The current default, build-id=fast, is only 8 bytes due to the usage of
64-bit XXH3. This is incompatible with RPM packaging tools which
requires >=16 bytes [1].
In Clang the ENABLE_LINKER_BUILD_ID define makes it pass --build-id
without a specific hash type. When also defaulting to LLD, this provides
a pretty broken default out-of-box.
Using XXH3 was a considerable performance advantage when build-id was
first implemented, because sha1 was really sha1 and rather slow.
Nowadays sha1 is just 160-bit BLAKE3 which is decently fast and not
cryptographically broken, so it should be a good default.
Note that the default remains "fast" for wasm because sha1 for wasm is
still real sha1.
Close https://github.com/llvm/llvm-project/issues/43483.
[1]:
b7d427728b/build/files.c (L1883)
lld Documentation ================= The lld documentation is written using the Sphinx documentation generator. It is currently tested with Sphinx 1.1.3. We currently use the 'nature' theme and a Beaker inspired structure. See sphinx_intro.rst for more details.