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P2316R2 Consistent character literal encoding #4994

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Oct 15, 2021
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P2316R2 Consistent character literal encoding #4994

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28 changes: 4 additions & 24 deletions source/preprocessor.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -478,32 +478,12 @@
expression even though it is unsigned in translation phase
7\iref{lex.phases}.
\end{note}
This includes interpreting \grammarterm{character-literal}s, which may involve
converting escape sequences into execution character set members.
Whether the numeric value for these \grammarterm{character-literal}s
matches the value obtained when an identical \grammarterm{character-literal}
occurs in an expression
(other than within a
\tcode{\#if}
or
\tcode{\#elif}
directive)
is \impldef{numeric values of \grammarterm{character-literal}s in \tcode{\#if}
directives}.
This includes interpreting \grammarterm{character-literal}s
according to the rules in \ref{lex.ccon}.
\begin{note}
Thus, the constant expression in the following
\tcode{\#if}
directive and
\keyword{if} statement\iref{stmt.if}
is not guaranteed to evaluate to the same value in these two
contexts:
\begin{codeblock}
#if 'z' - 'a' == 25
if ('z' - 'a' == 25)
\end{codeblock}
The associated character encodings of literals are the same
in \tcode{\#if} and \tcode{\#elif} directives and in any expression.
\end{note}
Also, whether a single-character \grammarterm{character-literal} may have a negative
value is \impldef{negative value of \grammarterm{character-literal} in preprocessor}.
Each subexpression with type
\tcode{bool}
is subjected to integral promotion before processing continues.
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