Files
mesa/src/compiler/glsl/glcpp
Timothy Arceri 3a9edfc494 glsl: isolate object macro replacments
Here we use a leading space to isolate them from
the code they will be inserted into. For example:

    #define VALUE -1.0
    int a = -VALUE;

Should be evaluated to int a = - -1.0; not int a = --1.0;

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/7932

Cc: mesa-stable
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21352>
2023-02-20 01:50:05 +00:00
..
2021-03-25 00:23:43 +00:00

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).