dualfroz
91e0d866bc
FormatCommandLine wrote option and value arguments using the ambient thread culture via value.ToString(), while the parser reads them back with ParserSettings.ParsingCulture (invariant by default). On threads whose culture uses a comma decimal separator (for example de-DE) a double 1.5 was unparsed as "1,5" and reparsed as 15, and a sequence [1.5, 2.5] became "1,5,2,5" and reparsed as four elements [1,5,2,5], so the format/parse round-trip was broken. Format IFormattable values (numeric and date/time types) with the parser ParsingCulture instead of the current thread culture, for both scalar and separator-joined sequence values. Other types keep their default string representation, so behaviour on invariant/en-US is unchanged. Add round-trip tests under de-DE for a scalar double and a comma-separated double sequence.