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Delegation: ast lowering refactor #126947

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Jun 25, 2024
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Delegation: ast lowering refactor #126947

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107 changes: 49 additions & 58 deletions compiler/rustc_ast_lowering/src/delegation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -66,14 +66,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
let Ok(sig_id) = sig_id else {
return false;
};
if let Some(local_sig_id) = sig_id.as_local() {
self.has_self(sig_id, span)
}

fn has_self(&self, def_id: DefId, span: Span) -> bool {
if let Some(local_sig_id) = def_id.as_local() {
// The value may be missing due to recursive delegation.
// Error will be emmited later during HIR ty lowering.
self.resolver.delegation_fn_sigs.get(&local_sig_id).map_or(false, |sig| sig.has_self)
} else {
match self.tcx.def_kind(sig_id) {
match self.tcx.def_kind(def_id) {
DefKind::Fn => false,
DefKind::AssocFn => self.tcx.associated_item(sig_id).fn_has_self_parameter,
DefKind::AssocFn => self.tcx.associated_item(def_id).fn_has_self_parameter,
_ => span_bug!(span, "unexpected DefKind for delegation item"),
}
}
Expand Down Expand Up @@ -107,12 +111,17 @@ impl<'hir> LoweringContext<'_, 'hir> {
span: Span,
) -> Result<DefId, ErrorGuaranteed> {
let sig_id = if self.is_in_trait_impl { item_id } else { path_id };
let sig_id =
self.resolver.get_partial_res(sig_id).and_then(|r| r.expect_full_res().opt_def_id());
sig_id.ok_or_else(|| {
self.tcx
.dcx()
.span_delayed_bug(span, "LoweringContext: couldn't resolve delegation item")
self.get_resolution_id(sig_id, span)
}

fn get_resolution_id(&self, node_id: NodeId, span: Span) -> Result<DefId, ErrorGuaranteed> {
let def_id =
self.resolver.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id());
def_id.ok_or_else(|| {
self.tcx.dcx().span_delayed_bug(
span,
format!("LoweringContext: couldn't resolve node {:?} in delegation item", node_id),
)
})
}

Expand All @@ -122,7 +131,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
predicates: &[],
has_where_clause_predicates: false,
where_clause_span: span,
span: span,
span,
})
}

Expand Down Expand Up @@ -222,12 +231,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
}));

let path = self.arena.alloc(hir::Path { span, res: Res::Local(param_id), segments });

hir::Expr {
hir_id: self.next_id(),
kind: hir::ExprKind::Path(hir::QPath::Resolved(None, path)),
span,
}
self.mk_expr(hir::ExprKind::Path(hir::QPath::Resolved(None, path)), span)
}

fn lower_delegation_body(
Expand All @@ -236,19 +240,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
param_count: usize,
span: Span,
) -> BodyId {
let path = self.lower_qpath(
delegation.id,
&delegation.qself,
&delegation.path,
ParamMode::Optional,
ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
let block = delegation.body.as_deref();

self.lower_body(|this| {
let mut parameters: Vec<hir::Param<'_>> = Vec::new();
let mut args: Vec<hir::Expr<'hir>> = Vec::new();
let mut parameters: Vec<hir::Param<'_>> = Vec::with_capacity(param_count);
let mut args: Vec<hir::Expr<'_>> = Vec::with_capacity(param_count);

for idx in 0..param_count {
let (param, pat_node_id) = this.generate_param(span);
Expand All @@ -264,55 +260,49 @@ impl<'hir> LoweringContext<'_, 'hir> {
};
self_resolver.visit_block(block);
let block = this.lower_block(block, false);
hir::Expr {
hir_id: this.next_id(),
kind: hir::ExprKind::Block(block, None),
span: block.span,
}
this.mk_expr(hir::ExprKind::Block(block, None), block.span)
} else {
let pat_hir_id = this.lower_node_id(pat_node_id);
this.generate_arg(pat_hir_id, span)
};
args.push(arg);
}

let args = self.arena.alloc_from_iter(args);
let final_expr = this.generate_call(path, args);
let final_expr = this.finalize_body_lowering(delegation, args, span);
(this.arena.alloc_from_iter(parameters), final_expr)
})
}

fn generate_call(
// Generates fully qualified call for the resulting body.
fn finalize_body_lowering(
&mut self,
path: hir::QPath<'hir>,
args: &'hir [hir::Expr<'hir>],
delegation: &Delegation,
args: Vec<hir::Expr<'hir>>,
span: Span,
) -> hir::Expr<'hir> {
let callee = self.arena.alloc(hir::Expr {
hir_id: self.next_id(),
kind: hir::ExprKind::Path(path),
span: path.span(),
});
let path = self.lower_qpath(
delegation.id,
&delegation.qself,
&delegation.path,
ParamMode::Optional,
ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);

let expr = self.arena.alloc(hir::Expr {
hir_id: self.next_id(),
kind: hir::ExprKind::Call(callee, args),
span: path.span(),
});
let args = self.arena.alloc_from_iter(args);
let path_expr = self.arena.alloc(self.mk_expr(hir::ExprKind::Path(path), span));
let call = self.arena.alloc(self.mk_expr(hir::ExprKind::Call(path_expr, args), span));

let block = self.arena.alloc(hir::Block {
stmts: &[],
expr: Some(expr),
expr: Some(call),
hir_id: self.next_id(),
rules: hir::BlockCheckMode::DefaultBlock,
span: path.span(),
span,
targeted_by_break: false,
});

hir::Expr {
hir_id: self.next_id(),
kind: hir::ExprKind::Block(block, None),
span: path.span(),
}
self.mk_expr(hir::ExprKind::Block(block, None), span)
}

fn generate_delegation_error(
Expand All @@ -333,11 +323,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
let header = self.generate_header_error();
let sig = hir::FnSig { decl, header, span };

let body_id = self.lower_body(|this| {
let expr =
hir::Expr { hir_id: this.next_id(), kind: hir::ExprKind::Err(err), span: span };
(&[], expr)
});
let body_id = self.lower_body(|this| (&[], this.mk_expr(hir::ExprKind::Err(err), span)));
DelegationResults { generics, body_id, sig }
}

Expand All @@ -349,6 +335,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
abi: abi::Abi::Rust,
}
}

#[inline]
fn mk_expr(&mut self, kind: hir::ExprKind<'hir>, span: Span) -> hir::Expr<'hir> {
hir::Expr { hir_id: self.next_id(), kind, span }
}
}

struct SelfResolver<'a> {
Expand Down
8 changes: 4 additions & 4 deletions tests/ui/delegation/explicit-paths.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -110,10 +110,10 @@ error[E0308]: mismatched types
--> $DIR/explicit-paths.rs:78:30
|
LL | reuse <S2 as Trait>::foo1;
| ---------------^^^^
| | |
| | expected `&S2`, found `&S`
| arguments to this function are incorrect
| ^^^^
| |
| expected `&S2`, found `&S`
| arguments to this function are incorrect
|
= note: expected reference `&S2`
found reference `&S`
Expand Down
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