Created attachment 236689 [details]
unit test that reveals problem

See attached unit-test (based on on top of master branch).

C code generated for it looks like this (only meaningful part left):

typedef gint StaticTableEntry;

static gchar* static_table_table[4];

StaticTableEntry static_table_get_top (void) {
        StaticTableEntry result;
        result = (StaticTableEntry) 0;
        return result;
}

const gchar* static_table_entry_get_data (StaticTableEntry self) {
        const gchar* result;
        const gchar* _tmp2_;
        _tmp2_ = static_table_table[(gint) self];
        result = _tmp2_;
        return result;
}


void static_table_entry_set_data (StaticTableEntry self, const gchar* value) {
        const gchar* _tmp2_;
        gchar* _tmp3_;
        _tmp2_ = value;
        _tmp3_ = g_strdup (_tmp2_);
        _g_free0 (static_table_table[(gint) self]);
        static_table_table[(gint) self] = _tmp3_;
}

void _vala_main (void) {
        StaticTableEntry _tmp0_;
        StaticTableEntry _tmp1_;
        StaticTableEntry entry;
        const gchar* _tmp4_;
        const gchar* _tmp5_;
        const gchar* _tmp8_;
        const gchar* _tmp9_;
        static_table_init ();
        _tmp0_ = static_table_get_top ();
        _tmp1_ = _tmp0_;
        entry = _tmp1_;

        _tmp4_ = static_table_entry_get_data (entry);
        _tmp5_ = _tmp4_;
        _vala_assert (g_strcmp0 (_tmp5_, "black") == 0, "entry.data == \"black\"");
        static_table_entry_set_data (&entry, "white");
        _tmp8_ = static_table_entry_get_data (entry);
        _tmp9_ = _tmp8_;
        _vala_assert (g_strcmp0 (_tmp9_, "white") == 0, "entry.data == \"white\"");
}

Note that "&entry". This doesn't match declaration and doesn't fit well into [SimpleType] idea.
Using [SimpleType] setter allows to create bindings for such functions like cpufreq_set_policy (from libcpufreq).