Implement generating of private cpp exports

Add the generating of private cpp exports for Qt modules.

Add the GENERATE_PRIVATE_CPP_EXPORTS option to qt_internal_add_module
that is the manual switch for private exports generator. Existing
modules in qtbase doesn't follow any strict convention of using
private cpp export. So there is no clue how to detect if generating of
the private exports is required or not for the module.

Use autogenerated private cpp exports in QtNetwork module.

CPP_EXPORT_HEADER_NAME argument of the qt_internal_add_module function
is replaced by the CPP_EXPORT_HEADER_BASE_NAME and has a different
meaning. The provided name is used as a base name for the private and
non-private headers that contains cpp exports. Header files suffixes
are constant: .h and _p.h for the non-private and private header files
accordingly.

Pick-to: 6.2
Task-number: QTBUG-90492
Change-Id: Icf11304e00379fb8521a865965c19b974e01e62f
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

3 files changed, 149 insertions, 24 deletions

diff --git a/cmake/QtModuleHelpers.cmake b/cmake/QtModuleHelpers.cmake
index eeebd05de9..39088a64fd 100644
--- a/cmake/QtModuleHelpers.cmake
+++ b/cmake/QtModuleHelpers.cmake
@@ -21,7 +21,6 @@ macro(qt_internal_get_internal_add_module_keywords option_args single_args multi
         CONFIG_MODULE_NAME
         PRECOMPILED_HEADER
         CONFIGURE_FILE_PATH
-        CPP_EXPORT_HEADER_NAME
         ${__default_target_info_args}
     )
     set(${multi_args}
@@ -35,6 +34,16 @@ macro(qt_internal_get_internal_add_module_keywords option_args single_args multi
     )
 endmacro()
 
+macro(qt_internal_get_generate_cpp_global_exports_keywords option_args single_args multi_args)
+    set(${option_args}
+        GENERATE_PRIVATE_CPP_EXPORTS
+    )
+    set(${single_args}
+        CPP_EXPORT_HEADER_BASE_NAME
+    )
+    set(${multi_args} "")
+endmacro()
+
 # This is the main entry function for creating a Qt module, that typically
 # consists of a library, public header files, private header files and configurable
 # features.
@@ -62,9 +71,30 @@ endmacro()
 #
 function(qt_internal_add_module target)
     qt_internal_get_internal_add_module_keywords(
-        option_args
-        single_args
-        multi_args
+        module_option_args
+        module_single_args
+        module_multi_args
+    )
+
+    qt_internal_get_generate_cpp_global_exports_keywords(
+        cpp_exports_option_args
+        cpp_exports_single_args
+        cpp_exports_multi_args
+    )
+
+    set(option_args
+        ${module_option_args}
+        ${cpp_exports_option_args}
+    )
+
+    set(single_args
+        ${module_single_args}
+        ${cpp_exports_single_args}
+    )
+
+    set(multi_args
+        ${module_multi_args}
+        ${cpp_exports_multi_args}
     )
 
     qt_parse_all_arguments(arg "qt_internal_add_module"
@@ -154,15 +184,6 @@ function(qt_internal_add_module target)
     string(REPLACE "-" "_" module_define_infix "${module_define_infix}")
     string(REPLACE "." "_" module_define_infix "${module_define_infix}")
 
-    if(arg_GENERATE_CPP_EXPORTS)
-        if(arg_CPP_EXPORT_HEADER_NAME)
-            set(cpp_export_header_name "CPP_EXPORT_HEADER_NAME;${arg_CPP_EXPORT_HEADER_NAME}")
-        endif()
-        qt_internal_generate_cpp_global_exports(${target} ${module_define_infix}
-            "${cpp_export_header_name}"
-        )
-    endif()
-
     set(property_prefix "INTERFACE_")
     if(NOT arg_HEADER_MODULE)
         qt_set_common_target_properties(${target})
@@ -316,6 +337,25 @@ function(qt_internal_add_module target)
 
