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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
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| glcpp-lex.l | ||
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| glcpp.c | ||
| glcpp.h | ||
| pp.c | ||
| README | ||
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).