36 lines
934 B
Rust
36 lines
934 B
Rust
// This is a reduction of a concrete test illustrating a case that was
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// annoying to Rust developer stephaneyfx (see issue #46413).
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//
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// With resolving issue #54556, pnkfelix hopes that the new diagnostic
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// output produced by NLL helps to *explain* the semantic significance
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// of temp drop order, and thus why storing the result in `x` and then
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// returning `x` works.
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pub struct Statement;
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pub struct Rows<'stmt>(&'stmt Statement);
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impl<'stmt> Drop for Rows<'stmt> {
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fn drop(&mut self) {}
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}
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impl<'stmt> Iterator for Rows<'stmt> {
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type Item = String;
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fn next(&mut self) -> Option<Self::Item> {
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None
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}
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}
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fn get_names() -> Option<String> {
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let stmt = Statement;
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let rows = Rows(&stmt); //~ ERROR does not live long enough
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rows.map(|row| row).next()
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// let x = rows.map(|row| row).next();
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// x
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//
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// Removing the map works too as does removing the Drop impl.
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}
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fn main() {}
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