[Backport] Tiny improvements for build system

* Basic `clang-msvc` support
* Fixes for `msvc` and `mingw`
* Support for LTO (`CONFIG+=ltcg`) builds on all platforms
* Minor code improvements, including build scripts unification

(cherry picked from commit MeVisLab/pythonqt@fb1eb93)

Author: iakov

build/PythonQt.prf

@@ -12,5 +12,5 @@ CONFIG(debug, debug|release) {
 }
 
 win32-g++: LIBS += $$DESTDIR/../lib/PythonQt-Qt5-Python$${PYTHON_VERSION}$${DEBUG_EXT}.dll
-win32-msvc*: LIBS += $$DESTDIR/../lib/PythonQt-Qt5-Python$${PYTHON_VERSION}$${DEBUG_EXT}.lib
+win32-*msvc*: LIBS += $$DESTDIR/../lib/PythonQt-Qt5-Python$${PYTHON_VERSION}$${DEBUG_EXT}.lib
 unix: LIBS += -L$$DESTDIR/../lib -lPythonQt-Qt5-Python$${PYTHON_VERSION}$${DEBUG_EXT}

build/common.prf

@@ -67,7 +67,9 @@ PYTHONQT_GENERATED_PATH = $$PWD/../generated_cpp
 }
 
 VERSION = 3.2.0
-
+greaterThan(QT_MAJOR_VERSION, 5) | greaterThan(QT_MINOR_VERSION, 9): CONFIG += c++11
 win32: CONFIG += skip_target_version_ext
-unix: CONFIG += c++11
-gcc: QMAKE_CXXFLAGS += -Wno-deprecated-declarations
+gcc|win32-clang-msvc:QMAKE_CXXFLAGS += -Wno-deprecated-declarations -Wuninitialized -Winit-self -ansi -pedantic
+win32-clang-msvc:QMAKE_CXXFLAGS += -Wno-unused-command-line-argument
+#Do not issue warning to system includes
+gcc:!isEmpty(QT_INSTALL_HEADERS): QMAKE_CXXFLAGS += -isystem $$[QT_INSTALL_HEADERS]

build/python.prf

@@ -6,8 +6,7 @@ isEmpty( PYTHON_VERSION ) {
   PYTHON_VERSION=$$(PYTHON_VERSION)
 }
 isEmpty( PYTHON_VERSION ) {
-  win32:PYTHON_VERSION=27
-  unix:PYTHON_VERSION=2.7
+  PYTHON_VERSION=2.7
 }
 
 isEmpty( PYTHON_DIR ) {
@@ -30,8 +29,18 @@ PYTHON_VERSION_MINOR=$$section(PYTHON_VERSION, ., 1, 1)
 # Python 2.x has problems:
 # 1) https://wiki.gentoo.org/wiki/Project:Python/Strict_aliasing
 # 2) deprecated implicit cast of string literals to char*
-equals(PYTHON_VERSION_MAJOR, 2):gcc:QMAKE_CXXFLAGS *= -fno-strict-aliasing -Wno-error=write-strings
+equals(PYTHON_VERSION_MAJOR, 2) {
+   gcc:QMAKE_CXXFLAGS *= -fno-strict-aliasing -Wno-write-strings
+   # Qt 5.4 adds this option, but this is not compatible with the Python API
+   msvc: QMAKE_CXXFLAGS -= -Zc:strictStrings
+}
+
 contains(PKGCONFIG, "python.*"){
+# If `pkg-config` is configured, use `qmake PKGCONFIG+=python3.8-embed CONFIG+=...`
+# or `PKGCONFIG+=python2.7m`-like form for older versions,
+# see `pkg-config --list-all | grep python` for details.
+# This can help with GNU/Linux (including macOS with Homebrew), MSYS2/MinGW environment,
+# and also with OpenEmbedded and other cross-builds
   CONFIG += link_pkgconfig
   PYTHON_PKGCONFIG = $$member($$unique($$find(PKGCONFIG, "python.*")), 1, 1)
   # add rpath
@@ -63,8 +72,26 @@ contains(PKGCONFIG, "python.*"){
     DEBUG_EXT = 
   }
 
