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Rollup merge of #124135 - petrochenkov:deleglob, r=fmease
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delegation: Implement glob delegation

Support delegating to all trait methods in one go.
Overriding globs with explicit definitions is also supported.

The implementation is generally based on the design from rust-lang/rfcs#3530 (comment), but unlike with list delegation in #123413 we cannot expand glob delegation eagerly.
We have to enqueue it into the queue of unexpanded macros (most other macros are processed this way too), and then a glob delegation waits in that queue until its trait path is resolved, and enough code expands to generate the identifier list produced from the glob.

Glob delegation is only allowed in impls, and can only point to traits.
Supporting it in other places gives very little practical benefit, but significantly raises the implementation complexity.

Part of #118212.
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jieyouxu authored Jun 19, 2024
2 parents 8fcd4dd + 22d0b1e commit f8ce1cf
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Showing 29 changed files with 878 additions and 123 deletions.
9 changes: 6 additions & 3 deletions compiler/rustc_ast/src/ast.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3161,13 +3161,16 @@ pub struct Delegation {
pub path: Path,
pub rename: Option<Ident>,
pub body: Option<P<Block>>,
/// The item was expanded from a glob delegation item.
pub from_glob: bool,
}

#[derive(Clone, Encodable, Decodable, Debug)]
pub struct DelegationMac {
pub qself: Option<P<QSelf>>,
pub prefix: Path,
pub suffixes: ThinVec<(Ident, Option<Ident>)>,
// Some for list delegation, and None for glob delegation.
pub suffixes: Option<ThinVec<(Ident, Option<Ident>)>>,
pub body: Option<P<Block>>,
}

Expand Down Expand Up @@ -3294,7 +3297,7 @@ pub enum ItemKind {
///
/// E.g. `reuse <Type as Trait>::name { target_expr_template }`.
Delegation(Box<Delegation>),
/// A list delegation item (`reuse prefix::{a, b, c}`).
/// A list or glob delegation item (`reuse prefix::{a, b, c}`, `reuse prefix::*`).
/// Treated similarly to a macro call and expanded early.
DelegationMac(Box<DelegationMac>),
}
Expand Down Expand Up @@ -3375,7 +3378,7 @@ pub enum AssocItemKind {
MacCall(P<MacCall>),
/// An associated delegation item.
Delegation(Box<Delegation>),
/// An associated delegation item list.
/// An associated list or glob delegation item.
DelegationMac(Box<DelegationMac>),
}

