Subject: [PATCH v3] meson: disable PCRE2 dependency by default in macOS

From: Carlo Marcelo Arenas Belón <[email-masked]>
Date: Sun, 13 Jul 2025 10:48:07 -0700

Makefile requires the user to provide the USE_LIBPCRE2 flag to
enable this dependency, but meson has it enabled by default,
which can be problematic, at least in macOS.

macOS provides a PCRE2 library in base that is not usable and not
configured properly, as it installs a pkgconf module that
points to a non existent pcre2.h header in /usr/local/include.

Add an option that will need to be turned to true once an
alternative PCRE2 library is installed (which hopefully provides
its own pkgconf module earlier in PKG_CONFIG_PATH) or meson has
been instructed to use its subproject as a suitable dependency
by `--force-fallback-for=pcre2`.

Signed-off-by: Carlo Marcelo Arenas Belón <[email-masked]>
---
 meson.build       | 3 ++-
 meson_options.txt | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/meson.build b/meson.build
index 7fea4a34d6..e1475be6c8 100644
--- a/meson.build
+++ b/meson.build
@@ -1055,7 +1055,8 @@ else
   build_options_config.set('NO_ICONV', '1')
 endif
 
-pcre2 = dependency('libpcre2-8', required: get_option('pcre2'), default_options: ['default_library=static', 'test=false'])
+pcre2_feature = get_option('pcre2').disable_auto_if(host_machine.system() == 'darwin' and not get_option('macos_workaround_system_pcre2'))
+pcre2 = dependency('libpcre2-8', required: pcre2_feature, default_options: ['default_library=static', 'test=false'])
 if pcre2.found()
   libgit_dependencies += pcre2
   libgit_c_args += '-DUSE_LIBPCRE2'
diff --git a/meson_options.txt b/meson_options.txt
index e7f768df24..f63ff32556 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -45,7 +45,7 @@ option('gitweb', type: 'feature', value: 'auto',
   description: 'Build Git web interface. Requires Perl.')
 option('iconv', type: 'feature', value: 'auto',
   description: 'Support reencoding strings with different encodings.')
-option('pcre2', type: 'feature', value: 'enabled',
+option('pcre2', type: 'feature', value: 'auto',
   description: 'Support Perl-compatible regular expressions in e.g. git-grep(1).')
 option('perl', type: 'feature', value: 'auto',
   description: 'Build tools written in Perl.')
@@ -73,6 +73,8 @@ option('breaking_changes', type: 'boolean', value: false,
   description: 'Enable upcoming breaking changes.')
 option('macos_use_homebrew_gettext', type: 'boolean', value: true,
   description: 'Use gettext from Homebrew instead of the slightly-broken system-provided one.')
+option('macos_workaround_system_pcre2', type: 'boolean', value: false,
+  description: 'A working PCRE2 library is available or will be provided by a subproject.')
 
 # gitweb configuration.
 option('gitweb_config', type: 'string', value: 'gitweb_config.perl')
-- 
2.39.5 (Apple Git-154)