Remove pre-init assertion to check for non-debug GTK builds

While previously checking for this could be used to determine if GTK was
built with assertions enabled or not, this is not true anymore with
later versions of GTK. There is no way to know if assertions were
disabled or not at runtime.

While disabling assertions easily causes memory unsafety in GTK code,
it is nothing that can be disabled accidentally. Users deploying and
running such code will have to live with the consequences.

Fixes #821

src/rt.rs

@@ -95,7 +95,7 @@ pub fn init() -> Result<(), glib::BoolError> {
         panic!("Attempted to initialize GTK from two different threads.");
     }
     unsafe {
-        if pre_init() && from_glib(gtk_sys::gtk_init_check(ptr::null_mut(), ptr::null_mut())) {
+        if from_glib(gtk_sys::gtk_init_check(ptr::null_mut(), ptr::null_mut())) {
             if !glib::MainContext::default().acquire() {
                 return Err(glib_bool_error!("Failed to acquire default main context"));
             }
@@ -109,45 +109,6 @@ pub fn init() -> Result<(), glib::BoolError> {
     }
 }
 
-/// Ensures `libgtk-3` was built with safety assertions.
-///
-/// Detects the presence of safety checks by testing if the library handles
-/// the `--gtk-debug` command line argument.
-///
-/// Panics if `enable-debug=no` is detected, which means `g_return_if_fail`
-/// checks are disabled and it's impossible to guarantee memory safety.
-fn pre_init() -> bool {
-    skip_assert_initialized!();
-    // We're going to spoof `--gtk-debug=misc` command line argument so first
-    // check if GTK_DEBUG enables 'misc' to know if we need to unset it later.
-    // See #270 for details.
-    let gtk_debug = env::var_os("GTK_DEBUG")
-        .map_or(String::new(), |s| s.to_string_lossy().to_lowercase());
-    let words = gtk_debug.split(|c| {
-        match c {
-            ':' | ';' | ',' | ' ' | '\t' => true,
-            _ => false,
-        }
-    }).collect::<Vec<_>>();
-    let has_misc = words.contains(&"all") ^ words.contains(&"misc");
-
-    unsafe {
-        let argv = ["", "--gtk-debug=misc"];
-        let mut argc = argv.len() as c_int;
-        let mut argv_stash = argv.to_glib_none();
-        let ret = from_glib(gtk_sys::gtk_parse_args(&mut argc, &mut argv_stash.0));
-        let flags = gtk_sys::gtk_get_debug_flags();
-        if flags == 0 {
-            panic!("libgtk-3 was configured with `--enable-debug=no`. \
-                   See https://github.com/gtk-rs/gtk/issues/270 for details");
-        }
-        if !has_misc {
-            gtk_sys::gtk_set_debug_flags(flags & !gtk_sys::GTK_DEBUG_MISC);
-        }
-        ret
-    }
-}
-
 pub fn main_quit() {
     assert_initialized_main_thread!();
     unsafe {