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Passing This code compiles and runs correctly.
Code
// Test 210_128: MUST_FAIL — bare `| ?!` (panic marker with no branch name)
// is a grammar error.
//
// `?!` is the panic-branch marker; it must be followed by a branch name
// (e.g. `| ?!oom u32`). A bare `| ?!` with nothing after it is malformed
// and must be rejected at parse time. This pins the grammar boundary so a
// later loosening of the `?!` detection can't silently accept it.
//
// Expected: parser rejects `| ?!` with PARSE003 "branch missing name".
~pub event e { n: u32 }
| success u32
| ?!
Must fail at frontend compile:
Parsing or type-checking must reject the program.