From 1e384423a9cfd678f976cf0183c81a770da2a325 Mon Sep 17 00:00:00 2001 From: Takayuki Maeda Date: Wed, 7 Sep 2022 02:37:18 +0900 Subject: [PATCH] suggest adding array lengths to references to arrays --- compiler/rustc_hir/src/hir.rs | 8 +++ compiler/rustc_typeck/src/check/expr.rs | 47 ++++++------- .../suggest-array-length.fixed | 12 ++++ .../array-slice-vec/suggest-array-length.rs | 12 ++++ .../suggest-array-length.stderr | 70 +++++++++++++++++-- 5 files changed, 120 insertions(+), 29 deletions(-) diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs index 9535ccfe8b69d..c17702d624a7d 100644 --- a/compiler/rustc_hir/src/hir.rs +++ b/compiler/rustc_hir/src/hir.rs @@ -2396,6 +2396,14 @@ impl<'hir> Ty<'hir> { _ => None, } } + + pub fn peel_refs(&self) -> &Self { + let mut final_ty = self; + while let TyKind::Rptr(_, MutTy { ty, .. }) = &final_ty.kind { + final_ty = &ty; + } + final_ty + } } /// Not represented directly in the AST; referred to by name through a `ty_path`. diff --git a/compiler/rustc_typeck/src/check/expr.rs b/compiler/rustc_typeck/src/check/expr.rs index e4141647d7d2d..44f845bde6154 100644 --- a/compiler/rustc_typeck/src/check/expr.rs +++ b/compiler/rustc_typeck/src/check/expr.rs @@ -1305,31 +1305,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } fn suggest_array_len(&self, expr: &'tcx hir::Expr<'tcx>, array_len: u64) { - if let Some(parent_hir_id) = self.tcx.hir().find_parent_node(expr.hir_id) { - let ty = match self.tcx.hir().find(parent_hir_id) { - Some( - hir::Node::Local(hir::Local { ty: Some(ty), .. }) - | hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _), .. }), - ) => Some(ty), - _ => None, - }; - if let Some(ty) = ty - && let hir::TyKind::Array(_, length) = ty.kind - && let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length - && let Some(span) = self.tcx.hir().opt_span(hir_id) - { - match self.tcx.sess.diagnostic().steal_diagnostic(span, StashKey::UnderscoreForArrayLengths) { - Some(mut err) => { - err.span_suggestion( - span, - "consider specifying the array length", - array_len, - Applicability::MaybeIncorrect, - ); - err.emit(); - } - None => () + let parent_node = self.tcx.hir().parent_iter(expr.hir_id).find(|(_, node)| { + !matches!(node, hir::Node::Expr(hir::Expr { kind: hir::ExprKind::AddrOf(..), .. })) + }); + let Some((_, + hir::Node::Local(hir::Local { ty: Some(ty), .. }) + | hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _), .. })) + ) = parent_node else { + return + }; + if let hir::TyKind::Array(_, length) = ty.peel_refs().kind + && let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length + && let Some(span) = self.tcx.hir().opt_span(hir_id) + { + match self.tcx.sess.diagnostic().steal_diagnostic(span, StashKey::UnderscoreForArrayLengths) { + Some(mut err) => { + err.span_suggestion( + span, + "consider specifying the array length", + array_len, + Applicability::MaybeIncorrect, + ); + err.emit(); } + None => () } } } diff --git a/src/test/ui/array-slice-vec/suggest-array-length.fixed b/src/test/ui/array-slice-vec/suggest-array-length.fixed index bae3ab74af676..867c18a7d5e6b 100644 --- a/src/test/ui/array-slice-vec/suggest-array-length.fixed +++ b/src/test/ui/array-slice-vec/suggest-array-length.fixed @@ -5,10 +5,22 @@ fn main() { const Foo: [i32; 3] = [1, 2, 3]; //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment //~| ERROR using `_` for array lengths is unstable + const REF_FOO: &[u8; 1] = &[1]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable let foo: [i32; 3] = [1, 2, 3]; //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment //~| ERROR using `_` for array lengths is unstable let bar: [i32; 3] = [0; 3]; //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment //~| ERROR using `_` for array lengths is unstable + let ref_foo: &[i32; 3] = &[1, 2, 3]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable + let ref_bar: &[i32; 3] = &[0; 3]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable + let multiple_ref_foo: &&[i32; 3] = &&[1, 2, 3]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable } diff --git a/src/test/ui/array-slice-vec/suggest-array-length.rs b/src/test/ui/array-slice-vec/suggest-array-length.rs index b0867f4e39676..f66b3d4a89991 100644 --- a/src/test/ui/array-slice-vec/suggest-array-length.rs +++ b/src/test/ui/array-slice-vec/suggest-array-length.rs @@ -5,10 +5,22 @@ fn main() { const Foo: [i32; _] = [1, 2, 3]; //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment //~| ERROR using `_` for array lengths is unstable + const REF_FOO: &[u8; _] = &[1]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable let foo: [i32; _] = [1, 2, 3]; //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment //~| ERROR using `_` for array lengths is unstable let bar: [i32; _] = [0; 3]; //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment //~| ERROR using `_` for array lengths is unstable + let ref_foo: &[i32; _] = &[1, 2, 3]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable + let ref_bar: &[i32; _] = &[0; 3]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable + let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3]; + //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment + //~| ERROR using `_` for array lengths is unstable } diff --git a/src/test/ui/array-slice-vec/suggest-array-length.stderr b/src/test/ui/array-slice-vec/suggest-array-length.stderr index 9000f71602850..16c90a04784d0 100644 --- a/src/test/ui/array-slice-vec/suggest-array-length.stderr +++ b/src/test/ui/array-slice-vec/suggest-array-length.stderr @@ -1,21 +1,45 @@ error: in expressions, `_` can only be used on the left-hand side of an assignment - --> $DIR/suggest-array-length.rs:8:20 + --> $DIR/suggest-array-length.rs:11:20 | LL | let foo: [i32; _] = [1, 2, 3]; | ^ `_` not allowed here error: in expressions, `_` can only be used on the left-hand side of an assignment - --> $DIR/suggest-array-length.rs:11:20 + --> $DIR/suggest-array-length.rs:14:20 | LL | let bar: [i32; _] = [0; 3]; | ^ `_` not allowed here +error: in expressions, `_` can only be used on the left-hand side of an assignment + --> $DIR/suggest-array-length.rs:17:25 + | +LL | let ref_foo: &[i32; _] = &[1, 2, 3]; + | ^ `_` not allowed here + +error: in expressions, `_` can only be used on the left-hand side of an assignment + --> $DIR/suggest-array-length.rs:20:25 + | +LL | let ref_bar: &[i32; _] = &[0; 3]; + | ^ `_` not allowed here + +error: in expressions, `_` can only be used on the left-hand side of an assignment + --> $DIR/suggest-array-length.rs:23:35 + | +LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3]; + | ^ `_` not allowed here + error: in expressions, `_` can only be used on the left-hand side of an assignment --> $DIR/suggest-array-length.rs:5:22 | LL | const Foo: [i32; _] = [1, 2, 3]; | ^ `_` not allowed here +error: in expressions, `_` can only be used on the left-hand side of an assignment + --> $DIR/suggest-array-length.rs:8:26 + | +LL | const REF_FOO: &[u8; _] = &[1]; + | ^ `_` not allowed here + error[E0658]: using `_` for array lengths is unstable --> $DIR/suggest-array-length.rs:5:22 | @@ -26,7 +50,16 @@ LL | const Foo: [i32; _] = [1, 2, 3]; = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable error[E0658]: using `_` for array lengths is unstable - --> $DIR/suggest-array-length.rs:8:20 + --> $DIR/suggest-array-length.rs:8:26 + | +LL | const REF_FOO: &[u8; _] = &[1]; + | ^ help: consider specifying the array length: `1` + | + = note: see issue #85077 for more information + = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable + +error[E0658]: using `_` for array lengths is unstable + --> $DIR/suggest-array-length.rs:11:20 | LL | let foo: [i32; _] = [1, 2, 3]; | ^ help: consider specifying the array length: `3` @@ -35,7 +68,7 @@ LL | let foo: [i32; _] = [1, 2, 3]; = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable error[E0658]: using `_` for array lengths is unstable - --> $DIR/suggest-array-length.rs:11:20 + --> $DIR/suggest-array-length.rs:14:20 | LL | let bar: [i32; _] = [0; 3]; | ^ help: consider specifying the array length: `3` @@ -43,6 +76,33 @@ LL | let bar: [i32; _] = [0; 3]; = note: see issue #85077 for more information = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable -error: aborting due to 6 previous errors +error[E0658]: using `_` for array lengths is unstable + --> $DIR/suggest-array-length.rs:17:25 + | +LL | let ref_foo: &[i32; _] = &[1, 2, 3]; + | ^ help: consider specifying the array length: `3` + | + = note: see issue #85077 for more information + = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable + +error[E0658]: using `_` for array lengths is unstable + --> $DIR/suggest-array-length.rs:20:25 + | +LL | let ref_bar: &[i32; _] = &[0; 3]; + | ^ help: consider specifying the array length: `3` + | + = note: see issue #85077 for more information + = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable + +error[E0658]: using `_` for array lengths is unstable + --> $DIR/suggest-array-length.rs:23:35 + | +LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3]; + | ^ help: consider specifying the array length: `3` + | + = note: see issue #85077 for more information + = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable + +error: aborting due to 14 previous errors For more information about this error, try `rustc --explain E0658`.