Expand Down
38 changes: 28 additions & 10 deletions compiler/rustc_ast/src/mut_visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1162,7 +1162,14 @@ impl NoopVisitItemKind for ItemKind {
}
ItemKind::MacCall(m) => vis.visit_mac_call(m),
ItemKind::MacroDef(def) => vis.visit_macro_def(def),
ItemKind::Delegation(box Delegation { id, qself, path, rename, body }) => {
ItemKind::Delegation(box Delegation {
id,
qself,
path,
rename,
body,
from_glob: _,
}) => {
vis.visit_id(id);
vis.visit_qself(qself);
vis.visit_path(path);
Expand All @@ -1176,10 +1183,12 @@ impl NoopVisitItemKind for ItemKind {
ItemKind::DelegationMac(box DelegationMac { qself, prefix, suffixes, body }) => {
vis.visit_qself(qself);
vis.visit_path(prefix);
for (ident, rename) in suffixes {
vis.visit_ident(ident);
if let Some(rename) = rename {
vis.visit_ident(rename);
if let Some(suffixes) = suffixes {
for (ident, rename) in suffixes {
vis.visit_ident(ident);
if let Some(rename) = rename {
vis.visit_ident(rename);
}
}
}
if let Some(body) = body {
Expand Down Expand Up @@ -1218,7 +1227,14 @@ impl NoopVisitItemKind for AssocItemKind {
visit_opt(ty, |ty| visitor.visit_ty(ty));
}
AssocItemKind::MacCall(mac) => visitor.visit_mac_call(mac),
AssocItemKind::Delegation(box Delegation { id, qself, path, rename, body }) => {
AssocItemKind::Delegation(box Delegation {
id,
qself,
path,
rename,
body,
from_glob: _,
}) => {
visitor.visit_id(id);
visitor.visit_qself(qself);
visitor.visit_path(path);
Expand All @@ -1232,10 +1248,12 @@ impl NoopVisitItemKind for AssocItemKind {
AssocItemKind::DelegationMac(box DelegationMac { qself, prefix, suffixes, body }) => {
visitor.visit_qself(qself);
visitor.visit_path(prefix);
for (ident, rename) in suffixes {
visitor.visit_ident(ident);
if let Some(rename) = rename {
visitor.visit_ident(rename);
if let Some(suffixes) = suffixes {
for (ident, rename) in suffixes {
visitor.visit_ident(ident);
if let Some(rename) = rename {
visitor.visit_ident(rename);
}
}
}
if let Some(body) = body {
Expand Down
38 changes: 28 additions & 10 deletions compiler/rustc_ast/src/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -408,7 +408,14 @@ impl WalkItemKind for ItemKind {
}
ItemKind::MacCall(mac) => try_visit!(visitor.visit_mac_call(mac)),
ItemKind::MacroDef(ts) => try_visit!(visitor.visit_mac_def(ts, item.id)),
ItemKind::Delegation(box Delegation { id, qself, path, rename, body }) => {
ItemKind::Delegation(box Delegation {
id,
qself,
path,
rename,
body,
from_glob: _,
}) => {
if let Some(qself) = qself {
try_visit!(visitor.visit_ty(&qself.ty));
}
Expand All @@ -421,10 +428,12 @@ impl WalkItemKind for ItemKind {
try_visit!(visitor.visit_ty(&qself.ty));
}
try_visit!(visitor.visit_path(prefix, item.id));
for (ident, rename) in suffixes {
visitor.visit_ident(*ident);
if let Some(rename) = rename {
visitor.visit_ident(*rename);
if let Some(suffixes) = suffixes {
for (ident, rename) in suffixes {
visitor.visit_ident(*ident);
if let Some(rename) = rename {
visitor.visit_ident(*rename);
}
}
}
visit_opt!(visitor, visit_block, body);
Expand Down Expand Up @@ -837,7 +846,14 @@ impl WalkItemKind for AssocItemKind {
AssocItemKind::MacCall(mac) => {
try_visit!(visitor.visit_mac_call(mac));
}
AssocItemKind::Delegation(box Delegation { id, qself, path, rename, body }) => {
AssocItemKind::Delegation(box Delegation {
id,
qself,
path,
rename,
body,
from_glob: _,
}) => {
if let Some(qself) = qself {
try_visit!(visitor.visit_ty(&qself.ty));
}
Expand All @@ -850,10 +866,12 @@ impl WalkItemKind for AssocItemKind {
try_visit!(visitor.visit_ty(&qself.ty));
}
try_visit!(visitor.visit_path(prefix, item.id));
for (ident, rename) in suffixes {
visitor.visit_ident(*ident);
if let Some(rename) = rename {
visitor.visit_ident(*rename);
if let Some(suffixes) = suffixes {
for (ident, rename) in suffixes {
visitor.visit_ident(*ident);
if let Some(rename) = rename {
visitor.visit_ident(*rename);
}
}
}
visit_opt!(visitor, visit_block, body);
Expand Down
51 changes: 32 additions & 19 deletions compiler/rustc_ast_pretty/src/pprust/state/item.rs
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,12 @@ use rustc_ast::ptr::P;
use rustc_ast::ModKind;
use rustc_span::symbol::Ident;

