Added improvements, found in review

meson.build

@@ -81,12 +81,8 @@ endif
 
 if cc.has_argument('--std=gnu99')
   add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
-  lang_opt = ['c_std=gnu99']
 elif cc.has_argument('--std=c99')
   add_project_arguments('--std=c99', language: ['c', 'cpp'])
-  lang_opt = ['c_std=c99']
-else
-  lang_opt = []
 endif
 
 # Sanitize correct usage of rz_strf()
@@ -179,15 +175,15 @@ cmake_package_relative_path = run_command(py3_exe, cmake_package_prefix_dir_py,
 subproject_clean_error_msg = 'Subprojects are not updated. Please run `git clean -dxff subprojects/` to delete all local subprojects directories. If you want to compile against current subprojects then set option `subprojects_check=false`.'
 
 # handle capstone dependency
-capstone_dep = dependency('capstone', version: '>=4.0.2', required: get_option('use_sys_capstone'), static: is_static_build, default_options: lang_opt)
+capstone_dep = dependency('capstone', version: '>=4.0.2', required: get_option('use_sys_capstone'), static: is_static_build)
 if not capstone_dep.found()
   capstone_version = get_option('use_capstone_version')
   if fs.is_file('subprojects/capstone-' + capstone_version + '.wrap')
     r = run_command(py3_exe, check_meson_subproject_py, 'capstone-' + capstone_version, check: false)
     if r.returncode() == 1 and get_option('subprojects_check')
       error(subproject_clean_error_msg)
     endif
-    capstone_proj = subproject('capstone-' + capstone_version, default_options: ['default_library=static'] + lang_opt)
+    capstone_proj = subproject('capstone-' + capstone_version, default_options: ['default_library=static'])
   else
     error('Wrong capstone version selected. Please use one of the supported versions.')
   endif
@@ -635,13 +631,13 @@ if r.returncode() == 1 and get_option('subprojects_check')
   error(subproject_clean_error_msg)
 endif
 
-libzip_dep = dependency('libzip', required: get_option('use_sys_libzip'), static: is_static_build, default_options: lang_opt)
+libzip_dep = dependency('libzip', required: get_option('use_sys_libzip'), static: is_static_build)
 if not libzip_dep.found()
   libzip_proj = subproject('libzip', default_options: [
     'default_library=static',
     'static_runtime=@0@'.format(is_static_build),
     'use_sys_openssl=@0@'.format(get_option('use_sys_libzip_openssl')),
-  ] + lang_opt)
+  ])
   libzip_dep = libzip_proj.get_variable('libzip_dep')
 endif
 

subprojects/packagefiles/capstone-4.0.2/meson.build

@@ -3,9 +3,15 @@ project('capstone', 'c',
   meson_version: '>=0.55.0',
   default_options: [
     'c_std=c99',
-  ]
+  ],
 )
 
+cc = meson.get_compiler('c')
+
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
+  add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
+endif
+
 cs_files = [
   'arch/AArch64/AArch64BaseInfo.c',
   'arch/AArch64/AArch64Disassembler.c',

subprojects/packagefiles/capstone-5.0.1/meson.build

@@ -3,9 +3,15 @@ project('capstone', 'c',
   meson_version: '>=0.55.0',
   default_options: [
     'c_std=c99',
-  ]
+  ],
 )
 
+cc = meson.get_compiler('c')
+
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
+  add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
+endif
+
 cs_files = [
   'arch/AArch64/AArch64BaseInfo.c',
   'arch/AArch64/AArch64Disassembler.c',

subprojects/packagefiles/capstone-auto-sync-aarch64/meson.build

@@ -6,6 +6,12 @@ project('capstone', 'c',
   ]
 )
 
+cc = meson.get_compiler('c')
+
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
+  add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
+endif
+
 cs_files = [
   'arch/AArch64/AArch64BaseInfo.c',
   'arch/AArch64/AArch64Disassembler.c',

subprojects/packagefiles/capstone-next/meson.build

@@ -3,9 +3,15 @@ project('capstone', 'c',
   meson_version: '>=0.55.0',
   default_options: [
     'c_std=c99',
-  ]
+  ],
 )
 
+cc = meson.get_compiler('c')
+
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
+  add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
+endif
+
 cs_files = [
   'arch/Alpha/AlphaDisassembler.c',
   'arch/Alpha/AlphaInstPrinter.c',

subprojects/packagefiles/libzip-1.9.2/meson.build

@@ -4,13 +4,17 @@ project('libzip', 'c',
   meson_version: '>=0.55.0',
   default_options: [
     'c_std=c99',
-  ]
+  ],
 )
 
 py3_exe = import('python').find_installation()
 cc = meson.get_compiler('c')
 is_static_build = get_option('static_runtime')
 
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
+  add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
+endif
+
 # Create config.h file
 conf_data = configuration_data()
 zlib_dep = dependency('zlib', required: get_option('use_sys_zlib'), static: is_static_build)

subprojects/rzar/meson.build

@@ -1,6 +1,9 @@
 project('rzar', 'c',
   license: 'LGPL-3.0-only',
   meson_version: '>=0.55.0',
+  default_options: [
+    'c_std=c99',
+  ],
 )
 
 # handle ar dependency
@@ -10,10 +13,8 @@ ar_files = [
 
 cc = meson.get_compiler('c')
 
-if cc.has_argument('--std=gnu99')
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
   add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
-elif cc.has_argument('--std=c99')
-  add_project_arguments('--std=c99', language: ['c', 'cpp'])
 endif
 
 rz_util_dep = dependency('rz_util')

subprojects/rzwinkd/meson.build

@@ -1,10 +1,17 @@
 project('rzwinkd', 'c',
   license: 'LGPL-3.0-only',
   meson_version: '>=0.55.0',
+  default_options: [
+    'c_std=c99',
+  ],
 )
 
 cc = meson.get_compiler('c')
 
+if not cc.has_argument('--std=c99') && cc.has_argument('--std=gnu99')
+  add_project_arguments('--std=gnu99', language: ['c', 'cpp'])
+endif
+
 winkd_files = [
   'iob_pipe.c',
   'iob_net.c',