The repository's Cargo defaults and the Makefile development targets
(make test, make lint, make typecheck and the debug build) use the
parallel rustc frontend (-Zthreads=8) and, on Linux, the mold linker. On
Linux, install mold and clang before building, because the configuration
names them and a build without them fails at link time. A release build
(make release) and the coverage build use neither: they assign their own
RUSTFLAGS, which displaces the configuration's flags, so a shipped artefact
keeps the platform linker. To build with the platform linker directly, assign
an empty RUSTFLAGS:
RUSTFLAGS="" cargo build --release