From 68160448b9f725668b5e18390bc9ab15fe99e1a9 Mon Sep 17 00:00:00 2001
Message-Id: <68160448b9f725668b5e18390bc9ab15fe99e1a9.1379087702.git.brad.king@kitware.com>
From: Brad King <brad.king@kitware.com>
Date: Fri, 13 Sep 2013 11:52:48 -0400
Subject: [PATCH] FindPNG: Honor old PNG_LIBRARY if provided (#14398)

In commit 2a797539 (FindPNG: improve library detection, 2013-07-27) we
split the search for PNG into separate PNG_LIBRARY_DEBUG and
PNG_LIBRARY_RELEASE variables.  However, if a project or user sets the
old PNG_LIBRARY value we must honor it instead of searching.

While at it, mark PNG_LIBRARY_RELEASE and PNG_LIBRARY_DEBUG as advanced
and remove a stray debug message.
---
 Modules/FindPNG.cmake | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/Modules/FindPNG.cmake b/Modules/FindPNG.cmake
index 33c2971..a2577d2 100644
--- a/Modules/FindPNG.cmake
+++ b/Modules/FindPNG.cmake
@@ -58,15 +58,19 @@ if(ZLIB_FOUND)
     list(APPEND PNG_NAMES png${v} libpng${v})
     list(APPEND PNG_NAMES_DEBUG png${v}d libpng${v}d)
   endforeach()
-message(STATUS "PNG r: ${PNG_NAMES} d: ${PNG_NAMES_DEBUG}")
   unset(_PNG_VERSION_SUFFIXES)
-  find_library(PNG_LIBRARY_RELEASE NAMES ${PNG_NAMES})
-  find_library(PNG_LIBRARY_DEBUG NAMES ${PNG_NAMES_DEBUG})
+  # For compatiblity with versions prior to this multi-config search, honor
+  # any PNG_LIBRARY that is already specified and skip the search.
+  if(NOT PNG_LIBRARY)
+    find_library(PNG_LIBRARY_RELEASE NAMES ${PNG_NAMES})
+    find_library(PNG_LIBRARY_DEBUG NAMES ${PNG_NAMES_DEBUG})
+    include(${CMAKE_CURRENT_LIST_DIR}/SelectLibraryConfigurations.cmake)
+    select_library_configurations(PNG)
+    mark_as_advanced(PNG_LIBRARY_RELEASE PNG_LIBRARY_DEBUG)
+  endif()
   unset(PNG_NAMES)
   unset(PNG_NAMES_DEBUG)
 
-  include(${CMAKE_CURRENT_LIST_DIR}/SelectLibraryConfigurations.cmake)
-  select_library_configurations(PNG)
   # Set by select_library_configurations(), but we want the one from
   # find_package_handle_standard_args() below.
   unset(PNG_FOUND)
-- 
1.8.4.rc3