diff --git a/CHANGELOG.md b/CHANGELOG.md index 4d6aff398..8fdc1487b 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,6 +1,8 @@ # Change Log All notable changes to this project will be documented in this file. +* New [`mut_from_ref`] lint + ## 0.0.114 — 2017-02-08 * Rustup to rustc 1.17.0-nightly (c49d10207 2017-02-07) * Tests are now ui tests (testing the exact output of rustc) @@ -370,6 +372,7 @@ All notable changes to this project will be documented in this file. [`mixed_case_hex_literals`]: https://github.com/Manishearth/rust-clippy/wiki#mixed_case_hex_literals [`module_inception`]: https://github.com/Manishearth/rust-clippy/wiki#module_inception [`modulo_one`]: https://github.com/Manishearth/rust-clippy/wiki#modulo_one +[`mut_from_ref`]: https://github.com/Manishearth/rust-clippy/wiki#mut_from_ref [`mut_mut`]: https://github.com/Manishearth/rust-clippy/wiki#mut_mut [`mutex_atomic`]: https://github.com/Manishearth/rust-clippy/wiki#mutex_atomic [`mutex_integer`]: https://github.com/Manishearth/rust-clippy/wiki#mutex_integer diff --git a/README.md b/README.md index de01a2533..c87733f9d 100644 --- a/README.md +++ b/README.md @@ -256,7 +256,7 @@ name [iter_next_loop](https://github.com/Manishearth/rust-clippy/wiki#iter_next_loop) | warn | for-looping over `_.next()` which is probably not intended [iter_nth](https://github.com/Manishearth/rust-clippy/wiki#iter_nth) | warn | using `.iter().nth()` on a standard library type with O(1) element access [iter_skip_next](https://github.com/Manishearth/rust-clippy/wiki#iter_skip_next) | warn | using `.skip(x).next()` on an iterator -[large_enum_variant](https://github.com/Manishearth/rust-clippy/wiki#large_enum_variant) | warn | large variants on an enum +[large_enum_variant](https://github.com/Manishearth/rust-clippy/wiki#large_enum_variant) | warn | large size difference between variants on an enum [len_without_is_empty](https://github.com/Manishearth/rust-clippy/wiki#len_without_is_empty) | warn | traits or impls with a public `len` method but no corresponding `is_empty` method [len_zero](https://github.com/Manishearth/rust-clippy/wiki#len_zero) | warn | checking `.len() == 0` or `.len() > 0` (or similar) when `.is_empty()` could be used instead [let_and_return](https://github.com/Manishearth/rust-clippy/wiki#let_and_return) | warn | creating a let-binding and then immediately returning it like `let x = expr; x` at the end of a block @@ -279,6 +279,7 @@ name [mixed_case_hex_literals](https://github.com/Manishearth/rust-clippy/wiki#mixed_case_hex_literals) | warn | hex literals whose letter digits are not consistently upper- or lowercased [module_inception](https://github.com/Manishearth/rust-clippy/wiki#module_inception) | warn | modules that have the same name as their parent module [modulo_one](https://github.com/Manishearth/rust-clippy/wiki#modulo_one) | warn | taking a number modulo 1, which always returns 0 +[mut_from_ref](https://github.com/Manishearth/rust-clippy/wiki#mut_from_ref) | warn | fns that create mutable refs from immutable ref args [mut_mut](https://github.com/Manishearth/rust-clippy/wiki#mut_mut) | allow | usage of double-mut refs, e.g. `&mut &mut ...` [mutex_atomic](https://github.com/Manishearth/rust-clippy/wiki#mutex_atomic) | warn | using a mutex where an atomic value could be used instead [mutex_integer](https://github.com/Manishearth/rust-clippy/wiki#mutex_integer) | allow | using a mutex for an integer type diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs index 36c5e7a28..f656d513b 100644 --- a/clippy_lints/src/large_enum_variant.rs +++ b/clippy_lints/src/large_enum_variant.rs @@ -1,4 +1,4 @@ -//! lint when there are large variants on an enum +//! lint when there is a large size difference between variants on an enum use rustc::lint::*; use rustc::hir::*; @@ -7,7 +7,7 @@ use rustc::ty::layout::TargetDataLayout; use rustc::ty::TypeFoldable; use rustc::traits::Reveal; -/// **What it does:** Checks for large variants on `enum`s. +/// **What it does:** Checks for large size differences between variants on `enum`s. /// /// **Why is this bad?