Sort overlap errors by position (#4975)

cranelift/isle/isle/src/overlap.rs

@@ -5,12 +5,17 @@ use std::collections::hash_map::Entry;
 use std::collections::{HashMap, HashSet};
 
 use crate::error::{Error, Result, Source, Span};
+use crate::lexer::Pos;
 use crate::sema::{self, Rule, RuleId, Sym, TermEnv, TermId, TermKind, TypeEnv, VarId};
 
 /// Check for overlap.
 pub fn check(tyenv: &TypeEnv, termenv: &TermEnv) -> Result<()> {
     let mut errors = check_overlaps(termenv).report(tyenv, termenv);
     if cfg!(feature = "overlap-errors") {
+        errors.sort_by_key(|err| match err {
+            Error::OverlapError { rules, .. } => rules.first().unwrap().1.from,
+            _ => Pos::default(),
+        });
         match errors.len() {
             0 => Ok(()),
             1 => Err(errors.pop().unwrap()),