llvm lint: "Return statement in function with noreturn attribute" caused by .count() ? #48227

matthiaskrgr · 2018-02-15T08:29:13Z

This was reduced from diff.rs https://github.com/utkarshkukreti/diff.rs

pub fn lines<'a>(left: &'a str) {
    iter(left.lines());
}

fn iter<I, T>(left: I)
where
    I: Clone + Iterator<Item = T> + DoubleEndedIterator,
    T: PartialEq,
{
    let _left_count = left.clone().count();
}

RUSTFLAGS="-C passes=lint"  cargo build  --release
   Compiling diff v0.1.11 (file:///tmp/diff.rs)
Unusual: Return statement in function with noreturn attribute
  ret void
    Finished release [optimized] target(s) in 0.30 secs

The lint warning vanishes when I remove the .count().

rustc 1.25.0-nightly (3ec5a99aa 2018-02-14)
binary: rustc
commit-hash: 3ec5a99aaa0084d97a9e845b34fdf03d1462c475
commit-date: 2018-02-14
host: x86_64-unknown-linux-gnu
release: 1.25.0-nightly
LLVM version: 6.0

EDIT: //cc #7463

The text was updated successfully, but these errors were encountered:

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now mark such return values with a new `IgnoreMode::Uninhabited`, and emit an `abort` anywhere that would have returned. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now mark such return values with a new `IgnoreMode::Uninhabited`, and emit an `abort` anywhere that would have returned. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `-C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now emit an `abort` anywhere that would have tried to return an uninhabited value. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `-C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now emit an `abort` anywhere that would have tried to return an uninhabited value. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `-C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now emit an `abort` anywhere that would have tried to return an uninhabited value. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `-C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now emit an `abort` anywhere that would have tried to return an uninhabited value. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

@eddyb

Never return uninhabited values at all Functions with uninhabited return values are already marked `noreturn`, but we were still generating return instructions for this. When running with `-C passes=lint`, LLVM prints: Unusual: Return statement in function with noreturn attribute The LLVM manual makes a stronger statement about `noreturn` though: > This produces undefined behavior at runtime if the function ever does dynamically return. We now emit an `abort` anywhere that would have tried to return an uninhabited value. Fixes rust-lang#48227 cc rust-lang#7463 rust-lang#48229 r? @eddyb

matthiaskrgr changed the title ~~llvm lint: "Return statement in function with noreturn attribute" caused by .count()~~ llvm lint: "Return statement in function with noreturn attribute" caused by .count() ? Feb 15, 2018

leonardo-m mentioned this issue Feb 15, 2018

Few LLVM lint "Unusual" #48229

Closed

bstrie added the A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. label Feb 19, 2018

XAMPPRocky added C-enhancement Category: An issue proposing an enhancement or a PR with one. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels May 7, 2018

cuviper mentioned this issue Apr 2, 2019

Never return uninhabited values at all #59639

Merged

bors closed this as completed in #59639 Apr 4, 2019

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llvm lint: "Return statement in function with noreturn attribute" caused by .count() ? #48227

llvm lint: "Return statement in function with noreturn attribute" caused by .count() ? #48227

matthiaskrgr commented Feb 15, 2018 •

edited

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llvm lint: "Return statement in function with noreturn attribute" caused by .count() ? #48227

llvm lint: "Return statement in function with noreturn attribute" caused by .count() ? #48227

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