curses: terminfo numeric capabilities are unsigned

fish-rust/src/curses.rs

@@ -121,7 +121,7 @@ pub struct Term {
     pub set_title: Option<CString>,
 
     // Number capabilities
-    pub max_colors: Option<i32>,
+    pub max_colors: Option<usize>,
 
     // Flag/boolean capabilities
     pub eat_newline_glitch: bool,
@@ -241,11 +241,11 @@ fn get_str_cap(code: &str) -> Option<CString> {
 
 /// Return a number capability from termcap, or None if missing.
 /// Panics if the given code string does not contain exactly two bytes.
-fn get_num_cap(code: &str) -> Option<i32> {
+fn get_num_cap(code: &str) -> Option<usize> {
     let code = to_cstr_code(code);
     match unsafe { sys::tgetnum(code.as_ptr()) } {
         -1 => None,
-        n => Some(n),
+        n => Some(usize::try_from(n).unwrap()),
     }
 }
 

fish-rust/src/output.rs

@@ -35,10 +35,10 @@ extern "C" fn output_set_color_support(val: u8) {
 }
 
 /// Returns true if we think tparm can handle outputting a color index.
-fn term_supports_color_natively(term: &Term, c: i32) -> bool {
+fn term_supports_color_natively(term: &Term, c: u8) -> bool {
     #[allow(clippy::int_plus_one)]
     if let Some(max_colors) = term.max_colors {
-        max_colors >= c + 1
+        max_colors >= usize::try_from(c).unwrap() + 1
     } else {
         false
     }
@@ -61,7 +61,7 @@ fn index_for_color(c: RgbColor) -> u8 {
 }
 
 fn write_color_escape(outp: &mut Outputter, term: &Term, todo: &CStr, mut idx: u8, is_fg: bool) {
-    if term_supports_color_natively(term, idx.into()) {
+    if term_supports_color_natively(term, idx) {
         // Use tparm to emit color escape.
         outp.tputs_if_some(&tparm1(todo, idx.into()));
     } else {