add -safe switch

[WalterBright]

The new return scope and other added @safe checking will require some updates to existing code, hence the need for this transitional switch.

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[wilzbach]

What about the man page? AFAIK it's not updated automatically?

[WalterBright]

done

[dnadlinger]

Shouldn't this be -transition=<...>?

I'd also like to see a clear rationale and design before this is merged. The change log and doc entries are useless in their current form ("enhanced @safe checking"?).

[WalterBright]

It will basically be difficult to continue developing DIP1000 without this switch. The switch will enable things that break too much existing code, like #5860

I'll probably have to tweak around just what it does based on experience.

[wilzbach]

Shouldn't this be -transition=<...>?

I really like this -transition=.., because

• it clearly conveys to the user what this switch is about (the word transition automatically implies that it will be enabled by default)
• it's a nice grouping for experimental behavior
• once the flag is removed, it will be moderately cheap to remove it completely and just let transition print a nice error message that helps the user ("Hey the transition you requested is over and now enabled by default)
• we don't "burn" the flag yet (probably not so problematic in this case)

The switch will enable things that break too much existing code,

Btw in case you missed the announcement @skoppe is working on tooling to assess the caused "damage".

[andralex]

What happened to the -dip convention?

[WalterBright]

The -transition=???? seems much better.

This is blocking #5860

[JackStouffer]

Could you please enumerate these enhancements? This is the change log after all.

[WalterBright]

What they will specifically be is unknown at the moment, because it depends on which of the @safe improvements will break significant amounts of code. The only thing that is clear is that we'll need this switch.

[andralex]

"@safe" should be in backquotes (anything not part of the English text should be adorned appropriately)

[andralex]

#6107