/* We would have to include <limits.h> to get a definition of MB_LEN_MAX.
But this would only disturb the namespace. So we define our own
version here. */
#define __STDLIB_MB_LEN_MAX 16
#if defined MB_LEN_MAX && MB_LEN_MAX != __STDLIB_MB_LEN_MAX
# error "Assumed value of MB_LEN_MAX wrong"
#endifM4: Assumed value of MB_LEN_MAX wrong
This error message usually indicates that limits.h provided by GCC isn't including limits.h from Glibc as it should be. There is one command as a workaround for limits.h in GCC Pass 1. Do not forget to run the command.
In LFS 10.0 through 11.3, there is another command as the workaround running mkheaders after installing Glibc (Chapter 5). This command has been removed in LFS 11.4. Either running this command building LFS 11.4 or later (likely because of a reuse of old scripts - note that such a reuse is strongly discouraged) or forgetting this command building LFS 10.0 through 11.3 will also lead to this error message.
If you've encountered this issue, untar the GCC tarball again and run the command at the bottom of GCC Pass 1 page to create limits.h. Then if you are building LFS 11.4 or later, run rm -f $LFS/tools/lib/gcc/$LFS_TGT/*/include-fixed/limits.h which would fix the issue in case you've mistakenly run the mkheaders command which does not belong to the LFS version you are building. If you are building LFS 11.0 through 11.3, run the mkheaders command in Chapter 5 Glibc.