LWG4044 Confusing requirements for std::print on POSIX platforms

[ostream.formatted.print] New paragraphs not numbered as indicated since they are part of the \effects clause.

Author: burblebee

source/iostreams.tex

@@ -6854,25 +6854,31 @@
 without regard to the value of \tcode{os.exceptions()} and
 without turning on \tcode{ios_base::badbit} in the error state of \tcode{os}.
 \end{itemize}
+
+\par % This paragraph is part of the \effects clause.
 After constructing a \tcode{sentry} object,
 the function initializes a variable with automatic storage duration via
 \begin{codeblock}
 string out = vformat(os.getloc(), fmt, args);
 \end{codeblock}
+\begin{itemize}
+\item
 If the function is \tcode{vprint_unicode} and
-\tcode{os} is a stream that refers to a terminal capable of displaying Unicode
+\tcode{os} is a stream that refers to a terminal that
+is only capable of displaying Unicode via a native Unicode API,
 which is determined in an implementation-defined manner,
+flushes \tcode{os} and then
 writes \tcode{out} to the terminal using the native Unicode API;
 if \tcode{out} contains invalid code units,
 \indextext{undefined}%
-the behavior is undefined and
-implementations are encouraged to diagnose it.
-If the native Unicode API is used,
-the function flushes \tcode{os} before writing \tcode{out}.
-Otherwise (if \tcode{os} is not such a stream or
-the function is \tcode{vprint_nonunicode}),
+the behavior is undefined.
+\item
+Otherwise
 inserts the character sequence
 \range{out.begin()}{out.end()} into \tcode{os}.
+\end{itemize}
+
+\par % This paragraph is part of the \effects clause.
 If writing to the terminal or inserting into \tcode{os} fails,
 calls \tcode{os.setstate(ios_base::badbit)}
 (which may throw \tcode{ios_base::failure}).
@@ -7837,28 +7843,27 @@
 Let \tcode{out} denote the character representation of
 formatting arguments provided by \tcode{args}
 formatted according to specifications given in \tcode{fmt}.
-If \tcode{stream} refers to a terminal capable of displaying Unicode,
+\begin{itemize}
+\item
+If \tcode{stream} refers to a terminal that
+is only capable of displaying Unicode via a native Unicode API,
+flushes \tcode{stream} and then
 writes \tcode{out} to the terminal using the native Unicode API;
 if \tcode{out} contains invalid code units,
 \indextext{undefined}%
-the behavior is undefined and
-implementations are encouraged to diagnose it.
+the behavior is undefined.
+\item
 Otherwise writes \tcode{out} to \tcode{stream} unchanged.
-If the native Unicode API is used,
-the function flushes \tcode{stream} before writing \tcode{out}.
+\end{itemize}
 Unconditionally unlocks \tcode{stream} on function exit.
 
 \xrefc{7.21.2}.
 
 \begin{note}
-On POSIX and Windows, \tcode{stream} referring to a terminal means that,
-respectively,
-\tcode{isatty(fileno(\linebreak{}stream))} and
+On Windows the native Unicode API is \tcode{WriteConsoleW} and
+\tcode{stream} referring to a terminal means that
 \tcode{GetConsoleMode(_get_osfhandle(_fileno(stream)), ...)}
-return nonzero.
-\end{note}
-\begin{note}
-On Windows, the native Unicode API is \tcode{WriteConsoleW}.
+returns nonzero.
 \end{note}
 
 \pnum