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Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

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merged 4 commits into from
Jul 1, 2021
Merged

Don't suggest doc(hidden) or unstable variants in wildcard lint #7407

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3e59563
Don't use exact definition of std's ErrorKind in test.
m-ou-se Jun 26, 2021
38569c0
Don't suggest unstable and doc(hidden) variants.
m-ou-se Jun 26, 2021
0ffba7a
Simplify wildcard_enum_match_arm test
flip1995 Jul 1, 2021
fae7a09
match_wildcard_for_single_variants: don't produce bad suggestion
flip1995 Jul 1, 2021
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11 changes: 6 additions & 5 deletions clippy_lints/src/matches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -992,9 +992,9 @@ impl CommonPrefixSearcher<'a> {
}
}

fn is_doc_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
fn is_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
let attrs = cx.tcx.get_attrs(variant_def.def_id);
clippy_utils::attrs::is_doc_hidden(attrs)
clippy_utils::attrs::is_doc_hidden(attrs) || clippy_utils::attrs::is_unstable(attrs)
}

#[allow(clippy::too_many_lines)]
Expand Down Expand Up @@ -1033,7 +1033,8 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])

// Accumulate the variants which should be put in place of the wildcard because they're not
// already covered.
let mut missing_variants: Vec<_> = adt_def.variants.iter().collect();
let has_hidden = adt_def.variants.iter().any(|x| is_hidden(cx, x));
let mut missing_variants: Vec<_> = adt_def.variants.iter().filter(|x| !is_hidden(cx, x)).collect();
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I think here it would be good to differentiate between the enums origin. It would make sense to me to also cover hidden/unstable variations if they originate from the same crate. (I couldn't find a check for that in the current implementation)

I'm also debating if that should be configurable, but I believe there is no real reason for that.

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I don't think this has to be done in this PR. I like this idea though. Can you open a good-first-issue issue for this, please?

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cc: #7419


let mut path_prefix = CommonPrefixSearcher::None;
for arm in arms {
Expand Down Expand Up @@ -1118,7 +1119,7 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])

match missing_variants.as_slice() {
[] => (),
[x] if !adt_def.is_variant_list_non_exhaustive() && !is_doc_hidden(cx, x) => span_lint_and_sugg(
[x] if !adt_def.is_variant_list_non_exhaustive() && !has_hidden => span_lint_and_sugg(
cx,
MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
wildcard_span,
Expand All @@ -1129,7 +1130,7 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])
),
variants => {
let mut suggestions: Vec<_> = variants.iter().copied().map(format_suggestion).collect();
let message = if adt_def.is_variant_list_non_exhaustive() {
let message = if adt_def.is_variant_list_non_exhaustive() || has_hidden {
suggestions.push("_".into());
"wildcard matches known variants and will also match future added variants"
} else {
Expand Down
5 changes: 5 additions & 0 deletions clippy_utils/src/attrs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -157,3 +157,8 @@ pub fn is_doc_hidden(attrs: &[ast::Attribute]) -> bool {
.filter_map(ast::Attribute::meta_item_list)
.any(|l| attr::list_contains_name(&l, sym::hidden))
}

/// Return true if the attributes contain `#[unstable]`
pub fn is_unstable(attrs: &[ast::Attribute]) -> bool {
attrs.iter().any(|attr| attr.has_name(sym::unstable))
}
8 changes: 8 additions & 0 deletions tests/ui/auxiliary/non-exhaustive-enum.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
// Stripped down version of the ErrorKind enum of std
#[non_exhaustive]
pub enum ErrorKind {
NotFound,
PermissionDenied,
#[doc(hidden)]
Uncategorized,
}
7 changes: 7 additions & 0 deletions tests/ui/match_wildcard_for_single_variants.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -115,9 +115,16 @@ fn main() {
pub enum Enum {
A,
B,
C,
#[doc(hidden)]
__Private,
}
match Enum::A {
Enum::A => (),
Enum::B => (),
Enum::C => (),
_ => (),
}
match Enum::A {
Enum::A => (),
Enum::B => (),
Expand Down
7 changes: 7 additions & 0 deletions tests/ui/match_wildcard_for_single_variants.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -115,9 +115,16 @@ fn main() {
pub enum Enum {
A,
B,
C,
#[doc(hidden)]
__Private,
}
match Enum::A {
Enum::A => (),
Enum::B => (),
Enum::C => (),
_ => (),
}
match Enum::A {
Enum::A => (),
Enum::B => (),
Expand Down
39 changes: 19 additions & 20 deletions tests/ui/wildcard_enum_match_arm.fixed
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
// run-rustfix
// aux-build:non-exhaustive-enum.rs

