ci: Unstable MC/DC support has been removed in upstream

rust-lang/rust#144999

Author: taiki-e

.github/workflows/ci.yml

@@ -125,11 +125,13 @@ jobs:
           pushd -- tests/fixtures/crates/cargo_config >/dev/null
           # TODO: --fail-under-branches?
           cargo llvm-cov test --branch --text --fail-under-lines 80
-          cargo llvm-cov test --mcdc --text --fail-under-lines 80
+          # TODO: Unstable MC/DC support has been removed in https://github.com/rust-lang/rust/pull/144999
+          # cargo llvm-cov test --mcdc --text --fail-under-lines 80
           popd >/dev/null
           pushd -- easytime >/dev/null
           cargo llvm-cov test --branch --doctests --text --fail-under-lines 30
-          cargo llvm-cov test --mcdc --doctests --text --fail-under-lines 30
+          # TODO: Unstable MC/DC support has been removed in https://github.com/rust-lang/rust/pull/144999
+          # cargo llvm-cov test --mcdc --doctests --text --fail-under-lines 30
           popd >/dev/null
 
           # Test minimum runnable Cargo version.

src/main.rs

@@ -203,6 +203,7 @@ fn set_env(cx: &Context, env: &mut dyn EnvTarget, IsNextest(is_nextest): IsNexte
         }
         if cx.args.cov.mcdc {
             // Tracking issue: https://github.com/rust-lang/rust/issues/124144
+            // TODO: Unstable MC/DC support has been removed in https://github.com/rust-lang/rust/pull/144999
             flags.push("-Z");
             flags.push("coverage-options=mcdc");
         } else if cx.args.cov.branch {