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Skip lint for assertion evaluated to false #119958

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Skip lint for assertion evaluated to false #119958

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8 changes: 7 additions & 1 deletion compiler/rustc_mir_transform/src/const_prop_lint.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -456,9 +456,15 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
let value = &self.eval_operand(cond, location)?;
trace!("assertion on {:?} should be {:?}", value, expected);

let expected = Scalar::from_bool(expected);
let value_const = self.use_ecx(location, |this| this.ecx.read_scalar(value))?;

if value_const == Scalar::from_bool(false) {
// Skip the assertion if the condition is evaluated to false.
return None;
}

let expected = Scalar::from_bool(expected);

if expected != value_const {
// Poison all places this operand references so that further code
// doesn't use the invalid value
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7 changes: 7 additions & 0 deletions tests/ui/const_prop/issue-119908.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
// run-pass
fn main() {
let x: [i32; 0] = [];
if x.len() > 0 {
x[0];
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@matthiaskrgr matthiaskrgr Jan 14, 2024 •
edited
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does this trigger an unreachable/dead code warning?

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@barabadzhi barabadzhi Jan 14, 2024 •
edited
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Nope, lint is omitted for the whole block, as it will never run anyway.

}
}
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