Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
expand/resolve: Turn
#[derive]
into a regular macro attribute
- Loading branch information
1 parent
ae00b62
commit dbdbd30
Showing
58 changed files
with
1,249 additions
and
1,008 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,132 @@ | ||
use rustc_ast::{self as ast, token, ItemKind, MetaItemKind, NestedMetaItem, StmtKind}; | ||
use rustc_errors::{struct_span_err, Applicability}; | ||
use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier}; | ||
use rustc_expand::config::StripUnconfigured; | ||
use rustc_feature::AttributeTemplate; | ||
use rustc_parse::validate_attr; | ||
use rustc_session::Session; | ||
use rustc_span::symbol::sym; | ||
use rustc_span::Span; | ||
|
||
crate struct Expander; | ||
|
||
impl MultiItemModifier for Expander { | ||
fn expand( | ||
&self, | ||
ecx: &mut ExtCtxt<'_>, | ||
span: Span, | ||
meta_item: &ast::MetaItem, | ||
item: Annotatable, | ||
) -> ExpandResult<Vec<Annotatable>, Annotatable> { | ||
let sess = ecx.sess; | ||
if report_bad_target(sess, &item, span) { | ||
// We don't want to pass inappropriate targets to derive macros to avoid | ||
// follow up errors, all other errors below are recoverable. | ||
return ExpandResult::Ready(vec![item]); | ||
} | ||
|
||
let template = | ||
AttributeTemplate { list: Some("Trait1, Trait2, ..."), ..Default::default() }; | ||
let attr = ecx.attribute(meta_item.clone()); | ||
validate_attr::check_builtin_attribute(&sess.parse_sess, &attr, sym::derive, template); | ||
|
||
let derives: Vec<_> = attr | ||
.meta_item_list() | ||
.unwrap_or_default() | ||
.into_iter() | ||
.filter_map(|nested_meta| match nested_meta { | ||
NestedMetaItem::MetaItem(meta) => Some(meta), | ||
NestedMetaItem::Literal(lit) => { | ||
// Reject `#[derive("Debug")]`. | ||
report_unexpected_literal(sess, &lit); | ||
None | ||
} | ||
}) | ||
.map(|meta| { | ||
// Reject `#[derive(Debug = "value", Debug(abc))]`, but recover the paths. | ||
report_path_args(sess, &meta); | ||
meta.path | ||
}) | ||
.collect(); | ||
|
||
// FIXME: Try to cache intermediate results to avoid collecting same paths multiple times. | ||
match ecx.resolver.resolve_derives(ecx.current_expansion.id, derives, ecx.force_mode) { | ||
Ok(()) => { | ||
let mut visitor = | ||
StripUnconfigured { sess, features: ecx.ecfg.features, modified: false }; | ||
let mut item = visitor.fully_configure(item); | ||
if visitor.modified { | ||
// Erase the tokens if cfg-stripping modified the item | ||
// This will cause us to synthesize fake tokens | ||
// when `nt_to_tokenstream` is called on this item. | ||
match &mut item { | ||
Annotatable::Item(item) => item, | ||
Annotatable::Stmt(stmt) => match &mut stmt.kind { | ||
StmtKind::Item(item) => item, | ||
_ => unreachable!(), | ||
}, | ||
_ => unreachable!(), | ||
} | ||
.tokens = None; | ||
} | ||
ExpandResult::Ready(vec![item]) | ||
} | ||
Err(Indeterminate) => ExpandResult::Retry(item), | ||
} | ||
} | ||
} | ||
|
||
fn report_bad_target(sess: &Session, item: &Annotatable, span: Span) -> bool { | ||
let item_kind = match item { | ||
Annotatable::Item(item) => Some(&item.kind), | ||
Annotatable::Stmt(stmt) => match &stmt.kind { | ||
StmtKind::Item(item) => Some(&item.kind), | ||
_ => None, | ||
}, | ||
_ => None, | ||
}; | ||
|
||
let bad_target = | ||
!matches!(item_kind, Some(ItemKind::Struct(..) | ItemKind::Enum(..) | ItemKind::Union(..))); | ||
if bad_target { | ||
struct_span_err!( | ||
sess, | ||
span, | ||
E0774, | ||
"`derive` may only be applied to structs, enums and unions", | ||
) | ||
.emit(); | ||
} | ||
bad_target | ||
} | ||
|
||
fn report_unexpected_literal(sess: &Session, lit: &ast::Lit) { | ||
let help_msg = match lit.token.kind { | ||
token::Str if rustc_lexer::is_ident(&lit.token.symbol.as_str()) => { | ||
format!("try using `#[derive({})]`", lit.token.symbol) | ||
} | ||
_ => "for example, write `#[derive(Debug)]` for `Debug`".to_string(), | ||
}; | ||
struct_span_err!(sess, lit.span, E0777, "expected path to a trait, found literal",) | ||
.help(&help_msg) | ||
.emit(); | ||
} | ||
|
||
fn report_path_args(sess: &Session, meta: &ast::MetaItem) { | ||
let report_error = |title, action| { | ||
let span = meta.span.with_lo(meta.path.span.hi()); | ||
sess.struct_span_err(span, title) | ||
.span_suggestion(span, action, String::new(), Applicability::MachineApplicable) | ||
.emit(); | ||
}; | ||
match meta.kind { | ||
MetaItemKind::Word => {} | ||
MetaItemKind::List(..) => report_error( | ||
"traits in `#[derive(...)]` don't accept arguments", | ||
"remove the arguments", | ||
), | ||
MetaItemKind::NameValue(..) => { | ||
report_error("traits in `#[derive(...)]` don't accept values", "remove the value") | ||
} | ||
} | ||
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.