Use checked_sub

src/librustdoc/html/format.rs

@@ -1439,7 +1439,7 @@ impl clean::FnDecl {
  write!(f, "\n{}", Indent(n + 4))?;
  }
 
- let last_input_index = self.inputs.values.len() - 1;
+ let last_input_index = self.inputs.values.len().checked_sub(1);
  for (i, input) in self.inputs.values.iter().enumerate() {
  if let Some(selfty) = input.to_self() {
  match selfty {
@@ -1473,11 +1473,12 @@ impl clean::FnDecl {
  write!(f, "{}: ", input.name)?;
  input.type_.print(cx).fmt(f)?;
  }
- match line_wrapping_indent {
- None if i == last_input_index => (),
- None => write!(f, ", ")?,
- Some(_n) if i == last_input_index => write!(f, ",\n")?,
- Some(n) => write!(f, ",\n{}", Indent(n + 4))?,
+ match (line_wrapping_indent, last_input_index) {
+ (_, None) => (),
+ (None, Some(last_i)) if i != last_i => write!(f, ", ")?,
+ (None, Some(_)) => (),
+ (Some(n), Some(last_i)) if i != last_i => write!(f, ",\n{}", Indent(n + 4))?,
+ (Some(_), Some(_)) => write!(f, ",\n")?,
  }
  }