Prefer '%define api.value.type' to '#define YYSTYPE', so that Bison
know the type.
Use '%code requires' to declare what is needed to define the api.value.type
(that code is output in the generated header before the generated
definition of YYSTYPE).
Prefer '%define api.prefix' inside the grammar file to '-p' outside,
as anyway the functions defined in the file actually use this prefix.
Prefer `%param` to both `%parse-param` and `%lex-param`.
Closes GH-5138
The annotation %empty is properly enforced: warnings when it's
missing, and errors when it's inappropriate. Support for %empty was
introduced in Bison 3.0.
Pass -Wempty-rule to Bison.
Closes GH-5134
This patch adds missing newlines, trims multiple redundant final
newlines into a single one, and trims redundant leading newlines.
According to POSIX, a line is a sequence of zero or more non-' <newline>'
characters plus a terminating '<newline>' character. [1] Files should
normally have at least one final newline character.
C89 [2] and later standards [3] mention a final newline:
"A source file that is not empty shall end in a new-line character,
which shall not be immediately preceded by a backslash character."
Although it is not mandatory for all files to have a final newline
fixed, a more consistent and homogeneous approach brings less of commit
differences issues and a better development experience in certain text
editors and IDEs.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206
[2] https://port70.net/~nsz/c/c89/c89-draft.html#2.1.1.2
[3] https://port70.net/~nsz/c/c99/n1256.html#5.1.1.2
