Move the formatting of <chrono> durations to QDebug & QtTest

[ChangeLog][QtCore][QDebug] Added pretty formatting of C++ <chrono>
durations.

[ChangeLog][QtTest] Added pretty formatting of C++ <chrono> durations
for QCOMPARE expressions.

Change-Id: I3b169860d8bd41e9be6bfffd1757cc087ba957fa
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 98 insertions, 0 deletions

diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index 0a72696a37..56deeb7cf7 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -15,6 +15,8 @@
 #include <private/qtextstream_p.h>
 #include <private/qtools_p.h>
 
+#include <q20chrono.h>
+
 QT_BEGIN_NAMESPACE
 
 using namespace QtMiscUtils;
@@ -346,6 +348,90 @@ void QDebug::putByteArray(const char *begin, size_t length, Latin1Content conten
 }
 
 /*!
+    \since 6.6
+    \internal
+    Helper to the std::chrono::duration debug streaming output.
+ */
+QByteArray QDebug::timeUnit(qint64 num, qint64 den)
+{
+    using namespace std::chrono;
+    using namespace q20::chrono;
+
+    if (num == 1 && den > 1) {
+        // sub-multiple of seconds
+        char prefix = '\0';
+        auto tryprefix = [&](auto d, char c) {
+            static_assert(decltype(d)::num == 1, "not an SI prefix");
+            if (den == decltype(d)::den)
+                prefix = c;
+        };
+
+        // "u" should be "µ", but debugging output is not always UTF-8-safe
+        tryprefix(std::milli{}, 'm');
+        tryprefix(std::micro{}, 'u');
+        tryprefix(std::nano{}, 'n');
+        tryprefix(std::pico{}, 'p');
+        tryprefix(std::femto{}, 'f');
+        tryprefix(std::atto{}, 'a');
+        // uncommon ones later
+        tryprefix(std::centi{}, 'c');
+        tryprefix(std::deci{}, 'd');
+        if (prefix) {
+            char unit[3] = { prefix, 's' };
+            return QByteArray(unit, sizeof(unit) - 1);
+        }
+    }
+
+    const char *unit = nullptr;
+    if (num > 1 && den == 1) {
+        // multiple of seconds - but we don't use SI prefixes
+        auto tryunit = [&](auto d, const char *name) {
+            static_assert(decltype(d)::period::den == 1, "not a multiple of a second");
+            if (unit || num % decltype(d)::period::num)
+                return;
+            unit = name;
+            num /= decltype(d)::period::num;
+        };
+        tryunit(years{}, "yr");
+        tryunit(weeks{}, "wk");
+        tryunit(days{}, "d");
+        tryunit(hours{}, "h");
+        tryunit(minutes{}, "min");
+    }
+    if (!unit)
+        unit = "s";
+
+    if (num == 1 && den == 1)
+        return unit;
+    if (Q_UNLIKELY(num < 1 || den < 1))
+        return QString::asprintf("<invalid time unit %lld/%lld>", num, den).toLatin1();
+
+    // uncommon units: will return something like "[2/3]s"
+    //  strlen("[/]min") = 6
+    char buf[2 * (std::numeric_limits<qint64>::digits10 + 2) + 10];
+    size_t len = 0;
+    auto appendChar = [&](char c) {
+        Q_ASSERT(len < sizeof(buf));
+        buf[len++] = c;
+    };
+    auto appendNumber = [&](qint64 value) {
+        if (value >= 10'000 && (value % 1000) == 0)
+            len += qsnprintf(buf + len, sizeof(buf) - len, "%.6g", double(value));  // "1e+06"
+        else
+            len += qsnprintf(buf + len, sizeof(buf) - len, "%lld", value);
+    };
+    appendChar('[');
+    appendNumber(num);
+    if (den != 1) {
+        appendChar('/');
+        appendNumber(den);
+    }
+    appendChar(']');
+    memcpy(buf + len, unit, strlen(unit));
+    return QByteArray(buf, len + strlen(unit));
+}
+
+/*!
     \fn QDebug::swap(QDebug &other)
     \since 5.0
 
@@ -777,6 +863,18 @@ QDebug &QDebug::resetFormat()
 */
 
 /*!
+    \since 6.6
+    \fn template <typename Rep, typename Period> QDebug &QDebug::operator<<(std::chrono::duration<Rep, Period> duration)
+
+    Prints the time duration \a duration to the stream and returns a reference
+    to the stream. The printed string is the numeric representation of the
+    period followed by the time unit, similar to what the C++ Standard Library
+    would produce with \c{std::ostream}.
+
+    The unit is not localized.
+*/
+
+/*!
     \fn template <class T> QString QDebug::toString(T &&object)
     \since 6.0