Add panic=immediate-abort support to Cargo #16041

saethlin · 2025-10-03T00:52:34Z

I recently turned -Zbuild-std-features=panic_immediate_abort into -Cpanic=immediate-abort in rust-lang/rust#146317. There was some discussion of the feature on Zulip here: #t-compiler/major changes > Unstably add -Cpanic=immediate-abort compiler-team#909

One of the outcomes of this shipping in nightly is that a few use patterns were broken, see rust-lang/rust#146974 and rust-lang/rust#146317 for examples. I think most of the users commenting on these issues are having trouble with how RUSTFLAGS is propagated through Cargo, and most likely they would have just gotten what they wanted if they could have set a profile option instead. So I'm trying to implement that.

rustbot · 2025-10-03T00:52:39Z

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weihanglo · 2025-10-03T02:48:48Z

src/cargo/core/features.rs

    (unstable, multiple_build_scripts, "", "reference/unstable.html#multiple-build-scripts"),
+
+    /// Allows use of panic="immediate-abort".
+    (unstable, panic_immediate_abort, "", "reference/unstable.html#panic-immediate-abort"),


As the [profile] table is also supported in Cargo configuration, you might want to add both feature gates:

Unstable feature in Cargo.toml manifest

Unstable flag in CLI/config.toml

See the first few commits in #12625 for reference

28b169b

08c5e35#diff-b41d07c80cef8a3eb85bb3cece56ec4e5e90ab8d3aa4f5b2923f365f8cf1449c

weihanglo · 2025-10-03T02:49:19Z

src/doc/src/reference/unstable.md

+
+* Tracking Issue: [#16042](https://github.com/rust-lang/cargo/issues/16042)
+
+Allow use of the ImmediateAbort panic strategy in a Cargo profile


Could we link to rustc book and tracking issue (if any)?

weihanglo · 2025-10-03T03:00:01Z

src/cargo/core/profiles.rs


 /// The `panic` setting.
 #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash, PartialOrd, Ord, serde::Serialize)]
 #[serde(rename_all = "lowercase")]


Hmm. Traced that serialization is used by unit-graph. Before it is too late, i think we should change this to kebab-case.

And strip seems wrong as well

cargo/src/cargo/core/profiles.rs

Lines 921 to 922 in 94f6379

#[serde(rename_all = "lowercase")]

pub enum Strip {

cargo/src/cargo/core/profiles.rs

Lines 607 to 608 in 56bdf49

#[derive(Clone, Eq, PartialOrd, Ord, serde::Serialize)]

pub struct Profile {

Hey we don't even specify anything for the entire struct! Probably worth a separate PR/issue to address it.

We're holding 2 things behind: - The toolchain because of rust-lang/rust#146974. We'll wait until rust-lang/cargo#16041 is fixed to update. - The WebAssembly spec because non-trivial changes might be needed to update the interpreter (or at least the test-suite).

epage · 2025-10-03T13:29:57Z

src/cargo/core/profiles.rs

+            "immediate-abort" => PanicStrategy::ImmediateAbort,
            // This should be validated in TomlProfile::validate
            _ => panic!("Unexpected panic setting `{}`", panic),


The validation in there needs to be updated

I'm afraid I'm lost. What validation? I can't find any validation of the panic setting or a TomlProfile::validate.

cargo/src/cargo/util/toml/mod.rs

Lines 2552 to 2560 in 56bdf49

if let Some(panic) = &root.panic {

if panic != "unwind" && panic != "abort" {

bail!(

"`panic` setting of `{}` is not a valid setting, \

must be `unwind` or `abort`",

panic

);

}

}

Outdated comment always 🙇🏾‍♂️

epage · 2025-10-03T13:31:45Z

Generally, we have end-to-end tests for new features (which would have caught #16041 (comment)) and feature gate tests for unstable features.

weihanglo

Looks good. Thank you!

