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NGINX Unit - universal web app server - a lightweight and versatile open source server that simplifies the application stack by natively executing application code across eight different programming language runtimes.
https://unit.nginx.org
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Fix building the Perl language module with clang (on some systems) #1228

Closed ac000 closed 1 month ago

ac000 commented 2 months ago

When we added -fno-strict-overflow to the CFLAGS back in c1e3f02f9 ("Compile with -fno-strict-overflow") we inadvertently broke building the Perl language module with clang, e.g

  $ make
    CC     build/src/perl/nxt_perl_psgi-perl.o
  clang: error: argument unused during compilation: '-fno-strict-overflow' [-Werror,-Wunused-command-line-argument]

This is due to for example on Apline

  $ perl -MExtUtils::Embed -e ccflags
   -D_REENTRANT -D_GNU_SOURCE -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64

Where on clang the -fwrapv causes the -fno-strict-overflow to be discarded resulting in the above error.

We can get around that by simply appending -Qunused-arguments to the Perl CFLAGS.

This fixes things for some systems, as there is actually another issue with building this with clang on Fedora (and probably Red Hat) in that there the Perl ccflags & ldopts have been heavily modified and uses flags simply not only not in clang (which we can work around as above) but also incompatible flags, e.g

  $ make perl
    CC     build/src/perl/nxt_perl_psgi-perl.o
  clang: error: optimization flag '-ffat-lto-objects' is not supported [-Werror,-Wignored-optimization-argument]

There ddoesn't seem to be an easy workaround like -Qunused-arguments for this.

While we could work around it in some way, I'm not sure it's worth the effort right now. On Red Hat & Fedora GCC is the system compiler.

This could be revisited if we find people trying to build this on Red Hat/Fedora with clang...

For comparison this is the Alpine Perl ccflags & ldops

$ perl -MExtUtils::Embed -e ccflags
 -D_REENTRANT -D_GNU_SOURCE -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 alpine:~$
$ perl -MExtUtils::Embed -e ldopts
-rdynamic -Wl,-rpath,/usr/lib/perl5/core_perl/CORE  -fstack-protector-strong -L/usr/local/lib  -L/usr/lib/perl5/core_perl/CORE -lperl -lpthread -ldl -lm -lcrypt -lutil -lc

Fedora

$ perl -MExtUtils::Embed -e ccflags
 -D_REENTRANT -D_GNU_SOURCE -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Wno-complain-wrong-lang -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -fwrapv -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64
$ perl -MExtUtils::Embed -e ldopts
-Wl,--enable-new-dtags -Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1  -Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1  -fstack-protector-strong -L/usr/local/lib  -L/usr/lib64/perl5/CORE -lperl -lpthread -lresolv -ldl -lm -lcrypt -lutil -lc
ac000 commented 2 months ago

Fix commit message typo

$ git range-diff 347016a8...9c5d6036
1:  347016a8 ! 1:  9c5d6036 auto, perl: Fix building the Perl language module with clang
    @@ Commit message
             CC     build/src/perl/nxt_perl_psgi-perl.o
           clang: error: optimization flag '-ffat-lto-objects' is not supported [-Werror,-Wignored-optimization-argument]

    -    There ddoesn't seem to be an easy workaround like -Qunused-arguments for
    +    There doesn't seem to be an easy workaround like -Qunused-arguments for
         this.

         While we could work around it in some way, I'm not sure it's worth the
ac000 commented 1 month ago

Hi @hongzhidao

Just to check if you have any issues or questions about this patch?

Just to re-cap, this basically re-enables the building of the perl language module with clang to how it was before commit https://github.com/nginx/unit/commit/c1e3f02f99a3cab181c36d1f55c552e2bcfba370

Fixing this is a prerequisite of merging https://github.com/nginx/unit/pull/1223

hongzhidao commented 1 month ago

Just to check if you have any issues or questions about this patch?

Not at all, feel free to ship it.

ac000 commented 1 month ago

Great, thanks!

ac000 commented 1 month ago

Rebased with master...