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Re: Java token names containing C trigraphs


From: Tim Landscheidt
Subject: Re: Java token names containing C trigraphs
Date: Sat, 05 Nov 2011 22:55:20 +0000
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)

Paul Eggert <address@hidden> wrote:

> I don't see the bug here.  The Bison documentation says:

> Bison does not look for trigraphs, so if braced code uses
> trigraphs you should ensure that they do not affect the nesting of
> braces or the boundaries of comments, string literals, or character
> constants.

The problem lies not in trigraphs in braced code, but tri-
graphs in "literal string tokens" (so "token names" was
probably a misleading error on my part).  Cf. "3.2 Symbols,
Terminal and Nonterminal":

|      All the escape sequences used in string literals in C
|      can be used in 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).

So the string "??=" is allowed in literal string tokens, but
the generated Java code does not compile.

Tim




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