1 files changed, 66 insertions, 0 deletions
diff --git a/src/tools/fix-old-flex-code.pl b/src/tools/fix-old-flex-code.pl
new file mode 100644
index 0000000..8059cb5
--- /dev/null
+++ b/src/tools/fix-old-flex-code.pl
@@ -0,0 +1,66 @@
+#!/usr/bin/perl
+#----------------------------------------------------------------------
+#
+# fix-old-flex-code.pl
+#
+# flex versions before 2.5.36, with certain option combinations, produce
+# code that causes an "unused variable" warning.  That's annoying, so
+# let's suppress it by inserting a dummy reference to the variable.
+# (That's exactly what 2.5.36 and later do ...)
+#
+# Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+# Portions Copyright (c) 1994, Regents of the University of California
+#
+# src/tools/fix-old-flex-code.pl
+#
+#----------------------------------------------------------------------
+
+use strict;
+use warnings;
+
+# Get command line argument.
+usage() if $#ARGV != 0;
+my $filename = shift;
+
+# Suck in the whole file.
+local $/ = undef;
+my $cfile;
+open($cfile, '<', $filename) || die "opening $filename for reading: $!";
+my $ccode = <$cfile>;
+close($cfile);
+
+# No need to do anything if it's not flex 2.5.x for x < 36.
+exit 0 if $ccode !~ m/^#define YY_FLEX_MAJOR_VERSION 2$/m;
+exit 0 if $ccode !~ m/^#define YY_FLEX_MINOR_VERSION 5$/m;
+exit 0 if $ccode !~ m/^#define YY_FLEX_SUBMINOR_VERSION (\d+)$/m;
+exit 0 if $1 >= 36;
+
+# Apply the desired patch.
+$ccode =~
+  s|(struct yyguts_t \* yyg = \(struct yyguts_t\*\)yyscanner; /\* This var may be unused depending upon options. \*/
+.*?)
+	return yy_is_jam \? 0 : yy_current_state;
+|$1
+	(void) yyg;
+	return yy_is_jam ? 0 : yy_current_state;
+|s;
+
+# Write the modified file back out.
+open($cfile, '>', $filename) || die "opening $filename for writing: $!";
+print $cfile $ccode;
+close($cfile);
+
+exit 0;
+
+
+sub usage
+{
+	die <<EOM;
+Usage: fix-old-flex-code.pl c-file-name
+
+fix-old-flex-code.pl modifies a flex output file to suppress
+an unused-variable warning that occurs with older flex versions.
+
+Report bugs to <pgsql-bugs\@lists.postgresql.org>.
+EOM
+}