(alx-0014r6-E) Refactor syntax of line directives

Signed-off-by: Alejandro Colomar <[email protected]>

Author: alejandro-colomar

source/preprocessor.tex

@@ -52,7 +52,7 @@
     embed-directive\br
     define-directive\br
     undef-directive\br
-    \terminal{\# line \ \ } pp-tokens new-line\br
+    line-directive\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
@@ -2090,6 +2090,11 @@
 \indextext{preprocessing directive!line control}%
 \indextext{\idxcode{\#line}|see{preprocessing directive, line control}}
 
+\begin{bnf}
+\nontermdef{line-directive}\br
+    \terminal{\# line \ \ } pp-tokens new-line\br
+\end{bnf}
+
 \pnum
 The \grammarterm{string-literal} of a
 \tcode{\#line}