From bfc687284eea4588aee2b36bffc726573fc4153d Mon Sep 17 00:00:00 2001
From: Robert Schumacher <roschuma@microsoft.com>
Date: Mon, 19 Jun 2017 22:18:05 -0700
Subject: [libpng] Define CMAKE_SYSTEM_PROCESSOR to avoid double-eval failure

---
 ports/libpng/CONTROL        | 2 +-
 ports/libpng/portfile.cmake | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/ports/libpng/CONTROL b/ports/libpng/CONTROL
index ec827ebd7..561cc81f8 100644
--- a/ports/libpng/CONTROL
+++ b/ports/libpng/CONTROL
@@ -1,4 +1,4 @@
 Source: libpng
-Version: 1.6.29-1
+Version: 1.6.29-2
 Build-Depends: zlib
 Description: libpng is a library implementing an interface for reading and writing PNG (Portable Network Graphics) format files.
diff --git a/ports/libpng/portfile.cmake b/ports/libpng/portfile.cmake
index be4cb526d..ebcf78aa8 100644
--- a/ports/libpng/portfile.cmake
+++ b/ports/libpng/portfile.cmake
@@ -23,6 +23,13 @@ else()
     set(PNG_SHARED_LIBS OFF)
 endif()
 
+# Libpng's cmake uses if(${CMAKE_SYSTEM_PROCESSOR} ....) which performs double-evaluation and breaks if the variable is not defined.
+if(VCPKG_TARGET_ARCHITECTURE STREQUAL x64)
+    set(CMAKE_SYSTEM_PROCESSOR AMD64)
+else()
+    set(CMAKE_SYSTEM_PROCESSOR ${VCPKG_TARGET_ARCHITECTURE})
+endif()
+
 vcpkg_configure_cmake(
     SOURCE_PATH ${SOURCE_PATH}
     OPTIONS
@@ -32,6 +39,7 @@ vcpkg_configure_cmake(
         -DSKIP_INSTALL_PROGRAMS=ON
         -DSKIP_INSTALL_EXECUTABLES=ON
         -DSKIP_INSTALL_FILES=ON
+        -DCMAKE_SYSTEM_PROCESSOR=${CMAKE_SYSTEM_PROCESSOR}
     OPTIONS_DEBUG
         -DSKIP_INSTALL_HEADERS=ON
 )
-- 
cgit v1.2.3