Here you go - but as I mentioned earlier - extracting the relevant pieces of the application is next to impossible - and I am not getting the same errors when running microhttpd's `make check`.
g++ -m64 -O3 -DNDEBUG -fdata-sections -ffunction-sections -s -flto -fPIE -fPIC -fstack-protector-strong -D_FORTIFY_SOURCE=2 -std=c++20 -Waddress -Waggressive-loop-optimizations -Wall -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment -Wconversion -Wdisabled-optimization -Wdouble-promotion -Werror -Wextra -Wfatal-errors -Wfloat-equal -Wformat-nonliteral -Wformat-security -Wformat-y2k -Wformat=2 -Wimport -Winit-self -Wno-inline -Winvalid-pch -Wlogical-op -Wmissing-braces -Wmissing-declarations -Wmissing-field-initializers -Wmissing-format-attribute -Wmissing-noreturn -Woverlength-strings -Wparentheses -Wpedantic -Wpointer-arith -Wredundant-decls -Wreturn-type -Wsequence-point -Wshadow -Wsign-compare -Wsign-conversion -Wstack-protector -Wstrict-aliasing -Wstrict-aliasing=2 -Wswitch -Wswitch-default -Wswitch-enum -Wtrigraphs -Wundef -Wuninitialized -Wunknown-pragmas -Wunreachable-code -Wunsafe-loop-optimizations -Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value -Wunused-variable -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings -Wno-deprecated-declarations -Wc++11-compat -Wconversion-null -Wctor-dtor-privacy -Weffc++ -Winvalid-pch -Wold-style-cast -Woverloaded-virtual -Wredundant-decls -Wsign-promo -Wstrict-null-sentinel -Wno-useless-cast -Wzero-as-null-pointer-constant -Wstack-protector -fstack-protector-all -Wno-non-virtual-dtor -Wno-reorder -Wno-sign-conversion -Wno-float-equal -Wno-old-style-cast -Wno-zero-as-null-pointer-constant -m64 -Wl,--gc-sections -s -flto -pie -z noexecstack -z relro -z now -fuse-ld=gold -s main.cpp.o -o bin/main myapplication_libs.a -lmicrohttpd -lcurl -lgnutls /usr/lib64/libz.so -lpthread -lgcrypt -lgpg-error -lhogweed -lnettle -lgmp src/microhttpd/connection.c: In function ‘connection_alloc_memory’: src/microhttpd/connection.c:281:10: error: ‘need_to_free’ may be used uninitialized [-Werror=maybe-uninitialized] 281 | if (c->read_buffer_size - c->read_buffer_offset >= need_to_free) | ^ compilation terminated due to -Wfatal-errors. lto1: all warnings being treated as errors On Thu, 28 Dec 2023 at 06:26, Christian Grothoff <groth...@gnunet.org> wrote: > I think it might be helpful if you could share the *exact* compiler > invocation (make V=1) and error message you are getting... > > On 12/27/23 11:38, Sergey Sudnitsyn wrote: > > Thank you. > > I don't know what's so special about my setup - I am getting the same > > error with GCC 12 & 13 - compiling for both x86_64 & aarch64. > > Compiler flags - nothing unusual - -O3 -flto - but maybe warnings are a > > bit overzealous (-Wuninitialized -Wstack-protector). > > I'll try producing a sample that reproduces this - and will use > > suggested workaround in the meantime. > > > > On Tue, 26 Dec 2023 at 17:21, Evgeny Grin <k...@yandex.ru > > <mailto:k...@yandex.ru>> wrote: > > > > Hi Sergey, > > > > Are you using some special compiler or linker parameters? Some > special > > compiler or linker versions? > > > > I regularly test MHD with LTO. I've retested the current git master > > with > > LTO and cannot reproduce. > > No errors, nor even warnings. > > > > If you check the code you will find that both mentioned variables are > > not used before initialisation. (Please provide the code path if I'm > > wrong). > > > > Unless variables are really used as uninitialised (which should be a > > bug > > and needs to be fixed), I'd avoid unneeded initialisation to save the > > code size (and negligible performance). > > > > If your compiler/linker complaint is false positive, you probably may > > workaround it with '-ftrivial-auto-var-init' parameter. > > > > Let me know the details, please. > > > > -- > > Evgeny > > > > On 26/12/2023 16:14, Sergey Sudnitsyn wrote: > > > When LTO is enabled, linking fails complaining about potentially > > > uninitialized variables; > > > It's hard to provide a small sample reproducing this, but I hope > the > > > patch can be applied even without it since it's innocent enough > > (diff > > > against commit 8bb481f ): > > > > > > diff --git a/src/microhttpd/connection.c > > b/src/microhttpd/connection.c > > > index f9892a55..e5dd1a45 100644 > > > --- a/src/microhttpd/connection.c > > > +++ b/src/microhttpd/connection.c > > > @@ -653,7 +653,7 @@ MHD_connection_alloc_memory_ (struct > > MHD_Connection > > > *connection, > > > { > > > struct MHD_Connection *const c = connection; /* a short alias > */ > > > struct MemoryPool *const pool = c->pool; /* a short alias */ > > > - size_t need_to_be_freed; /**< The required amount of additional > > free > > > memory */ > > > + size_t need_to_be_freed = 0; /**< The required amount of > > additional > > > free memory */ > > > void *res; > > > > > > res = MHD_pool_try_alloc (pool, size, &need_to_be_freed); > > > @@ -4468,7 +4468,7 @@ process_request_body (struct MHD_Connection > > > *connection) > > > { /* Need the parse the chunk size line */ > > > /** The number of found digits in the chunk size number > */ > > > size_t num_dig; > > > - uint64_t chunk_size; > > > + uint64_t chunk_size = 0; > > > bool broken; > > > bool overflow; > > > > > > >