         ### FIXME: Can we replace headers.pri?
         qt_read_headers_pri("${module_build_interface_include_dir}" "module_headers")
+        if(arg_GENERATE_CPP_EXPORTS)
+            if(arg_CPP_EXPORT_HEADER_BASE_NAME)
+                set(cpp_export_header_base_name
+                    "CPP_EXPORT_HEADER_BASE_NAME;${arg_CPP_EXPORT_HEADER_BASE_NAME}"
+                )
+            endif()
+            if(arg_GENERATE_PRIVATE_CPP_EXPORTS)
+                set(generate_private_cpp_export "GENERATE_PRIVATE_CPP_EXPORTS")
+            endif()
+            qt_internal_generate_cpp_global_exports(${target} ${module_define_infix}
+                generated_public_cpp_export
+                generated_private_cpp_export
+                "${cpp_export_header_base_name}"
+                "${generate_private_cpp_export}"
+            )
+            list(APPEND module_headers_public "${generated_public_cpp_export}")
+            list(APPEND module_headers_private "${generated_private_cpp_export}")
+        endif()
+
         set(module_depends_header
             "${module_build_interface_include_dir}/${module_include_name}Depends")
         if(is_framework)
@@ -922,24 +962,51 @@ function(qt_describe_module target)
     qt_install(FILES "${descfile_out}" DESTINATION "${install_dir}")
 endfunction()
 
-function(qt_internal_generate_cpp_global_exports target module_define_infix)
+function(qt_internal_generate_cpp_global_exports target module_define_infix
+    out_public_header out_private_header)
+
+    qt_internal_get_generate_cpp_global_exports_keywords(
+        option_args
+        single_args
+        multi_args
+    )
+
     cmake_parse_arguments(arg
-        ""
-        "CPP_EXPORT_HEADER_NAME"
-        "" ${ARGN})
+        "${option_args}"
+        "${single_args}"
+        "${multi_args}" ${ARGN}
+    )
+
     qt_internal_module_info(module "${target}")
-    if(NOT arg_CPP_EXPORT_HEADER_NAME)
-        set(arg_CPP_EXPORT_HEADER_NAME "qt${module_lower}exports.h")
+
+    set(header_base_name "qt${module_lower}exports")
+    if(arg_CPP_EXPORT_HEADER_BASE_NAME)
+        set(header_base_name "${arg_CPP_EXPORT_HEADER_BASE_NAME}")
     endif()
+    # Is used as a part of the header guard define.
+    string(TOUPPER "${header_base_name}" header_base_name_upper)
 
     set(generated_header_path
-        "${module_build_interface_include_dir}/${arg_CPP_EXPORT_HEADER_NAME}"
+        "${module_build_interface_include_dir}/${header_base_name}.h"
     )
 
     configure_file("${QT_CMAKE_DIR}/modulecppexports.h.in"
         "${generated_header_path}" @ONLY
     )
 
+    set(${out_public_header} "${generated_header_path}" PARENT_SCOPE)
     target_sources(${target} PRIVATE "${generated_header_path}")
-    set_property(TARGET ${target} APPEND PROPERTY PUBLIC_HEADER "${generated_header_path}")
+
+    if(arg_GENERATE_PRIVATE_CPP_EXPORTS)
+        set(generated_private_header_path
+            "${module_build_interface_private_include_dir}/${header_base_name}_p.h"
+        )
+
+        configure_file("${QT_CMAKE_DIR}/modulecppexports_p.h.in"
+            "${generated_private_header_path}" @ONLY
+        )
+
+        set(${out_private_header} "${generated_private_header_path}" PARENT_SCOPE)
+        target_sources(${target} PRIVATE "${generated_private_header_path}")
+    endif()
 endfunction()
diff --git a/cmake/modulecppexports.h.in b/cmake/modulecppexports.h.in
index fb5c0d918c..68b0353a97 100644
--- a/cmake/modulecppexports.h.in
+++ b/cmake/modulecppexports.h.in
@@ -37,8 +37,8 @@
 **
 ****************************************************************************/
 
-#ifndef QT@module_define_infix@EXPORTS_H
-#define QT@module_define_infix@EXPORTS_H
+#ifndef @header_base_name_upper@_H
+#define @header_base_name_upper@_H
 
 #include <QtCore/qglobal.h>
 
@@ -52,4 +52,4 @@
 #  define Q_@module_define_infix@_EXPORT
 #endif
 
-#endif // QT@module_define_infix@EXPORTS_H
+#endif // @header_base_name_upper@_H
diff --git a/cmake/modulecppexports_p.h.in b/cmake/modulecppexports_p.h.in
new file mode 100644
index 0000000000..5912bbba70
--- /dev/null
+++ b/cmake/modulecppexports_p.h.in
@@ -0,0 +1,58 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the @module@ 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_base_name_upper@_P_H
+#define @header_base_name_upper@_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <@module_include_name@/@header_base_name@.h>
+
+#define Q_@module_define_infix@_PRIVATE_EXPORT Q_@module_define_infix@_EXPORT
+
+#endif // @header_base_name_upper@_P_H