meson: fix warnings in build files

meson prefers that project-level options for Wall/Wextra/pedantic be
used, rather than hardcoding raw flags in add_project_arguments. If you
do the latter anyway, it raises a meson warning.

Set the default options for the project to use all this.

Also move the -Werror comment to the project default options with
appropriate format, but leave it commented out since it does not work.

build/meson/contrib/pzstd/meson.build

@@ -18,7 +18,7 @@ pzstd_sources = [join_paths(zstd_rootdir, 'programs/util.c'),
   join_paths(zstd_rootdir, 'contrib/pzstd/SkippableFrame.cpp')]
 pzstd = executable('pzstd',
   pzstd_sources,
-  cpp_args: [ '-DNDEBUG', '-Wno-shadow', '-pedantic', '-Wno-deprecated-declarations' ],
+  cpp_args: [ '-DNDEBUG', '-Wno-shadow', '-Wno-deprecated-declarations' ],
   include_directories: pzstd_includes,
   dependencies: [ libzstd_dep, thread_dep ],
   install: true)

build/meson/meson.build

@@ -14,7 +14,11 @@ project('zstd',
   default_options : [
     'c_std=gnu99',
     'cpp_std=c++11',
-    'buildtype=release'
+    'buildtype=release',
+    'warning_level=3',
+    # -Wdocumentation does not actually pass, nor do the test binaries,
+    # so this isn't safe
+    #'werror=true'
   ],
   version: 'DUMMY',
   meson_version: '>=0.47.0')
@@ -106,10 +110,8 @@ use_lz4 = lz4_dep.found()
 add_project_arguments('-DXXH_NAMESPACE=ZSTD_', language: ['c'])
 
 if [compiler_gcc, compiler_clang].contains(cc_id)
-  common_warning_flags = [ '-Wextra', '-Wundef', '-Wshadow', '-Wcast-align', '-Wcast-qual' ]
+  common_warning_flags = [ '-Wundef', '-Wshadow', '-Wcast-align', '-Wcast-qual' ]
   if cc_id == compiler_clang
-    # Should use Meson's own --werror build option
-    #common_warning_flags += '-Werror'
     common_warning_flags += ['-Wconversion', '-Wno-sign-conversion', '-Wdocumentation']
   endif
   cc_compile_flags = cc.get_supported_arguments(common_warning_flags + ['-Wstrict-prototypes'])