Carl Worth
ec6222ef01
The GLSL ES Specification 3.00.4 says:
#if, #ifdef, #ifndef, #else, #elif, and #endif are defined to operate
as for C++ except for the following:
...
• Undefined identifiers not consumed by the defined operator do not
default to '0'. Use of such identifiers causes an error.
[Page 11 (page 127 of the PDF file)]
as well as:
The semantics of applying operators in the preprocessor match those
standard in the C++ preprocessor with the following exceptions:
• The 2nd operand in a logical and ('&&') operation is evaluated if
and only if the 1st operand evaluates to non-zero.
• The 2nd operand in a logical or ('||') operation is evaluated if
and only if the 1st operand evaluates to zero.
If an operand is not evaluated, the presence of undefined identifiers
in the operand will not cause an error.
(Note that neither of these deviations from C++ preprocessor behavior apply to
non-ES GLSL, at least as of specfication version 4.30.6).
The first portion of this, (generating an error for an undefined macro in an
(short-circuiting to squelch errors), was not implemented previously, but is
implemented in this commit.
A test is added for "make check" to ensure this behavior.
Note: The change as implemented does make the error message a bit less
precise, (it just states that an undefined macro was encountered, but not the
name of the macro).
This commit fixes the following Khronos GLES3 conformance test:
undefined_identifiers.valid_undefined_identifier_1_vertex
undefined_identifiers.valid_undefined_identifier_1_fragment
undefined_identifiers.valid_undefined_identifier_2_vertex
undefined_identifiers.valid_undefined_identifier_2_fragment
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
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).