** Enum size is bounded by the largest variant. Having a large variant /// can penalize the memory layout of that enum. @@ -24,17 +24,17 @@ use rustc::traits::Reveal; declare_lint! { pub LARGE_ENUM_VARIANT, Warn, - "large variants on an enum" + "large size difference between variants on an enum" } #[derive(Copy,Clone)] pub struct LargeEnumVariant { - maximum_variant_size_allowed: u64, + maximum_size_difference_allowed: u64, } impl LargeEnumVariant { - pub fn new(maximum_variant_size_allowed: u64) -> Self { - LargeEnumVariant { maximum_variant_size_allowed: maximum_variant_size_allowed } + pub fn new(maximum_size_difference_allowed: u64) -> Self { + LargeEnumVariant { maximum_size_difference_allowed: maximum_size_difference_allowed } } } @@ -50,6 +50,10 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { if let ItemEnum(ref def, _) = item.node { let ty = cx.tcx.item_type(did); let adt = ty.ty_adt_def().expect("already checked whether this is an enum"); + + let mut smallest_variant: Option<(_, _)> = None; + let mut largest_variant: Option<(_, _)> = None; + for (i, variant) in adt.variants.iter().enumerate() { let data_layout = TargetDataLayout::parse(cx.sess()); cx.tcx.infer_ctxt((), Reveal::All).enter(|infcx| { @@ -67,32 +71,57 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { } }) .sum(); - if size > self.maximum_variant_size_allowed { - span_lint_and_then(cx, - LARGE_ENUM_VARIANT, - def.variants[i].span, - "large enum variant found", - |db| { - if variant.fields.len() == 1 { - let span = match def.variants[i].node.data { - VariantData::Struct(ref fields, _) | - VariantData::Tuple(ref fields, _) => fields[0].ty.span, - VariantData::Unit(_) => unreachable!(), - }; - if let Some(snip) = snippet_opt(cx, span) { - db.span_suggestion(span, - "consider boxing the large fields to reduce the total size of \ - the enum", - format!("Box<{}>", snip)); - return; - } - } - db.span_help(def.variants[i].span, - "consider boxing the large fields to reduce the total size of the enum"); - }); - } + + let grouped = (size, (i, variant)); + + update_if(&mut smallest_variant, grouped, |a, b| b.0 <= a.0); + update_if(&mut largest_variant, grouped, |a, b| b.0 >= a.0); }); } + + if let (Some(smallest), Some(largest)) = (smallest_variant, largest_variant) { + let difference = largest.0 - smallest.0; + + if difference > self.maximum_size_difference_allowed { + let (i, variant) = largest.1; + + span_lint_and_then(cx, + LARGE_ENUM_VARIANT, + def.variants[i].span, + "large size difference between variants", + |db| { + if variant.fields.len() == 1 { + let span = match def.variants[i].node.data { + VariantData::Struct(ref fields, _) | + VariantData::Tuple(ref fields, _) => fields[0].ty.span, + VariantData::Unit(_) => unreachable!(), + }; + if let Some(snip) = snippet_opt(cx, span) { + db.span_suggestion(span, + "consider boxing the large fields to reduce the total size of the \ + enum", + format!