Hi Joseph, As we discussed, this patch just makes C23 include every check that is performed by C11. I tested the commit by adding the ISO23 Make and Python variables to be the same as ISO11. So the only difference was compiling with -DISO23 instead of -DISO11. And changed the temporary directories to instead use the format f'/tmp/glibc-{self.standard}-{self.header}'. Then I used a shell script to run 'cmp' on each file in the ISO11 and ISO23 directories for each header to make sure they were the same. -- 8< -- Make C23 checks include every test that is performed by C11. Done by running the following command: find conform -name '*.h-data' | xargs sed -i \ -e 's| !defined ISO11| !defined ISO11 \&\& !defined ISO23|g' \ -e 's| defined ISO11| defined ISO11 \|\| defined ISO23|g' \ -e 's|ifdef ISO11|if defined ISO11 \|\| defined ISO23|g' \ -e 's|ifndef ISO11|if !defined ISO11 \&\& !defined ISO23|g' Signed-off-by: Collin Funk <collin.funk1@gmail.com>