The deprecated attribute missing from many deprecated builtins

[anderseknert]

Currently, only the any and all functions have the deprecated: true attribute set. There are however many more builtins that have been deprecated, and re_match in particular seems to be quite prevalent in policies found in the wild. Properly marking them as deprecated will allow the strict mode checker to fail compilation when encountering these functions, which will help users move away from them.

In addition to adding the attribute to all deprecated functions, make sure to update the docs for strict mode to reflect this.

[srenatus]

When these are properly marked, we can remove this kludge:

opa/internal/cmd/genbuiltinmetadata/main.go

Lines 159 to 161 in 1841703

	case "assign", "cast_array", "cast_boolean", "cast_null", "cast_object", "cast_set", "cast_string",
	"eq", "print", "re_match", "set_diff":
	// Do nothing.

[srenatus]

Thinking about it, a useful follow-up would be to introduce a new category, "deprecated", and render some docs for those deprecated built-in functions, too. After all, if a user finds a use of re_match somewhere, they have no chance to figure out what it is given our current docs.

[anderseknert]

@srenatus won't that kludge still be needed for assign, eq and print? 🙂

[srenatus]

Yeah. But that's less than before 😄