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fix[154166]: closure debug capture print #162154

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Merged
rust-bors merged 1 commit into from
Sep 4, 2026
+30 −14
Merged

fix[154166]: closure debug capture print #162154

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24 changes: 10 additions & 14 deletions compiler/rustc_middle/src/mir/pretty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1256,13 +1256,11 @@ impl<'tcx> Debug for Rvalue<'tcx> {
};
let mut struct_fmt = fmt.debug_struct(&name);

// FIXME(project-rfc-2229#48): This should be a list of capture names/places
if let Some(def_id) = def_id.as_local()
&& let Some(upvars) = tcx.upvars_mentioned(def_id)
{
for (&var_id, place) in iter::zip(upvars.keys(), places) {
let var_name = tcx.hir_name(var_id);
struct_fmt.field(var_name.as_str(), place);
if let Some(def_id) = def_id.as_local() {
let captures = tcx.closure_captures(def_id);
assert_eq!(captures.len(), places.len());
for (&capture, place) in iter::zip(captures, places) {
struct_fmt.field(capture.to_symbol().as_str(), place);
}
} else {
for (index, place) in places.iter().enumerate() {
Expand All @@ -1277,13 +1275,11 @@ impl<'tcx> Debug for Rvalue<'tcx> {
let name = format!("{{coroutine@{:?}}}", tcx.def_span(def_id));
let mut struct_fmt = fmt.debug_struct(&name);

// FIXME(project-rfc-2229#48): This should be a list of capture names/places
if let Some(def_id) = def_id.as_local()
&& let Some(upvars) = tcx.upvars_mentioned(def_id)
{
for (&var_id, place) in iter::zip(upvars.keys(), places) {
let var_name = tcx.hir_name(var_id);
struct_fmt.field(var_name.as_str(), place);
if let Some(def_id) = def_id.as_local() {
let captures = tcx.closure_captures(def_id);
assert_eq!(captures.len(), places.len());
for (&capture, place) in iter::zip(captures, places) {
struct_fmt.field(capture.to_symbol().as_str(), place);
}
} else {
for (index, place) in places.iter().enumerate() {
Expand Down
20 changes: 20 additions & 0 deletions tests/mir-opt/issues/issue_154166.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
// Check that closure debug implementation correctly displays all captures precisely.

//@ revisions: e2018 e2021
//@[e2018] edition: 2018
//@[e2021] edition: 2021

#![crate_type = "lib"]

pub fn foo(x: (String, String)) {
// CHECK-LABEL: foo(
// e2018: {closure{{.*}}issue_154166{{.*}}} { x: {{.*}} };
// e2021: {closure{{.*}}issue_154166{{.*}}} { x__0: {{.*}}, x__1: {{.*}} };
let _closure = || {
if std::hint::black_box(true) {
let _a = &x.1;
} else {
let _b = x.0;
}
};
}
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