'm following the steps in LFS stable version, and got to point 5.8, passing the sanity test for the tool chain. When trying to configure the lbstdc++, contained in the gcc-7.3.0 package, with the following commands:

../libstdc++-v3/configure \
--host=$LFS_TGT \
--prefix=/tools \
--disable-multilib \
--disable-nls \
--disable-libstdcxx-threads \
--disable-libstdcxx-pch \
--with-gxx-include-dir=/tools/$LFS_TGT/include/c++/7.3.0

I get these warning messages:

configure: WARNING: stdbool.h: present but cannot be compiled
configure: WARNING: stdbool.h: check for missing prerequisite headers?
configure: WARNING: stdbool.h: see the Autoconf documentation
configure: WARNING: stdbool.h: section "Present But Cannot Be Compiled"
configure: WARNING: stdbool.h: proceeding with the compiler's result
checking for stdbool.h... no
checking stdalign.h usability... no
checking stdalign.h presence... yes
configure: WARNING: stdalign.h: present but cannot be compiled
configure: WARNING: stdalign.h: check for missing prerequisite headers?
configure: WARNING: stdalign.h: see the Autoconf documentation
configure: WARNING: stdalign.h: section "Present But Cannot Be Compiled"
configure: WARNING: stdalign.h: proceeding with the compiler's result
checking for stdalign.h... no
checking for the value of EOF... configure: error: computing EOF failed
I checked if $LFS is correct, and it is. When I opened the config.log, I saw this highlighted error message:

conftest.c:10:10: fatal error: stdio.h: No such file or directory
#include <stdio.h>
I imagine that these two are connected, but I don't know how to solve it. Any help would be greatly appreciated.

Autoconf can't find the include header: stdio.h. You not only need stdio.h, but it must be the correct version. stdio and stdbool are both part of libc. You might have version problems.

Thanks for answering. Do you have any idea How I can determine the appropriate versions?
I am very much at a loss of what to do next.

OK, libc is part of the operating system. It's a number of objects called headers that are used in c programming. In the Linux the package is called glibc, for GNU libc. Check here for headersThey end with '.h'.

Your configure error messages have many causes, but mostly missing headers and incorrect versions of header packages. An overall survey of the problem is not possible in a forum thread. There is no specific solution to this problem.

As not very far in to the process I would start again as you must have missed some of the pre-requsite requirements.

Thank ypu both for your answers.
I just saw that the bin/bash link wasn't correctly set.
I think I will just start again. I imagine that the other instalations must be also defective.

I have the same error when compiling gcc and well I am curious because in the previous message says that is a problem with the location of /bin/bash and if you could tell me where the error is I would be grateful.