-  win32:INCLUDEPATH += $$(PYTHON_PATH)/PC $$(PYTHON_PATH)/include
-  win32:LIBS += $$(PYTHON_LIB)/python$${PYTHON_VERSION}$${DEBUG_EXT}.lib
+  isEmpty(PYTHON_PATH):PYTHON_PATH=$(PYTHON_PATH)
+  isEmpty(PYTHON_PATH)|!exists("$$PYTHON_PATH\\include") | !exists("$$PYTHON_PATH\\libs\\") {
+     error("PYTHON_PATH must be set to correct folder with \\libs and \\include subfolders ")
+  }
+
+  #We need to destinguish 64-bit build to add a workaround option
+  #The only known problematic case is MinGW with external (MSVC-built) Python2
+  mingw:equals(PYTHON_VERSION_MAJOR, 2): isEmpty(QMAKE_TARGET.arch):system(\
+  $$system_quote($$system_path($${PYTHON_PATH}/python.exe)) -c \
+  $$system_quote(import sysconfig;exit(0 if 0 <= sysconfig.get_platform().find(\'win-amd64\') else 1))\
+  ):DEFINES += MS_WIN64
+
+  INCLUDEPATH += $$shell_path($${PYTHON_PATH}/include)
+
+  LIBS += $$shell_path(-L$${PYTHON_PATH}/libs)
+  LIBS += -lpython$${PYTHON_VERSION_MAJOR}$${PYTHON_VERSION_MINOR}$${DEBUG_EXT}
+
+  # Hack for "CONFIG+=testcase" and 'make check' to add python's dll to PATH
+  deppath += $$shell_path($${PYTHON_PATH})
+
 } else:unix {
   # on linux, python-config is used to autodetect Python.
   # make sure that you have installed a matching python-dev package.

extensions/PythonQt_QtAll/PythonQt_QtAll.pro

@@ -35,7 +35,13 @@ include ( ../../build/common.prf )
 include ( ../../build/PythonQt.prf )  
 TARGET = $$replace(TARGET, PythonXY, Python$${PYTHON_VERSION})
 
-CONFIG += dll qt
+CONFIG += qt strict_c++
+
+!static:!staticlib {
+  CONFIG += dll
+  # Force linker to complain on undefined references for dll/so/dylib build when possible
+  QMAKE_LFLAGS_SHLIB += $$QMAKE_LFLAGS_NOUNDEF
+}
 
 DEFINES += PYTHONQT_QTALL_EXPORTS
 
@@ -74,6 +80,7 @@ defineTest(Xinclude) {
 PythonQtCore {
   DEFINES += PYTHONQT_WITH_CORE
   Xinclude (com_trolltech_qt_core)
+  QT += core
 }
 
 PythonQtGui  {
@@ -85,7 +92,7 @@ PythonQtGui  {
 PythonQtSvg {
   DEFINES += PYTHONQT_WITH_SVG
   Xinclude (com_trolltech_qt_svg)
-  QT +=svg
+  QT += svg
 }
 
 PythonQtSql {

generator/generator.h

@@ -42,10 +42,7 @@
 #ifndef GENERATOR_H
 #define GENERATOR_H
 
-#include "metajava.h"
-#include "typesystem.h"
-
-#include "codemodel.h"
+#include "abstractmetalang.h"
 
 #include <QObject>
 #include <QFile>
@@ -57,7 +54,7 @@ class Generator : public QObject
     Q_PROPERTY(QString outputDirectory READ outputDirectory WRITE setOutputDirectory)
 
 public:
-    enum Option {
+    enum Option:uint32_t {
         NoOption                 = 0x00000000,
         BoxedPrimitive           = 0x00000001,
         ExcludeConst             = 0x00000002,

generator/generator.pri

@@ -17,12 +17,20 @@ include($$GENERATORPATH/parser/rxx.pri)
 
 include($$GENERATORPATH/parser/rpp/rpp.pri)
 
