New Contributor
Super ContributorYou don't indicate which version of Quartus (Lite, Standard, or Pro) you are using, but VHDL2008 is not supported in Lite. The supported 2008 features in Pro are listed here:
TBH, I'm trying to understand what the ? there does and the only paragraph I can find in the standard that describes it (section 10.5.4) is a little vague:
"If a selected signal assignment statement includes the question mark delimiter, then the equivalent sequential statement includes a question mark delimiter after both occurrences of the reserved word case; otherwise the equivalent sequential statement does not include the question mark delimiters."
New ContributorInteresting, One can select VHDL 2008 in the lite edition, I assume that it is vestigial. One can read more about the ? artifact here: https://www.doulos.com/knowhow/vhdl/vhdl-2008-small-changes/
Tl;DR: it allows wildcards in the when statements.
