Fix the precompile_header configure test

This configure test always failed, and its result was never used.

Pick-to: 6.2
Change-Id: I5112464b247efb5327ef5c23c96ef27168c11afc
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

config.tests/precompile_header/CMakeLists.txt

@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 3.15.0)
+project(precompile_header LANGUAGES CXX)
+
+add_executable(precompile_header main.cpp)
+target_precompile_headers(precompile_header PRIVATE header.h)

config.tests/precompile_header/header.h

@@ -0,0 +1,44 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the FOO module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#ifndef HEADER_H
+#define HEADER_H
+
+// Nothing to see here. We just want the HEADER_H define.
+
+#endif

config.tests/precompile_header/main.cpp

@@ -0,0 +1,43 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the FOO module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#ifndef HEADER_H
+#    error no go
+#endif
+
+int main() {}

configure.cmake

@@ -95,18 +95,7 @@ int main(void)
 # precompile_header
 qt_config_compile_test(precompile_header
     LABEL "precompiled header support"
-    CODE
+    PROJECT_PATH "${CMAKE_CURRENT_SOURCE_DIR}/config.tests/precompile_header"
-"#ifndef HEADER_H
-#error no go
-#endif
-
-int main(void)
-{
-    /* BEGIN TEST: */
-    /* END TEST: */
-    return 0;
-}
-"# FIXME: qmake: ['CONFIG += precompile_header', 'PRECOMPILED_DIR = .pch', 'PRECOMPILED_HEADER = header.h']
 )
 
 qt_config_compiler_supports_flag_test(use_bfd_linker
@@ -614,7 +603,7 @@ qt_feature("c11" PUBLIC
 )
 qt_feature("precompile_header"
     LABEL "Using precompiled headers"
-    CONDITION BUILD_WITH_PCH
+    CONDITION BUILD_WITH_PCH AND TEST_precompile_header
     AUTODETECT NOT WASM
 )
 qt_feature_config("precompile_header" QMAKE_PRIVATE_CONFIG)