Re: [PATCH doc] Explain options precedence and difference between -pedantic-errors and -Werror=pedantic

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Fri, 17 Oct 2014, Manuel López-Ibáñez wrote:

> +Some options, such as @option{-Wall} and @option{-Wextra}, turn on other
> +options, such as @option{-Wunused}, which may turn on further options,
> +such as @option{-Wunused-value}. The combined effect of positive and
> +negative forms is that more specific options have priority over less
> +specific ones, independently of their position in the command-line. For
> +options of the same specificity, the last one takes effect. Options
> +enabled or disabled via pragmas (@pxref{Diagnostic Pragmas}) take effect
> +as if they appeared at the end of the command-line.

This part is OK.

> @@ -3318,8 +3327,8 @@
> 
>  @item -pedantic-errors
>  @opindex pedantic-errors
> -Like @option{-Wpedantic}, except that errors are produced rather than
> -warnings.
> +This is equivalent to @option{-Werror=pedantic} plus making into errors
> +a few warnings that are not controlled by @option{-Wpedantic}.

But I think the previous version is better here.  Maybe at present your 
version is true, but in principle -Wpedantic can control warnings that 
aren't pedwarns.  Some of the -Wformat warnings are conditional on having 
both -Wformat and -Wpedantic enabled - we can only represent those using 
OPT_Wformat in the warning calls at present, but there's at least as case 
for -Werror=pedantic to turn them into errors (while -pedantic-errors 
definitely should not turn them into errors, as the code is only invalid 
at runtime and is valid at compile time as long as it never gets 
executed).

-- 
Joseph S. Myers
joseph@codesourcery.com