Error if an autodiff user does not set lto=fat#148855

ZuseZ4 · 2025-11-12T03:46:28Z

Based on your feedback, I started to provide a nice error message for a lack of lto=fat, instead of us forcing it.

In a next step, we should replace RUSTFLAGS="-Zautodiff=Enable" with another Cargo.toml setting, as discussed here: #147487 (comment)

As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting.

@bjorn3

rustbot · 2025-11-12T03:46:32Z

r? @madsmtm

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ZuseZ4 · 2025-11-12T03:47:15Z

r? @bjorn3

rustbot · 2025-11-12T03:47:18Z

Failed to set assignee to bjorn: invalid assignee

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rustbot · 2025-11-12T03:51:01Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

rustbot · 2025-11-16T03:04:03Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

bjorn3 · 2025-11-16T10:44:34Z

The first two commits LGTM.

rustbot · 2025-11-16T13:34:02Z

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

ZuseZ4 · 2025-11-16T23:41:47Z

Thanks, I'll leave the newer commits to another PR.

@bors r=bjorn3 rollup

bors · 2025-11-16T23:41:50Z

📌 Commit c8bae8c has been approved by bjorn3

It is now in the queue for this repository.

Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: rust-lang#147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. `@bjorn3`

Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: rust-lang#147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. ``@bjorn3``

Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: rust-lang#147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. ```@bjorn3```

Rollup of 6 pull requests Successful merges: - #147760 ([Debugger Visualizers] Unify `*-gnu` and `*-msvc` enum output) - #148505 (add larger test for `proc_macro` `FromStr` implementations) - #148855 (Error if an autodiff user does not set lto=fat) - #148958 (Run codegen tests on a 32-bit target in PR CI) - #149004 (compiletest: Avoid race condition in file deletion) - #149008 (triagebot: remove jsha from notifications for rustdoc HTML) r? `@ghost` `@rustbot` modify labels: rollup

Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: rust-lang#147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. ````@bjorn3````

Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: rust-lang#147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. `````@bjorn3`````

Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: rust-lang#147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. ``````@bjorn3``````

Rollup of 11 pull requests Successful merges: - #148505 (add larger test for `proc_macro` `FromStr` implementations) - #148752 (Constify `ManuallyDrop::take`) - #148757 (Constify `mem::take`) - #148855 (Error if an autodiff user does not set lto=fat) - #148912 (add note to `lines` docs about empty str behavior) - #148958 (Run codegen tests on a 32-bit target in PR CI) - #148994 (Abi compatibility test cleanup) - #148999 (Tweak Motor OS linker preset, fix `remote-test-server` for Motor OS) - #149004 (compiletest: Avoid race condition in file deletion) - #149008 (triagebot: remove jsha from notifications for rustdoc HTML) - #149010 (compiletest: Remove the "wasm32-bare" alias for `wasm32-unknown-unknown`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #148855 - ZuseZ4:autodiff-lto-error, r=bjorn3 Error if an autodiff user does not set lto=fat Based on your feedback, I started to provide a nice error message for a lack of `lto=fat`, instead of us forcing it. In a next step, we should replace `RUSTFLAGS="-Zautodiff=Enable"` with another Cargo.toml setting, as discussed here: #147487 (comment) As another improvement, we should also figure out why rlib builds do not properly obey the fat=lto setting. ```````@bjorn3```````

Rollup of 11 pull requests Successful merges: - rust-lang/rust#148505 (add larger test for `proc_macro` `FromStr` implementations) - rust-lang/rust#148752 (Constify `ManuallyDrop::take`) - rust-lang/rust#148757 (Constify `mem::take`) - rust-lang/rust#148855 (Error if an autodiff user does not set lto=fat) - rust-lang/rust#148912 (add note to `lines` docs about empty str behavior) - rust-lang/rust#148958 (Run codegen tests on a 32-bit target in PR CI) - rust-lang/rust#148994 (Abi compatibility test cleanup) - rust-lang/rust#148999 (Tweak Motor OS linker preset, fix `remote-test-server` for Motor OS) - rust-lang/rust#149004 (compiletest: Avoid race condition in file deletion) - rust-lang/rust#149008 (triagebot: remove jsha from notifications for rustdoc HTML) - rust-lang/rust#149010 (compiletest: Remove the "wasm32-bare" alias for `wasm32-unknown-unknown`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 11 pull requests Successful merges: - rust-lang#148505 (add larger test for `proc_macro` `FromStr` implementations) - rust-lang#148752 (Constify `ManuallyDrop::take`) - rust-lang#148757 (Constify `mem::take`) - rust-lang#148855 (Error if an autodiff user does not set lto=fat) - rust-lang#148912 (add note to `lines` docs about empty str behavior) - rust-lang#148958 (Run codegen tests on a 32-bit target in PR CI) - rust-lang#148994 (Abi compatibility test cleanup) - rust-lang#148999 (Tweak Motor OS linker preset, fix `remote-test-server` for Motor OS) - rust-lang#149004 (compiletest: Avoid race condition in file deletion) - rust-lang#149008 (triagebot: remove jsha from notifications for rustdoc HTML) - rust-lang#149010 (compiletest: Remove the "wasm32-bare" alias for `wasm32-unknown-unknown`) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned madsmtm Nov 12, 2025