Add an easter egg in msg.c.

5 files changed, 42 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 8c92378b..47e5cdd3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2019-04-18         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* msg.c (msg): Add an undocumented feature. "Use the Source, Luke."
+
 2019-04-12         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* configure.ac: Update version to 5.0.0.
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 6f4467d9..f3964012 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,7 @@
+2019-04-18         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* gawktexi.in (Undocumented): Note an undocumented feature.
+
 2019-04-14         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* gawktexi.in (Case-sensitivity): Document that single-byte
diff --git a/doc/gawk.texi b/doc/gawk.texi
index e5371c61..02481a7c 100644
--- a/doc/gawk.texi
+++ b/doc/gawk.texi
@@ -5035,6 +5035,19 @@ returns a textual version of the flags for scalar variables, and the
 array back-end implementation type for arrays. This interface is subject
 to change and may not be stable.
 
+When not in POSIX or compatibility mode, if you set @code{LINENO} to a
+numeric value using the @option{-v} option, @command{gawk} adds that value
+to the real line number for use in error messages.  This is intended for
+use within Bash shell scripts, such that the error message will reflect
+the line number in the shell script, instead of in the @command{awk}
+program. To demonstrate:
+
+@exmaple
+$ @kbd{gawk -v LINENO=10 'BEGIN @{ print("hi" @}'}
+@error{} gawk: cmd. line:11: BEGIN @{ print("hi" @}
+@error{} gawk: cmd. line:11:                    ^ syntax error
+@end example
+
 @end ignore
 
 @node Invoking Summary
diff --git a/doc/gawktexi.in b/doc/gawktexi.in
index 14e20b7a..0408d61c 100644
--- a/doc/gawktexi.in
+++ b/doc/gawktexi.in
@@ -4945,6 +4945,19 @@ returns a textual version of the flags for scalar variables, and the
 array back-end implementation type for arrays. This interface is subject
 to change and may not be stable.
 
+When not in POSIX or compatibility mode, if you set @code{LINENO} to a
+numeric value using the @option{-v} option, @command{gawk} adds that value
+to the real line number for use in error messages.  This is intended for
+use within Bash shell scripts, such that the error message will reflect
+the line number in the shell script, instead of in the @command{awk}
+program. To demonstrate:
+
+@exmaple
+$ @kbd{gawk -v LINENO=10 'BEGIN @{ print("hi" @}'}
+@error{} gawk: cmd. line:11: BEGIN @{ print("hi" @}
+@error{} gawk: cmd. line:11:                    ^ syntax error
+@end example
+
 @end ignore
 
 @node Invoking Summary
diff --git a/msg.c b/msg.c
index 12cc2aac..ca988ad3 100644
--- a/msg.c
+++ b/msg.c
@@ -46,10 +46,17 @@ err(bool isfatal, const char *s, const char *emsg, va_list argp)
 
 	static bool first = true;
 	static bool add_src_info = false;
+	static long lineno_val = 0;	// Easter Egg
 
 	if (first) {
 		first = false;
 		add_src_info = (getenv("GAWK_MSG_SRC") != NULL);
+		if (! do_traditional) {
+			NODE *n = lookup("LINENO");
+
+			if (n != NULL && n->type == Node_var)
+				lineno_val = get_number_d(n->var_value);
+		}
 	}
 
 	(void) fflush(output_fp);
@@ -67,7 +74,7 @@ err(bool isfatal, const char *s, const char *emsg, va_list argp)
 		else
 			(void) fprintf(stderr, _("cmd. line:"));
 
-		(void) fprintf(stderr, "%d: ", sourceline);
+		(void) fprintf(stderr, "%d: ", sourceline + lineno_val);
 	}
 
 #ifdef HAVE_MPFR