mesa/src/compiler/glsl/glcpp
Timothy Arceri d2711f9b61 glsl/glcpp: make sure to expand new token after concatenation
Previously the code was using a hack to change the token type from
INDETIFIER -> OTHER in order to avoid getting in an infinite loop
expanding the tokens. This worked ok until we got to a paste where
the replacement parameters had already had their type changed
to OTHER because the newly created paste token would then
inherit the OTHER type and never get expanded inself.

For example with the follow code:

   #define STEP_ONE() \
	out_Color = vec4(0.0,1.0,0.0,1.0)

   #define GLUE(x,y) x ## _ ## y
   #define EVALUATE(x,y)  GLUE(x,y)
   #define STEP(stepname) EVALUATE(STEP, stepname)()
   #define PERFORM_RAYCASTING_STEP STEP(ONE)

This would get all the way to expanding PERFORM_RAYCASTING_STEP to
STEP_ONE() but because it was created via the paste `x ## _ ## y`
it would never get any further.

To fix this we remove the OTHER hack and instead just track if the
token has already been handled via a bool value `explanding`.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5724

Fixes: 28842c2331 ("glcpp: Implement token pasting for non-function-like macros")

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14101>
2022-01-04 23:36:42 +00:00
..
tests glcpp: Disable the valgrind tests. 2021-12-23 09:10:11 +00:00
README
glcpp-lex.l
glcpp-parse.y glsl/glcpp: make sure to expand new token after concatenation 2022-01-04 23:36:42 +00:00
glcpp.c glcpp: Fully initialize struct gl_context 2021-03-19 08:50:37 +00:00
glcpp.h glsl/glcpp: make sure to expand new token after concatenation 2022-01-04 23:36:42 +00:00
meson.build glcpp: Disable the valgrind tests. 2021-12-23 09:10:11 +00:00
pp.c glcpp: Fix undefined behaviour in glcpp 2021-03-25 00:23:43 +00:00
pp_standalone_scaffolding.c
pp_standalone_scaffolding.h

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).