Check for shader version mismatch

gpu/command_buffer/service/program_manager.cc

Index: gpu/command_buffer/service/program_manager.cc
diff --git a/gpu/command_buffer/service/program_manager.cc b/gpu/command_buffer/service/program_manager.cc
index b27614721022acb2d5e50b0bb786c2d809916d7e..00712bc7d4dd3c1005390a611a2f7c3f1bafc18f 100644
--- a/gpu/command_buffer/service/program_manager.cc
+++ b/gpu/command_buffer/service/program_manager.cc
@@ -558,6 +558,10 @@ bool Program::Link(ShaderManager* manager,
       set_log_info("invalid shaders");
       return false;
     }
+    if (DetectShaderVersionMismatch()) {
+      set_log_info("Versions of linked shaders have to match.");
+      return false;
+    }
     if (DetectAttribLocationBindingConflicts()) {
       set_log_info("glBindAttribLocation() conflicts");
       return false;
@@ -1034,6 +1038,22 @@ bool Program::CanLink() const {
   return true;
 }
 
+bool Program::DetectShaderVersionMismatch() const {
+  int version = Shader::kUndefinedShaderVersion;
+  for (int ii = 0; ii < kMaxAttachedShaders; ++ii) {
+    Shader* shader = attached_shaders_[ii].get();
+    if (shader) {
+      if (version != Shader::kUndefinedShaderVersion &&
+          shader->shader_version() != version) {
+        return true;

[Zhenyao Mo, 2015/05/06 17:57:42]

This is based on the assumption that kMaxAttachedShaders == 2.

We should make the algorithm more robust without this hidden assumption here.

[oetuaho-nv, 2015/05/07 08:02:41]

I don't see how this would be based on that assumption. If any of the shaders
has a different version this function will report the mismatch.

[Jamie Madill, 2015/05/07 11:27:54]

Yes, I think it's sufficient to detect any mismatch between pairs of shaders.

[Zhenyao Mo, 2015/05/07 14:33:08]

You are right.  I misread the code.

+      }
+      version = shader->shader_version();
+      DCHECK(version != Shader::kUndefinedShaderVersion);
+    }
+  }
+  return false;
+}
+
 bool Program::DetectAttribLocationBindingConflicts() const {
   std::set<GLint> location_binding_used;
   for (LocationMap::const_iterator it = bind_attrib_location_map_.begin();