There is a known limitation with the Component Editor in SOPC Builder and Qsys. It does not allow the user to specify which language version to use for the VHDL source file analysis.
To workaround this issue, add the following comment line at top of the custom component VHDL file.
-- altera vhdl_input_version vhdl_2008
This directive instructs the front-end to use VHDL 2008 for the remaining portion of the file.
For information on VHDL 2008 constructs defined in the IEEE Std 1076-2008 version that are supported by Quartus II, refer to Quartus II Help on VHDL 2008 support at: