Add initial clang-cl support to Qt

This adds the functionality to build Qt with clang under Windows against
the Microsoft Visual Studio 2015 runtime.

In order to replicate this, a Clang 3.8 build with Visual Studio 2015
Update 1 is needed.

Adds compiler detection to Qt to distinguish correctly the clang compiler
and Windows with Visual Studio.

Clang has some built-in numeric functions, there is no need to use the
Microsoft versions, which also conflict here.

Task-number: QTBUG-50804
Change-Id: Ia4b267a298310ac7d73edf473b12792991249d8a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

7 files changed, 97 insertions, 13 deletions

diff --git a/configure.bat b/configure.bat
index ecb1518f66..372b3faac5 100644
--- a/configure.bat
+++ b/configure.bat
@@ -34,7 +34,7 @@ set QTDIR=%CD%
 if not exist %QTSRC%.gitignore goto sconf
 echo Please wait while bootstrapping configure ...
 
-for %%C in (cl.exe icl.exe g++.exe perl.exe jom.exe) do set %%C=%%~$PATH:C
+for %%C in (clang-cl.exe cl.exe icl.exe g++.exe perl.exe jom.exe) do set %%C=%%~$PATH:C
 
 if "%perl.exe%" == "" (
     echo Perl not found in PATH. Aborting. >&2
@@ -81,6 +81,12 @@ if not "%icl.exe%" == "" (
     rem This must have a trailing space.
     echo QTSRC = %QTSRC% >> Makefile
     set tmpl=win32
+) else if not "%clang-cl.exe%" == "" (
+    echo CXX = clang-cl>>Makefile
+    echo EXTRA_CXXFLAGS = -fms-compatibility-version=19.00.23506 -Wno-microsoft-enum-value>>Makefile
+    rem This must have a trailing space.
+    echo QTSRC = %QTSRC% >> Makefile
+    set tmpl=win32
 ) else if not "%cl.exe%" == "" (
     echo CXX = cl>>Makefile
     echo EXTRA_CXXFLAGS =>>Makefile
diff --git a/mkspecs/win32-clang-msvc2015/qmake.conf b/mkspecs/win32-clang-msvc2015/qmake.conf
new file mode 100644
index 0000000000..73cfdcbab9
--- /dev/null
+++ b/mkspecs/win32-clang-msvc2015/qmake.conf
@@ -0,0 +1,24 @@
+#
+# qmake configuration for win32-clang-msvc2015
+
+#
+# Written for Clang 3.8 with Microsoft Visual C++ 2015 Update 1
+# Notice: this uses the clang-cl wrapper
+#
+
+MSC_VER                 = 1900
+MSVC_VER                = 14.0
+include(../common/msvc-desktop.conf)
+
+QMAKE_COMPILER         += clang_cl llvm
+
+QMAKE_CC                = clang-cl
+QMAKE_CXX               = $$QMAKE_CC
+
+QMAKE_CFLAGS           += -fms-compatibility-version=19.00.23506 -Wno-microsoft-enum-value
+QMAKE_CXXFLAGS          = $$QMAKE_CFLAGS
+
+# Precompiled headers are not supported yet by clang
+CONFIG -= precompile_header
+
+load(qt_config)
diff --git a/mkspecs/win32-clang-msvc2015/qplatformdefs.h b/mkspecs/win32-clang-msvc2015/qplatformdefs.h
new file mode 100644
index 0000000000..7100e3aa41
--- /dev/null
+++ b/mkspecs/win32-clang-msvc2015/qplatformdefs.h
@@ -0,0 +1,34 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the qmake spec of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://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 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "../win32-msvc2005/qplatformdefs.h"
diff --git a/qmake/Makefile.win32 b/qmake/Makefile.win32
index 1e8c5129be..1d50f872d9 100644
--- a/qmake/Makefile.win32
+++ b/qmake/Makefile.win32
@@ -14,6 +14,10 @@ QMKSRC = $(SOURCE_PATH)\qmake
 CXX               = icl
 LINKER            = link
 CFLAGS_EXTRA      = /Zc:forScope /Qstd=c++11
+!elseif "$(QMAKESPEC)" == "win32-clang-msvc2015"
+CXX               = clang-cl
+LINKER            = link
+CFLAGS_EXTRA      = -fms-compatibility-version=19.00.23506 -Wno-microsoft-enum-value
 !else
 CXX               = cl
 LINKER            = link
@@ -21,13 +25,18 @@ LINKER            = link
 CFLAGS_EXTRA      = /Zc:wchar_t-
 !  elseif "$(QMAKESPEC)" == "win32-msvc2008" || "$(QMAKESPEC)" == "win32-msvc2010" || "$(QMAKESPEC)" == "win32-msvc2012" || "$(QMAKESPEC)" == "win32-msvc2013"
 CFLAGS_EXTRA      = /MP /D_CRT_SECURE_NO_WARNINGS /D_SCL_SECURE_NO_WARNINGS $(CFLAGS_CRT)
-!  elseif "$(QMAKESPEC)" == "win32-msvc2015"
+!  elseif "$(QMAKESPEC)" == "win32-msvc2015" || "$(QMAKESPEC)" == "win32-clang-msvc2015"
 CFLAGS_EXTRA      = /MP /D_CRT_SECURE_NO_WARNINGS /D_SCL_SECURE_NO_WARNINGS /Zc:strictStrings /w44456 /w44457 /w44458 /wd4577 $(CFLAGS_CRT)
 !  else
 !    error Unsupported compiler for this Makefile
 !  endif
 !endif  # !win32-icc
 
