Implements correct error handling for DetachShader
TRAC #11663
Signed-off-by: Andrew Lewycky
Signed-off-by: Daniel Koch

Author:    Shannon Woods

git-svn-id: http://angleproject.googlecode.com/svn/trunk@125 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/libGLESv2/libGLESv2.cpp b/src/libGLESv2/libGLESv2.cpp
index 61fbed1..13f6e21 100644
--- a/src/libGLESv2/libGLESv2.cpp
+++ b/src/libGLESv2/libGLESv2.cpp
@@ -1108,12 +1108,35 @@
 
         if (context)
         {
+
             gl::Program *programObject = context->getProgram(program);
             gl::Shader *shaderObject = context->getShader(shader);
-
-            if (!programObject || !shaderObject)
+            
+            if (!programObject)
             {
-                return error(GL_INVALID_VALUE);
+                gl::Shader *shaderByProgramHandle;
+                shaderByProgramHandle = context->getShader(program);
+                if (!shaderByProgramHandle)
+                {
+                    return error(GL_INVALID_VALUE);
+                }
+                else
+                {
+                    return error(GL_INVALID_OPERATION);
+                }
+            }
+
+            if (!shaderObject)
+            {
+                gl::Program *programByShaderHandle = context->getProgram(shader);
+                if (!programByShaderHandle)
+                {
+                    return error(GL_INVALID_VALUE);
+                }
+                else
+                {
+                    return error(GL_INVALID_OPERATION);
+                }
             }
 
             if (!programObject->detachShader(shaderObject))