Make moc obey the preprocessor environment variable for include paths

C preprocessors augment their standard list of include paths from the
environment: Unix preprocessors use $C_INCLUDE_PATH (for C) and
$CPLUS_INCLUDE_PATH (for C++), plus CPATH for both, whereas MSVC uses
the an environment variable simply called "INCLUDE". Handling this for
MSVC is particularly important because the VCVARSALL.BAT script sets the
necessary #include paths in the environment for important things.
Without that being parsed, moc won't find some #defines, like
WINAPI_DESKTOP_FAMILY.

[ChangeLog][moc] qmake and moc now cooperate to use the Visual Studio
environment variables (set by the VCVARSALL.BAT script) to find system
include files. A possible consequence is that moc parses application
headers slightly differently, depending on #if conditions that depended
on macros that previous versions had not seen #define'd. Implementers of
other buildsystems are advised to pass the --compiler-flavor=msvc option
to moc.

Change-Id: I7e06274214d1939b0124e5b4bf169cceaef9ca46
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

5 files changed, 85 insertions, 0 deletions

diff --git a/mkspecs/features/moc.prf b/mkspecs/features/moc.prf
index 693be4a22d..6368c8e394 100644
--- a/mkspecs/features/moc.prf
+++ b/mkspecs/features/moc.prf
@@ -51,6 +51,7 @@ defineReplace(mocCmdBase) {
     }
 
     RET = $$QMAKE_MOC $(DEFINES)
+    msvc: RET += --compiler-flavor=msvc
 
     isEmpty(MOC_PREDEF_FILE): RET += $$join(QMAKE_COMPILER_DEFINES, " -D", -D)
     else: RET += --include $$moc_predefs.output
diff --git a/src/corelib/Qt5CoreMacros.cmake b/src/corelib/Qt5CoreMacros.cmake
index 9235641544..23909c9f3f 100644
--- a/src/corelib/Qt5CoreMacros.cmake
+++ b/src/corelib/Qt5CoreMacros.cmake
@@ -90,6 +90,9 @@ macro(QT5_GET_MOC_FLAGS _moc_flags)
     if(WIN32)
         set(${_moc_flags} ${${_moc_flags}} -DWIN32)
     endif()
+    if (MSVC)
+        set(${_moc_flags} --compiler-flavor=msvc)
+    endif()
 endmacro()
 
 
diff --git a/src/network/socket/socket.pri b/src/network/socket/socket.pri
index 2d80f38bec..2e3e26d37d 100644
--- a/src/network/socket/socket.pri
+++ b/src/network/socket/socket.pri
@@ -39,6 +39,10 @@ unix: {
 unix:HEADERS += \
                 socket/qnet_unix_p.h
 
+# Suppress deprecation warnings with moc because MS headers have
+# invalid C/C++ code otherwise.
+msvc: QMAKE_MOC_OPTIONS += -D_WINSOCK_DEPRECATED_NO_WARNINGS
+
 win32:!winrt:SOURCES += socket/qnativesocketengine_win.cpp \
                 socket/qlocalsocket_win.cpp \
                 socket/qlocalserver_win.cpp
diff --git a/src/tools/moc/main.cpp b/src/tools/moc/main.cpp
index c111fa4e6b..0a10aef989 100644
--- a/src/tools/moc/main.cpp
+++ b/src/tools/moc/main.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2016 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the tools applications of the Qt Toolkit.
@@ -242,6 +243,11 @@ int runMoc(int argc, char **argv)
     metadataOption.setFlags(QCommandLineOption::ShortOptionStyle);
     parser.addOption(metadataOption);
 
