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remove large_enum_variant suggestion for Copy types

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This commit is contained in:
Andre Bogus 2022-05-28 01:36:05 +02:00
parent 1dd55471b4
commit 19f94d52b3
3 changed files with 99 additions and 31 deletions
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66
clippy_lints/src/large_enum_variant.rs
View file

@ -1,7 +1,7 @@
//! lint when there is a large size difference between variants on an enum
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::{diagnostics::span_lint_and_then, ty::is_copy};
use rustc_errors::Applicability;
use rustc_hir::{Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
@ -132,37 +132,43 @@ impl<'tcx> LateLintPass<'tcx> for LargeEnumVariant {
let fields = def.variants[variants_size[0].ind].data.fields();
variants_size[0].fields_size.sort_by(|a, b| (a.size.cmp(&b.size)));
let mut applicability = Applicability::MaybeIncorrect;
let sugg: Vec<(Span, String)> = variants_size[0]
.fields_size
.iter()
.rev()
.map_while(|val| {
if difference > self.maximum_size_difference_allowed {
difference = difference.saturating_sub(val.size);
Some((
fields[val.ind].ty.span,
format!(
"Box<{}>",
snippet_with_applicability(
cx,
fields[val.ind].ty.span,
"..",
&mut applicability
)
.into_owned()
),
))
} else {
None
}
})
.collect();
if is_copy(cx, ty) {
diag.span_note(
item.ident.span,
"boxing a variant would require the type no longer be `Copy`",
);
} else {
let sugg: Vec<(Span, String)> = variants_size[0]
.fields_size
.iter()
.rev()
.map_while(|val| {
if difference > self.maximum_size_difference_allowed {
difference = difference.saturating_sub(val.size);
Some((
fields[val.ind].ty.span,
format!(
"Box<{}>",
snippet_with_applicability(
cx,
fields[val.ind].ty.span,
"..",
&mut applicability
)
.into_owned()
),
))
} else {
None
}
})
.collect();
if !sugg.is_empty() {
diag.multipart_suggestion(help_text, sugg, Applicability::MaybeIncorrect);
return;
if !sugg.is_empty() {
diag.multipart_suggestion(help_text, sugg, Applicability::MaybeIncorrect);
return;
}
}
diag.span_help(def.variants[variants_size[0].ind].span, help_text);
},
);

18
tests/ui/large_enum_variant.rs
View file

@ -98,6 +98,24 @@ struct Struct2 {
a: [i32; 8000],
}
#[derive(Copy, Clone)]
enum CopyableLargeEnum {
A(bool),
B([u128; 4000]),
}
enum ManuallyCopyLargeEnum {
A(bool),
B([u128; 4000]),
}
impl Clone for ManuallyCopyLargeEnum {
fn clone(&self) -> Self {
*self
}
}
impl Copy for ManuallyCopyLargeEnum {}
fn main() {
large_enum_variant!();
}

46
tests/ui/large_enum_variant.stderr
View file

@ -127,5 +127,49 @@ help: consider boxing the large fields to reduce the total size of the enum
LL | B(Box<Struct2>),
| ~~~~~~~~~~~~
error: aborting due to 8 previous errors
error: large size difference between variants
--> $DIR/large_enum_variant.rs:104:5
|
LL | B([u128; 4000]),
| ^^^^^^^^^^^^^^^ this variant is 64000 bytes
|
note: and the second-largest variant is 1 bytes:
--> $DIR/large_enum_variant.rs:103:5
|
LL | A(bool),
| ^^^^^^^
note: boxing a variant would require the type no longer be `Copy`
--> $DIR/large_enum_variant.rs:102:6
|
LL | enum CopyableLargeEnum {
| ^^^^^^^^^^^^^^^^^
help: consider boxing the large fields to reduce the total size of the enum
--> $DIR/large_enum_variant.rs:104:5
|
LL | B([u128; 4000]),
| ^^^^^^^^^^^^^^^
error: large size difference between variants
--> $DIR/large_enum_variant.rs:109:5
|
LL | B([u128; 4000]),
| ^^^^^^^^^^^^^^^ this variant is 64000 bytes
|
note: and the second-largest variant is 1 bytes:
--> $DIR/large_enum_variant.rs:108:5
|
LL | A(bool),
| ^^^^^^^
note: boxing a variant would require the type no longer be `Copy`
--> $DIR/large_enum_variant.rs:107:6
|
LL | enum ManuallyCopyLargeEnum {
| ^^^^^^^^^^^^^^^^^^^^^
help: consider boxing the large fields to reduce the total size of the enum
--> $DIR/large_enum_variant.rs:109:5
|
LL | B([u128; 4000]),
| ^^^^^^^^^^^^^^^
error: aborting due to 10 previous errors