Re: [PATCH] Notes on the warnings-as-errors change in GCC 14

[Gerald Pfeifer <gerald@pfeifer.com>]

On Fri, 2 Feb 2024, Florian Weimer wrote:
> +<h3 id="warnings-as-errors">Certain warnings are now errors</h3>

That's quite a nice description, thank you, Florian!

> +The initial ISO C standard and its 1999 revision removed support for

May I suggest to wrap paragraphs in <p>...</p>? Not strictly necessary any 
more, now that we switched to HTML 5, though more consistent and explicit.

> [For backwards]
> +compatibility, GCC 13 and earlier compiler versions diagnosed use of
> +these features as warnings only.  Although these warnings have been
> +enabled by default for many releases, experience shows that these
> +warnings are easily ignored, resulting in difficult-to-diagnose bugs.

Can we just say "GCC 13 and earlier" (or "GCC 13 and earlier versions")?

And "...shows that they are easily ignored, resulting in difficult to 
diagnose bugs"?

> +Several GNU/Linux distributions have shared patches from their porting
> +efforts on relevant upstream mailing lists and bug trackers, but of
> +course there is a strong overlap between programs that have these
> +historic C compatibility issues and are dormant today.

At first I thought something is missing here, then I realized it may be a 
difference between German (which also is my mother tongue) and English.

One way to address it would be saying "and those that are dormant", though
I believe something like

  ...but of course many programs that exhibit these historic C 
  compatibility issues are dormant today.

> +In most cases, simply adding the missing <code>int</code> keyword
> +addresses the error.  For example, a flag like
> +
> +<pre>
> +  static initialized;
> +</pre>
> +
> +might turn into:
> +
> +<pre>
> +  static <ins>int</ins> initialized;
> +</pre>

How about "For example, a variable like ... becomes"?

> +<p>If the return type of a function is omitted, the correct type to
> +add could be <code>int</code> or <code>void</code>, depending on
> +whether the function returns a value or not.

"can be"

> +<p>In some cases, the previously implied <code>int</code> type
> +was not correct.

I'd omit the comma here.

>  This mostly happens in function definitions
> +that are not prototypes

Naive questions: Can definitions really be prototypes (in C)?

> +declared outside the parameter list.  Using the correct
> +type maybe required to avoid int-conversion errors (see below).

Something feels odd with this sentence?

> +<pre>
> +  <ins>void</ins>
> +  write_string (<ins>int</ins> fd, const char *s)

<ins>const char</ins> *s) as well?

> +Some programs are built with <code>-std=c11</code> or
> +similar <code>-std</code> options that do not contain the
> +string <code>gnu</code>, but these programs still use POSIX or other

...but still use... (omit "these programs")

> +If undeclared functions from the same project are called and there is
> +yet no suitable shared header file, you should add a declaration to a

"no suitable shared header file yet, you can add..."

> +However, this is an obsolete C feature that will change meaning in C23
> +(declaration a function with a prototype and accepting no arguments,
> +similar to C++).

"declaration of a function", or some other change here?

> +Incorrectly spelled type names in function declarations are treated as
> +errors in more cases, under a
> +new <code>-Wdeclaration-missing-parameter-type</code> warning.  The
> +second line in the following example is now treated as an error
> +(previously this resulted in an unnamed warning):

What is an "unnamed" warning? Can we simply omit "unnamed" here?

> +GCC will type-check function arguments after that, potentially
> +requiring further changes.  (Previously, the function declaration was
> +treated as not having no prototype.)

That second sentence uses double negation, which logically is the same as 
just the original statement.

> +<p>
> +By default, GCC still accepts returning an expression of
> +type <code>void</code> from within a function that itself
> +returns <code>void</code>, as a GNU extension that matches C++ rules
> +in this area.

Does the GNU extension match C++ (standard rules)?


Wee, this is a patch. All the more kudos to you.. 

I'll be looking into the second half of the patch tomorrow; feel free to 
commit the aspects covered above (after considering my review).

Cheers,