Fix error code on invalid shader/program operation

The spec states that GL_INVALID_OPERATION is generated when a shader or
program function is called on the wrong object type. GL_INVALID_VALUE is
generated when there's no shader nor program object by that name.

Change-Id: Ia819857b533f226a90d9a9805b254b127da8c667
Reviewed-on: https://swiftshader-review.googlesource.com/5540
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>

src/OpenGL/libGLESv2/libGLESv2.cpp

diff --git a/src/OpenGL/libGLESv2/libGLESv2.cpp b/src/OpenGL/libGLESv2/libGLESv2.cpp
index 7beb616..2a14613 100644
--- a/src/OpenGL/libGLESv2/libGLESv2.cpp
+++ b/src/OpenGL/libGLESv2/libGLESv2.cpp
@@ -3876,14 +3876,21 @@
 
 	if(context)
 	{
-		if(program == 0)
-		{
-			return error(GL_INVALID_VALUE);
-		}
-
 		es2::Program *programObject = context->getProgram(program);
 
-		if(!programObject || !programObject->isLinked())
+		if(!programObject)
+		{
+			if(context->getShader(program))
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+			else
+			{
+				return error(GL_INVALID_VALUE);
+			}
+		}
+
+		if(!programObject->isLinked())
 		{
 			return error(GL_INVALID_OPERATION);
 		}
@@ -3903,14 +3910,21 @@
 
 	if(context)
 	{
-		if(program == 0)
-		{
-			return error(GL_INVALID_VALUE);
-		}
-
 		es2::Program *programObject = context->getProgram(program);
 
-		if(!programObject || !programObject->isLinked())
+		if(!programObject)
+		{
+			if(context->getShader(program))
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+			else
+			{
+				return error(GL_INVALID_VALUE);
+			}
+		}
+
+		if(!programObject->isLinked())
 		{
 			return error(GL_INVALID_OPERATION);
 		}
@@ -3936,19 +3950,21 @@
 
 	if(context)
 	{
-		if(program == 0)
-		{
-			return error(GL_INVALID_VALUE);
-		}
-
 		es2::Program *programObject = context->getProgram(program);
 
-		if(!programObject || !programObject->isLinked())
+		if(!programObject)
 		{
-			return error(GL_INVALID_OPERATION);
+			if(context->getShader(program))
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+			else
+			{
+				return error(GL_INVALID_VALUE);
+			}
 		}
 
-		if(!programObject)
+		if(!programObject->isLinked())
 		{
 			return error(GL_INVALID_OPERATION);
 		}
@@ -3968,19 +3984,21 @@
 
 	if(context)
 	{
-		if(program == 0)
-		{
-			return error(GL_INVALID_VALUE);
-		}
-
 		es2::Program *programObject = context->getProgram(program);
 
-		if(!programObject || !programObject->isLinked())
+		if(!programObject)
 		{
-			return error(GL_INVALID_OPERATION);
+			if(context->getShader(program))
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+			else
+			{
+				return error(GL_INVALID_VALUE);
+			}
 		}
 
-		if(!programObject)
+		if(!programObject->isLinked())
 		{
 			return error(GL_INVALID_OPERATION);
 		}