fix: prevent panic from string_slice (#1140)

<https://rust-lang.github.io/rust-clippy/master/index.html#string_slice>

Cargo.toml

@@ -94,6 +94,7 @@ or_fun_call = "warn"
 redundant_type_annotations = "warn"
 rest_pat_in_fully_bound_structs = "warn"
 string_lit_chars_any = "warn"
+string_slice = "warn"
 string_to_string = "warn"
 use_self = "warn"
 

src/style/color.rs

@@ -313,16 +313,7 @@ impl FromStr for Color {
                 _ => {
                     if let Ok(index) = s.parse::<u8>() {
                         Self::Indexed(index)
-                    } else if let (Ok(r), Ok(g), Ok(b)) = {
-                        if !s.starts_with('#') || s.len() != 7 {
-                            return Err(ParseColorError);
-                        }
-                        (
-                            u8::from_str_radix(&s[1..3], 16),
-                            u8::from_str_radix(&s[3..5], 16),
-                            u8::from_str_radix(&s[5..7], 16),
-                        )
-                    } {
+                    } else if let Some((r, g, b)) = parse_hex_color(s) {
                         Self::Rgb(r, g, b)
                     } else {
                         return Err(ParseColorError);
@@ -333,6 +324,16 @@ impl FromStr for Color {
     }
 }
 
+fn parse_hex_color(input: &str) -> Option<(u8, u8, u8)> {
+    if !input.starts_with('#') || input.len() != 7 {
+        return None;
+    }
+    let r = u8::from_str_radix(input.get(1..3)?, 16).ok()?;
+    let g = u8::from_str_radix(input.get(3..5)?, 16).ok()?;
+    let b = u8::from_str_radix(input.get(5..7)?, 16).ok()?;
+    Some((r, g, b))
+}
+
 impl fmt::Display for Color {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
@@ -587,6 +588,7 @@ mod tests {
             "abcdef0",       // 7 chars is not a color
             " bcdefa",       // doesn't start with a '#'
             "#abcdef00",     // too many chars
+            "#1🦀2",         // len 7 but on char boundaries shouldnt panic
             "resett",        // typo
             "lightblackk",   // typo
         ];

src/widgets/reflow.rs

@@ -336,6 +336,7 @@ fn trim_offset(src: &str, mut offset: usize) -> &str {
             break;
         }
     }
+    #[allow(clippy::string_slice)] // Is safe as it comes from UnicodeSegmentation
     &src[start..]
 }
 
@@ -431,17 +432,17 @@ mod test {
         let (line_truncator, _, _) = run_composer(Composer::LineTruncator, text, width as u16);
 
         let wrapped = vec![
-            &text[..width],
-            &text[width..width * 2],
-            &text[width * 2..width * 3],
-            &text[width * 3..],
+            text.get(..width).unwrap(),
+            text.get(width..width * 2).unwrap(),
+            text.get(width * 2..width * 3).unwrap(),
+            text.get(width * 3..).unwrap(),
         ];
         assert_eq!(
             word_wrapper, wrapped,
             "WordWrapper should detect the line cannot be broken on word boundary and \
              break it at line width limit."
         );
-        assert_eq!(line_truncator, vec![&text[..width]]);
+        assert_eq!(line_truncator, [text.get(..width).unwrap()]);
     }
 
     #[test]
@@ -471,7 +472,7 @@ mod test {
         assert_eq!(word_wrapper_single_space, word_wrapped);
         assert_eq!(word_wrapper_multi_space, word_wrapped);
 
-        assert_eq!(line_truncator, vec![&text[..width]]);
+        assert_eq!(line_truncator, [text.get(..width).unwrap()]);
     }
 
     #[test]