bjoernager/rust
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Avoid empty identifiers for delegate params and args.

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Instead use `argN`. The empty identifiers could flow to
`Liveness::should_warn`, where they would trigger a bounds error.

Fixes #139512.
This commit is contained in:
Nicholas Nethercote 2025-04-10 13:44:57 +10:00
parent 3cb9966235
commit 9bb1008e1d
2 changed files with 10 additions and 9 deletions
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15
compiler/rustc_ast_lowering/src/delegation.rs
View file

@ -47,7 +47,7 @@ use rustc_errors::ErrorGuaranteed;
use rustc_hir::def_id::DefId; use rustc_hir::def_id::DefId;
use rustc_middle::span_bug; use rustc_middle::span_bug;
use rustc_middle::ty::{Asyncness, ResolverAstLowering}; use rustc_middle::ty::{Asyncness, ResolverAstLowering};
use rustc_span::{Ident, Span}; use rustc_span::{Ident, Span, Symbol};
use {rustc_ast as ast, rustc_hir as hir}; use {rustc_ast as ast, rustc_hir as hir};
use super::{GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode}; use super::{GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode};
@ -234,12 +234,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
hir::FnSig { decl, header, span } hir::FnSig { decl, header, span }
} }
fn generate_param(&mut self, span: Span) -> (hir::Param<'hir>, NodeId) { fn generate_param(&mut self, idx: usize, span: Span) -> (hir::Param<'hir>, NodeId) {
let pat_node_id = self.next_node_id(); let pat_node_id = self.next_node_id();
let pat_id = self.lower_node_id(pat_node_id); let pat_id = self.lower_node_id(pat_node_id);
let ident = Ident::with_dummy_span(Symbol::intern(&format!("arg{idx}")));
let pat = self.arena.alloc(hir::Pat { let pat = self.arena.alloc(hir::Pat {
hir_id: pat_id, hir_id: pat_id,
kind: hir::PatKind::Binding(hir::BindingMode::NONE, pat_id, Ident::empty(), None), kind: hir::PatKind::Binding(hir::BindingMode::NONE, pat_id, ident, None),
span, span,
default_binding_modes: false, default_binding_modes: false,
}); });
@ -247,9 +248,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
(hir::Param { hir_id: self.next_id(), pat, ty_span: span, span }, pat_node_id) (hir::Param { hir_id: self.next_id(), pat, ty_span: span, span }, pat_node_id)
} }
fn generate_arg(&mut self, param_id: HirId, span: Span) -> hir::Expr<'hir> { fn generate_arg(&mut self, idx: usize, param_id: HirId, span: Span) -> hir::Expr<'hir> {
let segments = self.arena.alloc_from_iter(iter::once(hir::PathSegment { let segments = self.arena.alloc_from_iter(iter::once(hir::PathSegment {
ident: Ident::empty(), ident: Ident::with_dummy_span(Symbol::intern(&format!("arg{idx}"))),
hir_id: self.next_id(), hir_id: self.next_id(),
res: Res::Local(param_id), res: Res::Local(param_id),
args: None, args: None,
@ -273,7 +274,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
let mut args: Vec<hir::Expr<'_>> = Vec::with_capacity(param_count); let mut args: Vec<hir::Expr<'_>> = Vec::with_capacity(param_count);
for idx in 0..param_count { for idx in 0..param_count {
let (param, pat_node_id) = this.generate_param(span); let (param, pat_node_id) = this.generate_param(idx, span);
parameters.push(param); parameters.push(param);
let arg = if let Some(block) = block let arg = if let Some(block) = block
@ -289,7 +290,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
this.ident_and_label_to_local_id.insert(pat_node_id, param.pat.hir_id.local_id); this.ident_and_label_to_local_id.insert(pat_node_id, param.pat.hir_id.local_id);
this.lower_target_expr(&block) this.lower_target_expr(&block)
} else { } else {
this.generate_arg(param.pat.hir_id, span) this.generate_arg(idx, param.pat.hir_id, span)
}; };
args.push(arg); args.push(arg);
} }

4
tests/pretty/hir-delegation.pp
View file

@ -11,13 +11,13 @@ extern crate std;
fn b<C>(e: C) { } fn b<C>(e: C) { }
trait G { trait G {
fn b(: _) -> _ { b({ }) } fn b(arg0: _) -> _ { b({ }) }
} }
mod m { mod m {
fn add(a: u32, b: u32) -> u32 { a + b } fn add(a: u32, b: u32) -> u32 { a + b }
} }
fn add(: _, : _) -> _ { m::add(, ) } fn add(arg0: _, arg1: _) -> _ { m::add(arg0, arg1) }
fn main() { { let _ = add(1, 2); }; } fn main() { { let _ = add(1, 2); }; }