Docs: Fix day/year format in QDateTime

QDateTime takes dd and yyyy.  It is confusing when the example format
strings don't work because they use DD YYYY, and it is a silent error
with the characters not getting substituted and can be easy to miss.

Improved Qt::ISODate, TZD isn't a format character so skip writing out
a bad format example.

Task-number: QTBUG-62111
Change-Id: Ia61d561074ae885fc0a99238d93cb34aaa9953bb
Reviewed-by: David Fries <david@fries.net>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

2 files changed, 9 insertions, 8 deletions

diff --git a/src/corelib/global/qnamespace.qdoc b/src/corelib/global/qnamespace.qdoc
index 076b006235..4ddb89014e 100644
--- a/src/corelib/global/qnamespace.qdoc
+++ b/src/corelib/global/qnamespace.qdoc
@@ -672,8 +672,9 @@
     be short, localized names. This is basically equivalent to using the date format
     string, "ddd MMM d yyyy". See QDate::toString() for more information.
 
-    \value ISODate \l{ISO 8601} extended format: either \c{YYYY-MM-DD} for dates or
-    \c{YYYY-MM-DDTHH:mm:ss}, \c{YYYY-MM-DDTHH:mm:ssTZD} (e.g., 1997-07-16T19:20:30+01:00)
+    \value ISODate \l{ISO 8601} extended format: either \c{yyyy-MM-dd} for dates or
+    \c{yyyy-MM-ddTHH:mm:ss} (e.g. 2017-07-24T15:46:29), or with a time-zone
+    suffix (Z for UTC otherwise an offset as [+|-]HH:mm) where appropriate
     for combined dates and times.
 
     \value ISODateWithMs \l{ISO 8601} extended format, including milliseconds if applicable.
diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 88270643d9..b6bec9b376 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -211,7 +211,7 @@ static ParsedRfcDateTime rfcDateImpl(const QString &s)
 {
     ParsedRfcDateTime result;
 
-    // Matches "Wdy, DD Mon YYYY HH:mm:ss ±hhmm" (Wdy, being optional)
+    // Matches "Wdy, dd Mon yyyy HH:mm:ss ±hhmm" (Wdy, being optional)
     QRegExp rex(QStringLiteral("^(?:[A-Z][a-z]+,)?[ \\t]*(\\d{1,2})[ \\t]+([A-Z][a-z]+)[ \\t]+(\\d\\d\\d\\d)(?:[ \\t]+(\\d\\d):(\\d\\d)(?::(\\d\\d))?)?[ \\t]*(?:([+-])(\\d\\d)(\\d\\d))?"));
     if (s.indexOf(rex) == 0) {
         const QStringList cap = rex.capturedTexts();
@@ -223,7 +223,7 @@ static ParsedRfcDateTime rfcDateImpl(const QString &s)
         const int minOffset = cap[9].toInt();
         result.utcOffset = ((hourOffset * 60 + minOffset) * (positiveOffset ? 60 : -60));
     } else {
-        // Matches "Wdy Mon DD HH:mm:ss YYYY"
+        // Matches "Wdy Mon dd HH:mm:ss yyyy"
         QRegExp rex(QStringLiteral("^[A-Z][a-z]+[ \\t]+([A-Z][a-z]+)[ \\t]+(\\d\\d)(?:[ \\t]+(\\d\\d):(\\d\\d):(\\d\\d))?[ \\t]+(\\d\\d\\d\\d)[ \\t]*(?:([+-])(\\d\\d)(\\d\\d))?"));
         if (s.indexOf(rex) == 0) {
             const QStringList cap = rex.capturedTexts();
@@ -810,8 +810,8 @@ static QString toStringIsoDate(qint64 jd)
 
     If the \a format is Qt::ISODate, the string format corresponds
     to the ISO 8601 extended specification for representations of
-    dates and times, taking the form YYYY-MM-DD, where YYYY is the
-    year, MM is the month of the year (between 01 and 12), and DD is
+    dates and times, taking the form yyyy-MM-dd, where yyyy is the
+    year, MM is the month of the year (between 01 and 12), and dd is
     the day of the month between 01 and 31.
 
     If the \a format is Qt::SystemLocaleShortDate or
@@ -3785,13 +3785,13 @@ void QDateTime::setTime_t(uint secsSince1Jan1970UTC)
 
     If the \a format is Qt::ISODate, the string format corresponds
     to the ISO 8601 extended specification for representations of
-    dates and times, taking the form YYYY-MM-DDTHH:mm:ss[Z|[+|-]HH:mm],
+    dates and times, taking the form yyyy-MM-ddTHH:mm:ss[Z|[+|-]HH:mm],
     depending on the timeSpec() of the QDateTime. If the timeSpec()
     is Qt::UTC, Z will be appended to the string; if the timeSpec() is
     Qt::OffsetFromUTC, the offset in hours and minutes from UTC will
     be appended to the string. To include milliseconds in the ISO 8601
     date, use the \a format Qt::ISODateWithMs, which corresponds to
-    YYYY-MM-DDTHH:mm:ss.zzz[Z|[+|-]HH:mm].
+    yyyy-MM-ddTHH:mm:ss.zzz[Z|[+|-]HH:mm].
 
     If the \a format is Qt::SystemLocaleShortDate or
     Qt::SystemLocaleLongDate, the string format depends on the locale