Configure: make it possible to have generated generators

This makes it possible to chain GENERATOR statements, which allows
constructs like this:

    GENERATE[something.html]=something.pod
    GENERATE[something.pod]=something.pod.in

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6236)

1 files changed, 11 insertions, 3 deletions

diff --git a/Configure b/Configure
index 11c9479416..bad09ed8a3 100755
--- a/Configure
+++ b/Configure
@@ -2124,10 +2124,18 @@ EOF
             my $dest = $_;
             my $ddest = cleanfile($buildd, $_, $blddir);
             die "more than one generator for $dest: "
-                    ,join(" ", @{$generate{$_}}),"\n"
-                    if scalar @{$generate{$_}} > 1;
+                ,join(" ", @{$generate{$_}}),"\n"
+                if scalar @{$generate{$_}} > 1;
             my @generator = split /\s+/, $generate{$dest}->[0];
-            $generator[0] = cleanfile($sourced, $generator[0], $blddir),
+            my $gen = $generator[0];
+            $generator[0] = cleanfile($sourced, $gen, $blddir);
+
+            # If the generator isn't in the source tree, we assume it's
+            # generated in the build tree
+            if ($generate{$gen}) {
+                $generator[0] = cleanfile($buildd, $gen, $blddir);
+            }
+
             $unified_info{generate}->{$ddest} = [ @generator ];
         }