Attributes at the beginning of a file have confusing semantics

[catamorphism]

I was trying to add a #warn attribute to a test case in order to turn a warning into an error, and I spent an embarrassingly large amount of time trying to debug why the warning still seemed to be treated as a warning. The reason was that I put: #[warn(err_non_implicitly_copyable_typarams)]

at the very beginning of the file, which of course meant it applied to only the first item in the file -- which wasn't the one containing the code that triggers the warning. I'd forgotten that attributes only apply to the next item, not the whole file (or module). But I'm sure I'm not the only one who will get confused by this.

I'm not sure what a good solution would be, but I thought I would report it as a potential source of confusion. Maybe when the compiler prints a lint warning or error, it could also print something like "Printing a warning because this is the default setting for item fn quux(...", or "Printing an error because the item class foo {... has a #[warn(err_no_cats_allowed)] attribute"?

[brson]

This is sort of related to #2498 - I want to add javadoc comments (to the parser probably as a special type of attribute), but attributes can either be 'outer' or 'inner' types so that needs to be indicated by the javadocs as well.

Adding significant semicolons after comments is bizarre so I was going to use doxygen's /**< ... */ comments to indicate that a comment is associated with what came before, not what comes after. I was also thinking to change attribute syntax to match. This doesn't fix your problem at all that having two different syntaxes is just confusing, but at least something with the differentiating character in front (#<) would be more visible than the trailing semi.

[bstrie]

+1 for getting rid of the significant semicolon on attributes. Those may very well be the most frightening thing in the language.

[brson]

Added #2569 for changing the inner attribute syntax

[catamorphism]

I didn't even know you could put a semicolon after an attribute, so there you go.

[graydon]

This is now effectively a dupe of #2498 and #2569, closing.