From d0c1f8ada2306801f2a6ce193e1f9f75471dbb3c Mon Sep 17 00:00:00 2001 From: Aleksei Latyshev Date: Sat, 2 May 2020 14:18:27 +0300 Subject: [PATCH] fix fp on while-let-on-iterator - fix `is_refutable` for slice patterns - fix `is_refutable` for bindings - add some TODO-s for cases, which can not be fixed easily --- clippy_lints/src/utils/mod.rs | 34 ++++++++++------ tests/ui/while_let_on_iterator.fixed | 58 +++++++++++++++++++++++++++ tests/ui/while_let_on_iterator.rs | 58 +++++++++++++++++++++++++++ tests/ui/while_let_on_iterator.stderr | 28 ++++++++++--- 4 files changed, 160 insertions(+), 18 deletions(-) diff --git a/clippy_lints/src/utils/mod.rs b/clippy_lints/src/utils/mod.rs index 04b4b4237..1c7b40fa9 100644 --- a/clippy_lints/src/utils/mod.rs +++ b/clippy_lints/src/utils/mod.rs @@ -933,6 +933,7 @@ pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_, '_>, expr: &Exp } /// Returns `true` if a pattern is refutable. +// TODO: should be implemented using rustc/mir_build/hair machinery pub fn is_refutable(cx: &LateContext<'_, '_>, pat: &Pat<'_>) -> bool { fn is_enum_variant(cx: &LateContext<'_, '_>, qpath: &QPath<'_>, id: HirId) -> bool { matches!( @@ -946,27 +947,34 @@ pub fn is_refutable(cx: &LateContext<'_, '_>, pat: &Pat<'_>) -> bool { } match pat.kind { - PatKind::Binding(..) | PatKind::Wild => false, + PatKind::Wild => false, + PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)), PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => is_refutable(cx, pat), PatKind::Lit(..) | PatKind::Range(..) => true, PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id), - PatKind::Or(ref pats) | PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)), + PatKind::Or(ref pats) => { + // TODO: should be the honest check, that pats is exhaustive set + are_refutable(cx, pats.iter().map(|pat| &**pat)) + }, + PatKind::Tuple(ref pats, _) => are_refutable(cx, pats.iter().map(|pat| &**pat)), PatKind::Struct(ref qpath, ref fields, _) => { - if is_enum_variant(cx, qpath, pat.hir_id) { - true - } else { - are_refutable(cx, fields.iter().map(|field| &*field.pat)) - } + is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| &*field.pat)) }, PatKind::TupleStruct(ref qpath, ref pats, _) => { - if is_enum_variant(cx, qpath, pat.hir_id) { - true - } else { - are_refutable(cx, pats.iter().map(|pat| &**pat)) - } + is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats.iter().map(|pat| &**pat)) }, PatKind::Slice(ref head, ref middle, ref tail) => { - are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)) + match &cx.tables.node_type(pat.hir_id).kind { + ty::Slice(..) => { + // [..] is the only irrefutable slice pattern. + !head.is_empty() || middle.is_none() || !tail.is_empty() + }, + ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter()).map(|pat| &**pat)), + _ => { + // unreachable!() + true + }, + } }, } } diff --git a/tests/ui/while_let_on_iterator.fixed b/tests/ui/while_let_on_iterator.fixed index f5fcabf63..e99c98ac7 100644 --- a/tests/ui/while_let_on_iterator.fixed +++ b/tests/ui/while_let_on_iterator.fixed @@ -2,6 +2,7 @@ #![warn(clippy::while_let_on_iterator)] #![allow(clippy::never_loop, unreachable_code, unused_mut)] +#![feature(or_patterns)] fn base() { let mut iter = 1..20; @@ -77,6 +78,62 @@ fn refutable() { // */ } +fn refutable2() { + // Issue 3780 + { + let v = vec![1, 2, 3]; + let mut it = v.windows(2); + while let Some([x, y]) = it.next() { + println!("x: {}", x); + println!("y: {}", y); + } + + let mut it = v.windows(2); + while let Some([x, ..]) = it.next() { + println!("x: {}", x); + } + + let mut it = v.windows(2); + while let Some([.., y]) = it.next() { + println!("y: {}", y); + } + + let mut it = v.windows(2); + for [..] in it {} + + let v = vec![[1], [2], [3]]; + let mut it = v.iter(); + while let Some([1]) = it.next() {} + + let mut it = v.iter(); + for [_x] in it {} + } + + // binding + { + let v = vec![1, 2, 3]; + let mut it = v.iter(); + while let Some(x @ 1) = it.next() { + println!("{}", x); + } + + let v = vec![[1], [2], [3]]; + let mut it = v.iter(); + for x @ [_] in it { + println!