Am 09.02.2021 um 16:46 schrieb Xi Ruoyao:
> On 2021-02-09 16:11 +0100, Viktor Engelmann wrote:
>> Hello everyone,
>>
>> I'm building LFS 10.0 on a fully updated Manjaro Linux on an x86_64 for
>> x86_64.
>>
>> When I compile M4 (chapter 6.2), I get two errors:
>>
>> - gcc complains about a void function ("fault_handler") being declared
>> as "pure" in line 146 of m4.c
>> - gcc complains about the flag -Wabi which is deprecated and doesn't do
>> anything
>>
>> (see the attached log file)
>>
>> I was able to circumvent the problems by setting the environment variable
>> CFLAGS=" -fpermissive -Wabi=11 " before ./configure, but I think that
>> these are infact bugs
>> in M4, so gcc is rightfully complaining.
>>
>> It seems that an older gcc version had failed if that function was NOT
>> declared "pure"
>> and the M4 team has also discussed this topic in july 2020, see
>> https://lists.gnu.org/archive/cgi-bin/namazu.cgi?query=fault_handler&submit=Search%21&idxname=bug-m4&max=20&result=normal&sort=score
>> they had also decided to make the function NOT "pure" (because
>> fault_handler has sideeffects
>> and should therefore not be pure). This was implemented by commit
>> 74915227e245c2f93d0db1ff3c53544d8f594dfa in the m4 git repository, but
>> the declaration
>> is still present in the .tar.xz from 2016 on http://ftp.gnu.org/gnu/m4/
>> that is used in LFS.
>>
>> I verified that LFS and LFS_TGT are set and that I'm compiling with
>> x86_64-lfs-linux-gnu-gcc.
>> Everything before M4 was built as regular user.
> Those warnings should not be enabled by default.
>
> Is your M4 tarball has the same MD5 checksum in the book? Or did you use some
> configure options not mentioned by the book?
Yes, I have compared all the MD5 sums. I followed the book very closely
and I have just compared my scripts to the book again and rebuilt again.
Everything else from chapter 5 and 6 worked fine.
The only thing I can think of that I (might) have done differently is
that I deleted the gcc-10.2.0 directory between building gcc and
libstdc++. The book doesn't explicitly say whether you should do that
and my script deletes target-directories before untaring to prevent
conflicts with previous builds (so the gcc directory is deleted because
libstdc++ is extracted to the same directory as gcc, because it comes
from the same tarball)
In the end, the function /is/ declared as pure and that /is/ logically
wrong, so it's correct of gcc to at least issue a warning. A warning is
also arguable when you pass a deprecated parameter such as -Wabi. It
seems that the warnings are turned into errors because -Werror is also
passed somewhere - I'm still looking into where that happens. But I
would argue that you should use -Werror whenever possible to avoid
unwanted results as much as possible.
--
http://lists.linuxfromscratch.org/listinfo/lfs-support
FAQ: http://www.linuxfromscratch.org/blfs/faq.html
Unsubscribe: See the above information page
Do not top post on this list.
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
http://en.wikipedia.org/wiki/Posting_style
