apply requested changes in review

Author: pymongo

compiler/rustc_builtin_macros/src/format_foreign.rs

@@ -265,9 +265,7 @@ pub(crate) mod printf {
     impl Num {
         fn from_str(s: &str, arg: Option<&str>) -> Option<Self> {
             if let Some(arg) = arg {
-                Some(Num::Arg(
-                    arg.parse().unwrap_or_else(|_| panic!("invalid format arg `{arg:?}`")),
-                ))
+                arg.parse().ok().map(|arg| Num::Arg(arg))
             } else if s == "*" {
                 Some(Num::Next)
             } else {
@@ -423,7 +421,7 @@ pub(crate) mod printf {
                             state = Prec;
                             parameter = None;
                             flags = "";
-                            width = Num::from_str(at.slice_between(end).unwrap(), None);
+                            width = at.slice_between(end).map(|num| Num::from_str(num, None));
                             if width.is_none() {
                                 return fallback();
                             }
@@ -457,7 +455,7 @@ pub(crate) mod printf {
                 '1'..='9' => {
                     let end = at_next_cp_while(next, char::is_ascii_digit);
                     state = Prec;
-                    width = Num::from_str(at.slice_between(end).unwrap(), None);
+                    width = at.slice_between(end).map(|num| Num::from_str(num, None));
                     if width.is_none() {
                         return fallback();
                     }
@@ -476,7 +474,7 @@ pub(crate) mod printf {
             match end.next_cp() {
                 Some(('$', end2)) => {
                     state = Prec;
-                    width = Some(Num::from_str("", Some(at.slice_between(end).unwrap())).unwrap());
+                    width = Num::from_str("", at.slice_between(end));
                     move_to!(end2);
                 }
                 _ => {
@@ -508,7 +506,7 @@ pub(crate) mod printf {
                     match end.next_cp() {
                         Some(('$', end2)) => {
                             state = Length;
-                            precision = Some(Num::from_str("*", next.slice_between(end)).unwrap());
+                            precision = Num::from_str("*", next.slice_between(end));
                             move_to!(end2);
                         }
                         _ => {
@@ -521,7 +519,7 @@ pub(crate) mod printf {
                 '0'..='9' => {
                     let end = at_next_cp_while(next, char::is_ascii_digit);
                     state = Length;
-                    precision = Some(Num::from_str(at.slice_between(end).unwrap(), None).unwrap());
+                    precision = at.slice_between(end).map(|num| Num::from_str(num, None));
                     move_to!(end);
                 }
                 _ => return fallback(),