From 7e4b633417fe4886d35c11d38b28b3f98ff4e373 Mon Sep 17 00:00:00 2001 From: Owen Sanchez Date: Sat, 4 Feb 2017 17:42:35 -0700 Subject: [PATCH 1/6] Add some writes to a log file for debugging --- clippy_lints/src/large_enum_variant.rs | 8 ++++++++ log | 1 + 2 files changed, 9 insertions(+) create mode 100644 log diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs index 36c5e7a288ae..aa7db1f77e2c 100644 --- a/clippy_lints/src/large_enum_variant.rs +++ b/clippy_lints/src/large_enum_variant.rs @@ -67,7 +67,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { } }) .sum(); + + use std::io::Write; + let mut f = ::std::fs::File::create("log").unwrap(); + + writeln!(f, "size, max size: {}, {}", size, self.maximum_variant_size_allowed).unwrap(); if size > self.maximum_variant_size_allowed { + writeln!(f, "size > max").unwrap(); + // panic!("foo"); + span_lint_and_then(cx, LARGE_ENUM_VARIANT, def.variants[i].span, diff --git a/log b/log new file mode 100644 index 000000000000..0cbafc978894 --- /dev/null +++ b/log @@ -0,0 +1 @@ +size, max size: 0, 200 From 1938904fcd581e87c2be63d537fd402805627a0e Mon Sep 17 00:00:00 2001 From: Owen Sanchez Date: Sat, 4 Feb 2017 20:12:55 -0700 Subject: [PATCH 2/6] Change large_enum_variant to lint against size differences rather than size --- clippy_lints/src/large_enum_variant.rs | 90 +++++++++++++++----------- log | 1 - tests/ui/large_enum_variant.rs | 55 ++++++++++------ 3 files changed, 88 insertions(+), 58 deletions(-) delete mode 100644 log diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs index aa7db1f77e2c..1363183cb810 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 } } } @@ -50,7 +50,11 @@ 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"); - for (i, variant) in adt.variants.iter().enumerate() { + + let mut sizes = Vec::new(); + let mut variants = Vec::new(); + + for variant in &adt.variants { let data_layout = TargetDataLayout::parse(cx.sess()); cx.tcx.infer_ctxt((), Reveal::All).enter(|infcx| { let size: u64 = variant.fields @@ -68,39 +72,49 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { }) .sum(); - use std::io::Write; - let mut f = ::std::fs::File::create("log").unwrap(); - - writeln!(f, "size, max size: {}, {}", size, self.maximum_variant_size_allowed).unwrap(); - if size > self.maximum_variant_size_allowed { - writeln!(f, "size > max").unwrap(); - // panic!("foo"); - - 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"); - }); - } + sizes.push(size); + variants.push(variant); }); } + + let mut grouped = sizes.into_iter().zip(variants.into_iter().enumerate()).collect::>(); + + grouped.sort_by_key(|g| g.0); + + let smallest_variant = grouped.first(); + let largest_variant = grouped.last(); + + 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"); + }); + } + } + } } } diff --git a/log b/log deleted file mode 100644 index 0cbafc978894..000000000000 --- a/log +++ /dev/null @@ -1 +0,0 @@ -size, max size: 0, 200 diff --git a/tests/ui/large_enum_variant.rs b/tests/ui/large_enum_variant.rs index 5bbcb93910b9..26ba883b1baa 100644 --- a/tests/ui/large_enum_variant.rs +++ b/tests/ui/large_enum_variant.rs @@ -7,19 +7,21 @@ enum LargeEnum { A(i32), - B([i32; 8000]), - - + B([i32; 8000]), //~ ERROR large size difference between variants + //~^ HELP consider boxing the large fields to reduce the total size of the enum + //~| SUGGESTION Box<[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]), //~ ERROR large size difference between variants + //~^ HELP consider boxing the large fields to reduce the total size of the enum } trait SomeTrait { @@ -30,24 +32,39 @@ enum LargeEnumGeneric { Var(A::Item), // regression test, this used to ICE } -enum AnotherLargeEnum { +enum LargeEnum2 { VariantOk(i32, u32), - ContainingLargeEnum(LargeEnum), - - - ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), - + ContainingLargeEnum(LargeEnum), //~ ERROR large size difference between variants + //~^ HELP consider boxing the large fields to reduce the total size of the enum + //~| SUGGESTION Box +} +enum LargeEnum3 { + ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), //~ ERROR large size difference between variants + //~^ HELP consider boxing the large fields to reduce the total size of the enum VoidVariant, StructLikeLittle { x: i32, y: i32 }, - StructLikeLarge { x: [i32; 8000], y: i32 }, +} - StructLikeLarge2 { +enum LargeEnum4 { + VariantOk(i32, u32), + StructLikeLarge { x: [i32; 8000], y: i32 }, //~ ERROR large size difference between variants + //~^ HELP consider boxing the large fields to reduce the total size of the enum +} + +enum LargeEnum5 { + VariantOk(i32, u32), + StructLikeLarge2 { //~ ERROR large size difference between variants x: - [i32; 8000] - + [i32; 8000] //~ SUGGESTION Box<[i32; 8000]> + //~^ HELP consider boxing the large fields to reduce the total size of the enum }, } +enum LargeEnumOk { + LargeA([i32; 8000]), + LargeB([i32; 8001]), +} + fn main() { } From 96ae7da9b60e05bf16c376be73facd444f99446e Mon Sep 17 00:00:00 2001 From: Owen Sanchez Date: Sat, 4 Feb 2017 20:26:08 -0700 Subject: [PATCH 3/6] Run update_lints.py --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 3f3ed135e0ce..1f6fb4ff9c0b 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 From 45a7012fd969ad97fcbcdd4af2530875e37663b7 Mon Sep 17 00:00:00 2001 From: Owen Sanchez Date: Mon, 6 Feb 2017 12:25:38 -0700 Subject: [PATCH 4/6] Search directly for the largest and smallest variants instead of sorting --- clippy_lints/src/large_enum_variant.rs | 29 +++++++++++++++----------- 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs index 1363183cb810..050362dede04 100644 --- a/clippy_lints/src/large_enum_variant.rs +++ b/clippy_lints/src/large_enum_variant.rs @@ -51,10 +51,10 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { let ty = cx.tcx.item_type(did); let adt = ty.ty_adt_def().expect("already checked whether this is an enum"); - let mut sizes = Vec::new(); - let mut variants = Vec::new(); + let mut smallest_variant: Option<(_, _)> = None; + let mut largest_variant: Option<(_, _)> = None; - for variant in &adt.variants { + for (i, variant) in adt.variants.iter().enumerate() { let data_layout = TargetDataLayout::parse(cx.sess()); cx.tcx.infer_ctxt((), Reveal::All).enter(|infcx| { let size: u64 = variant.fields @@ -72,18 +72,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { }) .sum(); - sizes.push(size); - variants.push(variant); + 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); }); } - let mut grouped = sizes.into_iter().zip(variants.into_iter().enumerate()).collect::>(); - - grouped.sort_by_key(|g| g.0); - - let smallest_variant = grouped.first(); - let largest_variant = grouped.last(); - if let (Some(smallest), Some(largest)) = (smallest_variant, largest_variant) { let difference = largest.0 - smallest.0; @@ -118,3 +113,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { } } } + +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); + } +} From 2a8ce7c4588d3847ffe91fd90fcd8d0be2edb4df Mon Sep 17 00:00:00 2001 From: Owen Sanchez Date: Fri, 10 Feb 2017 21:04:19 -0700 Subject: [PATCH 5/6] Update large_enum_variant test --- tests/ui/large_enum_variant.rs | 29 ++++-------- tests/ui/large_enum_variant.stderr | 72 ++++++++++++------------------ 2 files changed, 37 insertions(+), 64 deletions(-) diff --git a/tests/ui/large_enum_variant.rs b/tests/ui/large_enum_variant.rs index 26ba883b1baa..8ac7571c1b1f 100644 --- a/tests/ui/large_enum_variant.rs +++ b/tests/ui/large_enum_variant.rs @@ -7,9 +7,7 @@ enum LargeEnum { A(i32), - B([i32; 8000]), //~ ERROR large size difference between variants - //~^ HELP consider boxing the large fields to reduce the total size of the enum - //~| SUGGESTION Box<[i32; 8000]> + B([i32; 8000]), } enum GenericEnumOk { @@ -20,8 +18,7 @@ enum GenericEnumOk { enum GenericEnum2 { A(i32), B([i32; 8000]), - C(T, [i32; 8000]), //~ ERROR large size difference between variants - //~^ HELP consider boxing the large fields to reduce the total size of the enum + C(T, [i32; 8000]), } trait SomeTrait { @@ -29,35 +26,27 @@ trait SomeTrait { } enum LargeEnumGeneric { - Var(A::Item), // regression test, this used to ICE + Var(A::Item), } enum LargeEnum2 { VariantOk(i32, u32), - ContainingLargeEnum(LargeEnum), //~ ERROR large size difference between variants - //~^ HELP consider boxing the large fields to reduce the total size of the enum - //~| SUGGESTION Box + ContainingLargeEnum(LargeEnum), } enum LargeEnum3 { - ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), //~ ERROR large size difference between variants - //~^ HELP consider boxing the large fields to reduce the total size of the enum + ContainingMoreThanOneField(i32, [i32; 8000], [i32; 9500]), VoidVariant, StructLikeLittle { x: i32, y: i32 }, } enum LargeEnum4 { VariantOk(i32, u32), - StructLikeLarge { x: [i32; 8000], y: i32 }, //~ ERROR large size difference between variants - //~^ HELP consider boxing the large fields to reduce the total size of the enum + StructLikeLarge { x: [i32; 8000], y: i32 }, } enum LargeEnum5 { VariantOk(i32, u32), - StructLikeLarge2 { //~ ERROR large size difference between variants - x: - [i32; 8000] //~ SUGGESTION Box<[i32; 8000]> - //~^ HELP consider boxing the large fields to reduce the total size of the enum - }, + StructLikeLarge2 { x: [i32; 8000] }, } enum LargeEnumOk { @@ -65,6 +54,4 @@ enum LargeEnumOk { LargeB([i32; 8001]), } -fn main() { - -} +fn main() {} diff --git a/tests/ui/large_enum_variant.stderr b/tests/ui/large_enum_variant.stderr index 77155b6ab5fe..84213003eb70 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 From 8fb582ea1c4aece4c0f6634c562c4a46de481dc6 Mon Sep 17 00:00:00 2001 From: Owen Sanchez Date: Fri, 10 Feb 2017 21:08:50 -0700 Subject: [PATCH 6/6] rustfmt --- clippy_lints/src/large_enum_variant.rs | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs index 050362dede04..f656d513b516 100644 --- a/clippy_lints/src/large_enum_variant.rs +++ b/clippy_lints/src/large_enum_variant.rs @@ -114,7 +114,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant { } } -fn update_if(old: &mut Option, new: T, f: F) where F: Fn(&T, &T) -> bool { +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;