libunwind is reentrant and signal safe, and works faster then then
gcc_eh (plus it has some custom patches for problems that have been
found during it's usage in ClickHouse).
gcc_eh may be missing in the system (if gcc was not installed), and
even if it exists clickhouse uses -nodefaultlibs, so some care should be
made to make it work.
Also this library is tiny and there shouln't be any problem to require
it always (there is already tendency to require some contrib libraries,
i.e. poco).
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Previously, in #39387, this protection had been added only for linux x86_64.
And use include_guard() instead of manual if()+set().
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
gcc with -nodefaultlibs does not add sanitizers library during linkage
with -static-libasan and similar, fix this, by add them explicitly.
From the gcc(1) about -nodefaultlibs:
Do not use the standard system libraries when linking. Only the
libraries you specify are passed to the linker, and options specifying
linkage of the system libraries, such as -static-libgcc or
-shared-libgcc, are ignored. The standard startup files are used
normally, unless -nostartfiles is used.
Plus checked it manually, w/o -nodefaultlibs everything works without
this explicit linkage.
After this patch UBSAN under gcc compiled successfully.
v2: freebsd and darwin
