From 8b695647dbe9aaca5b5fa8aacca562928e85383e Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Wed, 6 Jun 2018 16:19:24 -0400
Subject: [PATCH] lxapigen.pl: Don't overwrite files that didn't change.

This prevents a full rebuild every time you add an API.
---
 lxapigen.pl | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lxapigen.pl b/lxapigen.pl
index 2668d92..31ebbb9 100755
--- a/lxapigen.pl
+++ b/lxapigen.pl
@@ -87,7 +87,8 @@ sub typesize {
 
     # Here we go...
 
-    my $outfname = "$dirname/$module-lx.h";
+    my $finalfname = "$dirname/$module-lx.h";
+    my $outfname = "$finalfname-new";
     open(OUT, '>', $outfname) or die("Failed to open '$outfname' for writing: $!\n");
 
     print OUT <<EOF
@@ -227,6 +228,12 @@ sub typesize {
 ;
 
     close(OUT);
+
+    if ((system("diff --brief '$finalfname' '$outfname'") == -1) || ($? != 0)) {
+        rename($outfname, $finalfname) or die("Failed to rename '$outfname' to '$finalfname': $!\n");
+    } else {
+        unlink($outfname);  # they match, just delete the new copy so build system doesn't rebuild everything.
+    }
 }
 
 closedir(DIRH);