mesa/src/glsl/glcpp
Ian Romanick de6068a218 glcpp: Only warn for macro names containing __
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@intel.com>
Cc: "9.2 10.0 10.1" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Tested-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Tested-by: Darius Spitznagel <d.spitznagel@goodbytez.de>
Cc: Tapani Pälli <lemody@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71870
Bugzilla: Khronos #11702
(cherry picked from commit 0bd7892630)
2014-03-04 13:23:46 -08:00
..
tests glcpp: Only warn for macro names containing __ 2014-03-04 13:23:46 -08:00
.gitignore glcpp: Add back tests/*.out to .gitignore 2013-01-11 11:49:33 +01:00
glcpp-lex.l glcpp: Reject token pasting operator in GLES 2013-01-11 10:57:25 -08:00
glcpp-parse.y glcpp: Only warn for macro names containing __ 2014-03-04 13:23:46 -08:00
glcpp.c glcpp: Add --disable-line-continuations argument to standalone glcpp 2013-01-11 13:55:41 -08:00
glcpp.h glcpp: error on multiple #else/#elif directives 2014-01-02 15:57:41 -08:00
pp.c glcpp: Fix post-decrement underflow in loop-control variable 2013-06-03 13:33:31 -07:00
README glcpp: Update README for new support of __LINE__ and __FILE__. 2012-11-29 13:03:02 -08:00

glcpp -- GLSL "C" preprocessor

This is a simple preprocessor designed to provide the preprocessing
needs of the GLSL language. The requirements for this preprocessor are
specified in the GLSL 1.30 specification availble from:

http://www.opengl.org/registry/doc/GLSLangSpec.Full.1.30.10.pdf

This specification is not precise on some semantics, (for example,
#define and #if), defining these merely "as is standard for C++
preprocessors". To fill in these details, I've been using a draft of
the C99 standard as available from:

http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

Any downstream compiler accepting output from glcpp should be prepared
to encounter and deal with the following preprocessor macros:

	#line
	#pragma
	#extension

All other macros will be handled according to the GLSL specification
and will not appear in the output.

Known limitations
-----------------
A file that ends with a function-like macro name as the last
non-whitespace token will result in a parse error, (where it should be
passed through as is).