[Mesa-dev] [PATCH 2/2] glcpp: Only disallow #undef of pre-defined macros on GLSL ES >= 3.00 shaders

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

Section 3.4 (Preprocessor) of the GLSL ES 3.00 spec says:

   It is an error to undefine or to redefine a built-in (pre-defined)
   macro name.

The GLSL ES 1.00 spec does not contain this text.

Section 3.3 (Preprocessor) of the GLSL 1.30 spec says:

   #define and #undef functionality are defined as is standard for C++
   preprocessors for macro definitions both with and without macro
   parameters.

At least as far as I can tell GCC allow '#undef __FILE__'.  Furthermore,
there are desktop OpenGL conformance tests that expect '#undef
__VERSION__' and '#undef GL_core_profile' to work.

Fixes:

    GL45-CTS.shaders.preprocessor.definitions.undefine_version_vertex
    GL45-CTS.shaders.preprocessor.definitions.undefine_version_fragment
    GL45-CTS.shaders.preprocessor.definitions.undefine_core_profile_vertex
    GL45-CTS.shaders.preprocessor.definitions.undefine_core_profile_fragment

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: mesa-stable at lists.freedesktop.org
---
 src/compiler/glsl/glcpp/glcpp-parse.y | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/compiler/glsl/glcpp/glcpp-parse.y b/src/compiler/glsl/glcpp/glcpp-parse.y
index 05a76c7..eff53be 100644
--- a/src/compiler/glsl/glcpp/glcpp-parse.y
+++ b/src/compiler/glsl/glcpp/glcpp-parse.y
@@ -278,10 +278,34 @@ control_line_success:
 	HASH_TOKEN DEFINE_TOKEN define
 |	HASH_TOKEN UNDEF IDENTIFIER NEWLINE {
 		macro_t *macro;
-		if (strcmp("__LINE__", $3) == 0
-		    || strcmp("__FILE__", $3) == 0
-		    || strcmp("__VERSION__", $3) == 0
-		    || strncmp("GL_", $3, 3) == 0)
+
+                /* Section 3.4 (Preprocessor) of the GLSL ES 3.00 spec says:
+                 *
+                 *    It is an error to undefine or to redefine a built-in
+                 *    (pre-defined) macro name.
+                 *
+                 * The GLSL ES 1.00 spec does not contain this text.
+                 *
+                 * Section 3.3 (Preprocessor) of the GLSL 1.30 spec says:
+                 *
+                 *    #define and #undef functionality are defined as is
+                 *    standard for C++ preprocessors for macro definitions
+                 *    both with and without macro parameters.
+                 *
+                 * At least as far as I can tell GCC allow '#undef __FILE__'.
+                 * Furthermore, there are desktop OpenGL conformance tests
+                 * that expect '#undef __VERSION__' and '#undef
+                 * GL_core_profile' to work.
+                 *
+                 * Only disallow #undef of pre-defined macros on GLSL ES >=
+                 * 3.00 shaders.
+                 */
+		if (parser->is_gles &&
+                    parser->version >= 300 &&
+                    (strcmp("__LINE__", $3) == 0
+                     || strcmp("__FILE__", $3) == 0
+                     || strcmp("__VERSION__", $3) == 0
+                     || strncmp("GL_", $3, 3) == 0))
 			glcpp_error(& @1, parser, "Built-in (pre-defined)"
 				    " macro names cannot be undefined.");
 
-- 
2.5.5