Add @enum_from_value

lib/std/core/builtin.c3

@@ -235,6 +235,24 @@ macro enum_by_name($Type, String enum_name) @builtin
 	return SearchResult.MISSING?;
 }
 
+<*
+ @param $Type `The type of the enum`
+ @require $Type.kindof == ENUM `Only enums may be used`
+ @require $defined($Type.#value1) `Expected '#value' to match an enum associated value`
+ @require $assignable(value, $typeof($Type{}.#value)) `Expected the value to match the type of the associated value`
+ @ensure @typeis(return, $Type)
+ @return! SearchResult.MISSING
+*>
+macro @enum_from_value($Type, #value, value) @builtin
+{
+	usz elements = $Type.elements;
+	foreach (e : $Type.values)
+	{
+		if (e.#value == value) return e;
+	}
+	return SearchResult.MISSING?;
+}
+
 <*
  Mark an expression as likely to be true
 

releasenotes.md

@@ -36,6 +36,7 @@
 - Added `iter()` `value_iter()` and `key_iter()` to HashMap.
 - Add "tokenizer" to String.
 - Add "skip_empty" to split methods. Add split_to_buffer method.
+- Add `@enum_from_value`.
 
 ## 0.6.5 Change list