Use `/* value */` as a placeholder
The expression `value` isn't a valid suggestion; let's use `/* value */` as a placeholder (which is also invalid) since it more clearly signals to the user that they need to fill it in with something meaningful. This parallels the suggestions we have in a couple other places, like arguments.
We could also print the type name instead of `/* value */`, especially if it's suggestable, but I don't care strongly about that.
An example directive is ignore-test. In legacy compiletest style, the header
would be written as
// ignore-test
but in ui_test style, the header would be written as
//@ ignore-test
compiletest is changed to accept only //@ directives for UI tests
(currently), and will reject and report an error if it encounters any
comments // <content> that may be parsed as an legacy compiletest-style
test header. To fix this, you should migrate to the ui_test-style header
//@ <content>.
Guillaume Gomez
4764dceb0f