Introduce o3tl::sprintf

...in preparation for follow-up commits that will replace many uses of
std::sprintf (which started to emit deprecation warnings with macOS 13 SDK now)
across the code base with various alternatives

Change-Id: I9602f1cb0e28d1b70c2356edb52d78dd165f1118
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/142317
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

include/o3tl/sprintf.hxx

@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+#include <sal/config.h>
+
+#include <cassert>
+#include <cstddef>
+#include <cstdio>
+#include <utility>
+
+#include <o3tl/safeint.hxx>
+
+namespace o3tl
+{
+// A drop-in replacement for safe uses of std::sprintf where it is statically known that the
+// provided buffer is large enough.  Compared to a plain use of std::sprintf, using o3tl::sprintf
+// for one makes it explicit that the call is considerd safe and for another avoids deprecation
+// warnings on platforms like the macOS 13 SDK that mark std::sprintf as deprecated.  Many simple
+// uses of std::sprintf across the code base can be replaced with alternative code using e.g.
+// OString::number.  This is for the remaining formatting-rich cases for which there is no easy
+// replacement yet in our C++17 baseline.  Ultimately, it should be removed again once alternatives
+// for those remaining cases, like C++20 std::format, are available.
+template <std::size_t N, typename... T>
+int sprintf(char (&s)[N], char const* format, T&&... arguments)
+{
+    auto const n = std::snprintf(s, N, format, std::forward<T>(arguments)...);
+    assert(n < 0 || o3tl::make_unsigned(n) < N);
+    (void)n;
+    return n;
+}
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */