Unfortunately it is not possible to reuse the %prec directive. This
is because to please POSIX, we do not require to end the rules with a
semicolon. As a result,
foo: bar %prec baz
is ambiguous: either a rule which precedence is that of baz, or a rule,
and then a declaration of the precedence of the token baz.
* doc/bison.texinfo: Document %precedence.
(Precedence Only): New.
* src/assoc.h, src/assoc.c (precedence_assoc): New.
* src/conflicts.c (resolve_sr_conflict): Support it.
* src/scan-gram.l, src/parse-gram.y (%precedence): New token.
Parse it.
* tests/calc.at: Use %precedence for NEG.
* tests/conflicts.at (%precedence does not suffice)
(%precedence suffices): New tests.
* src/assoc.h (assoc_to_string): Give a name to the arg, as
this is the usual Bison style.
* src/location.h (location_print): Likewise.
* src/reader.h (token_name): Likewise.
Adjust all former `associativity' dependencies.
* src/symtab.c (symbol_new): Default associativity is `undef', not
`right'.
(symbol_check_alias_consistence): Adjust.