-win32-msvc2005:{
+CONFIG += strict_c++ c++11
+win32-msvc*{
+#Disable warning C4996 (deprecated declarations)
         QMAKE_CXXFLAGS += -wd4996
         QMAKE_CFLAGS += -wd4996
+#Disable warnings for external headers
+	greaterThan(QMAKE_MSC_VER, 1599):QMAKE_CXXFLAGS += -external:anglebrackets -external:W0 -external:templates-
 }
-gcc:QMAKE_CXXFLAGS += -Wno-deprecated-declarations -Wpedantic
-clang: QMAKE_CXXFLAGS += -Wno-nested-anon-types -Wno-gnu-anonymous-struct -Wno-unused-private-field
+#Do not issue warning to Qt's system includes
+gcc:!isEmpty(QT_INSTALL_HEADERS): QMAKE_CXXFLAGS += -isystem $$[QT_INSTALL_HEADERS]
+gcc|win32-clang-msvc:QMAKE_CXXFLAGS += -Wno-deprecated-declarations -pedantic -ansi -Winit-self -Wuninitialized
+clang|win32-clang-msvc: QMAKE_CXXFLAGS += -Wno-nested-anon-types -Wno-gnu-anonymous-struct -Wno-unused-private-field
+win32-clang-msvc:QMAKE_CXXFLAGS += -Wno-language-extension-token -Wno-microsoft-enum-value
+
 
 # Input
 HEADERS += \

generator/shellheadergenerator.cpp

@@ -40,7 +40,6 @@
 ****************************************************************************/
 
 #include "shellheadergenerator.h"
-#include "fileout.h"
 
 #include <QtCore/QDir>
 
@@ -156,7 +155,6 @@ void ShellHeaderGenerator::write(QTextStream& s, const AbstractMetaClass* meta_c
       s << "};" << endl;
     }
     s << endl;
-    const AbstractMetaClass* c = meta_class;
     s << "   ~" << shellClassName(meta_class) << "()" << (meta_class->hasVirtualDestructor() ? " override" : "") << ";" << endl;
     s << endl;
 

generator/shellimplgenerator.cpp

@@ -176,7 +176,7 @@ void ShellImplGenerator::write(QTextStream &s, const AbstractMetaClass *meta_cla
           s << "        }" << endl;
           s << "      }" << endl;
         }
-        s << "      if (result) { Py_DECREF(result); } " << endl;
+        s << "      if (result) { Py_DECREF(result); }" << endl;
         s << "      Py_DECREF(obj);" << endl;
         // ugly hack, we don't support QGraphicsScene* nor QGraphicsItem* QVariants in PythonQt...
         if (fun->name() == "itemChange" && fun->type() && fun->type()->isVariant()) {

src/src.pri

@@ -4,14 +4,15 @@ INCLUDEPATH += $$PWD
 
 CONFIG += c++11
 
-gcc:!no_warn {
-    !clang:QMAKE_CXXFLAGS += -Werror -Wno-error=missing-field-initializers
-    clang:QMAKE_CXXFLAGS += -Wno-error=sometimes-uninitialized
-}
+gcc:!no_warn:!clang:QMAKE_CXXFLAGS += -Wno-error=missing-field-initializers
+*-clang*:!no_warn:QMAKE_CXXFLAGS += -Wno-error=sometimes-uninitialized
 
 # This was needed to work around "number of sections exceeded object file format limit" linker error
 win32-msvc*:QMAKE_CXXFLAGS += /bigobj
-win32-g++: QMAKE_CXXFLAGS += -Wa,-mbig-obj
+!ltcg:win32-g++: QMAKE_CXXFLAGS += -Wa,-mbig-obj
+
+# Force linker to complain on undefined references for dll/so/dylib build when possible
+QMAKE_LFLAGS_SHLIB += $$QMAKE_LFLAGS_NOUNDEF
 
 HEADERS +=                    \
   $$PWD/PythonQt.h                  \

src/src.pro

@@ -7,14 +7,11 @@
 TARGET   = PythonQt-Qt5-PythonXY
 TEMPLATE = lib
 
-
 DESTDIR    = ../lib
 
 CONFIG += qt
 CONFIG -= flat
 
-mingw:QMAKE_CXXFLAGS+=-Wa,-mbig-obj
-
 # allow to choose static linking through the environment variable PYTHONQT_STATIC
 isEmpty(PYTHONQT_STATIC) {
 PYTHONQT_STATIC = $$(PYTHONQT_STATIC)
@@ -31,9 +28,6 @@ DEFINES += PYTHONQT_CATCH_ALL_EXCEPTIONS
 contains(QT_MAJOR_VERSION, 5) {
   QT += widgets core-private
 }
-
-# Qt 5.4 adds this option, but this is not compatible with the Python API
-QMAKE_CXXFLAGS_RELEASE -= -Zc:strictStrings
 
 INCLUDEPATH += $$PWD