[PATCH wayland] scanner: Add --strict flag

[Pekka Paalanen]

On Wed, 11 Oct 2017 17:31:33 +0800
Jonas Ådahl <jadahl at gmail.com> wrote:

> Add a --strict flag for making wayland-scanner fail if the DTD
> verification fails. This is useful for testing, so that a test case can
> fail a scan when the protocol doesn't comply with the DTD.
> 
> Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
> ---
> 
> This could be used by wayland-protocols (and others) to verify that
> protocols comply to the DTD. wayland-protocols already test-scans
> protocols,  but protocols that doesn't pass the DTD just results in
> warnings, the test still succeeds. I realize this could probably be
> done by also using the dtd file directly, so this would only be for
> convenience.
> 
> 
> Jonas
> 
> 
>  src/scanner.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/src/scanner.c b/src/scanner.c
> index c345ed6..1308fc7 100644
> --- a/src/scanner.c
> +++ b/src/scanner.c
> @@ -72,7 +72,9 @@ usage(int ret)
>  			"                                 the scanner was built against.\n"
>  			"    -c,  --include-core-only     include the core version of the headers,\n"
>  			"                                 that is e.g. wayland-client-core.h instead\n"
> -			"                                 of wayland-client.h.\n");
> +			"                                 of wayland-client.h.\n"
> +			"    -s,  --strict                exit immediately with an error if DTD\n"
> +			"                                 verification fails.\n");

Hi Jonas,

I like the idea, but with a caveat, and I'd like to propose to take it
a little further.

Let's not limit the --strict option to just DTD validation. I assume
the scanner could do also other kinds of checks that we would not be
able to turn into errors by default because of backwards compatibility.
It would be useful for --strict to switch also those warnings into
errors.

Backwards compatiblity brings me to the caveat. We should be very
explicit in the scanner documentation that --strict does not preserve
backwards compatibility. We need to allow ourselves to add more
warnings in the future, DTD or otherwise, but we cannot add them if we
imply --strict to remain backwards compatible. In essence, --strict
would be like gcc's -Werror.

That also means that projects using --strict do so on their own. I
would guess that wayland-protocols could still use --strict since it's
only testing, and testing can be disabled(?) via configure. Or vice
versa, enabling --strict in wayland-protocols tests would require
explicit enabling via configure or meson options. I suppose
distributors would prefer the latter.


Thanks,
pq

>  	exit(ret);
>  }
>  
> @@ -1801,6 +1803,7 @@ int main(int argc, char *argv[])
>  	bool help = false;
>  	bool core_headers = false;
>  	bool version = false;
> +	bool strict = false;
>  	bool fail = false;
>  	int opt;
>  	enum {
> @@ -1813,11 +1816,12 @@ int main(int argc, char *argv[])
>  		{ "help",              no_argument, NULL, 'h' },
>  		{ "version",           no_argument, NULL, 'v' },
>  		{ "include-core-only", no_argument, NULL, 'c' },
> +		{ "strict",            no_argument, NULL, 's' },
>  		{ 0,                   0,           NULL, 0 }
>  	};
>  
>  	while (1) {
> -		opt = getopt_long(argc, argv, "hvc", options, NULL);
> +		opt = getopt_long(argc, argv, "hvcs", options, NULL);
>  
>  		if (opt == -1)
>  			break;
> @@ -1832,6 +1836,9 @@ int main(int argc, char *argv[])
>  		case 'c':
>  			core_headers = true;
>  			break;
> +		case 's':
> +			strict = true;
> +			break;
>  		default:
>  			fail = true;
>  			break;
> @@ -1894,6 +1901,10 @@ int main(int argc, char *argv[])
>  		"* WARNING: XML failed validation against built-in DTD *\n"
>  		"*                                                     *\n"
>  		"*******************************************************\n");
> +		if (strict) {
> +			fclose(input);
> +			exit(EXIT_FAILURE);
> +		}
>  	}
>  
>  	/* create XML parser */

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