Bug 89642

DEQP failed test:

dEQP-GLES3.functional.shaders.preprocessor.predefined_macros.line_2_vertex

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The test does a complex __LINE__ macro replacement. The shaders are created from the following template in modules/gles3/gles3/shader/preprocessor.test file:
         #version 300 es
         precision mediump float;
         ${DECLARATIONS:single-line}
         #define BBB      __LINE__, /*
            */ __LINE__
         #define AAA(a,b) BBB, a, b

         void main()
         {
            out0 = vec4(AAA(__LINE__,
                  __LINE__
                  ));
            ${OUTPUT}
         }

It expects to have out0 filled with (12, 12, 10, 11) values. Mesa gives (4, 5, 10, 11). I created a C program that mimics the shader (because Mesa follows a draft of C99 standard, see src/glsl/glcpp/README) but I got different results depending of which C compiler was used:

* gcc --std=c99 (or without c99, it doesn't matter) prints: 12, 12, 12, 12
* clang prints: 12, 12, 10, 11.

Mesa calculates the LINE macro values as the line numbers of where the macro is seen in the code before doing any expansion, as special case in glcpp-parse.y, function _glcpp_parser_expand_node().

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Tested on Haswell with Mesa master: 27bf37ba05b69ebf6f373d1637a26b4839265921