#![deny(clippy::wildcard_enum_match_arm)]
#![allow(
Expand All @@ -11,7 +12,9 @@
clippy::diverging_sub_expression
)]

use std::io::ErrorKind;
extern crate non_exhaustive_enum;

use non_exhaustive_enum::ErrorKind;

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum Color {
Expand Down Expand Up @@ -77,29 +80,25 @@ fn main() {
let error_kind = ErrorKind::NotFound;
match error_kind {
ErrorKind::NotFound => {},
ErrorKind::PermissionDenied | ErrorKind::ConnectionRefused | ErrorKind::ConnectionReset | ErrorKind::ConnectionAborted | ErrorKind::NotConnected | ErrorKind::AddrInUse | ErrorKind::AddrNotAvailable | ErrorKind::BrokenPipe | ErrorKind::AlreadyExists | ErrorKind::WouldBlock | ErrorKind::InvalidInput | ErrorKind::InvalidData | ErrorKind::TimedOut | ErrorKind::WriteZero | ErrorKind::Interrupted | ErrorKind::Other | ErrorKind::UnexpectedEof | ErrorKind::Unsupported | ErrorKind::OutOfMemory | _ => {},
ErrorKind::PermissionDenied | _ => {},
}
match error_kind {
ErrorKind::NotFound => {},
ErrorKind::PermissionDenied => {},
ErrorKind::ConnectionRefused => {},
ErrorKind::ConnectionReset => {},
ErrorKind::ConnectionAborted => {},
ErrorKind::NotConnected => {},
ErrorKind::AddrInUse => {},
ErrorKind::AddrNotAvailable => {},
ErrorKind::BrokenPipe => {},
ErrorKind::AlreadyExists => {},
ErrorKind::WouldBlock => {},
ErrorKind::InvalidInput => {},
ErrorKind::InvalidData => {},
ErrorKind::TimedOut => {},
ErrorKind::WriteZero => {},
ErrorKind::Interrupted => {},
ErrorKind::Other => {},
ErrorKind::UnexpectedEof => {},
ErrorKind::Unsupported => {},
ErrorKind::OutOfMemory => {},
_ => {},
}

{
#![allow(clippy::manual_non_exhaustive)]
pub enum Enum {
A,
B,
#[doc(hidden)]
__Private,
}
match Enum::A {
Enum::A => (),
Enum::B | _ => (),
}
}
}
37 changes: 18 additions & 19 deletions tests/ui/wildcard_enum_match_arm.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
// run-rustfix
// aux-build:non-exhaustive-enum.rs

#![deny(clippy::wildcard_enum_match_arm)]
#![allow(
Expand All @@ -11,7 +12,9 @@
clippy::diverging_sub_expression
)]

use std::io::ErrorKind;
extern crate non_exhaustive_enum;

use non_exhaustive_enum::ErrorKind;

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum Color {
Expand Down Expand Up @@ -82,24 +85,20 @@ fn main() {
match error_kind {
ErrorKind::NotFound => {},
ErrorKind::PermissionDenied => {},
ErrorKind::ConnectionRefused => {},
ErrorKind::ConnectionReset => {},
ErrorKind::ConnectionAborted => {},
ErrorKind::NotConnected => {},
ErrorKind::AddrInUse => {},
ErrorKind::AddrNotAvailable => {},
ErrorKind::BrokenPipe => {},
ErrorKind::AlreadyExists => {},
ErrorKind::WouldBlock => {},
ErrorKind::InvalidInput => {},
ErrorKind::InvalidData => {},
ErrorKind::TimedOut => {},
ErrorKind::WriteZero => {},
ErrorKind::Interrupted => {},
ErrorKind::Other => {},
ErrorKind::UnexpectedEof => {},
ErrorKind::Unsupported => {},
ErrorKind::OutOfMemory => {},
_ => {},
}

{
#![allow(clippy::manual_non_exhaustive)]
pub enum Enum {
A,
B,
#[doc(hidden)]
__Private,
}
match Enum::A {
Enum::A => (),
_ => (),
}
}
}
22 changes: 14 additions & 8 deletions tests/ui/wildcard_enum_match_arm.stderr
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Original file line number Diff line number Diff line change
@@ -1,38 +1,44 @@
error: wildcard match will also match any future added variants
--> $DIR/wildcard_enum_match_arm.rs:39:9
--> $DIR/wildcard_enum_match_arm.rs:42:9
|
LL | _ => eprintln!("Not red"),
| ^ help: try this: `Color::Green | Color::Blue | Color::Rgb(..) | Color::Cyan`
|
note: the lint level is defined here
--> $DIR/wildcard_enum_match_arm.rs:3:9
--> $DIR/wildcard_enum_match_arm.rs:4:9
|
LL | #![deny(clippy::wildcard_enum_match_arm)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: wildcard match will also match any future added variants
--> $DIR/wildcard_enum_match_arm.rs:43:9
--> $DIR/wildcard_enum_match_arm.rs:46:9
|
LL | _not_red => eprintln!("Not red"),
| ^^^^^^^^ help: try this: `_not_red @ Color::Green | _not_red @ Color::Blue | _not_red @ Color::Rgb(..) | _not_red @ Color::Cyan`

error: wildcard match will also match any future added variants
--> $DIR/wildcard_enum_match_arm.rs:47:9
--> $DIR/wildcard_enum_match_arm.rs:50:9
|
LL | not_red => format!("{:?}", not_red),
| ^^^^^^^ help: try this: `not_red @ Color::Green | not_red @ Color::Blue | not_red @ Color::Rgb(..) | not_red @ Color::Cyan`

error: wildcard match will also match any future added variants
--> $DIR/wildcard_enum_match_arm.rs:63:9
--> $DIR/wildcard_enum_match_arm.rs:66:9
|
LL | _ => "No red",
| ^ help: try this: `Color::Red | Color::Green | Color::Blue | Color::Rgb(..) | Color::Cyan`

error: wildcard matches known variants and will also match future added variants
--> $DIR/wildcard_enum_match_arm.rs:80:9
--> $DIR/wildcard_enum_match_arm.rs:83:9
|
LL | _ => {},
| ^ help: try this: `ErrorKind::PermissionDenied | ErrorKind::ConnectionRefused | ErrorKind::ConnectionReset | ErrorKind::ConnectionAborted | ErrorKind::NotConnected | ErrorKind::AddrInUse | ErrorKind::AddrNotAvailable | ErrorKind::BrokenPipe | ErrorKind::AlreadyExists | ErrorKind::WouldBlock | ErrorKind::InvalidInput | ErrorKind::InvalidData | ErrorKind::TimedOut | ErrorKind::WriteZero | ErrorKind::Interrupted | ErrorKind::Other | ErrorKind::UnexpectedEof | ErrorKind::Unsupported | ErrorKind::OutOfMemory | _`
| ^ help: try this: `ErrorKind::PermissionDenied | _`

error: aborting due to 5 previous errors
error: wildcard matches known variants and will also match future added variants
--> $DIR/wildcard_enum_match_arm.rs:101:13
|
LL | _ => (),
| ^ help: try this: `Enum::B | _`
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I find it confusing that the lint suggests here to use the enum value in the same arm as the wildcard. That would mean that future additions would also run into this branch.

It would be good to either add a note to explain why a wildcard has to be present here or to make the suggestion to have two arms like this:

Enum::B => {},
_ => { /* Hidden values */ }

Adding a note that the enum includes hidden, or unstable values would still be good.

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A X | _ pattern is already caught by another lint, so this shouldn't be an issue.


error: aborting due to 6 previous errors