test-suite fails when LTO compiler-flag is enabled

[antonfischl1980]

Hi,
I'm currently maintaining burp for Gentoo Linux. Our Tinderbox (some kind of automated build box) has run into a problem while running "make test" with burp when using "-flto" flag from gcc.

LTO seeks to optimize the resulting binary as a whole instead of just the object files seperatly.

Compiling and testing burp (from github master) with "-flto" results with a failed test run:

99%: Checks: 233, Failures: 1, Errors: 0
utest/builders/build_asfd_mock.c:77:F:Core:test_phase2_with_slist_changed_files:0: Assertion '!memcmp(expected->buf, wbuf->buf, wbuf->len)' failed
FAIL runner (exit status: 1)

To reproduce it consistently, I use a Dockerfile:

FROM ubuntu:latest
RUN apt-get update && apt-get -y install make pkg-config check g++ librsync-dev libz-dev libssl-dev uthash-dev git autoconf

inside a running container ( docker run --rm -it $(docker build -q .) ) I do:

mkdir -p /test
cd /test
git clone https://github.com/grke/burp.git
cd burp
export COMMON_FLAGS="-O2 -pipe -flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing"
export CFLAGS="${COMMON_FLAGS}"
export CXXFLAGS="${COMMON_FLAGS}"
export FCFLAGS="${COMMON_FLAGS}"
export FFLAGS="${COMMON_FLAGS}"
autoreconf -vif && ./configure && make clean && make && make test-suite.log
cat test-suite.log

Under Gento I tested it with different gcc-versions (11.5.0, 12.4.0, 13.3.1) with the same result.

Sadly, I don't have enough experience in C to find out why this is happening, or what LTO does differently in detail.

Please let me know if you need any more information or if I can be of any more help for you.