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| author | Ethan Brierley <ethanboxx@gmail.com> | 2020-12-05 14:40:56 +0000 |
|---|---|---|
| committer | Ethan Brierley <ethanboxx@gmail.com> | 2020-12-05 15:37:59 +0000 |
| commit | 6845e22bbabce5631c388c52eb367168ce9b14ce (patch) | |
| tree | fb7e54ebe616df185fd41e065bf41456f7c01d23 | |
| parent | e6225434fff7d493baac0aa91c57f2da923ea196 (diff) | |
| download | rust-6845e22bbabce5631c388c52eb367168ce9b14ce.tar.gz rust-6845e22bbabce5631c388c52eb367168ce9b14ce.zip | |
Const parameters can not be inferred with `_`
Small improvement. Thanks varkor Co-authored-by: varkor <github@varkor.com> Bless
4 files changed, 28 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/astconv/generics.rs b/compiler/rustc_typeck/src/astconv/generics.rs index 0db5fda272a..b7e77f389f8 100644 --- a/compiler/rustc_typeck/src/astconv/generics.rs +++ b/compiler/rustc_typeck/src/astconv/generics.rs @@ -44,6 +44,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { // the match is non-exhaustive. _ => bug!("invalid generic parameter kind {}", kind), }; + + if let ParamKindOrd::Const { .. } = kind_ord { + if let GenericArg::Type(hir::Ty { kind: hir::TyKind::Infer, .. }) = arg { + err.help("const arguments cannot yet be inferred with `_`"); + } + } + let arg_ord = match arg { GenericArg::Lifetime(_) => ParamKindOrd::Lifetime, GenericArg::Type(_) => ParamKindOrd::Type, diff --git a/src/test/ui/const-generics/issues/issue-62878.full.stderr b/src/test/ui/const-generics/issues/issue-62878.full.stderr index fc70be40497..dce2e27c71a 100644 --- a/src/test/ui/const-generics/issues/issue-62878.full.stderr +++ b/src/test/ui/const-generics/issues/issue-62878.full.stderr @@ -9,6 +9,8 @@ error[E0747]: type provided when a constant was expected | LL | foo::<_, {[1]}>(); | ^ + | + = help: const arguments cannot yet be inferred with `_` error[E0308]: mismatched types --> $DIR/issue-62878.rs:11:15 diff --git a/src/test/ui/const-generics/min_const_generics/inferred_const.rs b/src/test/ui/const-generics/min_const_generics/inferred_const.rs new file mode 100644 index 00000000000..dcd069ce3b0 --- /dev/null +++ b/src/test/ui/const-generics/min_const_generics/inferred_const.rs @@ -0,0 +1,8 @@ +#![feature(min_const_generics)] +fn foo<const N: usize, const K: usize>(data: [u32; N]) -> [u32; K] { + [0; K] +} +fn main() { + let a = foo::<_, 2>([0, 1, 2]); + //~^ ERROR type provided when a constant was expected +} diff --git a/src/test/ui/const-generics/min_const_generics/inferred_const.stderr b/src/test/ui/const-generics/min_const_generics/inferred_const.stderr new file mode 100644 index 00000000000..e17105b2aa9 --- /dev/null +++ b/src/test/ui/const-generics/min_const_generics/inferred_const.stderr @@ -0,0 +1,11 @@ +error[E0747]: type provided when a constant was expected + --> $DIR/inferred_const.rs:6:19 + | +LL | let a = foo::<_, 2>([0, 1, 2]); + | ^ + | + = help: const arguments cannot yet be inferred with `_` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0747`. |