Re: PING^2 Re: PATCH: fix collect2 handling of --demangle and --no-demangle

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Mon, Jul 11, 2011 at 10:45 AM, Sandra Loosemore
<sandra@codesourcery.com> wrote:
> Ping?
>
> http://gcc.gnu.org/ml/gcc-patches/2011-06/msg01368.html
>
>> We had a bug report from a customer that the linker was ignoring the
>> --demangle and --no-demangle options when generating map files.
>> Moreover, it was failing in a host-dependent way; on Windows hosts,
>> it was always emitting demangled names in the map file, while on
>> Linux hosts, it never did. ?Moreover, on Windows hosts it also
>> ignored the setting of the COLLECT_NO_DEMANGLE environment variable.
>>
>> This turns out to be a problem in collect2, or actually, three
>> problems:
>>
>> (1) By default, collect2 is configured to filter out --demangle and
>> --no-demangle from the linker options, and it tries to do demangling
>> on symbol names in stdout and stderr itself instead. ?But, it is too
>> stupid to know about the map file.
>>
>> (2) Collect2 is trying to set COLLECT_NO_DEMANGLE to disable
>> demangling in ld, but in a nonportable way that causes it to be
>> always unset instead on Windows.
>>
>> (3) If you configure with --with-demangler-in-ld to try to disable
>> the collect2 demangling, there's another bug that causes it to ignore
>> any explicit --demangle or --no-demangle options and only pay
>> attention to whether or not COLLECT_NO_DEMANGLE is set.
>>
>> The attached patch addresses all three problems:
>>
>> (1) I've flipped the default to --with-demangler-in-ld=yes. ?Note
>> that configure.ac already takes care not to let this percolate
>> through to collect2 without verifying that the linker is GNU ld and
>> that it is a version that supports --demangle. ?Perhaps back in 2004
>> when this option was first added, the ld demangling support was
>> deemed too experimental to make it the default, but that's surely not
>> the case any more. ?Also, since this has been broken since 2004, I'm
>> not sure there's much reason to be concerned with backwards
>> compatibility, here....
>>
>> (2) I fixed the COLLECT_NO_DEMANGLE environment variable setting
>> recipe.
>>
>> (3) I simplified the argument processing for --demangle and
>> --no-demangle to pass them straight through to the linker when
>> HAVE_LD_DEMANGLE is defined.
>>
>> OK to commit?
>>
>> -Sandra
>>
>> 2011-06-17 ?Sandra Loosemore ?<sandra@codesourcery.com>
>>
>> ? ?gcc/
>> ? ?* configure.ac (demangler_in_ld): Default to yes.
>> ? ?* configure: Regenerated.
>> ? ?* collect2.c (main): When HAVE_LD_DEMANGLE is defined, don't
>> ? ?mess with COLLECT_NO_DEMANGLE, and just pass --demangle and
>> ? ?--no-demangle options straight through to ld. ?When
>> ? ?HAVE_LD_DEMANGLE is not defined, set COLLECT_NO_DEMANGLE in a
>> ? ?way that has the intended effect on Windows.

It caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49835


-- 
H.J.