It's a command line argument. The undeniably correct way to render it is with two minus signs[1] and absolutely not something non-ascii.
[1] Not strictly a hyphen, which has its own unicode point (0x2010) outside of ascii. Unicode embraced the ambiguity by calling this point (0x2d) "HYPHEN-MINUS" formally, but really its only unique typographic usage is to represent subtraction.
> The undeniably correct way to render it is with two minus signs[1] and absolutely not something non-ascii.
> [1] Not strictly a hyphen, which has its own unicode point (0x2010) outside of ascii. Unicode embraced the ambiguity by calling this point (0x2d) "HYPHEN-MINUS" formally, but really its only unique typographic usage is to represent subtraction.
Strictly, its as you note, the hyphen-minus, and Unicode has separate, disambiguated code points for both hyphen (0x2010) and minus (0x2212); hyphen-minus has no "unique typographic usage".
The "sed" expressions that power the title "cleanup" here do overshoot quite often. It ruins --long-command-arguments and it definitely also reuins cpp::namespaces. Quite curious why these obvious shortcomings are not being fixed.
They meant “more appropriate [than an em dash]”. And that minus sign usage of hyphen-minus isn’t unique in Unicode either – see U+2212 MINUS SIGN.