Why do I get a VHDL Use Clause error in Quartus II when compiling a VHDL file generated by DSP Builder?

Description

You will get a VHDL Use Clause error in Quartus II when compiling a VHDL file generated by DSP Builder if you have not added the appropriate DSP Builder library files to your Quartus II project. These library files should already be added to the project for you if you run Quartus II from within SignalCompiler or if you use the Quartus II tcl script generated by DSP Builder. However, if you are running the Quartus II compile outside of SignalCompiler and are not using the Quartus II tcl script, you will need to set these library files up manually.

The text of the error will look similar to:
Error: VHDL Use Clause error at <filename>.vhd: design library does not contain primary unit dspbuilder block
Error: Ignored construct <entity name> at <filename>.vhd because of previous errors

To compile DSP Builder generated VHDL files in Quartus II, you must have the path to the DSPBUILDERPACK.vhd and DSPBUILDER.vhd files specified in your Quartus II project. These files are located in the <DSP Builder install directory>\altlib directory.

To add these files, select Add/Remove Files in Project... under the Project menu in Quartus II. Browse to the <DSP Builder install directory>\altlib directory and select the DSPBUILDERPACK.vhd and DSPBUILDER.vhd files and click OK to add the files. The compilation order of the files is important. DSPBUILDERPACK.vhd must be compiled before DSPBUILDER.vhd. Once you have included the files, rerun your Quartus II compile.