message: Use --print file-names instead of a match on uname
diff: set -e
  -unamestr=$(uname)
  -if [[ "$unamestr" == 'Linux' || "$unamestr" == 'FreeBSD' ]]; then
  - dylib_ext='so'
  -elif [[ "$unamestr" == 'Darwin' ]]; then
  - dylib_ext='dylib'
  -else
  - echo "Unsupported os"
  - exit 1
  -fi
  +dylib=$(echo "" | rustc --print file-names --crate-type dylib --crate-name rustc_codegen_cranelift -)
  if echo "$RUSTC_WRAPPER" | grep sccache; then
  echo
  @@ -24,10 +16,10 @@ dir=$(cd "$(dirname "${BASH_SOURCE[0]}")"; pwd)
  export RUSTC=$dir"/bin/cg_clif"
  export RUSTDOCFLAGS=$linker' -Cpanic=abort -Zpanic-abort-tests '\
  -'-Zcodegen-backend='$dir'/lib/librustc_codegen_cranelift.'$dylib_ext' --sysroot '$dir
  +'-Zcodegen-backend='$dir'/lib/'$dylib' --sysroot '$dir
  # FIXME fix `#[linkage = "extern_weak"]` without this
  -if [[ "$unamestr" == 'Darwin' ]]; then
  +if [[ "$(uname)" == 'Darwin' ]]; then
  export RUSTFLAGS="$RUSTFLAGS -Clink-arg=-undefined -Clink-arg=dynamic_lookup"
  fi
  