make: add a comment, no functional change

1 files changed, 8 insertions, 3 deletions

diff --git a/miscutils/make.c b/miscutils/make.c
index 49d10f5f5..df46256bb 100644
--- a/miscutils/make.c
+++ b/miscutils/make.c
@@ -17,7 +17,7 @@
 //config:       default n
 //config:       depends on MAKE
 //config:       help
-//config:       Allow strict enforcement of POSIX mode at runtime by:
+//config:       Allow strict enforcement of POSIX 2017 at runtime by:
 //config:       - .POSIX special target in makefile
 //config:       - '--posix' command line option
 //config:       - PDPMAKE_POSIXLY_CORRECT environment variable
@@ -1583,8 +1583,13 @@ input(FILE *fd, int ilevel)
                                 if (posix)
                                         break;
                         }
-                        if (posix && (p == NULL || gettok(&q)))
-                                error("one include file per line");
+                        if (posix) {
+                                // In POSIX 2017 zero or more than one include file is
+                                // unspecified behaviour.
+                                if (p == NULL || gettok(&q)) {
+                                        error("one include file per line");
+                                }
+                        }
 
                         makefile = old_makefile;
                         lineno = old_lineno;