Would you mind cleaning the commit history a bit. We usually follow atomic commit pattern and every commit shall pass all tests (not MUST we don't enforce that but encourage).

weihanglo · 2025-10-04T02:13:58Z

src/cargo/util/toml/mod.rs


    if let Some(panic) = &root.panic {
-        if panic != "unwind" && panic != "abort" {
+        if panic != "unwind" && panic != "abort" && panic != "immediate-abort" {


Not sure if we want to make it a warning or configurable lint in the future. It seems too restrictive. Anyway, it is worth its own separate topic.

saethlin · 2025-10-04T02:22:51Z

I don't think a PR that's this conceptually simple needs multiple commits, but I'll split it up if you prefer.

weihanglo

I personally don't mind for this kind of addition. For bugfix I'll be a bit more nitpicky.

Thanks!

saethlin · 2025-10-04T03:36:09Z

The test package::reserved_windows_name failed and I don't think it's related to my change. I force-pushed without a diff to re-run CI, just in case the test is flaky. Perhaps it's being broken by a runner update?

saethlin · 2025-10-04T03:37:16Z

Oh I see this test has been rather flaky recently. Ouch.

weihanglo · 2025-10-04T03:53:29Z

yeah, I should create an issue and temporarily ignore that

Update cargo submodule 3 commits in 2394ea6cea8b26d717aa67eb1663a2dbf2d26078..801d9b4981dd07e3aecdca1ab86834c13615737e 2025-10-03 14:13:01 +0000 to 2025-10-04 13:30:15 +0000 - chore: Disabled `reserved_windows_name` test temporaily (rust-lang/cargo#16048) - Add panic=immediate-abort support to Cargo (rust-lang/cargo#16041) - Accessing each build script's `OUT_DIR` (rust-lang/cargo#15891)

FooIbar · 2025-10-05T10:34:07Z

src/doc/src/reference/unstable.md

+
+This can be enabled like so:
+```toml
+cargo-features = ["immediate-abort"]


Should be

Suggested change

cargo-features = ["immediate-abort"]

cargo-features = ["panic-immediate-abort"]

rustbot assigned weihanglo Oct 3, 2025

saethlin mentioned this pull request Oct 3, 2025

Tracking Issue for panic-immediate-abort #16042

Open

weihanglo reviewed Oct 3, 2025

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ia0 mentioned this pull request Oct 3, 2025

Upgrade all dependencies google/wasefire#932

Merged

epage reviewed Oct 3, 2025

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rustbot added the A-manifest Area: Cargo.toml issues label Oct 4, 2025

weihanglo reviewed Oct 4, 2025

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saethlin force-pushed the panic=immediate-abort branch from efd675c to 50697eb Compare October 4, 2025 02:22

weihanglo approved these changes Oct 4, 2025

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weihanglo enabled auto-merge October 4, 2025 02:27

Add panic=immediate-abort support to Cargo

4cb6fe4

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Head branch was pushed to by a user without write access

saethlin force-pushed the panic=immediate-abort branch from 50697eb to 4cb6fe4 Compare October 4, 2025 03:34

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weihanglo added this pull request to the merge queue Oct 4, 2025

Merged via the queue into rust-lang:master with commit 029de48 Oct 4, 2025
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This was referenced Oct 4, 2025

package::reserved_windows_name test seems to be flaky recently #16047

Open

Update cargo submodule rust-lang/rust#147338

Merged

rustbot added this to the 1.92.0 milestone Oct 4, 2025

FooIbar reviewed Oct 5, 2025

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		* Tracking Issue: [#16042](https://github.com/rust-lang/cargo/issues/16042)

		Allow use of the ImmediateAbort panic strategy in a Cargo profile

	#[derive(Clone, Eq, PartialOrd, Ord, serde::Serialize)]
	pub struct Profile {

	if let Some(panic) = &root.panic {
	if panic != "unwind" && panic != "abort" {
	bail!(
	"`panic` setting of `{}` is not a valid setting, \
	must be `unwind` or `abort`",
	panic
	);
	}
	}

	cargo-features = ["immediate-abort"]
	cargo-features = ["panic-immediate-abort"]

Add panic=immediate-abort support to Cargo #16041

Add panic=immediate-abort support to Cargo #16041

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epage commented Oct 3, 2025

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weihanglo Oct 3, 2025 •

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