https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42300
--- Comment #3 from Ryan Sundberg <ryan at arctype dot co> --- I've stumbled upon this 30 year old bug also while trying to build a gcc cross compiler. The behavior is that LIBRARY_PATH="" is different than having LIBRARY_PATH not set at all in the environment. As Lluis said in 2009, LIBRARY_PATH="" behaves as if LIBRARY_PATH=".". See the attached minimal example: $ unset LIBRARY_PATH $ gcc --print-search-dirs install: /usr/lib/gcc/x86_64-linux-gnu/9/ programs: =/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/ libraries: =/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../lib/:/lib/x86_64-linux-gnu/9/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/9/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../:/lib/:/usr/lib/ $ LIBRARY_PATH= gcc --print-search-dirs install: /usr/lib/gcc/x86_64-linux-gnu/9/ programs: =/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/ libraries: =./x86_64-linux-gnu/9/:./x86_64-linux-gnu/:./../lib/:/usr/lib/gcc/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/9/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../lib/:/lib/x86_64-linux-gnu/9/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/9/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:./:/usr/lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/lib/:/usr/lib/gcc/x86_64-linux-gnu/9/../../../:/lib/:/usr/lib/ Notice that the search paths are different, the latter including ":./:" in the search path. If you happen to have a "specs" file in the search path (such as when building gcc) it will be accidentally loaded by GCC and can result in obscure errors (such as missing crt0.o, etc, depending on what is in the spec file).
