[Mesa-dev] [PATCH 1/3] glcpp: Only warn for macro names containing __

[Ian Romanick]

I'm hoping that Tapani or Darius will verify that this patch actually
fixes the problem.  That's why people CC other people on patches. :)

On 02/18/2014 10:19 AM, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> Section 3.3 (Preprocessor) of the GLSL 1.30 spec (and later) and the
> GLSL ES spec (all versions) say:
> 
>     "All macro names containing two consecutive underscores ( __ ) are
>     reserved for future use as predefined macro names. All macro names
>     prefixed with "GL_" ("GL" followed by a single underscore) are also
>     reserved."
> 
> The intention is that names containing __ are reserved for internal use
> by the implementation, and names prefixed with GL_ are reserved for use
> by Khronos.  Since every extension adds a name prefixed with GL_ (i.e.,
> the name of the extension), that should be an error.  Names simply
> containing __ are dangerous to use, but should be allowed.  In similar
> cases, the C++ preprocessor specification says, "no diagnostic is
> required."
> 
> Per the Khronos bug mentioned below, a future version of the GLSL
> specification will clarify this.
> 
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> Cc: "9.2 10.0 10.1" <mesa-stable at lists.freedesktop.org>
> Cc: Tapani Pälli <lemody at gmail.com>
> Cc: Kenneth Graunke <kenneth at whitecape.org>
> Cc: Darius Spitznagel <d.spitznagel at goodbytez.de>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71870
> Bugzilla: Khronos #11702
> ---
>  src/glsl/glcpp/glcpp-parse.y                       | 22 +++++++++++++++++++---
>  .../tests/086-reserved-macro-names.c.expected      |  4 ++--
>  2 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/src/glsl/glcpp/glcpp-parse.y b/src/glsl/glcpp/glcpp-parse.y
> index 5bb2891..bdc598f 100644
> --- a/src/glsl/glcpp/glcpp-parse.y
> +++ b/src/glsl/glcpp/glcpp-parse.y
> @@ -1770,11 +1770,27 @@ static void
>  _check_for_reserved_macro_name (glcpp_parser_t *parser, YYLTYPE *loc,
>  				const char *identifier)
>  {
> -	/* According to the GLSL specification, macro names starting with "__"
> -	 * or "GL_" are reserved for future use.  So, don't allow them.
> +	/* Section 3.3 (Preprocessor) of the GLSL 1.30 spec (and later) and
> +	 * the GLSL ES spec (all versions) say:
> +	 *
> +	 *     "All macro names containing two consecutive underscores ( __ )
> +	 *     are reserved for future use as predefined macro names. All
> +	 *     macro names prefixed with "GL_" ("GL" followed by a single
> +	 *     underscore) are also reserved."
> +	 *
> +	 * The intention is that names containing __ are reserved for internal
> +	 * use by the implementation, and names prefixed with GL_ are reserved
> +	 * for use by Khronos.  Since every extension adds a name prefixed
> +	 * with GL_ (i.e., the name of the extension), that should be an
> +	 * error.  Names simply containing __ are dangerous to use, but should
> +	 * be allowed.
> +	 *
> +	 * A future version of the GLSL specification will clarify this.
>  	 */
>  	if (strstr(identifier, "__")) {
> -		glcpp_error (loc, parser, "Macro names containing \"__\" are reserved.\n");
> +		glcpp_warning(loc, parser,
> +			      "Macro names containing \"__\" are reserved "
> +			      "for use by the implementation.\n");
>  	}
>  	if (strncmp(identifier, "GL_", 3) == 0) {
>  		glcpp_error (loc, parser, "Macro names starting with \"GL_\" are reserved.\n");
> diff --git a/src/glsl/glcpp/tests/086-reserved-macro-names.c.expected b/src/glsl/glcpp/tests/086-reserved-macro-names.c.expected
> index d8aa9f0..5ca42a9 100644
> --- a/src/glsl/glcpp/tests/086-reserved-macro-names.c.expected
> +++ b/src/glsl/glcpp/tests/086-reserved-macro-names.c.expected
> @@ -1,8 +1,8 @@
> -0:1(10): preprocessor error: Macro names containing "__" are reserved.
> +0:1(10): preprocessor warning: Macro names containing "__" are reserved for use by the implementation.
>  
>  0:2(9): preprocessor error: Macro names starting with "GL_" are reserved.
>  
> -0:3(9): preprocessor error: Macro names containing "__" are reserved.
> +0:3(9): preprocessor warning: Macro names containing "__" are reserved for use by the implementation.
>  
>  
>  
>