feat(error): deprecate E_USER_ERROR in PHP 8.4

Refs: #476

Author: Xenira

.lefthook.yml

@@ -2,7 +2,7 @@ pre-commit:
   parallel: true
   jobs:
     - name: fmt
-      run: rustfmt {staged_files}
+      run: rustfmt --edition 2021 {staged_files}
       glob: "*.rs"
       stage_fixed: true
     - name: clippy

src/embed/mod.rs

@@ -287,6 +287,8 @@ mod tests {
     #[test]
     fn test_eval_bailout() {
         Embed::run(|| {
+            // TODO: For PHP 8.5, this needs to be replaced, as `E_USER_ERROR` is deprecated.
+            //       Currently, this seems to still be the best way to trigger a bailout.
             let result = Embed::eval("trigger_error(\"Fatal error\", E_USER_ERROR);");
 
             assert!(result.is_err());

src/flags.rs

@@ -308,6 +308,7 @@ bitflags! {
         /// Compile warning
         const CompileWarning = E_COMPILE_WARNING;
         /// User error
+        #[cfg_attr(php84, deprecated = "`E_USER_ERROR` is deprecated since PHP 8.4. Throw an exception instead.")]
         const UserError = E_USER_ERROR;
         /// User warning
         const UserWarning = E_USER_WARNING;