Error on invalid signatures for interrupt ABIs #142633

folkertdev · 2025-06-17T16:50:44Z

We recently added extern "custom", which must have type fn(). The various extern "interrupt" ABIs impose similar constraints on the signature of functions with that ABI: x86-interrupt should not have a return type (linting on the exact argument types is left as future work), and the other interrupt ABIs cannot have any parameters or a return type.

r? @workingjubilee

Closes #132841

rustbot · 2025-06-17T16:50:49Z

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
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Cargo.lock

compiler/rustc_ast_passes/src/ast_validation.rs

workingjubilee

pass of style nits, will doublecheck more closely a bit later, you can apply them now or wait until second pass

compiler/rustc_ast_passes/messages.ftl

compiler/rustc_ast_passes/src/ast_validation.rs

bors · 2025-06-21T13:58:14Z

☔ The latest upstream changes (presumably #142817) made this pull request unmergeable. Please resolve the merge conflicts.

tests/ui/abi/cannot-be-called.rs

workingjubilee · 2025-06-21T21:12:03Z

compiler/rustc_ast_passes/messages.ftl

+
+ast_passes_abi_must_not_have_return_type=
+    invalid signature for `extern {$abi}` function
+    .note = functions with the `"custom"` ABI cannot have a return type


leftover

Suggested change

.note = functions with the `"custom"` ABI cannot have a return type

.note = functions with the "custom" ABI cannot have a return type

right, I left those unchanged easier but we can fold that into this PR. Fixed.

Oh, was this not new? GH UI may have fooled me.

hmm maybe this one was? but some others in that file were older. Anyway, it's all fixed now.

workingjubilee · 2025-06-21T21:12:39Z

compiler/rustc_ast_passes/src/ast_validation.rs

+                        // An `extern "custom"` function cannot be `async` and/or `gen`.
+                        self.check_abi_is_not_coroutine(abi, sig);
+
+                        // An `extern "custom"` function must have type `fn()`.


pedantic note: its type is unsafe extern "custom" fn(). and yes, you can have different implementations on unsafe fn() and fn().

don't actually change anything, I just couldn't resist noting.

workingjubilee · 2025-06-21T21:21:21Z

compiler/rustc_ast_passes/src/ast_validation.rs

-    /// type.
-    fn check_custom_abi(&self, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {
+    /// Check that this function does not violate the constraints of its ABI.
+    fn check_abi(&self, abi: ExternAbi, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {


I find these check_this names to be slightly nondescript.

sometimes they warn. sometimes they error.

we specifically check only the signature.

Suggested change

fn check_abi(&self, abi: ExternAbi, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {

fn reject_invalid_abi_sig(&self, abi: ExternAbi, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {

Could also be, at least, check_extern_fn_sig

I did some renaming. Most functions in that module do start with check_ so that is what I followed.

tests/ui/abi/cannot-be-coroutine.rs

bors · 2025-06-24T05:39:24Z

☔ The latest upstream changes (presumably #142929) made this pull request unmergeable. Please resolve the merge conflicts.

workingjubilee · 2025-06-24T18:16:16Z

hell yeah.

@bors r+

bors · 2025-06-24T18:16:18Z

📌 Commit 943d379 has been approved by workingjubilee

It is now in the queue for this repository.

…signature, r=workingjubilee Error on invalid signatures for interrupt ABIs We recently added `extern "custom"`, which must have type `fn()`. The various `extern "interrupt"` ABIs impose similar constraints on the signature of functions with that ABI: `x86-interrupt` should not have a return type (linting on the exact argument types is left as future work), and the other interrupt ABIs cannot have any parameters or a return type. r? `@workingjubilee`

…signature, r=workingjubilee Error on invalid signatures for interrupt ABIs We recently added `extern "custom"`, which must have type `fn()`. The various `extern "interrupt"` ABIs impose similar constraints on the signature of functions with that ABI: `x86-interrupt` should not have a return type (linting on the exact argument types is left as future work), and the other interrupt ABIs cannot have any parameters or a return type. r? ``@workingjubilee``

Rollup of 15 pull requests Successful merges: - #135731 (Implement parsing of pinned borrows) - #138780 (Add `#[loop_match]` for improved DFA codegen) - #142453 (Windows: make `read_dir` stop iterating after the first error is encountered) - #142633 (Error on invalid signatures for interrupt ABIs) - #142768 (Avoid a bitcast FFI call in transmuting) - #142825 (Port `#[track_caller]` to the new attribute system) - #142844 (Enable short-ice for Windows) - #142934 (Tweak `-Zmacro-stats` measurement.) - #142955 (Couple of test suite fixes for cg_clif) - #142977 (rustdoc: Don't mark `#[target_feature]` functions as ⚠) - #142980 (Reduce mismatched-lifetime-syntaxes suggestions to MaybeIncorrect) - #142982 (Corrected spelling mistake in c_str.rs) - #142983 (Taint body on invalid call ABI) - #142988 (Update wasm-component-ld to 0.5.14) - #142993 (Update cargo) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #142633 - folkertdev:interrupt-abi-restrict-signature, r=workingjubilee Error on invalid signatures for interrupt ABIs We recently added `extern "custom"`, which must have type `fn()`. The various `extern "interrupt"` ABIs impose similar constraints on the signature of functions with that ABI: `x86-interrupt` should not have a return type (linting on the exact argument types is left as future work), and the other interrupt ABIs cannot have any parameters or a return type. r? ```@workingjubilee```

rustbot assigned workingjubilee Jun 17, 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 Jun 17, 2025

folkertdev commented Jun 17, 2025

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folkertdev force-pushed the interrupt-abi-restrict-signature branch from 6c041ae to 6086486 Compare June 17, 2025 17:49

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folkertdev force-pushed the interrupt-abi-restrict-signature branch from 6086486 to 411fce5 Compare June 18, 2025 08:47

folkertdev force-pushed the interrupt-abi-restrict-signature branch from 411fce5 to aec1f72 Compare June 21, 2025 15:57

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workingjubilee mentioned this pull request Jun 21, 2025

extern "x86-interrupt" fn allows absurd signatures #132835

Open

folkertdev force-pushed the interrupt-abi-restrict-signature branch from 32fbbc2 to 7d6e5aa Compare June 21, 2025 23:06

Error on invalid signatures for interrupt ABIs

943d379

folkertdev force-pushed the interrupt-abi-restrict-signature branch from 7d6e5aa to 943d379 Compare June 24, 2025 12:40

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 Jun 24, 2025

workingjubilee mentioned this pull request Jun 25, 2025

Rollup of 15 pull requests #142995

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This was referenced Jun 25, 2025

Rollup of 2 pull requests #142996

Closed

Rollup of 15 pull requests #142997

Merged

bors merged commit 891dc0f into rust-lang:master Jun 25, 2025
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rustbot added this to the 1.90.0 milestone Jun 25, 2025

	.note = functions with the `"custom"` ABI cannot have a return type
	.note = functions with the "custom" ABI cannot have a return type

	fn check_abi(&self, abi: ExternAbi, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {
	fn reject_invalid_abi_sig(&self, abi: ExternAbi, ctxt: FnCtxt, ident: &Ident, sig: &FnSig) {

Error on invalid signatures for interrupt ABIs #142633

Error on invalid signatures for interrupt ABIs #142633

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bors commented Jun 21, 2025

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bors commented Jun 24, 2025

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workingjubilee commented Jun 24, 2025

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folkertdev commented Jun 17, 2025 •

edited by workingjubilee

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