From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- compiler/rustc_builtin_macros/src/derive.rs | 158 ++++++++++++++++++++++++++++ 1 file changed, 158 insertions(+) create mode 100644 compiler/rustc_builtin_macros/src/derive.rs (limited to 'compiler/rustc_builtin_macros/src/derive.rs') diff --git a/compiler/rustc_builtin_macros/src/derive.rs b/compiler/rustc_builtin_macros/src/derive.rs new file mode 100644 index 000000000..d3de10ca4 --- /dev/null +++ b/compiler/rustc_builtin_macros/src/derive.rs @@ -0,0 +1,158 @@ +use crate::cfg_eval::cfg_eval; + +use rustc_ast as ast; +use rustc_ast::{attr, token, GenericParamKind, ItemKind, MetaItemKind, NestedMetaItem, StmtKind}; +use rustc_errors::{struct_span_err, Applicability}; +use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier}; +use rustc_feature::AttributeTemplate; +use rustc_parse::validate_attr; +use rustc_session::Session; +use rustc_span::symbol::{sym, Ident}; +use rustc_span::Span; + +pub(crate) struct Expander; + +impl MultiItemModifier for Expander { + fn expand( + &self, + ecx: &mut ExtCtxt<'_>, + span: Span, + meta_item: &ast::MetaItem, + item: Annotatable, + ) -> ExpandResult, 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 (sess, features) = (ecx.sess, ecx.ecfg.features); + let result = + ecx.resolver.resolve_derives(ecx.current_expansion.id, ecx.force_mode, &|| { + let template = + AttributeTemplate { list: Some("Trait1, Trait2, ..."), ..Default::default() }; + let attr = attr::mk_attr_outer(meta_item.clone()); + validate_attr::check_builtin_attribute( + &sess.parse_sess, + &attr, + sym::derive, + template, + ); + + let mut resolutions: 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 + }) + .map(|path| (path, dummy_annotatable(), None)) + .collect(); + + // Do not configure or clone items unless necessary. + match &mut resolutions[..] { + [] => {} + [(_, first_item, _), others @ ..] => { + *first_item = cfg_eval( + sess, + features, + item.clone(), + ecx.current_expansion.lint_node_id, + ); + for (_, item, _) in others { + *item = first_item.clone(); + } + } + } + + resolutions + }); + + match result { + Ok(()) => ExpandResult::Ready(vec![item]), + Err(Indeterminate) => ExpandResult::Retry(item), + } + } +} + +// The cheapest `Annotatable` to construct. +fn dummy_annotatable() -> Annotatable { + Annotatable::GenericParam(ast::GenericParam { + id: ast::DUMMY_NODE_ID, + ident: Ident::empty(), + attrs: Default::default(), + bounds: Default::default(), + is_placeholder: false, + kind: GenericParamKind::Lifetime, + colon_span: None, + }) +} + +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 `struct`s, `enum`s and `union`s", + ) + .span_label(span, "not applicable here") + .span_label(item.span(), "not a `struct`, `enum` or `union`") + .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",) + .span_label(lit.span, "not a trait") + .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, "", 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") + } + } +} -- cgit v1.2.3