Code change:
<ins> error[E0261]: use of undeclared lifetime name `'short` --> $DIR/issue-107090.rs:4:9 | LL |     Foo<'short, 'out, T>: Convert<'a, 'b>; |         ^^^^^^ undeclared lifetime | = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html help: consider making the bound lifetime-generic with a new `'short` lifetime | LL |     for<'short> Foo<'short, 'out, T>: Convert<'a, 'b>; |     +++++++++++ help: consider introducing lifetime `'short` here | LL | struct Foo<'short, 'a, 'b, T>(PhantomData<(&'a (), &'b (), T)>) |            +++++++ error[E0261]: use of undeclared lifetime name `'out` --> $DIR/issue-107090.rs:4:17 | LL |     Foo<'short, 'out, T>: Convert<'a, 'b>; |                 ^^^^ undeclared lifetime | help: consider making the bound lifetime-generic with a new `'out` lifetime | LL |     for<'out> Foo<'short, 'out, T>: Convert<'a, 'b>; |     +++++++++ help: consider introducing lifetime `'out` here | LL | struct Foo<'out, 'a, 'b, T>(PhantomData<(&'a (), &'b (), T)>) |            +++++ error[E0261]: use of undeclared lifetime name `'b` --> $DIR/issue-107090.rs:13:47 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |      -                                        ^^ undeclared lifetime |      | |      help: consider introducing lifetime `'b` here: `'b,` error[E0261]: use of undeclared lifetime name `'out` --> $DIR/issue-107090.rs:13:67 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |      - help: consider introducing lifetime `'out` here: `'out,`   ^^^^ undeclared lifetime error[E0261]: use of undeclared lifetime name `'out` --> $DIR/issue-107090.rs:17:49 | LL |     fn cast(&'long self) -> &'short Foo<'short, 'out, T> { |                                                 ^^^^ undeclared lifetime | help: consider introducing lifetime `'out` here | LL |     fn cast<'out>(&'long self) -> &'short Foo<'short, 'out, T> { |            ++++++ help: consider introducing lifetime `'out` here | LL | impl<'out, 'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |      +++++ error[E0261]: use of undeclared lifetime name `'short` --> $DIR/issue-107090.rs:24:68 | LL | fn badboi<'in_, 'out, T>(x: Foo<'in_, 'out, T>, sadness: &'in_ Foo<'short, 'out, T>) -> &'out T { |           -                                                        ^^^^^^ undeclared lifetime |           | |           help: consider introducing lifetime `'short` here: `'short,` error[E0308]: mismatched types --> $DIR/issue-107090.rs:4:27 | LL |     Foo<'short, 'out, T>: Convert<'a, 'b>; |                           ^^^^^^^^^^^^^^^ lifetime mismatch | = note: expected trait `Convert<'static, 'static>` found trait `Convert<'a, 'b>` note: the lifetime `'a` as defined here... --> $DIR/issue-107090.rs:2:12 | LL | struct Foo<'a, 'b, T>(PhantomData<(&'a (), &'b (), T)>) |            ^^ = note: ...does not necessarily outlive the static lifetime error[E0308]: mismatched types --> $DIR/issue-107090.rs:4:27 | LL |     Foo<'short, 'out, T>: Convert<'a, 'b>; |                           ^^^^^^^^^^^^^^^ lifetime mismatch | = note: expected trait `Convert<'static, 'static>` found trait `Convert<'a, 'b>` note: the lifetime `'b` as defined here... --> $DIR/issue-107090.rs:2:16 | LL | struct Foo<'a, 'b, T>(PhantomData<(&'a (), &'b (), T)>) |                ^^ = note: ...does not necessarily outlive the static lifetime error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'long` due to conflicting requirements --> $DIR/issue-107090.rs:13:55 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |                                                       ^^^^^^^^^^^^^^^^^^^^ | note: first, the lifetime cannot outlive the lifetime `'short` as defined here... --> $DIR/issue-107090.rs:13:21 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |                     ^^^^^^ = note: ...but the lifetime must also be valid for the static lifetime... note: ...so that the types are compatible --> $DIR/issue-107090.rs:13:55 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |                                                       ^^^^^^^^^^^^^^^^^^^^ = note: expected `Convert<'short, 'static>` found `Convert<'_, 'static>` error: incompatible lifetime on type --> $DIR/issue-107090.rs:24:29 | LL | fn badboi<'in_, 'out, T>(x: Foo<'in_, 'out, T>, sadness: &'in_ Foo<'short, 'out, T>) -> &'out T { |                             ^^^^^^^^^^^^^^^^^^ | note: because this has an unmet lifetime requirement --> $DIR/issue-107090.rs:4:27 | LL |     Foo<'short, 'out, T>: Convert<'a, 'b>; |                           ^^^^^^^^^^^^^^^ introduces a `'static` lifetime requirement note: the lifetime `'out` as defined here... --> $DIR/issue-107090.rs:24:17 | LL | fn badboi<'in_, 'out, T>(x: Foo<'in_, 'out, T>, sadness: &'in_ Foo<'short, 'out, T>) -> &'out T { |                 ^^^^ note: ...does not necessarily outlive the static lifetime introduced by the compatible `impl` --> $DIR/issue-107090.rs:13:1 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error[E0759]: `x` has lifetime `'in_` but it needs to satisfy a `'static` lifetime requirement --> $DIR/issue-107090.rs:24:29 | LL | fn badboi<'in_, 'out, T>(x: Foo<'in_, 'out, T>, sadness: &'in_ Foo<'short, 'out, T>) -> &'out T { |                             ^^^^^^^^^^^^^^^^^^ |                             | |                             this data with lifetime `'in_`... |                             ...is used and required to live as long as `'static` here error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'long` due to conflicting requirements --> $DIR/issue-107090.rs:17:13 | LL |     fn cast(&'long self) -> &'short Foo<'short, 'out, T> { |             ^^^^^^^^^^^ | note: first, the lifetime cannot outlive the lifetime `'short` as defined here... --> $DIR/issue-107090.rs:13:21 | LL | impl<'long: 'short, 'short, T> Convert<'long, 'b> for Foo<'short, 'out, T> { |                     ^^^^^^ = note: ...but the lifetime must also be valid for the static lifetime... note: ...so that the types are compatible --> $DIR/issue-107090.rs:17:13 | LL |     fn cast(&'long self) -> &'short Foo<'short, 'out, T> { |             ^^^^^^^^^^^ = note: expected `Convert<'short, 'static>` found `Convert<'_, 'static>` error: aborting due to 12 previous errors Some errors have detailed explanations: E0261, E0308, E0495, E0759. For more information about an error, try `rustc --explain E0261`. </ins>

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This is another case for And except for the missing argument issue, there is an copy-paste bug in :