+!if "$(QMAKESPEC)" != "win32-clang-msvc2015"
+CFLAGS_PCH        = -Yuqmake_pch.h -FIqmake_pch.h -Fpqmake_pch.pch
+PCH_OBJECT        = qmake_pch.obj
+!endif
+
 CFLAGS_BARE = -c -Fo./ -Fdqmake.pdb \
               -W3 -nologo -O1 \
               $(CFLAGS_EXTRA) \
@@ -41,7 +50,7 @@ CFLAGS_BARE = -c -Fo./ -Fdqmake.pdb \
               -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_NO_COMPONENT -DQT_NO_COMPRESS \
               -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -DQT_NO_DATASTREAM \
               -DUNICODE -DQT_CRYPTOGRAPHICHASH_ONLY_SHA1 -DQT_JSON_READONLY -DQT_NO_STANDARDPATHS
-CFLAGS   = -Yuqmake_pch.h -FIqmake_pch.h -Fpqmake_pch.pch $(CFLAGS_BARE) $(CFLAGS)
+CFLAGS   = $(CFLAGS_PCH) $(CFLAGS_BARE) $(CFLAGS)
 
 CXXFLAGS_BARE = $(CFLAGS_BARE)
 CXXFLAGS = $(CFLAGS)
@@ -129,7 +138,7 @@ QTOBJS= \
 first all: qmake.exe
 
 qmake.exe: $(OBJS) $(QTOBJS)
-	$(LINKQMAKE) qmake_pch.obj
+	$(LINKQMAKE) $(PCH_OBJECT)
 	-copy qmake.exe $(BUILD_PATH)\bin\qmake.exe
 
 clean::
@@ -158,9 +167,9 @@ distclean:: clean
 .cxx.obj:
 	$(CXX) $(CXXFLAGS) $<
 
-$(OBJS): qmake_pch.obj
+$(OBJS): $(PCH_OBJECT)
 
-$(QTOBJS): qmake_pch.obj
+$(QTOBJS): $(PCH_OBJECT)
 
 qlibraryinfo.obj: $(BUILD_PATH)\src\corelib\global\qconfig.cpp
 
diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index e655aace32..7575fe06b2 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -83,6 +83,9 @@
 #  endif
 
 #elif defined(_MSC_VER)
+#  ifdef __clang__
+#    define Q_CC_CLANG ((__clang_major__ * 100) + __clang_minor__)
+#  endif
 #  define Q_CC_MSVC (_MSC_VER)
 #  define Q_CC_MSVC_NET
 #  define Q_OUTOFLINE_TEMPLATE inline
@@ -97,7 +100,9 @@
 #  define Q_UNREACHABLE_IMPL() __assume(0)
 #  define Q_NORETURN __declspec(noreturn)
 #  define Q_DECL_DEPRECATED __declspec(deprecated)
-#  define Q_DECL_DEPRECATED_X(text) __declspec(deprecated(text))
+#  ifndef Q_CC_CLANG
+#    define Q_DECL_DEPRECATED_X(text) __declspec(deprecated(text))
+#  endif
 #  define Q_DECL_EXPORT __declspec(dllexport)
 #  define Q_DECL_IMPORT __declspec(dllimport)
 /* Intel C++ disguising as Visual C++: the `using' keyword avoids warnings */
@@ -1177,7 +1182,7 @@
 #  define QT_WARNING_DISABLE_MSVC(number)
 #  define QT_WARNING_DISABLE_CLANG(text)
 #  define QT_WARNING_DISABLE_GCC(text)
-#elif defined(Q_CC_MSVC) && _MSC_VER >= 1500
+#elif defined(Q_CC_MSVC) && _MSC_VER >= 1500 && !defined(Q_CC_CLANG)
 #  undef QT_DO_PRAGMA                           /* not needed */
 #  define QT_WARNING_PUSH                       __pragma(warning(push))
 #  define QT_WARNING_POP                        __pragma(warning(pop))
diff --git a/src/corelib/global/qnumeric_p.h b/src/corelib/global/qnumeric_p.h
index f58e062dbd..5705bc29c8 100644
--- a/src/corelib/global/qnumeric_p.h
+++ b/src/corelib/global/qnumeric_p.h
@@ -222,7 +222,7 @@ template <> inline bool mul_overflow(unsigned long long v1, unsigned long long v
 #  define HAVE_MUL64_OVERFLOW
 #endif
 