+    QCommandLineOption compilerFlavorOption(QStringLiteral("compiler-flavor"));
+    compilerFlavorOption.setDescription(QStringLiteral("Set the compiler flavor: either \"msvc\" or \"unix\"."));
+    compilerFlavorOption.setValueName(QStringLiteral("flavor"));
+    parser.addOption(compilerFlavorOption);
+
     QCommandLineOption noIncludeOption(QStringLiteral("i"));
     noIncludeOption.setDescription(QStringLiteral("Do not generate an #include statement."));
     parser.addOption(noIncludeOption);
@@ -328,9 +334,32 @@ int runMoc(int argc, char **argv)
         if (parser.isSet(pathPrefixOption))
             moc.includePath = QFile::encodeName(parser.value(pathPrefixOption));
     }
+
     const auto includePaths = parser.values(includePathOption);
     for (const QString &path : includePaths)
         pp.includes += Preprocessor::IncludePath(QFile::encodeName(path));
+    QString compilerFlavor = parser.value(compilerFlavorOption);
+    if (compilerFlavor.isEmpty() || compilerFlavor == QLatin1String("unix")) {
+        // traditional Unix compilers use both CPATH and CPLUS_INCLUDE_PATH
+        // $CPATH feeds to #include <...> and #include "...", whereas
+        // CPLUS_INCLUDE_PATH is equivalent to GCC's -isystem, so we parse later
+        const auto cpath = qgetenv("CPATH").split(QDir::listSeparator().toLatin1());
+        for (const QByteArray &p : cpath)
+            pp.includes += Preprocessor::IncludePath(p);
+        const auto cplus_include_path = qgetenv("CPLUS_INCLUDE_PATH").split(QDir::listSeparator().toLatin1());
+        for (const QByteArray &p : cplus_include_path)
+            pp.includes += Preprocessor::IncludePath(p);
+    } else if (compilerFlavor == QLatin1String("msvc")) {
+        // MSVC uses one environment variable: INCLUDE
+        const auto include = qgetenv("INCLUDE").split(QDir::listSeparator().toLatin1());
+        for (const QByteArray &p : include)
+            pp.includes += Preprocessor::IncludePath(p);
+    } else {
+        error(qPrintable(QLatin1String("Unknown compiler flavor '") + compilerFlavor +
+                         QLatin1String("'; valid values are: msvc, unix.")));
+        parser.showHelp(1);
+    }
+
     const auto macFrameworks = parser.values(macFrameworkOption);
     for (const QString &path : macFrameworks) {
         // minimalistic framework support for the mac
diff --git a/tests/auto/tools/moc/tst_moc.cpp b/tests/auto/tools/moc/tst_moc.cpp
index 1cf6f94720..ab15f81939 100644
--- a/tests/auto/tools/moc/tst_moc.cpp
+++ b/tests/auto/tools/moc/tst_moc.cpp
@@ -577,6 +577,8 @@ private slots:
     void defineMacroViaCmdline();
     void defineMacroViaForcedInclude();
     void defineMacroViaForcedIncludeRelative();
+    void environmentIncludePaths_data();
+    void environmentIncludePaths();
     void specifyMetaTagsFromCmdline();
     void invokable();
     void singleFunctionKeywordSignalAndSlot();
@@ -1295,6 +1297,52 @@ void tst_Moc::defineMacroViaForcedIncludeRelative()
 #endif
 }
 
+
+void tst_Moc::environmentIncludePaths_data()
+{
+#if defined(Q_OS_LINUX) && defined(Q_CC_GNU) && !defined(QT_NO_PROCESS)
+    QTest::addColumn<QString>("cmdline");
+    QTest::addColumn<QString>("varname");
+
+    QTest::newRow("INCLUDE") << "--compiler-flavor=msvc" << "INCLUDE";
+    QTest::newRow("CPATH1") << QString() << "CPATH";
+    QTest::newRow("CPATH2") << "--compiler-flavor=unix" << "CPATH";
+    QTest::newRow("CPLUS_INCLUDE_PATH1") << QString() << "CPLUS_INCLUDE_PATH";
+    QTest::newRow("CPLUS_INCLUDE_PATH2") << "--compiler-flavor=unix" << "CPLUS_INCLUDE_PATH";
+#endif
+}
+
+void tst_Moc::environmentIncludePaths()
+{
+#if defined(Q_OS_LINUX) && defined(Q_CC_GNU) && !defined(QT_NO_PROCESS)
+    QFETCH(QString, cmdline);
+    QFETCH(QString, varname);
+
+    QStringList args;
+    if (!cmdline.isEmpty())
+        args << cmdline;
+    args << "--include" << QStringLiteral("extradefines.h")
+         << m_sourceDirectory + QStringLiteral("/macro-on-cmdline.h");
+
+    QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+    env.remove("INCLUDE");
+    env.remove("CPATH");
+    env.remove("CPLUS_INCLUDE_PATH");
+    env.insert(varname, m_sourceDirectory + "/subdir");
+
+    QProcess proc;
+    proc.setProcessEnvironment(env);
+    proc.start(m_moc, args);
+    QVERIFY(proc.waitForFinished());
+    QCOMPARE(proc.exitCode(), 0);
+    QCOMPARE(proc.readAllStandardError(), QByteArray());
+    QByteArray mocOut = proc.readAllStandardOutput();
+    QVERIFY(!mocOut.isEmpty());
+#else
+    QSKIP("Only tested on linux/gcc");
+#endif
+}
+
 // tst_Moc::specifyMetaTagsFromCmdline()
 // plugin_metadata.h contains a plugin which we register here. Since we're not building this
 // application as a plugin, we need top copy some of the initializer code found in qplugin.h: