QRandomGenerator: don't internally rely on QT_HAS_INCLUDE

GCC didn't support it until version 5 or 6, so add configure tests for
both <random> and <sys/auxv.h>. Normally I'd say "upgrade", but this is
too low-level and important a feature.

There's a good chance that all our supported compilers have <random>
anyway. As for <sys/auxv.h>, it's present on Glibc, Bionic and MUSL, but
I don't see it in uClibc (AT_RANDOM is a Linux-specific feature).

Change-Id: Ia3e896da908f42939148fffd14c5b2af491f7a77
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

config.tests/unix/cxx11_random/cxx11_random.cpp

@@ -0,0 +1,35 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <random>
+
+int main()
+{
+    std::mt19937 mt(0);
+    return 0;
+}

config.tests/unix/cxx11_random/cxx11_random.pro

@@ -0,0 +1 @@
+SOURCES = cxx11_random.cpp

config.tests/unix/sys_auxv/sys_auxv.cpp

@@ -0,0 +1,34 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <sys/auxv.h>
+
+int main()
+{
+    return getauxval(AT_NULL);
+}

config.tests/unix/sys_auxv/sys_auxv.pro

@@ -0,0 +1 @@
+SOURCES = sys_auxv.cpp

src/corelib/configure.json

@@ -138,6 +138,11 @@
             "type": "compile",
             "test": "unix/cloexec"
         },
+        "cxx11_random": {
+            "label": "C++11 <random>",
+            "type": "compile",
+            "test": "unix/cxx11_random"
+        },
         "eventfd": {
             "label": "eventfd",
             "type": "compile",
@@ -208,6 +213,11 @@
             "type": "compile",
             "test": "unix/syslog"
         },
+        "sys_auxv": {
+            "label": "sys/auxv.h",
+            "type": "compile",
+            "test": "unix/sys_auxv"
+        },
         "xlocalescanprint": {
             "label": "xlocale.h (or equivalents)",
             "type": "compile",
@@ -242,6 +252,11 @@
             "condition": "features.doubleconversion && libs.doubleconversion",
             "output": [ "privateFeature" ]
         },
+        "cxx11_random": {
+            "label": "C++11 <random>",
+            "condition": "tests.cxx11_random",
+            "output": [ "privateFeature" ]
+        },
         "eventfd": {
             "label": "eventfd",
             "condition": "tests.eventfd",
@@ -394,6 +409,11 @@
             "condition": "tests.syslog",
             "output": [ "privateFeature" ]
         },
+        "sys_auxv": {
+            "label": "sys/auxv.h",
+            "condition": "config.linux && tests.sys_auxv",
+            "output": [ "privateFeature" ]
+        },
         "threadsafe-cloexec": {
             "label": "Threadsafe pipe creation",
             "condition": "tests.cloexec",
@@ -630,6 +650,11 @@ If your users intend to develop applications against this build,
 ensure that the IDEs they use either set QT_LOGGING_TO_CONSOLE to 1
 or are able to read the logged output from journald, syslog or slog2."
         },
+        {
+            "type": "warning",
+            "condition": "!config.win32 && !config.darwin && !config.bsd && !features.cxx11_random",
+            "message": "No high-quality PRNG available for QRandomGenerator fallback.\nIf the HW or OS RNG fails, Qt will abort execution."
+        },
         {
             "type": "error",
             "condition": "input.doubleconversion == 'no' && !tests.xlocalescanprint",

src/corelib/global/qconfig-bootstrapped.h

@@ -75,6 +75,7 @@
 #else
 # define QT_FEATURE_alloca_malloc_h -1
 #endif
+#define QT_FEATURE_cxx11_random (QT_HAS_INCLUDE(<random>) ? 1 : -1)
 #define QT_FEATURE_iconv -1
 #define QT_FEATURE_icu -1
 #define QT_FEATURE_journald -1
@@ -96,6 +97,7 @@
 #define QT_NO_GEOM_VARIANT
 #define QT_FEATURE_sharedmemory -1
 #define QT_FEATURE_systemsemaphore -1
+#define QT_FEATURE_sys_auxv (QT_HAS_INCLUDE(<sys/auxv.h>) ? 1 : -1)
 
 #ifdef QT_BUILD_QMAKE
 #define QT_FEATURE_commandlineparser -1

src/corelib/global/qrandom.cpp

@@ -46,13 +46,13 @@
 #include <qthreadstorage.h>
 #include <private/qsimd_p.h>
 
-#if QT_HAS_INCLUDE(<random>)
+#if QT_CONFIG(cxx11_random)
 #  include <random>
 #  include "qdeadlinetimer.h"
 #  include "qhashfunctions.h"
 #endif
 
-#if QT_HAS_INCLUDE(<sys/auxv.h>)
+#if QT_CONFIG(sys_auxv)
 #  include <sys/auxv.h>
 #endif
 
@@ -213,7 +213,7 @@ static void fallback_fill(quint32 *ptr, qssize_t left) Q_DECL_NOTHROW
     // BSDs have arc4random(4) and these work even in chroot(2)
     arc4random_buf(ptr, left * sizeof(*ptr));
 }
-#elif QT_HAS_INCLUDE(<chrono>)
+#elif QT_CONFIG(cxx11_random)
 static QBasicAtomicInteger<unsigned> seed = Q_BASIC_ATOMIC_INITIALIZER(0U);
 static void fallback_update_seed(unsigned value)
 {

tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp

@@ -34,11 +34,11 @@
 #include <private/qrandom_p.h>
 
 #include <algorithm>
-#if QT_HAS_INCLUDE(<random>)
+#if QT_CONFIG(cxx11_random)
 #  include <random>
 #endif
 
-#if QT_HAS_INCLUDE(<random>) || defined(Q_OS_WIN)
+#if QT_CONFIG(cxx11_random) || defined(Q_OS_BSD4) || defined(Q_OS_WIN)
 #  define HAVE_FALLBACK_ENGINE
 #endif
 
@@ -468,7 +468,7 @@ template <typename Engine> void seedStdRandomEngine()
 
 void tst_QRandomGenerator::seedStdRandomEngines()
 {
-#if !QT_HAS_INCLUDE(<random>)
+#if !QT_CONFIG(cxx11_random)
     QSKIP("<random> not found");
 #else
     seedStdRandomEngine<std::default_random_engine>();
@@ -511,7 +511,7 @@ void tst_QRandomGenerator::stdUniformIntDistribution_data()
 
 void tst_QRandomGenerator::stdUniformIntDistribution()
 {
-#if !QT_HAS_INCLUDE(<random>)
+#if !QT_CONFIG(cxx11_random)
     QSKIP("<random> not found");
 #else
     QFETCH(uint, control);
@@ -580,8 +580,11 @@ void tst_QRandomGenerator::stdUniformIntDistribution()
 
 void tst_QRandomGenerator::stdGenerateCanonical()
 {
-#if !QT_HAS_INCLUDE(<random>)
+#if !QT_CONFIG(cxx11_random)
     QSKIP("<random> not found");
+#elif defined(Q_CC_MSVC) && Q_CC_MSVC < 1900
+    // see https://connect.microsoft.com/VisualStudio/feedback/details/811611
+    QSKIP("MSVC 2013's std::generate_canonical is broken");
 #else
     QFETCH(uint, control);
     setRNGControl(control);
@@ -631,7 +634,7 @@ void tst_QRandomGenerator::stdUniformRealDistribution_data()
 
 void tst_QRandomGenerator::stdUniformRealDistribution()
 {
-#if !QT_HAS_INCLUDE(<random>)
+#if !QT_CONFIG(cxx11_random)
     QSKIP("<random> not found");
 #else
     QFETCH(uint, control);
@@ -665,7 +668,7 @@ void tst_QRandomGenerator::stdUniformRealDistribution()
 
 void tst_QRandomGenerator::stdRandomDistributions()
 {
-#if !QT_HAS_INCLUDE(<random>)
+#if !QT_CONFIG(cxx11_random)
     QSKIP("<random> not found");
 #else
     // just a compile check for some of the distributions, besides