As said at https://debbugs.gnu.org/cgi/bugreport.cgi?bug=55025#24 (about an issue with Automake) by Nick Bowler, when ".POSIX:" is used, GNU Make does not conform to POSIX when errors are ignored. This affects commands like

  @-false; echo hello

where "hello" is not output because the shell is run with -e (the following applies at least to GNU Make 4.3 and the Git current repository), which is incorrect. Indeed, job.c contains:

  if (shellflags == 0)
    shellflags = posix_pedantic ? "-ec" : "-c";

i.e. -e is always used in POSIX mode.

The POSIX standard[*] says:

"An execution line is built from the command line by removing any prefix characters. Except as described under the at-sign prefix, the execution line shall be written to the standard output, optionally preceded by a <tab>. The execution line shall then be executed by a shell as if it were passed as the argument to the system() interface, except that if errors are not being ignored then the shell -e option shall also be in effect. If errors are being ignored for the command (as a result of the -i option, a '-' command prefix, or a .IGNORE special target), the shell -e option shall not be in effect. The environment for the command being executed shall contain all of the variables in the environment of make."

[*] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html

If I understand correctly, errors are ignored if child->noerror or ignore_errors_flag is true. So, in this case, -e should not be used.