[perl #20636] Make h2xs skip #define macros with empty rhs

Otherwise the generated C code uses such macros in expressions, which causes
compilation errors because the macro is expanded to an empty token list.

2 files changed, 25 insertions, 0 deletions

diff --git a/lib/h2xs.t b/lib/h2xs.t
index 6ce37ee357..d10ce75c1c 100644
--- a/lib/h2xs.t
+++ b/lib/h2xs.t
@@ -159,8 +159,10 @@ for (my $i = $#tests; $i > 0; $i-=3) {
   # 1 test for running it, 1 test for the expected result, and 1 for each file
   # plus 1 to open and 1 to check for the use in lib/$name.pm and Makefile.PL
   # And 1 more for our check for "bonus" files, 2 more for ExtUtil::Manifest.
+  # And 1 more to examine const-c.inc contents in tests that use $header.
   # use the () to force list context and hence count the number of matches.
   $total_tests += 9 + (() = $tests[$i] =~ /(Writing)/sg);
+  $total_tests++ if $tests[$i-2] =~ / \Q$header\E$/;
 }
 
 plan tests => $total_tests;
@@ -169,6 +171,8 @@ ok (open (HEADER, ">$header"), "open '$header'");
 print HEADER <<HEADER or die $!;
 #define Camel 2
 #define Dromedary 1
+#define Bactrian /* empty */
+#define Bactrian2
 HEADER
 ok (close (HEADER), "close '$header'");
 
@@ -215,6 +219,23 @@ while (my ($args, $version, $expectation) = splice @tests, 0, 3) {
   pop @INC;
   chdir ($up) or die "chdir $up failed: $!";
  
+  if ($args =~ / \Q$header\E$/) {
+    my $const_c = File::Spec->catfile($name, 'fallback', 'const-c.inc');
+    my ($found, $diag);
+    if (!open FILE, '<', $const_c) {
+      $diag = "can't open $const_c: $!";
+    }
+    else {
+      while (<FILE>) {
+        next unless /\b Bactrian 2? \b/x;
+        $found = 1;
+        last;
+      }
+    }
+    ok (!$found, "generated $const_c has no Bactrian(2)");
+    diag ($diag) if defined $diag;
+  }
+
   foreach my $leaf (File::Spec->catfile('lib', "$name.pm"), 'Makefile.PL') {
     my $file = File::Spec->catfile($name, $leaf);
     if (ok (open (FILE, $file), "open $file")) {
diff --git a/utils/h2xs.PL b/utils/h2xs.PL
index ee4079f8ea..6b2c78f092 100644
--- a/utils/h2xs.PL
+++ b/utils/h2xs.PL
@@ -862,6 +862,10 @@ if( @path_h ){
 	    $rest =~ s!/\*.*?(\*/|\n)|//.*!!g; # Remove comments
 	    $rest =~ s/^\s+//;
 	    $rest =~ s/\s+$//;
+	    if ($rest eq '') {
+	      print("Skip empty $def\n") if $opt_d;
+	      next defines;
+	    }
 	    # Cannot do: (-1) and ((LHANDLE)3) are OK:
 	    #print("Skip non-wordy $def => $rest\n"),
 	    #  next defines if $rest =~ /[^\w\$]/;