glsl/linker: Allow mixing of desktop GLSL versions.

Previously, Mesa followed the linkage rules outlined in the GLSL
1.20-1.40 specs, which (collectively) said that GLSL versions 1.10 and
1.20 could be linked together, but no other versions could be linked.

In GLSL 4.30, the linkage rules were relaxed so that any two desktop
GLSL versions can be linked together.  This change was made because it
reflected the behaviour of nearly all existing implementations (see
Khronos bug 8463).  Mesa was one of the few (perhaps the only)
exceptions to prohibit cross-linking of some GLSL versions.

Since the GLSL linkage rules were deliberately relaxed in order to
match the behaviour of existing implementations, it seems appropriate
to relax the rules in Mesa too (even though Mesa doesn't support GLSL
4.30 yet).

Note that linking ES and desktop shaders is still prohibited, as is
linking ES shaders having different GLSL versions.

Fixes piglit tests "shaders/version-mixing {interstage,intrastage}".

Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 3 insertions, 7 deletions

diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 9095a401540..0a949b46699 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -2057,14 +2057,10 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       }
    }
 
-   /* Previous to GLSL version 1.30, different compilation units could mix and
-    * match shading language versions.  With GLSL 1.30 and later, the versions
-    * of all shaders must match.
-    *
-    * GLSL ES has never allowed mixing of shading language versions.
+   /* In desktop GLSL, different shader versions may be linked together.  In
+    * GLSL ES, all shader versions must be the same.
     */
-   if ((is_es_prog || max_version >= 130)
-       && min_version != max_version) {
+   if (is_es_prog && min_version != max_version) {
       linker_error(prog, "all shaders must use same shading "
 		   "language version\n");
       goto done;