   LL|       |#![feature(coverage_attribute)]
   LL|       |//@ edition: 2021
   LL|       |//@ compile-flags: -Zcoverage-options=branch
   LL|       |//@ llvm-cov-flags: --show-branches=count
   LL|       |
   LL|       |// When instrumenting match expressions for branch coverage, make sure we don't
   LL|       |// cause an ICE or produce weird coverage output for matches with <2 arms.
   LL|       |
   LL|       |// Helper macro to prevent start-of-function spans from being merged into
   LL|       |// spans on the lines we care about.
   LL|       |macro_rules! no_merge {
   LL|       |    () => {
   LL|       |        for _ in 0..1 {}
   LL|       |    };
   LL|       |}
   LL|       |
   LL|       |enum Uninhabited {}
   LL|       |enum Trivial {
   LL|       |    Value,
   LL|       |}
   LL|       |
   LL|      0|fn _uninhabited(x: Uninhabited) {
   LL|      0|    no_merge!();
   LL|       |
   LL|       |    match x {}
   LL|       |
   LL|       |    consume("done");
   LL|       |}
   LL|       |
   LL|      1|fn trivial(x: Trivial) {
   LL|      1|    no_merge!();
   LL|       |
   LL|      1|    match x {
   LL|      1|        Trivial::Value => consume("trivial"),
   LL|      1|    }
   LL|      1|
   LL|      1|    consume("done");
   LL|      1|}
   LL|       |
   LL|       |#[coverage(off)]
   LL|       |fn consume<T>(x: T) {
   LL|       |    core::hint::black_box(x);
   LL|       |}
   LL|       |
   LL|       |#[coverage(off)]
   LL|       |fn main() {
   LL|       |    trivial(Trivial::Value);
   LL|       |}