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https://github.com/rust-lang/rust
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![Gurinder Singh](/assets/img/avatar_default.png)
and replace it with a simple note suggesting returning a value. The type mismatch error was never due to how many times the loop iterates. It is more because of the peculiar structure of what the for loop desugars to. So the note talking about iteration count didn't make sense
227 lines
6.1 KiB
Plaintext
227 lines
6.1 KiB
Plaintext
error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:13:5
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LL | fn a() -> Option<()> {
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| ---------- expected `Option<()>` because of return type
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LL | / while false {
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LL | |
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LL | | f();
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LL | | }
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| |_____^ expected `Option<()>`, found `()`
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= note: expected enum `Option<()>`
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found unit type `()`
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= note: `while` loops evaluate to unit type `()`
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help: try adding an expression at the end of the block
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LL ~ }
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LL + None
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LL ~ }
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LL + Some(())
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:21:5
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LL | fn b() -> Result<(), ()> {
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| -------------- expected `Result<(), ()>` because of return type
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LL | f()
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| ^^^ expected `Result<(), ()>`, found `()`
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= note: expected enum `Result<(), ()>`
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found unit type `()`
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help: try adding an expression at the end of the block
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LL ~ f();
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LL + Ok(())
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:27:5
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LL | fn c() -> Option<()> {
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| ---------- expected `Option<()>` because of return type
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LL | / for _ in [1, 2] {
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LL | |
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LL | | f();
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LL | | }
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| |_____^ expected `Option<()>`, found `()`
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= note: expected enum `Option<()>`
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found unit type `()`
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= note: `for` loops evaluate to unit type `()`
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help: try adding an expression at the end of the block
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LL ~ }
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LL + None
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LL ~ }
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LL + Some(())
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error[E0308]: `?` operator has incompatible types
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--> $DIR/compatible-variants.rs:35:5
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LL | fn d() -> Option<()> {
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| ---------- expected `Option<()>` because of return type
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LL | c()?
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| ^^^^ expected `Option<()>`, found `()`
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= note: `?` operator cannot convert from `()` to `Option<()>`
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= note: expected enum `Option<()>`
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found unit type `()`
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help: try removing this `?`
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LL - c()?
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LL + c()
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help: try adding an expression at the end of the block
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LL ~ c()?;
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LL + None
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LL ~ c()?;
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LL + Some(())
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:42:25
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LL | let _: Option<()> = while false {};
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| ---------- ^^^^^^^^^^^^^^ expected `Option<()>`, found `()`
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| |
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| expected due to this
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= note: expected enum `Option<()>`
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found unit type `()`
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help: try wrapping the expression in `Some`
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LL | let _: Option<()> = Some(while false {});
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| +++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:46:9
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LL | while false {}
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| ^^^^^^^^^^^^^^ expected `Option<()>`, found `()`
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= note: expected enum `Option<()>`
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found unit type `()`
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= note: `while` loops evaluate to unit type `()`
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help: try adding an expression at the end of the block
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LL ~ while false {}
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LL + None
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LL ~ while false {}
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LL + Some(())
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:50:31
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LL | let _: Result<i32, i32> = 1;
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| ---------------- ^ expected `Result<i32, i32>`, found integer
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| |
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| expected due to this
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= note: expected enum `Result<i32, i32>`
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found type `{integer}`
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help: try wrapping the expression in a variant of `Result`
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LL | let _: Result<i32, i32> = Ok(1);
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| +++ +
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LL | let _: Result<i32, i32> = Err(1);
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| ++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:53:26
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LL | let _: Option<i32> = 1;
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| ----------- ^ expected `Option<i32>`, found integer
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| |
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| expected due to this
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= note: expected enum `Option<i32>`
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found type `{integer}`
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help: try wrapping the expression in `Some`
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LL | let _: Option<i32> = Some(1);
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| +++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:56:28
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LL | let _: Hey<i32, i32> = 1;
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| ------------- ^ expected `Hey<i32, i32>`, found integer
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| |
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| expected due to this
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= note: expected enum `Hey<i32, i32>`
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found type `{integer}`
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help: try wrapping the expression in a variant of `Hey`
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LL | let _: Hey<i32, i32> = Hey::A(1);
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| +++++++ +
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LL | let _: Hey<i32, i32> = Hey::B(1);
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| +++++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:59:29
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LL | let _: Hey<i32, bool> = false;
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| -------------- ^^^^^ expected `Hey<i32, bool>`, found `bool`
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| |
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| expected due to this
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= note: expected enum `Hey<i32, bool>`
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found type `bool`
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help: try wrapping the expression in `Hey::B`
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LL | let _: Hey<i32, bool> = Hey::B(false);
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| +++++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:63:19
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LL | let _ = Foo { bar };
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| ^^^ expected `Option<i32>`, found `i32`
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= note: expected enum `Option<i32>`
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found type `i32`
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help: try wrapping the expression in `Some`
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LL | let _ = Foo { bar: Some(bar) };
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| ++++++++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:80:16
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LL | let a: A = B::Fst;
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| - ^^^^^^ expected `A`, found `B`
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| |
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| expected due to this
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help: try wrapping the expression in `A::B`
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LL | let a: A = A::B { b: B::Fst };
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| +++++++++ +
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error[E0308]: mismatched types
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--> $DIR/compatible-variants.rs:86:17
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LL | let a: A2 = B::Fst;
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| -- ^^^^^^ expected `A2`, found `B`
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| |
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| expected due to this
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help: try wrapping the expression in `A2`
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LL | let a: A2 = A2(B::Fst);
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| +++ +
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error: aborting due to 13 previous errors
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For more information about this error, try `rustc --explain E0308`.
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