fmt: prefer system package if found

mu embeds a "vendored" subset of the libfmt package under thirdparty; but it's
better to use the system-package if the user has one.

So, use the system package if found or user -Duse-embedded-fmt=true is
specified.

lib/utils/meson.build

@@ -1,4 +1,4 @@
-## Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+## Copyright (C) 2022-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ##
 ## This program is free software; you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -41,14 +41,15 @@ lib_mu_utils=static_library('mu-utils',
   gio_unix_dep,
   config_h_dep,
   readline_dep,
-  cld2_dep
+  cld2_dep,
+  fmt_dep
 ], include_directories:
      include_directories(['.', '..', thirdparty]),
 install: false)
 
 lib_mu_utils_dep = declare_dependency(
   link_with: lib_mu_utils,
-  compile_args: '-DFMT_HEADER_ONLY',
+  dependencies: [fmt_dep],
   include_directories:
     include_directories(['.', '..', thirdparty]))
 

lib/utils/mu-error.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2019-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2019-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -28,10 +28,6 @@
 #include "mu-utils.hh"
 #include <glib.h>
 
-#ifndef FMT_HEADER_ONLY
-#define FMT_HEADER_ONLY
-#endif
-
 #include <fmt/format.h>
 #include <fmt/core.h>
 

lib/utils/mu-utils.hh

@@ -1,5 +1,5 @@
 /*
-**  Copyright (C) 2020-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**  Copyright (C) 2020-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 **  This library is free software; you can redistribute it and/or
 **  modify it under the terms of the GNU Lesser General Public License
@@ -36,9 +36,6 @@
 
 #include "mu-option.hh"
 
-#ifndef FMT_HEADER_ONLY
-#define FMT_HEADER_ONLY
-#endif /*FMT_HEADER_ONLY*/
 #include <fmt/format.h>
 #include <fmt/core.h>
 #include <fmt/chrono.h>

meson.build

@@ -219,6 +219,26 @@ host_system = host_machine.system()
 # soft dependencies
 #
 
+# use system's fmt if found, otherwise fall back to embedded version
+# we can probably get away with a lower version, but want to have (roughly)
+# the same in embedded / system.
+fmt_dep = dependency('fmt', version: '>=11.1', required:false)
+if not fmt_dep.found() or get_option('use-embedded-fmt')
+  message('using embedded fmt')
+  fmt_dep = declare_dependency(
+    include_directories : join_paths('.', 'thirdparty/fmt'),
+    compile_args: '-DFMT_HEADER_ONLY')
+endif
+
+# use system's CLI11 if found, otherwise fall back to embedded version
+cli11_dep = dependency('CLI11', version: '>=2.4', required:false)
+if not cli11_dep.found() or get_option('use-embedded-cli11')
+  message('using embedded CLI11')
+  cli11_dep = declare_dependency(
+    compile_args: '-DUSE_EMBEDDED_CLI11',
+    include_directories : join_paths('.', 'thirdparty/cli11'))
+endif
+
 #
 # logging
 #
@@ -280,7 +300,6 @@ if get_option('readline').enabled()
   config_h_data.set('HAVE_READLINE_HISTORY_H', 1)
 endif
 
-
 ################################################################################
 # write out version.texi (for texinfo builds in mu4e, guile)
 version_texi_data=configuration_data()

meson_options.txt

@@ -15,6 +15,20 @@
 ## Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
 
+#
+# mu contains some 'vendored' dependencies under thirdparty/; those
+# are only used if the corresponding system package is not found
+# (if such exists). But, we can override:
+
+option('use-embedded-fmt',
+       type: 'boolean',
+       value: false,
+       description: 'Use the embedded fmt, even if system package is found')
+
+#
+# language detection
+#
+
 option('cld2',
        type : 'feature',
        value: 'auto',