enum DelegationKind<'a> {
Single,
List(&'a [(Ident, Option<Ident>)]),
Glob,
}

fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
format!("{}{}", State::to_string(|s| s.print_visibility(vis)), s)
}
Expand Down Expand Up @@ -387,15 +393,15 @@ impl<'a> State<'a> {
&item.vis,
&deleg.qself,
&deleg.path,
None,
DelegationKind::Single,
&deleg.body,
),
ast::ItemKind::DelegationMac(deleg) => self.print_delegation(
&item.attrs,
&item.vis,
&deleg.qself,
&deleg.prefix,
Some(&deleg.suffixes),
deleg.suffixes.as_ref().map_or(DelegationKind::Glob, |s| DelegationKind::List(s)),
&deleg.body,
),
}
Expand Down Expand Up @@ -579,28 +585,28 @@ impl<'a> State<'a> {
vis,
&deleg.qself,
&deleg.path,
None,
DelegationKind::Single,
&deleg.body,
),
ast::AssocItemKind::DelegationMac(deleg) => self.print_delegation(
&item.attrs,
vis,
&deleg.qself,
&deleg.prefix,
Some(&deleg.suffixes),
deleg.suffixes.as_ref().map_or(DelegationKind::Glob, |s| DelegationKind::List(s)),
&deleg.body,
),
}
self.ann.post(self, AnnNode::SubItem(id))
}

pub(crate) fn print_delegation(
fn print_delegation(
&mut self,
attrs: &[ast::Attribute],
vis: &ast::Visibility,
qself: &Option<P<ast::QSelf>>,
path: &ast::Path,
suffixes: Option<&[(Ident, Option<Ident>)]>,
kind: DelegationKind<'_>,
body: &Option<P<ast::Block>>,
) {
if body.is_some() {
Expand All @@ -614,21 +620,28 @@ impl<'a> State<'a> {
} else {
self.print_path(path, false, 0);
}
if let Some(suffixes) = suffixes {
self.word("::");
self.word("{");
for (i, (ident, rename)) in suffixes.iter().enumerate() {
self.print_ident(*ident);
if let Some(rename) = rename {
self.nbsp();
self.word_nbsp("as");
self.print_ident(*rename);
}
if i != suffixes.len() - 1 {
self.word_space(",");
match kind {
DelegationKind::Single => {}
DelegationKind::List(suffixes) => {
self.word("::");
self.word("{");
for (i, (ident, rename)) in suffixes.iter().enumerate() {
self.print_ident(*ident);
if let Some(rename) = rename {
self.nbsp();
self.word_nbsp("as");
self.print_ident(*rename);
}
if i != suffixes.len() - 1 {
self.word_space(",");
}
}
self.word("}");
}
DelegationKind::Glob => {
self.word("::");
self.word("*");
}
self.word("}");
}
if let Some(body) = body {
self.nbsp();
Expand Down
7 changes: 5 additions & 2 deletions compiler/rustc_expand/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,8 @@ expand_duplicate_matcher_binding = duplicate matcher binding
.label = duplicate binding
.label2 = previous binding
expand_empty_delegation_list =
empty list delegation is not supported
expand_empty_delegation_mac =
empty {$kind} delegation is not supported
expand_expected_paren_or_brace =
expected `(` or `{"{"}`, found `{$token}`
Expand All @@ -58,6 +58,9 @@ expand_feature_removed =
.label = feature has been removed
.reason = {$reason}
expand_glob_delegation_outside_impls =
glob delegation is only supported in impls
expand_helper_attribute_name_invalid =
`{$name}` cannot be a name of derive helper attribute
Expand Down
47 changes: 46 additions & 1 deletion compiler/rustc_expand/src/base.rs
Original file line number Diff line number Diff line change
Expand Up @@ -357,6 +357,10 @@ where
}
}

pub trait GlobDelegationExpander {
fn expand(&self, ecx: &mut ExtCtxt<'_>) -> ExpandResult<Vec<(Ident, Option<Ident>)>, ()>;
}

