Add lint warning for accessing $0 in an END rule.

3 files changed, 15 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 02dcbb33..fae44dd5 100755
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-09-16         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* field.c (get_field): Add lint check if accessing $0 inside
+	and END rule, print a "may not be portable" warning.
+	* builtin.c (do_print_rec): Call get_field() unconditionally
+	in order to do lint check.
+
 2018-09-14         Adrian Bunk           <bunk@debian.org>
 
 	* awk.h (init_debug, debug_prog): Move prototypes to here from ...
diff --git a/builtin.c b/builtin.c
index 44c484f5..8247ca33 100644
--- a/builtin.c
+++ b/builtin.c
@@ -2364,8 +2364,7 @@ do_print_rec(int nargs, int redirtype)
 	if (fp == NULL)
 		return;
 
-	if (! field0_valid)
-		(void) get_field(0L, NULL);	/* rebuild record */
+	(void) get_field(0L, NULL);	/* rebuild record if necessary */
 
 	f0 = fields_arr[0];
 
diff --git a/field.c b/field.c
index 52963249..3bcfb421 100644
--- a/field.c
+++ b/field.c
@@ -837,6 +837,13 @@ get_field(long requested, Func_ptr *assign)
 	 * then the whole line must be rebuilt
 	 */
 	if (requested == 0) {
+		static bool warned = false;
+		extern int currule;
+
+		if (do_lint && currule == END) {
+			warned = true;
+			lintwarn(_("accessing $0 from an END rule may not be portable"));
+		}
 		if (! field0_valid) {
 			/* first, parse remainder of input record */
 			if (NF == -1) {