client: Add CMake options to control visibility of generated symbols

Using public-code by default is problematic if multiple libraries
contain wayland interface definitions generated with public-code
which exports the symbols of the interface definitions from the
library. If not all libraries are build against the same protocol
version and the symbol is resolved to a version generated from an older
version of the protocol, then libwayland will detect a protocol error
if a request or event from the newer version is used.
This introduces two new options PRIVATE_CODE and PUBLIC_CODE to
qt6_generate_wayland_protocol_client_sources which correspond to the
wayland-scanner options. For backwards compatibility PUBLIC_CODE
is the default.

Change-Id: Ia30ec4b83419962b768207d7353c495e11b0268e
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

2 files changed, 22 insertions, 3 deletions

diff --git a/src/client/Qt6WaylandClientMacros.cmake b/src/client/Qt6WaylandClientMacros.cmake
index 485322e6a..b4266c558 100644
--- a/src/client/Qt6WaylandClientMacros.cmake
+++ b/src/client/Qt6WaylandClientMacros.cmake
@@ -1,8 +1,14 @@
+
 # Copyright (C) 2022 The Qt Company Ltd.
 # SPDX-License-Identifier: BSD-3-Clause
 
 function(qt6_generate_wayland_protocol_client_sources target)
-    cmake_parse_arguments(arg "NO_INCLUDE_CORE_ONLY" "__QT_INTERNAL_WAYLAND_INCLUDE_DIR" "FILES" ${ARGN})
+    cmake_parse_arguments(arg
+        "NO_INCLUDE_CORE_ONLY;PRIVATE_CODE;PUBLIC_CODE"
+        "__QT_INTERNAL_WAYLAND_INCLUDE_DIR"
+        "FILES"
+        ${ARGN})
+
     if(DEFINED arg_UNPARSED_ARGUMENTS)
         message(FATAL_ERROR "Unknown arguments were passed to qt6_generate_wayland_protocol_client_sources: (${arg_UNPARSED_ARGUMENTS}).")
     endif()
@@ -34,6 +40,14 @@ function(qt6_generate_wayland_protocol_client_sources target)
         if (NOT arg_NO_INCLUDE_CORE_ONLY)
             set(waylandscanner_extra_args "--include-core-only")
         endif()
+
+
+        if (arg_PRIVATE_CODE)
+            set(wayland_scanner_code_option "private-code")
+        else()
+            set(wayland_scanner_code_option "public-code")
+        endif()
+
         add_custom_command(
             OUTPUT "${waylandscanner_header_output}"
             #TODO: Maybe put the files in ${CMAKE_CURRENT_BINARY_DIR/wayland_generated instead?
@@ -43,7 +57,7 @@ function(qt6_generate_wayland_protocol_client_sources target)
 
         add_custom_command(
             OUTPUT "${waylandscanner_code_output}"
-            COMMAND Wayland::Scanner ${waylandscanner_extra_args} public-code < "${protocol_file}" > "${waylandscanner_code_output}"
+            COMMAND Wayland::Scanner ${waylandscanner_extra_args} ${wayland_scanner_code_option} < "${protocol_file}" > "${waylandscanner_code_output}"
             DEPENDS ${protocol_file} Wayland::Scanner
         )
 
diff --git a/src/client/doc/src/cmake/qt_generate_wayland_protocol_client_sources.qdoc b/src/client/doc/src/cmake/qt_generate_wayland_protocol_client_sources.qdoc
index 97a7f7ed4..43f448fbd 100644
--- a/src/client/doc/src/cmake/qt_generate_wayland_protocol_client_sources.qdoc
+++ b/src/client/doc/src/cmake/qt_generate_wayland_protocol_client_sources.qdoc
@@ -23,6 +23,7 @@ find_package(Qt6 REQUIRED COMPONENTS WaylandClient)
 
 \badcode
 qt_generate_wayland_protocol_client_sources(target
+                                            [PUBLIC_CODE | PRIVATE_CODE]
                                             FILES file1.xml [file2.xml ...])
 \endcode
 
@@ -30,11 +31,15 @@ qt_generate_wayland_protocol_client_sources(target
 
 \section1 Description
 
-qt_generate_wayland_protocol_client_sources() creates the build steps to run \c{waylandscanner} and
+qt_generate_wayland_protocol_client_sources() creates the build steps to run \c{wayland-scanner} and
 \c{qtwaylandscanner} on one or more Wayland protocol files. The tools will in turn generate binding
 code in C and C++ for implementing the protocols, and the resulting files will be built as part
 of the \c target.
 
+The options \c{PUBLIC_CODE} and \c{PRIVATE_CODE} correspond to the \c{public-code} and
+\c{private-code} options of \c{wayland-scanner}. For backwards compatibility \c{PUBLIC_CODE} is the
+default but generally \c{PRIVATE_CODE} is strongly recommended.
+
 qt_generate_wayland_protocol_client_sources() will trigger generation of the files needed to
 implement the client side of the protocol. \l{qt_generate_wayland_protocol_server_sources}{qt_generate_wayland_protocol_server_sources()}
 is the equivalent function for the compositor.