added default meson.build

meson.build

@@ -0,0 +1,62 @@
+project('<project name>', 'cpp',
+    version : '<version>',
+    default_options : [
+        'cpp_std=c++20',
+        
+        'warning_level=3',
+        'werror=true',
+
+        'b_lto=true',
+
+        'b_pie=true'
+    ]
+)
+
+cc = meson.get_compiler('cpp')
+cc_id = cc.get_id()
+system = host_machine.system()
+
+message(f'system: @system@')
+
+link_args = []
+
+if system == 'linux'
+    add_project_arguments(
+        '-Wconversion',
+        '-Wimplicit-fallthrough',
+
+        '-Wformat=2',
+        '-fno-delete-null-pointer-checks',
+
+        '-fstack-clash-protection',
+        '-fstack-protector-strong',
+
+        language : 'cpp',
+    )
+
+    link_args += [
+        '-Wl,-z,nodlopen',
+        '-Wl,-z,noexecstack',
+        '-Wl,-z,relro',
+        '-Wl,-z,now',
+    ]
+
+    if get_option('buildtype') == 'debug'
+        message('Compiling with -ftrapv and _GLIBCXX_ASSERTIONS')
+        
+        add_project_arguments(
+            '-ftrapv',
+            '-D_GLIBCXX_ASSERTIONS',
+
+            language : 'cpp',
+        )
+    else
+        message('Compiling with FORTIFY_SOURCE=3')
+
+        add_project_arguments(
+            '-D_FORTIFY_SOURCE=3',
+
+            language : 'cpp'
+        )
+    endif
+endif