("Box<{}>", snip)); + return; + } + } + db.span_help(def.variants[i].span, + "consider boxing the large fields to reduce the total size of the enum"); + }); + } + } + } } } + +fn update_if(old: &mut Option, new: T, f: F) + where F: Fn(&T, &T) -> bool +{ + if let Some(ref mut val) = *old { + if f(val, &new) { + *val = new; + } + } else { + *old = Some(new); + } +} diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 661e6415b..de5945df8 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -15,6 +15,7 @@ #![allow(needless_lifetimes)] extern crate syntax; +extern crate syntax_pos; #[macro_use] extern crate rustc; extern crate rustc_data_structures; @@ -465,6 +466,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) { precedence::PRECEDENCE, print::PRINT_WITH_NEWLINE, ptr::CMP_NULL, + ptr::MUT_FROM_REF, ptr::PTR_ARG, ranges::RANGE_STEP_BY_ZERO, ranges::RANGE_ZIP_WITH_LEN, diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs index 590e3d587..e9176372e 100644 --- a/clippy_lints/src/ptr.rs +++ b/clippy_lints/src/ptr.rs @@ -5,7 +5,9 @@ use rustc::hir::map::NodeItem; use rustc::lint::*; use rustc::ty; use syntax::ast::NodeId; -use utils::{match_path, match_type, paths, span_lint}; +use syntax::codemap::Span; +use syntax_pos::MultiSpan; +use utils::{match_path, match_type, paths, span_lint, span_lint_and_then}; /// **What it does:** This lint checks for function arguments of type `&String` or `&Vec` unless /// the references are mutable. @@ -44,13 +46,32 @@ declare_lint! { "comparing a pointer to a null pointer, suggesting to use `.is_null()` instead." } +/// **What it does:** This lint checks for functions that take immutable references and return +/// mutable ones. +/// +/// **Why is this bad?** This is trivially unsound, as one can create two mutable references +/// from the same (immutable!) source. This [error](https://github.com/rust-lang/rust/issues/39465) +/// actually lead to an interim Rust release 1.15.1. +/// +/// **Known problems:** To be on the conservative side, if there's at least one mutable reference +/// with the output lifetime, this lint will not trigger. In practice, this case is unlikely anyway. +/// +/// **Example:** +/// ```rust +/// fn foo(&Foo) -> &mut Bar { .. } +/// ``` +declare_lint! { + pub MUT_FROM_REF, + Warn, + "fns that create mutable refs from immutable ref args" +} #[derive(Copy,Clone)] pub struct PointerPass; impl LintPass for PointerPass { fn get_lints(&self) -> LintArray { - lint_array!(PTR_ARG, CMP_NULL) + lint_array!(PTR_ARG, CMP_NULL, MUT_FROM_REF) } } @@ -111,6 +132,37 @@ fn check_fn(cx: &LateContext, decl: &FnDecl, fn_id: NodeId) { } } } + + if let FunctionRetTy::Return(ref ty) = decl.output { + if let Some((out, MutMutable, _)) = get_rptr_lm(ty) { + let mut immutables = vec![]; + for (_, ref mutbl, ref argspan) in + decl.inputs + .iter() + .filter_map(|ty| get_rptr_lm(ty)) + .filter(|&(lt, _, _)| lt.name == out.name) { + if *mutbl == MutMutable { + return; + } + immutables.push(*argspan); + } + if immutables.is_empty() { + return; + } + span_lint_and_then(cx, MUT_FROM_REF, ty.span, "mutable borrow from immutable input(s)", |db| { + let ms = MultiSpan::from_spans(immutables); + db.span_note(ms, "immutable borrow here"); + }); + } + } +} + +fn get_rptr_lm(ty: &Ty) -> Option<(&Lifetime, Mutability, Span)> { + if let Ty_::TyRptr(ref lt, ref m) = ty.node { + Some((lt, m.mutbl, ty.span)) + } else { + None + } } fn is_null_path(expr: &Expr) -> bool { diff --git a/src/main.rs b/src/main.rs index 7a744356e..ac90528c6 100644 --- a/src/main.rs +++ b/src/main.rs @@ -1,7 +1,6 @@ // error-pattern:yummy #![feature(box_syntax)] #![feature(rustc_private)] -#![feature(static_in_const)] #![allow(unknown_lints, missing_docs_in_private_items)] diff --git a/tests/ui/large_enum_variant.rs b/tests/ui/large_enum_variant.rs index 5bbcb9391..8ac7571c1 100644 --- a/tests/ui/large_enum_variant.rs +++ b/tests/ui/large_enum_variant.rs @@ -8,18 +8,17 @@ enum LargeEnum { A(i32), B([i32; 8000]), - - } -enum GenericEnum { +enum GenericEnumOk { + A(i32), + B([T; 8000]), +} + +enum GenericEnum2 { A(i32), B([i32; 8000]), - - - C([T; 8000]), - D(T, [i32; 8000]), - + C(T, [i32; 8000]), } trait SomeTrait { @@ -27,27 +26,32 @@ trait SomeTrait { } enum LargeEnumGeneric { - Var(A::Item), // regression test, this used to ICE + Var(A::Item), } -enum AnotherLargeEnum { +enum LargeEnum2 { VariantOk(i32, u32), ContainingLargeEnum(LargeEnum), - - +} +enum LargeEnum3 { ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), - VoidVariant, StructLikeLittle { x: i32, y: i32 }, +} + +enum LargeEnum4 { + VariantOk(i32, u32), StructLikeLarge { x: [i32; 8000], y: i32 }, - - StructLikeLarge2 { - x: - [i32; 8000] - - }, } -fn main() { - +enum LargeEnum5 { + VariantOk(i32, u32), + StructLikeLarge2 { x: [i32; 8000] }, } + +enum LargeEnumOk { + LargeA([i32; 8000]), + LargeB([i32; 8001]), +} + +fn main() {} diff --git a/tests/ui/large_enum_variant.stderr b/tests/ui/large_enum_variant.stderr index 77155b6ab..84213003e 100644 --- a/tests/ui/large_enum_variant.stderr +++ b/tests/ui/large_enum_variant.stderr @@ -1,4 +1,4 @@ -error: large enum variant found +error: large size difference between variants --> $DIR/large_enum_variant.rs:10:5 | 10 | B([i32; 8000]), @@ -12,73 +12,59 @@ note: lint level defined here help: consider boxing the large fields to reduce the total size of the enum | B(Box<[i32; 8000]>), -error: large enum variant found - --> $DIR/large_enum_variant.rs:17:5 - | -17 | B([i32; 8000]), - | ^^^^^^^^^^^^^^ - | -help: consider boxing the large fields to reduce the total size of the enum - | B(Box<[i32; 8000]>), - -error: large enum variant found +error: large size difference between variants --> $DIR/large_enum_variant.rs:21:5 | -21 | D(T, [i32; 8000]), +21 | C(T, [i32; 8000]), | ^^^^^^^^^^^^^^^^^ | help: consider boxing the large fields to reduce the total size of the enum --> $DIR/large_enum_variant.rs:21:5 | -21 | D(T, [i32; 8000]), +21 | C(T, [i32; 8000]), | ^^^^^^^^^^^^^^^^^ -error: large enum variant found - --> $DIR/large_enum_variant.rs:35:5 +error: large size difference between variants + --> $DIR/large_enum_variant.rs:34:5 | -35 | ContainingLargeEnum(LargeEnum), +34 | ContainingLargeEnum(LargeEnum), | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | help: consider boxing the large fields to reduce the total size of the enum | ContainingLargeEnum(Box), -error: large enum variant found - --> $DIR/large_enum_variant.rs:38:5 +error: large size difference between variants + --> $DIR/large_enum_variant.rs:37:5 | -38 | ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), +37 | ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | help: consider boxing the large fields to reduce the total size of the enum - --> $DIR/large_enum_variant.rs:38:5 + --> $DIR/large_enum_variant.rs:37:5 | -38 | ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), +37 | ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -error: large enum variant found - --> $DIR/large_enum_variant.rs:42:5 - | -42 | StructLikeLarge { x: [i32; 8000], y: i32 }, - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - | -help: consider boxing the large fields to reduce the total size of the enum - --> $DIR/large_enum_variant.rs:42:5 - | -42 | StructLikeLarge { x: [i32; 8000], y: i32 }, - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -error: large enum variant found +error: large size difference between variants --> $DIR/large_enum_variant.rs:44:5 | -44 | StructLikeLarge2 { - | _____^ starting here... -45 | | x: -46 | | [i32; 