Build fails with aws-lc-sys 0.38.0 due to jitterentropy CFLAGS conflict

[rpodgorny]

Summary

Building vykar 0.12.12 fails when the environment injects CFLAGS with -O2 (e.g. Arch Linux makepkg). The jitterentropy-base.c file in aws-lc-sys requires -O0, but the system -O2 flag appears last on the compiler command line and overrides it, triggering:

#error "The CPU Jitter random number generator must not be compiled with optimizations."

Root Cause

This is a known upstream bug in aws-lc-sys v0.38.0, fixed in aws/aws-lc-rs#1064. The cc crate changed its env-var caching behavior, causing the build script's temporary CFLAGS override to no longer work.

Fix

The fix shipped in aws-lc-rs v1.16.2 / aws-lc-sys v0.39.0. Vykar 0.12.12 currently pins aws-lc-rs v1.16.1 / aws-lc-sys v0.38.0 — just one patch version behind.

Updating Cargo.lock to pull in aws-lc-sys >= 0.39.0 should resolve the issue.

Workaround

Setting AWS_LC_SYS_NO_JITTER_ENTROPY=1 before building skips jitterentropy compilation entirely and avoids the conflict.

Reproduction

Build on Arch Linux (or any distro whose build system injects -O2 into CFLAGS):

makepkg -s

[m3nu]

Hi, good find! I regularly bump versions so this new dependency version should get pulled with the next release.