gdb @13.1: opportunistic use of zstd

[tcwan (TC Wan)]

When attempting to build gdb +multiarch 13.1 on Apple M2 Mac Mini running Ventura 13.4, the build with fail. The build succeeded on Apple iMac with Intel processor running Monterey 12.6.7.

The previous version gdb +multiarch 12.1 can be built successfully on Apple M2 Mac Mini.

[tcwan (TC Wan)]

Build log of gdb +mulitarch for 13,1

[tcwan (TC Wan)]

I realize that the gdb version built on Apple Silicon Macs will be x86_64. However, the failure stems from:

:info:build ld: warning: ignoring file /opt/local/lib/libzstd.dylib, building for macOS-x86_64 but attempting to link with file built for macOS-arm64

Fix: I had to force uninstall zstd, and

$ sudo port install zstd +universal 

After that gdb 13.1 can be built. The portfile should be updated to reflect the dependency on zstd +universal

Edit 2: It might be necessary to flag all dependencies as requiring +universal for arm64 platform. Some of the dependencies were rebuilt as universal previously due to enabling gdb+multiarch+python310, which triggered rebuilds of some dependent libraries by the python rebuild.

[ryandesign (Ryan Carsten Schmidt)]

Replying to tcwan:

The portfile should be updated to reflect the dependency on zstd +universal

Only a dependency on zstd needs to be added to gdb. (Or gdb needs to be told not to use zstd even if it is installed.)

MacPorts will automatically handle rebuilding dependencies universal if that is needed.

There is no way in MacPorts to declare a dependency on a variant of another port. See #126.

[kencu (Ken)]

gcc started using zstd last year, so no surprise gdb uses it now too…

[tcwan (TC Wan)]

Now I'm getting the following error when building gdb 13.1 on M2 Mini macOS Ventura 13.6, gdb +multiarch +python311

:info:build   CXXLD  gdb
:info:build ld: warning: ignoring file /opt/local/lib/libxxhash.dylib, building for macOS-x86_64 but attempting to link with file built for macOS-arm64
:info:build Undefined symbols for architecture x86_64:
:info:build   "_XXH64", referenced from:
:info:build       gdb::bcache::hash(void const*, int) in bcache.o
:info:build       minimal_symbol_reader::install()::$_0::operator()(minimal_symbol*, minimal_symbol*) const in minsyms.o
:info:build       psymbol_bcache::hash(void const*, int) in psymtab.o
:info:build       hashname(char const*) in stabsread.o
:info:build       common_block_end(objfile*) in stabsread.o
:info:build       scan_file_globals(objfile*) in stabsread.o
:info:build       general_symbol_info::compute_and_set_names(gdb::basic_string_view<char, std::__1::char_traits<char>>, bool, objfile_per_bfd_storage*, gdb::optional<unsigned int>) in symtab.o
:info:build       ...
:info:build ld: symbol(s) not found for architecture x86_64
:info:build clang: error: linker command failed with exit code 1 (use -v to see invocation)

% port echo installed|fgrep xxhashlib         
xxhashlib                      @0.8.2_3

[tcwan (TC Wan)]

I had to add 'xxhashlib +unviersal' to fix the build.