Suggest removing Box::new instead of unboxing it#146259

camsteffen · 2025-09-06T02:37:31Z

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rustbot · 2025-09-06T02:37:35Z

rustbot has assigned @jackh726.
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fmease · 2025-09-06T02:47:41Z

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

+                                    vec![
+                                        (expr.span.until(arg.span), "".to_string()),
+                                        (
+                                            expr.span.with_lo(expr.span.hi() - BytePos(1)),


Does your code crash on this?

fn main() { let _: String = Box::new(String::new()❩; }

I've replaced the final ) (U+0028) with ❩ (U+2769). CC #128790.

Hmm, I didn't want to use the argument span since it could be a parent or child expansion...

If you want to keep basing things off of expr.span, consider using one of SourceMap::{start,end,next}_point or similar.

Otherwise, shouldn't you be able to use things like find_ancestor_inside{,_same_ctxt}?

Oh I saw your next comment after a refresh. end_point is good!

Otherwise, shouldn't you be able to use things like find_ancestor_inside{,_same_ctxt}?

That would work if the arg is a child expansion, but not if it's a parent. -- Box::new($x)

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

jackh726 · 2025-09-16T08:52:19Z

@bors r+

bors · 2025-09-16T08:52:22Z

📌 Commit d66fb49 has been approved by jackh726

It is now in the queue for this repository.

bors · 2025-09-16T09:05:15Z

⌛ Testing commit d66fb49 with merge f199c62...

Suggest removing Box::new instead of unboxing it

bors · 2025-09-16T09:17:25Z

💔 Test failed - checks-actions

rust-log-analyzer · 2025-09-16T09:25:45Z

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Zalathar · 2025-09-16T09:43:04Z

@bors retry (flaked out)

Suggest removing Box::new instead of unboxing it

Rollup of 3 pull requests Successful merges: - #145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - #146259 (Suggest removing Box::new instead of unboxing it) - #146588 (tests/run-make: Update list of statically linked musl targets) r? `@ghost` `@rustbot` modify labels: rollup

Suggest removing Box::new instead of unboxing it

Rollup of 9 pull requests Successful merges: - #144871 (Stabilize `btree_entry_insert` feature) - #145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - #145838 (don't apply temporary lifetime extension rules to non-extended `super let`) - #146259 (Suggest removing Box::new instead of unboxing it) - #146410 (Iterator repeat: no infinite loop for `last` and `count`) - #146460 (Add tidy readme) - #146581 (Detect attempt to use var-args in closure) - #146588 (tests/run-make: Update list of statically linked musl targets) - #146647 (Move `#[rustc_coherence_is_core]` to the `crate_level` file) r? `@ghost` `@rustbot` modify labels: rollup

Suggest removing Box::new instead of unboxing it

Rollup of 14 pull requests Successful merges: - #142807 (libtest: expose --fail-fast as an unstable command-line option) - #144871 (Stabilize `btree_entry_insert` feature) - #145071 (Update the minimum external LLVM to 20) - #145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - #145660 (initial implementation of the darwin_objc unstable feature) - #145838 (don't apply temporary lifetime extension rules to non-extended `super let`) - #146259 (Suggest removing Box::new instead of unboxing it) - #146410 (Iterator repeat: no infinite loop for `last` and `count`) - #146460 (Add tidy readme) - #146552 (StateTransform: Do not renumber resume local.) - #146564 (Remove Rvalue::Len again.) - #146581 (Detect attempt to use var-args in closure) - #146588 (tests/run-make: Update list of statically linked musl targets) - #146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3)) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #146259 - camsteffen:remove-the-box, r=jackh726 Suggest removing Box::new instead of unboxing it

Rollup of 14 pull requests Successful merges: - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option) - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature) - rust-lang/rust#145071 (Update the minimum external LLVM to 20) - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature) - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`) - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it) - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`) - rust-lang/rust#146460 (Add tidy readme) - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.) - rust-lang/rust#146564 (Remove Rvalue::Len again.) - rust-lang/rust#146581 (Detect attempt to use var-args in closure) - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets) - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3)) r? `@ghost` `@rustbot` modify labels: rollup

Suggest removing Box::new instead of unboxing it

Rollup of 14 pull requests Successful merges: - rust-lang#142807 (libtest: expose --fail-fast as an unstable command-line option) - rust-lang#144871 (Stabilize `btree_entry_insert` feature) - rust-lang#145071 (Update the minimum external LLVM to 20) - rust-lang#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - rust-lang#145660 (initial implementation of the darwin_objc unstable feature) - rust-lang#145838 (don't apply temporary lifetime extension rules to non-extended `super let`) - rust-lang#146259 (Suggest removing Box::new instead of unboxing it) - rust-lang#146410 (Iterator repeat: no infinite loop for `last` and `count`) - rust-lang#146460 (Add tidy readme) - rust-lang#146552 (StateTransform: Do not renumber resume local.) - rust-lang#146564 (Remove Rvalue::Len again.) - rust-lang#146581 (Detect attempt to use var-args in closure) - rust-lang#146588 (tests/run-make: Update list of statically linked musl targets) - rust-lang#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3)) r? `@ghost` `@rustbot` modify labels: rollup

