docs(flipperzero-rs#92): make enhance c_string's lifetime explicit

crates/flipperzero/examples/storage.rs

@@ -43,8 +43,7 @@ fn main(_args: *mut u8) -> i32 {
     // Next, we'll open a file browser dialog and let the user select the file.
     let mut dialogs_app = DialogsApp::open();
 
-    static EXTENSION: &CStr = cstr!("*");
-    let file_browser_options = DialogFileBrowserOptions::new(EXTENSION).set_hide_ext(false);
+    let file_browser_options = DialogFileBrowserOptions::new(cstr!("*")).set_hide_ext(false);
     let mut start_path = FuriString::from(path);
     let result_path =
         dialogs_app.show_file_browser(Some(&mut start_path), Some(&file_browser_options));

crates/sys/src/lib.rs

@@ -29,7 +29,12 @@ mod inlines;
 )]
 mod bindings;
 
-/// Create a static C string of type [`*const c_char`][core::ffi::c_char].
+/// Create a static C string of type [`&'static CStr`][`core::ffi::CStr`].
+/// Will automatically add a NUL terminator.
+pub use cstr::cstr;
+
+/// Create a static C string of type [`*const c_char`][core::ffi::c_char]
+/// referring to a `'static` string.
 /// Will automatically add a NUL terminator.
 // TODO: don't produce intermediate `CStr` whose `length` part we don't use
 #[macro_export]
@@ -39,10 +44,6 @@ macro_rules! c_string {
     }};
 }
 
-/// Create a static C string of type [`&CStr`][`core::ffi::CStr`].
-/// Will automatically add a NUL terminator.
-pub use cstr::cstr;
-
 /// Crash the system.
 #[macro_export]
 macro_rules! crash {