Re: [PATCH] warnings: introduced -Wprecedence

[Akim Demaille]

> The new warning category precedence is used for useless precedence and
> associativity reporting.
> 
> * src/complain.c, src/complain.h, src/getargs.c: Introduce precedence
> warning category.  -Wprecedence can now be used, but is disabled by default.

Start each new item on a new line.  So basically, start each sentence
on its own line.  Also, name what was introduced.  For instance:

commit e8f7155d98c22579c871c293a0daa5f7752e7c2b
Author: Valentin Tolmer <address@hidden>
Date:   Tue Jan 29 16:27:04 2013 +0100

    grammar: record used associativity and print useless ones
    
    Record which symbol associativity is used, and display useless ones.
    
    * src/symtab.h, src/symtab.c (register_assoc, print_assoc_warnings): New

> Precedence category regroups the useless precedence and associativity
> warnings.
> * doc/bison.texi: Document the warnings and provide an example.

Specify the @node name that you upgraded.  For instance:

    * doc/bison.texi (mfcalc example): Fix associativity to remove
    warning.

> * tests/conflicts.at tests/existing.at tests/local.at tests/regression.at:

Use ", " as separator.

> Adapt testsuite for the new category (-Wprecedence instead of -Wother for

Adapt (or adjust) _the_.

> these warnings).
> ---
>  NEWS                |   45 +++++++--
>  doc/bison.texi      |   18 ++++
>  src/complain.c      |    1 +
>  src/complain.h      |    4 +-
>  src/getargs.c       |    3 +
>  src/symtab.c        |    4 +-
>  tests/conflicts.at  |   68 +++++++-------
>  tests/existing.at   |  258 
> +++++++++++++++++++++++++--------------------------
>  tests/local.at      |    2 +-
>  tests/regression.at |   10 +-
>  10 files changed, 234 insertions(+), 179 deletions(-)
> 
> diff --git a/NEWS b/NEWS
> index 62f834b..57d6d26 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -198,13 +198,6 @@ GNU Bison NEWS
>      bar.y: error: shift/reduce conflicts: 1 found, 0 expected
>      bar.y: error: reduce/reduce conflicts: 2 found, 0 expected
>  
> -*** Useless precedence
> -
> -  Bison now warns about symbols with a declared precedence but no declared
> -  associativity (i.e. declared with %precedence), and whose precedence is
> -  never used.  In that case, the symbol can be safely declared with %token
> -  instead, without modifying the parsing tables.
> -
>  ** Additional yylex/yyparse arguments
>  
>    The new directive %param declares additional arguments to both yylex and
> @@ -303,6 +296,44 @@ GNU Bison NEWS
>    when declaring associativity at the same time, with %left (or %right,
>    %precedence, %nonassoc), B was inferior to A.
>  
> +** Useless precedence and associativity
> +
> +*** Precedence warning category
> +
> +  A new category of warning, precedence (-Wprecedence) has been introduced, 
> and
> +  is used for the useless precedence and associativity warnings.
> +
> +*** Useless associativity
> +
> +  Bison now warns about symbols with a declared associativity that is never
> +  used to resolve conflicts.  In that case, using %precedence is sufficient.
> +  Solving these warnings may raise useless precedence warnings, as the 
> symbols
> +  no longer have associativity.  For example :
> +
> +    %nonassoc '='
> +    %%
> +    e: VAR '=' NUM;

Use "var" and "num"

> +
> +  will produce a
> +
> +    warning: useless associativity for '=' [-Wprecedence]
> +
> +
> +*** Useless precedence
> +
> +  Bison now warns about symbols with a declared precedence but no declared
> +  associativity (i.e. declared with %precedence), and whose precedence is

"i.e., "

> +  never used.  In that case, the symbol can be safely declared with %token
> +  instead, without modifying the parsing tables.  For example :

No space before ":".

> +
> +    %precedence '='
> +    %%
> +    e: VAR '=' NUM;
> +
> +  will produce a
> +
> +    warning: useless precedence for '=' [-Wprecedence]
> +
>  * Noteworthy changes in release 2.7 (2012-12-12) [stable]
>  
>  ** Bug fixes
> diff --git a/doc/bison.texi b/doc/bison.texi
> index d2d3da3..39f2636 100644
> --- a/doc/bison.texi
> +++ b/doc/bison.texi
> @@ -9716,6 +9716,24 @@ no effect on the conflict report.
>  Deprecated constructs whose support will be removed in future versions of
>  Bison.
>  
> address@hidden precedence
> +Useless precedence and associativity.  Bison detects whether defined 
> precedence
> +and associativity are uselful, and warns if not. For example, in the grammar

useful.

> +below, Bison warns about useless associativity for @samp{=}:
> +
> address@hidden
> +%nonassoc '='
> +%%
> +assign: VAR '=' NUM;

Again.

> address@hidden example
> +
> +In this case, two @samp{=} in a row will be detected as a syntax error even 
> without

Give an example of what you call "in a row".

> address@hidden (there are no rule allowing that case), so the associativity is
> +useless, and can be replaced by @code{%precedence}.  Bison then warns about 
> useless
> +precedence, because @samp{=} can be safely declared as a @code{%token} 
> (there are no
> +conflicts involving @samp{=} solved with precedence comparison).  This 
> warning is
> +disabled by default.

All this is too wide.  No more than 76 col please.

> +
>  @item other
>  All warnings not categorized above.  These warnings are enabled by default.
>  
> diff --git a/src/complain.c b/src/complain.c
> index d43e623..c6e03d5 100644
> --- a/src/complain.c
> +++ b/src/complain.c
> @@ -50,6 +50,7 @@ warnings_print_categories (warnings warn_flags)
>            "conflicts-sr",
>            "conflicts-rr",
>            "deprecated",
> +          "precedence",
>            "other"
>          };
>