From 7277ffee522bdf57128d292b02d2b127f5038bee Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Fri, 4 Feb 2022 18:33:39 +0100
Subject: [PATCH] QCalendar: fix build

Apple Clang 12:

qcalendar.cpp:456:22: error: loop variable '[key, value]' is always a copy because the range of type 'QFlatMap<QString,
QCalendarBackend *, (anonymous namespace)::CaseInsensitiveAnyStringViewLessThan, QStringList, std::vector<QCalendarBackend *>
>' (aka 'QFlatMap<QString, QCalendarBackend *, (anonymous namespace)::CaseInsensitiveAnyStringViewLessThan, QList<QString>,
vector<QCalendarBackend *> >') does not return a reference [-Werror,-Wrange-loop-analysis]
    for (const auto &[key, value] : byName) {
                     ^

Change-Id: I54f205f6b7314351b078fffd16d05e5cd3ef4c22
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
---
 src/corelib/time/qcalendar.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/corelib/time/qcalendar.cpp b/src/corelib/time/qcalendar.cpp
index a7f6a634d6..3d990b7f5d 100644
--- a/src/corelib/time/qcalendar.cpp
+++ b/src/corelib/time/qcalendar.cpp
@@ -453,10 +453,16 @@ QStringList QCalendarRegistry::backendNames(const QCalendarBackend *backend)
     QStringList l;
     l.reserve(byName.size()); // too large, but never really large, so ok
 
+    QT_WARNING_PUSH
+    // Clang complains about the reference still causing a copy. The reference is idiomatic, but
+    // runs afoul of QFlatMap's iterators which return a pair of references instead of a reference
+    // to pair. Suppress the warning, because `const auto [key, value]` would look wrong.
+    QT_WARNING_DISABLE_CLANG("-Wrange-loop-analysis")
     for (const auto &[key, value] : byName) {
         if (value == backend)
             l.push_back(key);
     }
+    QT_WARNING_POP
 
     return l;
 }