("{:?}", x); + } + } + + // false negative + { + let v = vec![1, 2, 3]; + let mut it = v.iter().map(Some); + while let Some(Some(_) | None) = it.next() { + println!("1"); + } + } +} + fn nested_loops() { let a = [42, 1337]; let mut y = a.iter(); @@ -152,6 +209,7 @@ fn issue1654() { fn main() { base(); refutable(); + refutable2(); nested_loops(); issue1121(); issue2965(); diff --git a/tests/ui/while_let_on_iterator.rs b/tests/ui/while_let_on_iterator.rs index 04dce8a02..ba1317242 100644 --- a/tests/ui/while_let_on_iterator.rs +++ b/tests/ui/while_let_on_iterator.rs @@ -2,6 +2,7 @@ #![warn(clippy::while_let_on_iterator)] #![allow(clippy::never_loop, unreachable_code, unused_mut)] +#![feature(or_patterns)] fn base() { let mut iter = 1..20; @@ -77,6 +78,62 @@ fn refutable() { // */ } +fn refutable2() { + // Issue 3780 + { + let v = vec![1, 2, 3]; + let mut it = v.windows(2); + while let Some([x, y]) = it.next() { + println!("x: {}", x); + println!("y: {}", y); + } + + let mut it = v.windows(2); + while let Some([x, ..]) = it.next() { + println!("x: {}", x); + } + + let mut it = v.windows(2); + while let Some([.., y]) = it.next() { + println!("y: {}", y); + } + + let mut it = v.windows(2); + while let Some([..]) = it.next() {} + + let v = vec![[1], [2], [3]]; + let mut it = v.iter(); + while let Some([1]) = it.next() {} + + let mut it = v.iter(); + while let Some([_x]) = it.next() {} + } + + // binding + { + let v = vec![1, 2, 3]; + let mut it = v.iter(); + while let Some(x @ 1) = it.next() { + println!("{}", x); + } + + let v = vec![[1], [2], [3]]; + let mut it = v.iter(); + while let Some(x @ [_]) = it.next() { + println!("{:?}", x); + } + } + + // false negative + { + let v = vec![1, 2, 3]; + let mut it = v.iter().map(Some); + while let Some(Some(_) | None) = it.next() { + println!("1"); + } + } +} + fn nested_loops() { let a = [42, 1337]; let mut y = a.iter(); @@ -152,6 +209,7 @@ fn issue1654() { fn main() { base(); refutable(); + refutable2(); nested_loops(); issue1121(); issue2965(); diff --git a/tests/ui/while_let_on_iterator.stderr b/tests/ui/while_let_on_iterator.stderr index 6de138d72..aa980d996 100644 --- a/tests/ui/while_let_on_iterator.stderr +++ b/tests/ui/while_let_on_iterator.stderr @@ -1,5 +1,5 @@ error: this loop could be written as a `for` loop - --> $DIR/while_let_on_iterator.rs:8:5 + --> $DIR/while_let_on_iterator.rs:9:5 | LL | while let Option::Some(x) = iter.next() { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in iter` @@ -7,22 +7,40 @@ LL | while let Option::Some(x) = iter.next() { = note: `-D clippy::while-let-on-iterator` implied by `-D warnings` error: this loop could be written as a `for` loop - --> $DIR/while_let_on_iterator.rs:13:5 + --> $DIR/while_let_on_iterator.rs:14:5 | LL | while let Some(x) = iter.next() { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in iter` error: this loop could be written as a `for` loop - --> $DIR/while_let_on_iterator.rs:18:5 + --> $DIR/while_let_on_iterator.rs:19:5 | LL | while let Some(_) = iter.next() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for _ in iter` error: this loop could be written as a `for` loop - --> $DIR/while_let_on_iterator.rs:97:9 + --> $DIR/while_let_on_iterator.rs:102:9 + | +LL | while let Some([..]) = it.next() {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for [..] in it` + +error: this loop could be written as a `for` loop + --> $DIR/while_let_on_iterator.rs:109:9 + | +LL | while let Some([_x]) = it.next() {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for [_x] in it` + +error: this loop could be written as a `for` loop + --> $DIR/while_let_on_iterator.rs:122:9 + | +LL | while let Some(x @ [_]) = it.next() { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x @ [_] in it` + +error: this loop could be written as a `for` loop + --> $DIR/while_let_on_iterator.rs:154:9 | LL | while let Some(_) = y.next() { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for _ in y` -error: aborting due to 4 previous errors +error: aborting due to 7 previous errors