders, instead of completely discarding the message?

I had tried, and that works too in my case. I.e. you can use if this seems to be better:

Subject: [PATCH 2/2] Alternate fix for #25740 (error reporting mangles

 messages)

The symptoms are something like:

  Use of uninitialized value $msg in concatenation (.) or string at /usr/local/Cellar/autoconf/2.69/bin/autom4te line 1032.

  Use of uninitialized value $stacktrace in pattern match (m//) at /usr/local/Cellar/autoconf/2.69/bin/autom4te line 1032.

  unknown channel m4trace: -1- AS_VAR_APPEND(ac_configure_args, " '$ac_arg'")

   at /usr/local/Cellar/autoconf/2.69/share/autoconf/Autom4te/Channels.pm line 638.

      Autom4te::Channels::msg('m4trace: -1- AS_VAR_APPEND(ac_configure_args, " \'$ac_arg\'")\x{a}', undef, 'warning: ', 'partial', 0) called at /usr/local/Cellar/autoconf/2.69/bin/autom4te line 1032

The root cause is m4 traces without a file/line number shown.

So instead of something like:

   m4trace:configure.ac:48: -1- ...

you have something like:

  m4trace: -1- ...

In the scenarios I ran into, this is due to some error that throws m4 out.

Eliminating these messages from the temporary m4 file being generated

(which will not complete anyway) is sufficient for the rest of autoconf

to complete, until it prints errors.

In my case, the final error looks like:

  common/Makefile.am:20: error: Libtool library used but 'LIBTOOL' is undefined

  common/Makefile.am:20:   The usual way to define 'LIBTOOL' is to add 'LT_INIT'

  common/Makefile.am:20:   to 'configure.ac' and run 'aclocal' and 'autoconf' again.

  common/Makefile.am:20:   If 'LT_INIT' is in 'configure.ac', make sure

  common/Makefile.am:20:   its definition is in aclocal's search path.

  autoreconf: automake failed with exit status: 1

But I've seen various reports for other root causes that ran into the same

problem (see bug report)

Signed-off-by: Christophe de Dinechin <address@hidden>

---

 bin/autom4te.in | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/bin/autom4te.in b/bin/autom4te.in

index b3f3831..406ebfe 100644

--- a/bin/autom4te.in

+++ b/bin/autom4te.in

@@ -821,8 +821,6 @@ EOF

   my $traces = new Autom4te::XFile ($tcache . $req->id, "<");

   while ($_ = $traces->getline)

     {

-      # Traces without file/line

-      next if (m{^m4trace: -(\d+)- ([^(]+)\((.*)$});

       # Trace with arguments, as the example above.  We don't try

       # to match the trailing parenthesis as it might be on a

       # separate line.

@@ -831,6 +829,8 @@ EOF

       # Traces without arguments, always on a single line.

       s{^m4trace:(.+):(\d+): -(\d+)- ([^)]*)\n$}

        {AT_$4([$1], [$2], [$3], [$4])\n};

+      s{^m4trace: -(\d+)- ([^(]+)\((.*)$}

+       {AT_$2([nowhere], [0], [$1], [$2], $3};

       print $trace_m4 "$_";

     }

   $trace_m4->close;

-- 

2.10.1 (Apple Git-78)

I thought discarding lines that did not seem to correspond to any known file was more efficient and less risky.

      # Trace with arguments, as the example above.  We don't try
      # to match the trailing parenthesis as it might be on a
      # separate line.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org