X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/0cc3da3a4e993080b69ee94156c280b5f2630013..eda429346ae70445be1cffbe729c63fca7848ad6:/doc/bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 84761760..8f35ac60 100644
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -16,6 +16,10 @@
 @c @clear shorttitlepage-enabled
 @c @set shorttitlepage-enabled
 
+@c Set following if you want to document %default-prec and %no-default-prec.
+@c This feature is experimental and may change in future Bison versions.
+@c @set defaultprec
+
 @c ISPELL CHECK: done, 14 Jan 1993 --bob
 
 @c Check COPYRIGHT dates.  should be updated in the titlepage, ifinfo
@@ -352,7 +356,7 @@ encourage people to make other software free.  So we decided to make the
 practical conditions for using Bison match the practical conditions for
 using the other @acronym{GNU} tools.
 
-This exception applies only when Bison is generating C code for a
+This exception applies only when Bison is generating C code for an
 @acronym{LALR}(1) parser; otherwise, the @acronym{GPL} terms operate
 as usual.  You can
 tell whether the exception applies to your @samp{.c} output file by
@@ -2477,7 +2481,8 @@ does not enforce this convention, but if you depart from it, people who
 read your program will be confused.
 
 All the escape sequences used in string literals in C can be used in
-Bison as well.  However, unlike Standard C, trigraphs have no special
+Bison as well, except that you must not use a null character within a
+string literal.  Also, unlike Standard C, trigraphs have no special
 meaning in Bison string literals, nor is backslash-newline allowed.  A
 literal string token must contain two or more characters; for a token
 containing just one character, use a character token (see above).
@@ -3684,10 +3689,12 @@ Declare a terminal symbol (token type name) that is nonassociative
 Using it in a way that would be associative is a syntax error.
 @end deffn
 
+@ifset defaultprec
 @deffn {Directive} %default-prec
 Assign a precedence to rules lacking an explicit @code{%prec} modifier
 (@pxref{Contextual Precedence, ,Context-Dependent Precedence}).
 @end deffn
+@end ifset
 
 @deffn {Directive} %type
 Declare the type of semantic values for a nonterminal symbol
@@ -3759,11 +3766,13 @@ and so on.  @xref{Multiple Parsers, ,Multiple Parsers in the Same
 Program}.
 @end deffn
 
+@ifset defaultprec
 @deffn {Directive} %no-default-prec
 Do not assign a precedence to rules lacking an explicit @code{%prec}
 modifier (@pxref{Contextual Precedence, ,Context-Dependent
 Precedence}).
 @end deffn
+@end ifset
 
 @deffn {Directive} %no-parser
 Do not include any C code in the parser file; generate tables only.  The
@@ -4863,6 +4872,7 @@ exp:    @dots{}
 @end group
 @end example
 
+@ifset defaultprec
 If you forget to append @code{%prec UMINUS} to the rule for unary
 minus, Bison silently assumes that minus has its usual precedence.
 This kind of problem can be tricky to debug, since one typically
@@ -4882,6 +4892,7 @@ grammar, but it helps to protect against incorrect rule precedences.
 
 The effect of @code{%no-default-prec;} can be reversed by giving
 @code{%default-prec;}, which is the default.
+@end ifset
 
 @node Parser States
 @section Parser States
@@ -6814,11 +6825,13 @@ parsing.  @xref{Parser Function, ,The Parser Function @code{yyparse}}.
 Equip the parser for debugging.  @xref{Decl Summary}.
 @end deffn
 
+@ifset defaultprec
 @deffn {Directive} %default-prec
 Assign a precedence to rules that lack an explicit @samp{%prec}
 modifier.  @xref{Contextual Precedence, ,Context-Dependent
 Precedence}.
 @end deffn
+@end ifset
 
 @deffn {Directive} %defines
 Bison declaration to create a header file meant for the scanner.
@@ -6873,11 +6886,13 @@ function is applied to the two semantic values to get a single result.
 Bison declaration to rename the external symbols.  @xref{Decl Summary}.
 @end deffn
 
+@ifset defaultprec
 @deffn {Directive} %no-default-prec
 Do not assign a precedence to rules that lack an explicit @samp{%prec}
 modifier.  @xref{Contextual Precedence, ,Context-Dependent
 Precedence}.
 @end deffn
+@end ifset
 
 @deffn {Directive} %no-lines
 Bison declaration to avoid generating @code{#line} directives in the