8000] -47 | | -48 | | }, - | |_____^ ...ending here +44 | StructLikeLarge { x: [i32; 8000], y: i32 }, + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | help: consider boxing the large fields to reduce the total size of the enum - | Box<[i32; 8000]> + --> $DIR/large_enum_variant.rs:44:5 + | +44 | StructLikeLarge { x: [i32; 8000], y: i32 }, + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -error: aborting due to 7 previous errors +error: large size difference between variants + --> $DIR/large_enum_variant.rs:49:5 + | +49 | StructLikeLarge2 { x: [i32; 8000] }, + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | +help: consider boxing the large fields to reduce the total size of the enum + | StructLikeLarge2 { x: Box<[i32; 8000]> }, + +error: aborting due to 6 previous errors diff --git a/tests/ui/mut_from_ref.rs b/tests/ui/mut_from_ref.rs new file mode 100644 index 000000000..35bff9371 --- /dev/null +++ b/tests/ui/mut_from_ref.rs @@ -0,0 +1,48 @@ +#![feature(plugin)] +#![plugin(clippy)] +#![allow(unused)] +#![deny(mut_from_ref)] + +struct Foo; + +impl Foo { + fn this_wont_hurt_a_bit(&self) -> &mut Foo { + unimplemented!() + } +} + +trait Ouch { + fn ouch(x: &Foo) -> &mut Foo; +} + +impl Ouch for Foo { + fn ouch(x: &Foo) -> &mut Foo { + unimplemented!() + } +} + +fn fail(x: &u32) -> &mut u16 { + unimplemented!() +} + +fn fail_lifetime<'a>(x: &'a u32, y: &mut u32) -> &'a mut u32 { + unimplemented!() +} + +fn fail_double<'a, 'b>(x: &'a u32, y: &'a u32, z: &'b mut u32) -> &'a mut u32 { + unimplemented!() +} + +// this is OK, because the result borrows y +fn works<'a>(x: &u32, y: &'a mut u32) -> &'a mut u32 { + unimplemented!() +} + +// this is also OK, because the result could borrow y +fn also_works<'a>(x: &'a u32, y: &'a mut u32) -> &'a mut u32 { + unimplemented!() +} + +fn main() { + //TODO +} diff --git a/tests/ui/mut_from_ref.stderr b/tests/ui/mut_from_ref.stderr new file mode 100644 index 000000000..5098d7d0a --- /dev/null +++ b/tests/ui/mut_from_ref.stderr @@ -0,0 +1,67 @@ +error: mutable borrow from immutable input(s) + --> $DIR/mut_from_ref.rs:9:39 + | +9 | fn this_wont_hurt_a_bit(&self) -> &mut Foo { + | ^^^^^^^^ + | +note: lint level defined here + --> $DIR/mut_from_ref.rs:4:9 + | +4 | #![deny(mut_from_ref)] + | ^^^^^^^^^^^^ +note: immutable borrow here + --> $DIR/mut_from_ref.rs:9:29 + | +9 | fn this_wont_hurt_a_bit(&self) -> &mut Foo { + | ^^^^^ + +error: mutable borrow from immutable input(s) + --> $DIR/mut_from_ref.rs:15:25 + | +15 | fn ouch(x: &Foo) -> &mut Foo; + | ^^^^^^^^ + | +note: immutable borrow here + --> $DIR/mut_from_ref.rs:15:16 + | +15 | fn ouch(x: &Foo) -> &mut Foo; + | ^^^^ + +error: mutable borrow from immutable input(s) + --> $DIR/mut_from_ref.rs:24:21 + | +24 | fn fail(x: &u32) -> &mut u16 { + | ^^^^^^^^ + | +note: immutable borrow here + --> $DIR/mut_from_ref.rs:24:12 + | +24 | fn fail(x: &u32) -> &mut u16 { + | ^^^^ + +error: mutable borrow from immutable input(s) + --> $DIR/mut_from_ref.rs:28:50 + | +28 | fn fail_lifetime<'a>(x: &'a u32, y: &mut u32) -> &'a mut u32 { + | ^^^^^^^^^^^ + | +note: immutable borrow here + --> $DIR/mut_from_ref.rs:28:25 + | +28 | fn fail_lifetime<'a>(x: &'a u32, y: &mut u32) -> &'a mut u32 { + | ^^^^^^^ + +error: mutable borrow from immutable input(s) + --> $DIR/mut_from_ref.rs:32:67 + | +32 | fn fail_double<'a, 'b>(x: &'a u32, y: &'a u32, z: &'b mut u32) -> &'a mut u32 { + | ^^^^^^^^^^^ + | +note: immutable borrow here + --> $DIR/mut_from_ref.rs:32:27 + | +32 | fn fail_double<'a, 'b>(x: &'a u32, y: &'a u32, z: &'b mut u32) -> &'a mut u32 { + | ^^^^^^^ ^^^^^^^ + +error: aborting due to 5 previous errors +