build-sys: Disable LTO by default #3999
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Way back when, we landed a2bbc12 "rust: Enable lto by default". However at the time, rpm-ostree was a C program with a Rust shared library. Later we flipped it to being a Rust program with a C++ shared library. And...that fixes the problem of leaking symbols that motivated having LTO on by default. Let's defer the decision of using LTO to higher level build systems; operating systems/distros might set `RUSTFLAGS=-C lto` globally or per package as desired. The immediate motivation here is that I don't always remember to do non-release builds locally and LTO is still a lot slower than non-LTO.
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I verified that LTO only shrinks things by a tiny bit: Definitely not worth being on by default. |
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Er actually sorry, the real fix was f35afb1 which meant we're no longer dragging Rust at all into our (legacy) shared library. |
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Way back when, we landed a2bbc12 "rust: Enable lto by default".
However at the time, rpm-ostree was a C program with a Rust shared library. Later we flipped it to being a Rust program with a C++ shared library.
And...that fixes the problem of leaking symbols that motivated having LTO on by default.
Let's defer the decision of using LTO to higher level build systems; operating systems/distros might set
RUSTFLAGS=-C ltoglobally or per package as desired.The immediate motivation here is that I don't always remember to do non-release builds locally and LTO is still a lot slower than non-LTO.