OpenGL: Fix switch with only a default case.

src/OpenGL/compiler/OutputASM.cpp

@@ -2058,7 +2058,11 @@ namespace glsl
 		// If there's a default case, traverse it here
 		if(defaultIt != sequence.end())
 		{
-			emit(sw::Shader::OPCODE_ELSE);
+			if(nbCases != 0)
+			{
+				emit(sw::Shader::OPCODE_ELSE);
+			}
+
 			for(++defaultIt; defaultIt != sequence.end(); ++defaultIt)
 			{
 				(*defaultIt)->traverse(this);

tests/GLESUnitTests/unittests.cpp

@@ -2066,6 +2066,18 @@ TEST_F(SwiftShaderTest, BadNegation)
 		float F (float f) { return G(-m); })");
 }
 
+TEST_F(SwiftShaderTest, SwitchDefaultOnly)
+{
+	checkCompiles(R"(
+		float F (float f) {
+			switch (0u) {
+			default:
+				return -f;
+			}
+			return f;
+		})");
+}
+
 #ifndef EGL_ANGLE_iosurface_client_buffer
 #	define EGL_ANGLE_iosurface_client_buffer 1
 #	define EGL_IOSURFACE_ANGLE 0x3454