Parse the feature hint bits & assert their usability

1 files changed, 20 insertions, 0 deletions

diff --git a/regen/feature.pl b/regen/feature.pl
index 3e2057485e..b57a30e342 100644
--- a/regen/feature.pl
+++ b/regen/feature.pl
@@ -116,6 +116,26 @@ while (<DATA>) {
 
 read_only_bottom_close_and_rename($pm);
 
+open "perl.h", "perl.h" or die "$0 cannot open perl.h: $!";
+perlh: {
+    while (readline "perl.h") {
+	next unless /#define\s+HINT_FEATURE_MASK/;
+	/(0x[A-Fa-f0-9]+)/ or die "No hex number in:\n\n$_\n ";
+	my $hex = $1;
+	my $bits = sprintf "%b", oct $1;
+	$bits =~ /^0*1+0*\z/
+	 or die "Non-contiguous bits in $bits (binary for $hex):\n\n$_\n ";
+	my $bits_needed =
+	    length sprintf "%b", scalar keys(%feature_bundle) - @same;
+	$bits =~ /1{$bits_needed}/
+	    or die "Not enough bits (need $bits_needed)"
+		 . " in $bits (binary for $hex):\n\n$_\n";
+	last perlh;
+    }
+    die "No HINT_FEATURE_MASK defined in perl.h";
+}
+close "perl.h";
+
 __END__
 package feature;