From 0778eb79b1e2957743bbd577fc3d862a3dc007cf Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 18 Jul 2022 19:43:16 -0400
Subject: [PATCH] Improve perl style in ecpg's parser-construction scripts.

parse.pl and check_rules.pl used "no warnings 'uninitialized'",
which doesn't seem like it measures up to current project standards.
Removing that shows that it was hiding various places that accessed
off the end of an array, which are easily protected by minor logic
adjustments.  There's no change in the script results.

While here, improve the Makefile rule that invokes these scripts.
It neglected to depend on check_rules.pl, so that editing that file
didn't result in re-running the check; and it ran check_rules.pl
after building preproc.y, so that if check_rules.pl did fail the
next "make" attempt would just bypass it.  check_rules.pl failures
are sufficiently un-heard-of that I don't feel a need to back-patch
this.

Discussion: https://postgr.es/m/838180.1658181982@sss.pgh.pa.us
---
 src/interfaces/ecpg/preproc/Makefile       |  4 ++--
 src/interfaces/ecpg/preproc/check_rules.pl |  4 ++--
 src/interfaces/ecpg/preproc/parse.pl       | 28 ++++++++++++++++------
 3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/src/interfaces/ecpg/preproc/Makefile b/src/interfaces/ecpg/preproc/Makefile
index ec2359810e..3f33f4638f 100644
--- a/src/interfaces/ecpg/preproc/Makefile
+++ b/src/interfaces/ecpg/preproc/Makefile
@@ -64,9 +64,9 @@ preproc.h: preproc.c
 
 preproc.c: BISONFLAGS += -d
 
-preproc.y: ../../../backend/parser/gram.y parse.pl ecpg.addons ecpg.header ecpg.tokens ecpg.trailer ecpg.type
-	$(PERL) $(srcdir)/parse.pl --srcdir $(srcdir) --parser $< --output $@
+preproc.y: ../../../backend/parser/gram.y parse.pl check_rules.pl ecpg.addons ecpg.header ecpg.tokens ecpg.trailer ecpg.type
 	$(PERL) $(srcdir)/check_rules.pl --srcdir $(srcdir) --parser $<
+	$(PERL) $(srcdir)/parse.pl --srcdir $(srcdir) --parser $< --output $@
 
 # generate keyword headers
 c_kwlist_d.h: c_kwlist.h $(GEN_KEYWORDLIST_DEPS)
diff --git a/src/interfaces/ecpg/preproc/check_rules.pl b/src/interfaces/ecpg/preproc/check_rules.pl
index 58a755f454..23a3741993 100644
--- a/src/interfaces/ecpg/preproc/check_rules.pl
+++ b/src/interfaces/ecpg/preproc/check_rules.pl
@@ -18,7 +18,6 @@
 
 use strict;
 use warnings;
-no warnings 'uninitialized';
 use Getopt::Long;
 
 my $srcdir  = '.';
@@ -142,7 +141,8 @@ while (<$parser_fh>)
 			$in_rule = 0 if $arr[$fieldIndexer] eq ';';
 		}
 		elsif (($arr[$fieldIndexer] =~ '[A-Za-z0-9]+:')
-			|| $arr[ $fieldIndexer + 1 ] eq ':')
+			   || (   $fieldIndexer + 1 < $n
+					  && $arr[ $fieldIndexer + 1 ] eq ':'))
 		{
 			die "unterminated rule at grammar line $.\n"
 			  if $in_rule;
diff --git a/src/interfaces/ecpg/preproc/parse.pl b/src/interfaces/ecpg/preproc/parse.pl
index 8fb2224249..8de5c4457b 100644
--- a/src/interfaces/ecpg/preproc/parse.pl
+++ b/src/interfaces/ecpg/preproc/parse.pl
@@ -14,7 +14,6 @@
 
 use strict;
 use warnings;
-no warnings 'uninitialized';
 use Getopt::Long;
 
 my $srcdir  = '.';
@@ -40,7 +39,8 @@ my $tokenmode             = 0;
 
 my (%buff, $infield, $comment, %tokens, %addons);
 my ($stmt_mode, @fields);
-my ($line,      $non_term_id);
+my $line = '';
+my $non_term_id;
 
 
 # some token have to be replaced by other symbols
@@ -195,6 +195,16 @@ sub main
 		# Now split the line into individual fields
 		my @arr = split(' ');
 
+		if (!@arr)
+		{
+			# empty line: in tokenmode 1, emit an empty line, else ignore
+			if ($tokenmode == 1)
+			{
+				add_to_buffer('orig_tokens', '');
+			}
+			next line;
+		}
+
 		if ($arr[0] eq '%token' && $tokenmode == 0)
 		{
 			$tokenmode = 1;
@@ -341,7 +351,8 @@ sub main
 
 			# Are we looking at a declaration of a non-terminal ?
 			if (($arr[$fieldIndexer] =~ /[A-Za-z0-9]+:/)
-				|| $arr[ $fieldIndexer + 1 ] eq ':')
+				|| (   $fieldIndexer + 1 < scalar(@arr)
+					&& $arr[ $fieldIndexer + 1 ] eq ':'))
 			{
 				$non_term_id = $arr[$fieldIndexer];
 				$non_term_id =~ tr/://d;
@@ -409,11 +420,13 @@ sub main
 			if (   $copymode
 				&& !$prec
 				&& !$comment
+				&& $fieldIndexer < scalar(@arr)
 				&& length($arr[$fieldIndexer])
 				&& $infield)
 			{
 				if ($arr[$fieldIndexer] ne 'Op'
-					&& (   $tokens{ $arr[$fieldIndexer] } > 0
+					&& ((   defined $tokens{ $arr[$fieldIndexer] }
+							&& $tokens{ $arr[$fieldIndexer] } > 0)
 						|| $arr[$fieldIndexer] =~ /'.+'/)
 					|| $stmt_mode == 1)
 				{
@@ -472,11 +485,12 @@ sub include_addon
 	my $rec = $addons{$block};
 	return 0 unless $rec;
 
-	if ($rec->{type} eq 'rule')
+	my $rectype = (defined $rec->{type}) ? $rec->{type} : '';
+	if ($rectype eq 'rule')
 	{
 		dump_fields($stmt_mode, $fields, ' { ');
 	}
-	elsif ($rec->{type} eq 'addon')
+	elsif ($rectype eq 'addon')
 	{
 		add_to_buffer('rules', ' { ');
 	}
@@ -487,7 +501,7 @@ sub include_addon
 
 	push(@{ $buff{$buffer} }, @{ $rec->{lines} });
 
-	if ($rec->{type} eq 'addon')
+	if ($rectype eq 'addon')
 	{
 		dump_fields($stmt_mode, $fields, '');
 	}