sdk: use Qt's own qt.toolchain.cmake in build scripts

qt-cmake* helper build scripts by default use Qt's generated
qt.toolchain.cmake as the CMAKE_TOOLCHAIN_FILE. Keep this behavior and
patch qt.toolchain.cmake so that will chain-load our Qt6Toolchain.cmake.

qt.toolchain.cmake includes bits that are needed for the conan
integration to work correctly with the sdk.

Pick-to: 6.3 6.2
Change-Id: I89a5e152324178151ba8a5ab4734d542fa4c995c
Reviewed-by: Mikko Gronoff <mikko.gronoff@qt.io>

classes/populate_sdk_qt6_base.bbclass

@@ -96,15 +96,9 @@ set(CMAKE_TOOLCHAIN_FILE "${SDKPATHNATIVE}/usr/share/cmake/OEToolchainConfig.cma
 include("\${CMAKE_TOOLCHAIN_FILE}")
 EOF
 
-    # override qt-cmake
-    cat > ${SDK_OUTPUT}${SDKPATHNATIVE}${QT6_INSTALL_BINDIR}/qt-cmake <<EOF
-#!/bin/sh
-
-cmake_path="${SDKPATHNATIVE}${bindir}/cmake"
-toolchain_path="${SDKPATHNATIVE}/usr/share/cmake/Qt6Toolchain.cmake"
-exec "\$cmake_path" -DCMAKE_TOOLCHAIN_FILE="\$toolchain_path" "\$@"
-EOF
-
+    # and use that from the default toolchain file qt.toolchain.cmake
+    sed -i ${SDK_OUTPUT}${SDKPATHNATIVE}${QT6_INSTALL_LIBDIR}/cmake/Qt6/qt.toolchain.cmake \
+        -e 's|/.*/toolchain.cmake|${SDKPATHNATIVE}/usr/share/cmake/Qt6Toolchain.cmake|'
 }
 
 create_qt6_sdk_files:append:sdkmingw32() {

recipes-qt/qt6/qtbase/0004-Do-not-use-QT_TOOLCHAIN_RELOCATABLE-paths-in-qt.tool.patch

@@ -0,0 +1,29 @@
+From c15033fd4df14b08fc28ec8da61c990801c7e411 Mon Sep 17 00:00:00 2001
+From: Samuli Piippo <samuli.piippo@qt.io>
+Date: Thu, 16 Dec 2021 13:10:48 +0200
+Subject: [PATCH] Do not use QT_TOOLCHAIN_RELOCATABLE paths in
+ qt.toolchain.cmake
+
+The calculated paths for QT_TOOLCHAIN_RELOCATABLE paths point to
+host sysroot which must not be used when cross-compiling other projects.
+
+Upstream-Status: Inappropriate [embedded specific]
+---
+ cmake/qt.toolchain.cmake.in | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/cmake/qt.toolchain.cmake.in b/cmake/qt.toolchain.cmake.in
+index 5e9acd66b8..451de99633 100644
+--- a/cmake/qt.toolchain.cmake.in
++++ b/cmake/qt.toolchain.cmake.in
+@@ -68,8 +68,8 @@ get_filename_component(QT_TOOLCHAIN_RELOCATABLE_CMAKE_DIR "${CMAKE_CURRENT_LIST_
+ # Instead of collapsing the search prefix (which is the case when one is a subdir of the other),
+ # it concatenates them creating an invalid path. Workaround it by setting the root path to the
+ # Qt install prefix, and the prefix path to the lib/cmake subdir.
+-list(PREPEND CMAKE_PREFIX_PATH "${QT_TOOLCHAIN_RELOCATABLE_CMAKE_DIR}")
+-list(PREPEND CMAKE_FIND_ROOT_PATH "${QT_TOOLCHAIN_RELOCATABLE_INSTALL_PREFIX}")
++#list(PREPEND CMAKE_PREFIX_PATH "${QT_TOOLCHAIN_RELOCATABLE_CMAKE_DIR}")
++#list(PREPEND CMAKE_FIND_ROOT_PATH "${QT_TOOLCHAIN_RELOCATABLE_INSTALL_PREFIX}")
+ 
+ # Let CMake load our custom platform modules.
+ # CMake-provided platform modules take precedence.

recipes-qt/qt6/qtbase_git.bb

@@ -17,6 +17,7 @@ SRC_URI += "\
     file://0001-Add-linux-oe-g-platform.patch \
     file://0002-qlibraryinfo-allow-to-set-qt.conf-from-the-outside-u.patch \
     file://0003-tests-disable-failing-tests.patch \
+    file://0004-Do-not-use-QT_TOOLCHAIN_RELOCATABLE-paths-in-qt.tool.patch \
     file://0001-catch_p_p.h-don-t-use-MINSIGSTKSZ.patch \
     file://0005-Exclude-sources-from-HEADER_MODULE-if-cmake-version-.patch \
 "
@@ -155,10 +156,8 @@ set(QT_HOST_PATH "\$ENV{OECORE_NATIVE_SYSROOT}/usr" CACHE PATH "")
 set(QT_BUILD_TOOLS_WHEN_CROSSCOMPILING "TRUE" CACHE BOOL "")
 EOF
 
-    sed -i ${D}${QT6_INSTALL_BINDIR}/* \
-        -e 's|${RECIPE_SYSROOT_NATIVE}|${SDKPATHNATIVE}|' \
-        -e '/^toolchain_path=/s|.*|toolchain_path=${SDKPATHNATIVE}/usr/share/cmake/Qt6Toolchain.cmake|'
-
+    sed -i ${D}${QT6_INSTALL_BINDIR}/* ${D}${QT6_INSTALL_LIBDIR}/cmake/Qt6/qt.toolchain.cmake \
+        -e 's|${RECIPE_SYSROOT_NATIVE}|${SDKPATHNATIVE}|'
 }
 
 INSANE_SKIP:${PN}-ptest += "arch"