From 174d87063564978b7becfcfa0431271d89e9c9b6 Mon Sep 17 00:00:00 2001
From: Simon Hausmann <simon.hausmann@qt.io>
Date: Thu, 20 Jun 2019 14:15:59 +0200
Subject: Add support for picking up vcpkg automatically

If VCPKG_ROOT is defined, let's use it and chainload any previously set
toolchain file. The detection of vcpkg support via the VCPKG_ROOT
environment variable is per vcpkg documentation, the automatic
chainloading is something specific to us.

Change-Id: I0498effc5b948f0b6f5e223d0454a15a0cbb503a
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
---
 CMakeLists.txt  | 20 ++++++++++++++++++--
 cmake/README.md | 11 ++++++-----
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d47bc91cbf..5566870576 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,23 @@
 cmake_minimum_required(VERSION 3.15.0)
 
-if(DEFINED ENV{VCPKG_DEFAULT_TRIPLET} AND NOT DEFINED VCPKG_TARGET_TRIPLET)
-    set(VCPKG_TARGET_TRIPLET "$ENV{VCPKG_DEFAULT_TRIPLET}" CACHE STRING "")
+if(DEFINED ENV{VCPKG_ROOT})
+    set(vcpkg_toolchain_file "$ENV{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake")
+    get_filename_component(vcpkg_toolchain_file "${vcpkg_toolchain_file}" ABSOLUTE)
+
+    if(DEFINED CMAKE_TOOLCHAIN_FILE)
+        get_filename_component(supplied_toolchain_file "${CMAKE_TOOLCHAIN_FILE}" ABSOLUTE)
+        if(NOT supplied_toolchain_file STREQUAL vcpkg_toolchain_file)
+            set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE "${CMAKE_TOOLCHAIN_FILE}" CACHE STRING "")
+        endif()
+        unset(supplied_toolchain_file)
+    endif()
+    set(CMAKE_TOOLCHAIN_FILE "${vcpkg_toolchain_file}" CACHE STRING "" FORCE)
+    message(STATUS "Using vcpkg from $ENV{VCPKG_ROOT}")
+    if(DEFINED ENV{VCPKG_DEFAULT_TRIPLET} AND NOT DEFINED VCPKG_TARGET_TRIPLET)
+        set(VCPKG_TARGET_TRIPLET "$ENV{VCPKG_DEFAULT_TRIPLET}" CACHE STRING "")
+        message(STATUS "Using vcpkg triplet ${VCPKG_TARGET_TRIPLET}")
+    endif()
+    unset(vcpkg_toolchain_file)
 endif()
 
 project(QtBase
diff --git a/cmake/README.md b/cmake/README.md
index 868b4f2d33..1d00a438f5 100644
--- a/cmake/README.md
+++ b/cmake/README.md
@@ -27,9 +27,9 @@ You may use vcpkg to install dependencies needed to build QtBase.
   * ```git clone -b qt https://github.com/tronical/vcpkg```
   * Run ```bootstrap-vcpkg.bat``` or ```bootstrap-vcpkg.sh```
   * Set the ``VCPKG_DEFAULT_TRIPLET`` environment variable to ``qt-x64-windows-static`` or ``qt-x86-windows-static``
-  * Build Qt dependencies:  ``vcpkg install zlib pcre2 harfbuzz freetype openssl zstd``
-  * When running cmake in qtbase, pass ``-DCMAKE_TOOLCHAIN_FILE=/path/to/your/vcpkg/scripts/buildsystems/vcpkg.cmake``
-    Previously CMAKE_PREFIX_PATH was mentioned instead of CMAKE_TOOLCHAIN_FILE. Setting CMAKE_PREFIX_PATH to the vcpkg installed folder is not enough, because then find_package is not overridden by vcpkg and cmake might not propagate all library dependencies for static packages (freetype is one such package).
+  * Set the ``VCPKG_ROOT`` environment variable to the path where you cloned vcpkg
+  * Build Qt dependencies:  ``vcpkg install @qt-packages-windows.txt``
+  * When running cmake in qtbase, support for vcpkg will be picked up automatically when the VCPKG_ROOT environment variable is set.
 
 # Building against homebrew on macOS
 
@@ -138,11 +138,12 @@ Vcpkg for Android can be set up using the following steps:
   * ```git clone -b qt https://github.com/tronical/vcpkg```
   * Run ```bootstrap-vcpkg.bat``` or ```bootstrap-vcpkg.sh```
   * Set the ``VCPKG_DEFAULT_TRIPLET`` environment variable to ``arm-android``
+  * Set the ``VCPKG_ROOT`` environment variable to the path where you cloned vcpkg
   * Set the ``ANDROID_NDK_HOME`` environment variable to the path where you have installed the Android NDK.
   * Set the ``ANDROID_SDK_HOME`` environment variable to the path where you have installed the Android SDK.
-  * Build Qt dependencies:  ``vcpkg install zlib pcre2 harfbuzz freetype openssl zstd``
+  * Build Qt dependencies:  ``vcpkg install @qt-packages-android.txt``
 
-When running cmake in qtbase, pass ``-DCMAKE_TOOLCHAIN_FILE=/path/to/your/vcpkg/scripts/buildsystems/vcpkg.cmake -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake -DQT_HOST_PATH=/path/to/your/host/build -DANDROID_NATIVE_API_LEVEL=21 -DANDROID_SDK_ROOT=$ANDROID_SDK_HOME -DANDROID_STL=c++_shared -DCMAKE_INSTALL_PREFIX=$INSTALL_PATH``
+When running cmake in qtbase, pass ``-DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake -DQT_HOST_PATH=/path/to/your/host/build -DANDROID_NATIVE_API_LEVEL=21 -DANDROID_SDK_ROOT=$ANDROID_SDK_HOME -DANDROID_STL=c++_shared -DCMAKE_INSTALL_PREFIX=$INSTALL_PATH``
 
 # Debugging CMake files
 
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