meson.build: Avoid configuration warnings

kjellahl · kjellahl · commit 75d0c990c10e · 2022-05-13T14:35:09.000+02:00
diff --git a/meson.build b/meson.build
@@ -4,7 +4,8 @@ project('libxml++', 'cpp',
   version: '2.42.1',
   license: 'LGPLv2.1+',
   default_options: [
-    'cpp_std=c++11'
+    'cpp_std=c++11',
+    'warning_level=1',
   ],
   meson_version: '>= 0.55.0', # required for meson.add_dist_script(python3, ...)
                               # and meson.add_install_script(python3, ...)
@@ -73,10 +74,12 @@ maintainer_mode = maintainer_mode_opt == 'true' or \
 if is_dist_check
   message('Looks like a tarball is being tested. ' + \
     'Option "dist-warnings" is used instead of "warnings".')
-  warning_level = get_option('dist-warnings')
+  cpp_warnings = get_option('dist-warnings')
 else
-  warning_level = get_option('warnings')
+  cpp_warnings = get_option('warnings')
 endif
+warning_level = get_option('warning_level').to_int()
+werror = get_option('werror')
 build_deprecated_api = get_option('build-deprecated-api')
 build_documentation_opt = get_option('build-documentation')
 build_documentation = build_documentation_opt == 'true' or \
@@ -237,24 +240,37 @@ endif
 xmlxx_libname = 'xml++' + msvc14x_toolset_ver + '-' + xmlxx_api_version
 
 # Set compiler warnings.
+# Meson warns if any of the /W1, /W2, /W3, /W4, /Wall, -Wall, -Wextra, -Werror
+# compiler options are added with add_project_arguments().
+# Avoid such warnings, when possible.
+# See _warn_about_builtin_args() in meson/mesonbuild/interpreter/interpreter.py.
 warning_flags = []
-if warning_level == 'min'
-  if is_msvc
-    warning_flags = ['/W3']
-  else
-    warning_flags = ['-Wall']
-  endif
-elif warning_level == 'max' or warning_level == 'fatal'
-  if is_msvc
-    warning_flags = ['/W4']
-  else
-    warning_flags = '-pedantic -Wall -Wextra -Wformat-security -Wshadow -Wno-long-long'.split()
+if cpp_warnings == 'min'
+  if warning_level == 0
+    if is_msvc
+      warning_flags = ['/W2']
+    else
+      warning_flags = ['-Wall']
+    endif
   endif
-  if warning_level == 'fatal'
+elif cpp_warnings == 'max' or cpp_warnings == 'fatal'
+  if warning_level < 3
     if is_msvc
-      warning_flags += ['/WX']
+      warning_flags = ['/W4']
     else
-      warning_flags += ['-Werror']
+      warning_flags = ['-pedantic', '-Wall', '-Wextra']
+    endif
+  endif
+  if not is_msvc
+    warning_flags += '-Wformat-security -Wshadow -Wno-long-long'.split()
+  endif
+  if cpp_warnings == 'fatal'
+    if not werror
+      if is_msvc
+        warning_flags += ['/WX']
+      else
+        warning_flags += ['-Werror']
+      endif
     endif
     deprecations = 'G GLIBMM SIGCXX'.split()
     foreach d : deprecations
@@ -404,7 +420,8 @@ summary = [
   meson.project_name() + ' ' + meson.project_version(),
   '',
   '         Maintainer mode: @0@@1@'.format(maintainer_mode_opt, real_maintainer_mode),
-  '       Compiler warnings: @0@'.format(warning_level),
+  '       Compiler warnings: @0@ (warning_level: @1@, werror: @2@)'. \
+                             format(cpp_warnings, warning_level, werror),
   '    Build deprecated API: @0@'.format(build_deprecated_api),
   'Build HTML documentation: @0@@1@'.format(build_documentation_opt, real_build_documentation),
   '          XML validation: @0@@1@'.format(validate, explain_val),