// Use a macro because forwarding to a simple function has type system issues
macro_rules! make_stmts_default {
($me:expr) => {
Expand Down Expand Up @@ -714,6 +718,9 @@ pub enum SyntaxExtensionKind {
/// The produced AST fragment is appended to the input AST fragment.
Box<dyn MultiItemModifier + sync::DynSync + sync::DynSend>,
),

/// A glob delegation.
GlobDelegation(Box<dyn GlobDelegationExpander + sync::DynSync + sync::DynSend>),
}

/// A struct representing a macro definition in "lowered" form ready for expansion.
Expand Down Expand Up @@ -748,7 +755,9 @@ impl SyntaxExtension {
/// Returns which kind of macro calls this syntax extension.
pub fn macro_kind(&self) -> MacroKind {
match self.kind {
SyntaxExtensionKind::Bang(..) | SyntaxExtensionKind::LegacyBang(..) => MacroKind::Bang,
SyntaxExtensionKind::Bang(..)
| SyntaxExtensionKind::LegacyBang(..)
| SyntaxExtensionKind::GlobDelegation(..) => MacroKind::Bang,
SyntaxExtensionKind::Attr(..)
| SyntaxExtensionKind::LegacyAttr(..)
| SyntaxExtensionKind::NonMacroAttr => MacroKind::Attr,
Expand Down Expand Up @@ -922,6 +931,32 @@ impl SyntaxExtension {
SyntaxExtension::default(SyntaxExtensionKind::NonMacroAttr, edition)
}

pub fn glob_delegation(
trait_def_id: DefId,
impl_def_id: LocalDefId,
edition: Edition,
) -> SyntaxExtension {
struct GlobDelegationExpanderImpl {
trait_def_id: DefId,
impl_def_id: LocalDefId,
}
impl GlobDelegationExpander for GlobDelegationExpanderImpl {
fn expand(
&self,
ecx: &mut ExtCtxt<'_>,
) -> ExpandResult<Vec<(Ident, Option<Ident>)>, ()> {
match ecx.resolver.glob_delegation_suffixes(self.trait_def_id, self.impl_def_id) {
Ok(suffixes) => ExpandResult::Ready(suffixes),
Err(Indeterminate) if ecx.force_mode => ExpandResult::Ready(Vec::new()),
Err(Indeterminate) => ExpandResult::Retry(()),
}
}
}

let expander = GlobDelegationExpanderImpl { trait_def_id, impl_def_id };
SyntaxExtension::default(SyntaxExtensionKind::GlobDelegation(Box::new(expander)), edition)
}

pub fn expn_data(
&self,
parent: LocalExpnId,
Expand Down Expand Up @@ -1030,6 +1065,16 @@ pub trait ResolverExpand {

/// Tools registered with `#![register_tool]` and used by tool attributes and lints.
fn registered_tools(&self) -> &RegisteredTools;

/// Mark this invocation id as a glob delegation.
fn register_glob_delegation(&mut self, invoc_id: LocalExpnId);

/// Names of specific methods to which glob delegation expands.
fn glob_delegation_suffixes(
&mut self,
trait_def_id: DefId,
impl_def_id: LocalDefId,
) -> Result<Vec<(Ident, Option<Ident>)>, Indeterminate>;
}

pub trait LintStoreExpand {
Expand Down
12 changes: 10 additions & 2 deletions compiler/rustc_expand/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -435,8 +435,16 @@ pub struct ExpectedParenOrBrace<'a> {
}

#[derive(Diagnostic)]
#[diag(expand_empty_delegation_list)]
pub(crate) struct EmptyDelegationList {
#[diag(expand_empty_delegation_mac)]
pub(crate) struct EmptyDelegationMac {
#[primary_span]
pub span: Span,
pub kind: String,
}

#[derive(Diagnostic)]
#[diag(expand_glob_delegation_outside_impls)]
pub(crate) struct GlobDelegationOutsideImpls {
#[primary_span]
pub span: Span,
}
Expand Down
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