Here is a short program to demonstrate the issue:
void main(string[] args)
{
unichar c = 'a';
string str_from_to_string = c.to_string(); // Warning
stdout.printf("Converted by unichar.to_string: \"%s\"\n", str_from_to_string);
}
This also causes the same warning:
void main(string[] args)
{
unichar c = 'a';
string str_from_template = @"$c"; // Warning
stdout.printf("Converted by string template: \"%s\"\n", str_from_template);
}
This is the warning that I get:
/home/mpiroc/Desktop/unicode_to_string/unicode_to_string.vala.c: In function ‘g_unichar_to_string’:
/home/mpiroc/Desktop/unicode_to_string/unicode_to_string.vala.c:26:2: warning: passing argument 2 of ‘g_unichar_to_utf8’ discards ‘const’ qualifier from pointer target type [enabled by default]
/usr/include/glib-2.0/glib/gunicode.h:684:11: note: expected ‘gchar *’ but argument is of type ‘const gchar *’
And here is the generated c code mentioned in the warning:
18 static gchar* g_unichar_to_string (gunichar self) {
19 gchar* result = NULL;
20 gchar* _tmp0_ = NULL;
21 gchar* str;
22 const gchar* _tmp1_;
23 _tmp0_ = g_new0 (gchar, 7);
24 str = (gchar*) _tmp0_;
25 _tmp1_ = str;
26 g_unichar_to_utf8 (self, _tmp1_);
27 result = str;
28 return result;
29 }
It seems as though _tmp_ probably should not be marked const, but this is generated by valac, not written directly by me. Am I doing something wrong? Or is this a bug in valac? The code functions as expected, but I try to avoid warnings when possible.
Add --disable-warnings command-line option
IIRC Vala compiler can also use --disable-warnigs command-line option.
Edit:
Sorry, Valac is transpiler, so once valac --ccode output, and then need to run gcc or another compiler.
$ valac --ccode unicode_to_string.vala
$ gcc -o unicode_to_string -w unicode_to_string.c `pkg-config --libs --cflags gobject-2.0`