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* src/conflicts.c (conflicts_print): Don't print file name twice

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when %expect fails because there were no conflicts.
* doc/bison.texinfo (Expect Decl): Tighten up wording in previous
change.
* tests/conflicts.at (%expect not enough, %expect too much):
(%expect with reduce conflicts): Adjust to new behavior.

* src/conflicts.c (conflicts_print): Unsatisfied %expectation are
errors.
* NEWS: Document this.
* doc/bison.texinfo (Expect Decl): Likewise.
This commit is contained in:
Paul Eggert
2005-11-18 18:16:44 +00:00
parent d1ff7a7cc6
commit 035aa4a0bb
5 changed files with 65 additions and 41 deletions
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31
doc/bison.texinfo
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@@ -3913,19 +3913,18 @@ The declaration looks like this:
%expect @var{n}
@end example
Here @var{n} is a decimal integer. The declaration says there should be
no warning if there are @var{n} shift/reduce conflicts and no
reduce/reduce conflicts. The usual warning is
given if there are either more or fewer conflicts, or if there are any
reduce/reduce conflicts.
Here @var{n} is a decimal integer. The declaration says there should
be @var{n} shift/reduce conflicts and no reduce/reduce conflicts.
Bison reports an error if the number of shift/reduce conflicts differs
from @var{n}, or if there are any reduce/reduce conflicts.
For normal @acronym{LALR}(1) parsers, reduce/reduce conflicts are more serious,
and should be eliminated entirely. Bison will always report
reduce/reduce conflicts for these parsers. With @acronym{GLR} parsers, however,
both shift/reduce and reduce/reduce are routine (otherwise, there
would be no need to use @acronym{GLR} parsing). Therefore, it is also possible
to specify an expected number of reduce/reduce conflicts in @acronym{GLR}
parsers, using the declaration:
For normal @acronym{LALR}(1) parsers, reduce/reduce conflicts are more
serious, and should be eliminated entirely. Bison will always report
reduce/reduce conflicts for these parsers. With @acronym{GLR}
parsers, however, both kinds of conflicts are routine; otherwise,
there would be no need to use @acronym{GLR} parsing. Therefore, it is
also possible to specify an expected number of reduce/reduce conflicts
in @acronym{GLR} parsers, using the declaration:
@example
%expect-rr @var{n}
@@ -3946,12 +3945,12 @@ go back to the beginning.
@item
Add an @code{%expect} declaration, copying the number @var{n} from the
number which Bison printed.
number which Bison printed. With @acronym{GLR} parsers, add an
@code{%expect-rr} declaration as well.
@end itemize
Now Bison will stop annoying you if you do not change the number of
conflicts, but it will warn you again if changes in the grammar result
in more or fewer conflicts.
Now Bison will warn you if you introduce an unexpected conflict, but
will keep silent otherwise.
@node Start Decl
@subsection The Start-Symbol