Below is what I was told. I don't know the first Quartus version for which this applies.
Quartus automatically recognizes files with an .sv extension as SystemVerilog design files.
To process regular Verilog design files using SystemVerilog-2005, select SystemVerilog project wide or for an individual file.
Project wide: Assignments --> Settings --> Analysis & Synthesis Settings --> Verilog HDL Input --> Verilog version --> SystemVerilog-2005
Individual file: Assignments --> Settings --> Files, select the .v file, click Properties, set Type to Verilog HDL File and HDL version to SystemVerilog_2005.