Merge changes I81e76796,Iba319126 into main

* changes:
  libutil: Set boost defines for FreeBSD
  meson.build: Allow undefined symbols on FreeBSD

meson.build

@@ -167,6 +167,7 @@ message('canonical Nix system name:', host_system)
 
 is_linux = host_machine.system() == 'linux'
 is_darwin = host_machine.system() == 'darwin'
+is_freebsd = host_machine.system() == 'freebsd'
 is_x64 = host_machine.cpu_family() == 'x86_64'
 
 # Per-platform arguments that you should probably pass to shared_module() invocations.
@@ -462,6 +463,12 @@ if cxx.get_linker_id() in ['ld.bfd', 'ld.gold']
   add_project_link_arguments('-Wl,--no-copy-dt-needed-entries', language : 'cpp')
 endif
 
+if is_freebsd
+  # FreeBSD's `environ` is defined in `crt1.o`, not `libc.so`,
+  # so the linker thinks it's undefined
+  add_project_link_arguments('-Wl,-z,undefs', language: 'cpp')
+endif
+
 # Generate Chromium tracing files for each compiled file, which enables
 # maintainers/buildtime_report.sh BUILD-DIR to simply work in clang builds.
 #

src/libutil/fmt.hh

@@ -5,8 +5,8 @@
 #include <string>
 #include <optional>
 #include <boost/format.hpp>
-// Darwin stdenv does not define _GNU_SOURCE but does have _Unwind_Backtrace.
-#ifdef __APPLE__
+// Darwin and FreeBSD stdenv do not define _GNU_SOURCE but do have _Unwind_Backtrace.
+#if __APPLE__ || __FreeBSD__
 #define BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED
 #endif
 #include <boost/stacktrace.hpp>