Module attrs 

Defines the basics of attributes lowering.

The heart and soul of this module is expand_cfg_attr(), alongside its sibling expand_cfg_attr_with_doc_comments(). It is used to implement all attribute lowering in r-a. Its basic job is to list attributes; however, attributes do not necessarily map into [ast::Attr], because cfg_attr can map to zero, one, or more attributes (#[cfg_attr(predicate, attr1, attr2, ...)]). expand_cfg_attr() expands cfg_attrs as it goes (as its name implies), to list all attributes.

Another thing to note is that we need to be able to map an attribute back to a range (for diagnostic purposes etc.). This is only ever needed for attributes that participate in name resolution. An attribute is mapped back by its AttrId, which is just an index into the item tree attributes list. To minimize the risk of bugs, we have one place (here) and one function (is_item_tree_filtered_attr()) that decides whether an attribute participate in name resolution.

Structs

Attr

AttrId

This is an index of an attribute that always points to the item tree attributes.

Enums

AttrInput

Traits

AstKeyValueMetaExt

AstPathExt

Functions

collect_item_tree_attrs

This collects attributes exactly as the item tree needs them. This is used for the item tree, as well as for resolving AttrIds.

expand_cfg_attr

The callback is passed the attribute and the outermost ast::Attr. Note that one node may map to multiple [ast::Meta]s due to cfg_attr.

expand_cfg_attr_with_doc_comments

is_item_tree_filtered_attr 🔒

parse_path_comma_token_tree 🔒

unescape 🔒