-#if ((defined(Q_CC_MSVC) && _MSC_VER >= 1800) || defined(Q_CC_INTEL)) && defined(Q_PROCESSOR_X86)
+#if ((defined(Q_CC_MSVC) && _MSC_VER >= 1800) || defined(Q_CC_INTEL)) && defined(Q_PROCESSOR_X86) && !QT_HAS_BUILTIN(__builtin_uadd_overflow)
 template <> inline bool add_overflow(unsigned v1, unsigned v2, unsigned *r)
 { return _addcarry_u32(0, v1, v2, r); }
 #  ifdef Q_CC_MSVC      // longs are 32-bit
@@ -230,7 +230,7 @@ template <> inline bool add_overflow(unsigned long v1, unsigned long v2, unsigne
 { return _addcarry_u32(0, v1, v2, reinterpret_cast<unsigned *>(r)); }
 #  endif
 #endif
-#if ((defined(Q_CC_MSVC) && _MSC_VER >= 1800) || defined(Q_CC_INTEL)) && defined(Q_PROCESSOR_X86_64)
+#if ((defined(Q_CC_MSVC) && _MSC_VER >= 1800) || defined(Q_CC_INTEL)) && defined(Q_PROCESSOR_X86_64) && !QT_HAS_BUILTIN(__builtin_uadd_overflow)
 template <> inline bool add_overflow(quint64 v1, quint64 v2, quint64 *r)
 { return _addcarry_u64(0, v1, v2, reinterpret_cast<unsigned __int64 *>(r)); }
 #  ifndef Q_CC_MSVC      // longs are 64-bit
@@ -239,7 +239,7 @@ template <> inline bool add_overflow(unsigned long v1, unsigned long v2, unsigne
 #  endif
 #endif
 
-#if defined(Q_CC_MSVC) && (defined(Q_PROCESSOR_X86_64) || defined(Q_PROCESSOR_IA64))
+#if defined(Q_CC_MSVC) && (defined(Q_PROCESSOR_X86_64) || defined(Q_PROCESSOR_IA64)) && !QT_HAS_BUILTIN(__builtin_uadd_overflow)
 #pragma intrinsic(_umul128)
 template <> inline bool mul_overflow(quint64 v1, quint64 v2, quint64 *r)
 {
diff --git a/tools/configure/Makefile.win32 b/tools/configure/Makefile.win32
index c83ecaaeea..17a758c795 100644
--- a/tools/configure/Makefile.win32
+++ b/tools/configure/Makefile.win32
@@ -2,11 +2,17 @@ CORESRC = $(QTSRC)src\corelib
 TOOLSRC = $(QTSRC)tools
 CONFSRC = $(TOOLSRC)\configure
 
-PCH           = configure_pch.pch
 DEFINES       = -DUNICODE -DQT_NO_CODECS -DQT_NO_TEXTCODEC -DQT_NO_UNICODETABLES -DQT_LITE_COMPONENT -DQT_NO_COMPRESS -DQT_NO_THREAD -DQT_NO_QOBJECT -DQT_NO_GEOM_VARIANT -D_CRT_SECURE_NO_DEPRECATE -DQT_BOOTSTRAPPED -DQT_BUILD_CONFIGURE -DQT_VERSION_STR=\"$(QTVERSION)\" -DQT_VERSION_MAJOR=$(QT_VERSION_MAJOR) -DQT_VERSION_MINOR=$(QT_VERSION_MINOR) -DQT_VERSION_PATCH=$(QT_VERSION_PATCH)
 INCPATH       = -I"..\..\include" -I"..\..\include\QtCore" -I"..\..\include\QtCore\$(QTVERSION)" -I"..\..\include\QtCore\$(QTVERSION)\QtCore" -I"$(TOOLSRC)\shared" -I"$(QTSRC)mkspecs\win32-msvc2012"
 CXXFLAGS_BARE = -nologo -Zc:wchar_t -W3 -GR -EHsc -w34100 -w34189 -wd4577 $(CFLAGS_CRT) $(EXTRA_CXXFLAGS) $(DEFINES) $(INCPATH)
+!IF ("$(CXX)" != "clang-cl")
+PCH           = configure_pch.pch
+PCH_OBJECT    = configure_pch.obj
 CXXFLAGS      = -FIconfigure_pch.h -Yuconfigure_pch.h -Fp$(PCH) -MP $(CXXFLAGS_BARE)
+!ELSE
+PCH           =
+CXXFLAGS      = -Wmicrosoft $(CXXFLAGS_BARE)
+!ENDIF
 LINK          = link
 LFLAGS        = /NOLOGO /DYNAMICBASE /NXCOMPAT /INCREMENTAL:NO /SUBSYSTEM:CONSOLE "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /MANIFEST /MANIFESTFILE:"configure.intermediate.manifest"
 LIBS          = ole32.lib advapi32.lib shell32.lib
@@ -71,7 +77,7 @@ OBJECTS = \
     qxmlutils.obj \
     quuid.obj \
     registry.obj \
-    configure_pch.obj
+    $(PCH_OBJECT)
 
 $(TARGET): $(OBJECTS)
 	$(LINK) $(LFLAGS) /OUT:$(TARGET) @<<