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+Something other than numbers and characters has been used for a range.
+
+Erroneous code example:
+
+```compile_fail,E0029
+let string = "salutations !";
+
+// The ordering relation for strings cannot be evaluated at compile time,
+// so this doesn't work:
+match string {
+    "hello" ..= "world" => {}
+    _ => {}
+}
+
+// This is a more general version, using a guard:
+match string {
+    s if s >= "hello" && s <= "world" => {}
+    _ => {}
+}
+```
+
+In a match expression, only numbers and characters can be matched against a
+range. This is because the compiler checks that the range is non-empty at
+compile-time, and is unable to evaluate arbitrary comparison functions. If you
+want to capture values of an orderable type between two end-points, you can use
+a guard.