CI/CD: Don't use self-contained linking during code coverage.

Work around a bug in the Rust toolchain.

Author: briansmith

.github/workflows/ci.yml

@@ -304,15 +304,26 @@ jobs:
 
         # TODO: targets
         include:
+          # TODO: Use the -musl target after
+          # https://github.com/rust-lang/rust/issues/79556 and
+          # https://github.com/rust-lang/rust/issues/79555 are fixed.
           - target: aarch64-unknown-linux-gnu
             host_os: ubuntu-18.04
 
+          # TODO: Use the -musl target after
+          # https://github.com/rust-lang/rust/issues/79556 and
+          # https://github.com/rust-lang/rust/issues/79555 are fixed.
           - target: i686-unknown-linux-gnu
             host_os: ubuntu-18.04
 
           - target: x86_64-unknown-linux-musl
             host_os: ubuntu-18.04
 
+          # TODO: Add an ARM target after
+          # https://github.com/rust-lang/rust/issues/79555 is fixed. This may
+          # require https://github.com/rust-lang/rust/issues/79555 to be fixed
+          # too.
+
     steps:
       - uses: actions/checkout@v2
 

mk/cargo.sh

@@ -93,7 +93,12 @@ case $target in
   x86_64-unknown-linux-musl)
     export CC_x86_64_unknown_linux_musl=clang-$llvm_version
     export AR_x86_64_unknown_linux_musl=llvm-ar-$llvm_version
-    export CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_RUSTFLAGS="$rustflags_self_contained"
+    # XXX: Work around https://github.com/rust-lang/rust/issues/79555.
+    if [ -n "${RING_COVERAGE-}" ]; then
+      export CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER=clang-$llvm_version
+    else
+      export CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_RUSTFLAGS="$rustflags_self_contained"
+    fi
     ;;
   wasm32-unknown-unknown)
     # The first two are only needed for when the "wasm_c" feature is enabled.