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6b24fdf811
```
error: unconstrained generic constant
--> $DIR/const-argument-if-length.rs:18:10
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LL | pad: [u8; is_zst::<T>()],
| ^^^^^^^^^^^^^^^^^^^
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help: try adding a `where` bound
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LL | pub struct AtLeastByte<T: ?Sized> where [(); is_zst::<T>()]: {
| ++++++++++++++++++++++++++
```
Detect when the constant expression isn't `usize` and suggest casting:
```
error: unconstrained generic constant
--> f300.rs:6:10
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6 | bb::<{!N}>();
| ^^^^
-Ztrack-diagnostics: created at compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs:3539:36
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help: try adding a `where` bound
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5 | fn b<const N: bool>() where [(); {!N} as usize]: {
| ++++++++++++++++++++++++++
```
Fix #122395.
93 lines
2.9 KiB
Plaintext
93 lines
2.9 KiB
Plaintext
error[E0741]: `Foo` must implement `ConstParamTy` to be used as the type of a const generic parameter
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--> $DIR/unify-op-with-fn-call.rs:18:29
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LL | struct Evaluatable<const N: Foo>;
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| ^^^
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help: add `#[derive(ConstParamTy)]` to the struct
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LL + #[derive(ConstParamTy)]
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LL | struct Foo(u8);
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error[E0741]: `Foo` must implement `ConstParamTy` to be used as the type of a const generic parameter
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--> $DIR/unify-op-with-fn-call.rs:20:17
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LL | fn foo<const N: Foo>(a: Evaluatable<{ N + N }>) {
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help: add `#[derive(ConstParamTy)]` to the struct
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LL + #[derive(ConstParamTy)]
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LL | struct Foo(u8);
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error[E0741]: `Foo` must implement `ConstParamTy` to be used as the type of a const generic parameter
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--> $DIR/unify-op-with-fn-call.rs:24:17
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LL | fn bar<const N: Foo>() {}
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| ^^^
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help: add `#[derive(ConstParamTy)]` to the struct
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LL + #[derive(ConstParamTy)]
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LL | struct Foo(u8);
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error: unconstrained generic constant
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--> $DIR/unify-op-with-fn-call.rs:30:12
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LL | bar2::<{ std::ops::Add::add(N, N) }>();
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help: try adding a `where` bound
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LL | fn foo2<const N: usize>(a: Evaluatable2<{ N + N }>) where [(); { std::ops::Add::add(N, N) }]: {
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| +++++++++++++++++++++++++++++++++++++++++
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error[E0015]: cannot call non-const operator in constants
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--> $DIR/unify-op-with-fn-call.rs:20:39
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LL | fn foo<const N: Foo>(a: Evaluatable<{ N + N }>) {
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| ^^^^^
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note: impl defined here, but it is not `const`
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--> $DIR/unify-op-with-fn-call.rs:10:1
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LL | impl const std::ops::Add for Foo {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: calls in constants are limited to constant functions, tuple structs and tuple variants
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help: add `#![feature(effects)]` to the crate attributes to enable
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LL + #![feature(effects)]
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error[E0015]: cannot call non-const fn `<Foo as Add>::add` in constants
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--> $DIR/unify-op-with-fn-call.rs:21:13
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LL | bar::<{ std::ops::Add::add(N, N) }>();
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| ^^^^^^^^^^^^^^^^^^^^^^^^
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= note: calls in constants are limited to constant functions, tuple structs and tuple variants
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help: add `#![feature(effects)]` to the crate attributes to enable
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LL + #![feature(effects)]
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error[E0015]: cannot call non-const fn `<usize as Add>::add` in constants
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--> $DIR/unify-op-with-fn-call.rs:30:14
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LL | bar2::<{ std::ops::Add::add(N, N) }>();
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= note: calls in constants are limited to constant functions, tuple structs and tuple variants
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help: add `#![feature(effects)]` to the crate attributes to enable
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LL + #![feature(effects)]
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error: aborting due to 7 previous errors
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Some errors have detailed explanations: E0015, E0741.
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For more information about an error, try `rustc --explain E0015`.
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