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[cpp.line] Simplify specification of line directives #8354

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[cpp.line] Simplify specification of line directives #8354

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56 changes: 22 additions & 34 deletions source/preprocessor.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -47,15 +47,15 @@

\begin{bnf}
\nontermdef{control-line}\br
\terminal{\# include} pp-tokens new-line\br
pp-import\br
line-directive\br
\terminal{\# include} pp-tokens new-line\br
\terminal{\# embed \ } pp-tokens new-line\br
\terminal{\# define } identifier replacement-list new-line\br
\terminal{\# define } identifier lparen \opt{identifier-list} \terminal{)} replacement-list new-line\br
\terminal{\# define } identifier lparen \terminal{... )} replacement-list new-line\br
\terminal{\# define } identifier lparen identifier-list \terminal{, ... )} replacement-list new-line\br
\terminal{\# undef \ } identifier new-line\br
\terminal{\# line \ \ } pp-tokens new-line\br
\terminal{\# error \ } \opt{pp-tokens} new-line\br
\terminal{\# warning} \opt{pp-tokens} new-line\br
\terminal{\# pragma } \opt{pp-tokens} new-line\br
Expand Down Expand Up @@ -2070,12 +2070,20 @@
\indextext{preprocessing directive!line control}%
\indextext{\idxcode{\#line}|see{preprocessing directive, line control}}

\begin{bnf}
\nontermdef{line-directive}\br
\terminal{\# line} digit-sequence \opt{string-literal} new-line\br
\terminal{\# line} pp-tokens new-line
\end{bnf}

\pnum
The \grammarterm{string-literal} of a
\tcode{\#line}
directive, if present,
The \grammarterm{string-literal}, if present,
shall be a character string literal.

\pnum
If the digit sequence interpreted as a decimal integer is zero
or a number greater than 2147483647, the program is ill-formed.

\pnum
The
\defn{line number}
Expand All @@ -2087,41 +2095,21 @@
while processing the source file to the current preprocessing token.

\pnum
A preprocessing directive of the form
\begin{ncsimplebnf}
\terminal{\# line} digit-sequence new-line
\end{ncsimplebnf}
A \grammarterm{line-directive} that matches the first form
causes the implementation to behave as if
the following sequence of source lines begins with a
source line that has a line number as specified
by the digit sequence (interpreted as a decimal integer).
If the digit sequence specifies zero
or a number greater than 2147483647,
the program is ill-formed.
by the digit sequence (interpreted as a decimal integer)
and the presumed name of the source file becomes
the contents of the character string literal, if present.

\pnum
A preprocessing directive of the form
\begin{ncsimplebnf}
\terminal{\# line} digit-sequence \terminal{"} \opt{s-char-sequence} \terminal{"} new-line
\end{ncsimplebnf}
sets the presumed line number similarly and changes the
presumed name of the source file to be the contents
of the character string literal.

\pnum
A preprocessing directive of the form
\begin{ncsimplebnf}
\terminal{\# line} pp-tokens new-line
\end{ncsimplebnf}
(that does not match one of the two previous forms)
is permitted.
The preprocessing tokens after
\tcode{line}
on the directive are processed just as in normal text
(each identifier currently defined as a macro name is replaced by its
replacement list of preprocessing tokens).
The \grammarterm{pp-tokens} of a \grammarterm{line-directive} that does not
match the first form are processed just as in normal text
(i.e., each identifier currently defined as a macro name is replaced by
its replacement list of preprocessing tokens).
If the directive resulting after all replacements does not match
one of the two previous forms, the program is ill-formed;
the first form, the program is ill-formed;
otherwise, the result is processed as appropriate.

\rSec1[cpp.error]{Diagnostic directives}%
Expand Down