Build Qt (and client apps using it) with /permissive-

*Not* using /permissive- exposes Qt and client apps to interesting
bugs and/or build failures, (e.g. QTBUG-87225, or
19b5520abfb5f66d4b83c7a18cc72d68673d098a). We demand strict
conformance by any other compiler, it's time to demand it from
MSVC too.

The Windows headers themselves are clean starting from the
Windows Fall Creators SDK (10.0.16299.0), and moreover Qt 6 will
drop WinRT; therefore, the comment in the mkspecs does not apply
any more.

Since /permissive- implies /Zc:referenceBinding, drop that
option. The other implied options are set on MSVC < 2017,
but I leave them in to avoid tinkering with the fragile lists
of C/C++ flags.

Rename the CMake internal helper function to better describe
what it does.

Fixes: QTBUG-85633
Fixes: QTBUG-85637
Fixes: QTBUG-85635
Fixes: QTBUG-88244
Change-Id: Ie03fddb61aa066fdc14b7231c22e7108b4a02fbb
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

5 files changed, 6 insertions, 11 deletions

diff --git a/cmake/QtFlagHandlingHelpers.cmake b/cmake/QtFlagHandlingHelpers.cmake
index b9835a3639..250df5de2d 100644
--- a/cmake/QtFlagHandlingHelpers.cmake
+++ b/cmake/QtFlagHandlingHelpers.cmake
@@ -228,11 +228,11 @@ function(qt_set_language_standards_interface_compile_features target)
     target_compile_features("${target}" INTERFACE ${cpp_feature})
 endfunction()
 
-function(qt_enable_msvc_cplusplus_define target visibility)
+function(qt_set_msvc_cplusplus_options target visibility)
     # For MSVC we need to explicitly pass -Zc:__cplusplus to get correct __cplusplus.
     # Check qt_config_compile_test for more info.
     if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND MSVC_VERSION GREATER_EQUAL 1913)
-        target_compile_options("${target}" ${visibility} "-Zc:__cplusplus")
+        target_compile_options("${target}" ${visibility} "-Zc:__cplusplus" "-permissive-")
     endif()
 endfunction()
 
diff --git a/cmake/QtPublicTargetsHelpers.cmake b/cmake/QtPublicTargetsHelpers.cmake
index 8d916535ac..2e5eb564f4 100644
--- a/cmake/QtPublicTargetsHelpers.cmake
+++ b/cmake/QtPublicTargetsHelpers.cmake
@@ -20,7 +20,7 @@ function(qt_internal_setup_public_platform_target)
         target_link_libraries(Platform INTERFACE log)
     endif()
 
-    qt_enable_msvc_cplusplus_define(Platform INTERFACE)
+    qt_set_msvc_cplusplus_options(Platform INTERFACE)
 
     # Propagate minimum C++ 17 via Platform to Qt consumers (apps), after the global features
     # are computed.
diff --git a/mkspecs/common/msvc-version.conf b/mkspecs/common/msvc-version.conf
index eee5cc0dd5..26ff635e65 100644
--- a/mkspecs/common/msvc-version.conf
+++ b/mkspecs/common/msvc-version.conf
@@ -78,7 +78,7 @@ greaterThan(QMAKE_MSC_VER, 1909) {
     # Visual Studio 2017 (15.0) / Visual C++ 19.10 and up
     MSVC_VER            = 15.0
     COMPAT_MKSPEC       = win32-msvc2017
-    QMAKE_CXXFLAGS     += -Zc:referenceBinding
+    QMAKE_CXXFLAGS     += -permissive-
 
     # Only Visual Studio 2017 version 15.3 / Visual C++ 19.11 & up have support
     # for AVX-512. We enable the switches anyway and let configure check if they
@@ -93,11 +93,6 @@ greaterThan(QMAKE_MSC_VER, 1909) {
     QMAKE_CFLAGS_AVX512IFMA = -arch:AVX512
     QMAKE_CFLAGS_AVX512VBMI = -arch:AVX512
 
-    # For now permissive fails as soon as UWP API comes into play. In qtbase this
-    # API is used in direct2d, but also in multimedia, positioning and sensors.
-    # We can try again with a later version of Visual Studio.
-    # QMAKE_CXXFLAGS_STRICTCXX = -permissive-
-
     # MSVC partially supports the following, but '__cplusplus' definition is set
     # as for C++98 until MSVC fully conforms with C++14, see
     # https://developercommunity.visualstudio.com/content/problem/139261/msvc-incorrectly-defines-cplusplus.html
diff --git a/qmake/CMakeLists.txt b/qmake/CMakeLists.txt
index 0dc9d5f03c..133472b78d 100644
--- a/qmake/CMakeLists.txt
+++ b/qmake/CMakeLists.txt
@@ -275,7 +275,7 @@ set_target_properties(${target_name} PROPERTIES
 
 qt_internal_apply_gc_binaries(${target_name} PRIVATE) # special case
 
-qt_enable_msvc_cplusplus_define(${target_name} PUBLIC) # special case
+qt_set_msvc_cplusplus_options(${target_name} PUBLIC) # special case
 qt_skip_warnings_are_errors(${target_name}) # special case
 qt_internal_apply_intel_cet(Bootstrap PUBLIC) # special case
 
diff --git a/src/tools/bootstrap/CMakeLists.txt b/src/tools/bootstrap/CMakeLists.txt
index 7669207fdd..b61b7cbd99 100644
--- a/src/tools/bootstrap/CMakeLists.txt
+++ b/src/tools/bootstrap/CMakeLists.txt
@@ -265,6 +265,6 @@ target_link_libraries(Bootstrap PRIVATE PlatformCommonInternal)
 qt_internal_apply_gc_binaries(Bootstrap PUBLIC)
 set_target_properties(Bootstrap PROPERTIES AUTOMOC OFF AUTOUIC OFF AUTORCC OFF)
 qt_internal_add_target_aliases(Bootstrap)
-qt_enable_msvc_cplusplus_define(Bootstrap PUBLIC)
+qt_set_msvc_cplusplus_options(Bootstrap PUBLIC)
 qt_internal_apply_intel_cet(Bootstrap PUBLIC)
 # special case end