Suggest removing Box::new instead of unboxing it

Rollup of 14 pull requests Successful merges: - rust-lang#142807 (libtest: expose --fail-fast as an unstable command-line option) - rust-lang#144871 (Stabilize `btree_entry_insert` feature) - rust-lang#145071 (Update the minimum external LLVM to 20) - rust-lang#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - rust-lang#145660 (initial implementation of the darwin_objc unstable feature) - rust-lang#145838 (don't apply temporary lifetime extension rules to non-extended `super let`) - rust-lang#146259 (Suggest removing Box::new instead of unboxing it) - rust-lang#146410 (Iterator repeat: no infinite loop for `last` and `count`) - rust-lang#146460 (Add tidy readme) - rust-lang#146552 (StateTransform: Do not renumber resume local.) - rust-lang#146564 (Remove Rvalue::Len again.) - rust-lang#146581 (Detect attempt to use var-args in closure) - rust-lang#146588 (tests/run-make: Update list of statically linked musl targets) - rust-lang#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3)) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 14 pull requests Successful merges: - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option) - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature) - rust-lang/rust#145071 (Update the minimum external LLVM to 20) - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables) - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature) - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`) - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it) - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`) - rust-lang/rust#146460 (Add tidy readme) - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.) - rust-lang/rust#146564 (Remove Rvalue::Len again.) - rust-lang/rust#146581 (Detect attempt to use var-args in closure) - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets) - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3)) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned jackh726 Sep 6, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 6, 2025

fmease reviewed Sep 6, 2025

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camsteffen force-pushed the remove-the-box branch 5 times, most recently from be71edc to 09dca95 Compare September 6, 2025 03:41

hkBst reviewed Sep 7, 2025

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compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs Outdated Show resolved Hide resolved

jackh726 reviewed Sep 16, 2025

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compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs Outdated Show resolved Hide resolved

Suggest removing Box::new

d66fb49

jackh726 force-pushed the remove-the-box branch from c124128 to d66fb49 Compare September 16, 2025 08:23

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 16, 2025

bors added a commit that referenced this pull request Sep 16, 2025

Auto merge of #146259 - camsteffen:remove-the-box, r=jackh726

f199c62

Suggest removing Box::new instead of unboxing it

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 16, 2025

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 16, 2025

Zalathar added a commit to Zalathar/rust that referenced this pull request Sep 16, 2025

Rollup merge of rust-lang#146259 - camsteffen:remove-the-box, r=jackh726

f30be46

Suggest removing Box::new instead of unboxing it

Zalathar mentioned this pull request Sep 16, 2025

Rollup of 3 pull requests #146628

Closed

jhpratt added a commit to jhpratt/rust that referenced this pull request Sep 17, 2025

Rollup merge of rust-lang#146259 - camsteffen:remove-the-box, r=jackh726

5c4cef6

Suggest removing Box::new instead of unboxing it

jhpratt mentioned this pull request Sep 17, 2025

Rollup of 9 pull requests #146662

Closed

Zalathar added a commit to Zalathar/rust that referenced this pull request Sep 17, 2025

Rollup merge of rust-lang#146259 - camsteffen:remove-the-box, r=jackh726

1bc4e25

Suggest removing Box::new instead of unboxing it

Zalathar added a commit to Zalathar/rust that referenced this pull request Sep 17, 2025

Rollup merge of rust-lang#146259 - camsteffen:remove-the-box, r=jackh726

7cb0086

Suggest removing Box::new instead of unboxing it

This was referenced Sep 17, 2025

Rollup of 15 pull requests #146665

Closed

Rollup of 14 pull requests #146666

Merged

bors merged commit 79f8acb into rust-lang:master Sep 17, 2025
10 of 11 checks passed

rustbot added this to the 1.92.0 milestone Sep 17, 2025

rust-timer added a commit that referenced this pull request Sep 17, 2025

Unrolled build for #146259

9fddfc4

Rollup merge of #146259 - camsteffen:remove-the-box, r=jackh726 Suggest removing Box::new instead of unboxing it

camsteffen deleted the remove-the-box branch September 17, 2025 11:48

github-actions bot mentioned this pull request Sep 18, 2025

Toolchain upgrade to nightly-2025-10-09 flux-rs/flux#1271

Merged

makai410 pushed a commit to makai410/rust that referenced this pull request Nov 8, 2025

Rollup merge of rust-lang#146259 - camsteffen:remove-the-box, r=jackh726

d5eb2c7

Suggest removing Box::new instead of unboxing it

makai410 pushed a commit to makai410/rust that referenced this pull request Nov 10, 2025

Rollup merge of rust-lang#146259 - camsteffen:remove-the-box, r=jackh726

8c2ded8

Suggest removing Box::new instead of unboxing it

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