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Split out wildcard_enum_match_arm and match_wildcard_for_single_variants

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This commit is contained in:
Jason Newcomb 2022-02-06 16:18:05 -05:00
parent dc75695e97
commit 75923dff5b
2 changed files with 203 additions and 195 deletions
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198
clippy_lints/src/matches/match_wild_enum.rs Normal file
View File

@ -0,0 +1,198 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::{is_refutable, peel_hir_pat_refs, recurse_or_patterns};
use rustc_errors::Applicability;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::{Arm, Expr, PatKind, PathSegment, QPath, Ty, TyKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, VariantDef};
use rustc_span::sym;
use super::{MATCH_WILDCARD_FOR_SINGLE_VARIANTS, WILDCARD_ENUM_MATCH_ARM};
#[allow(clippy::too_many_lines)]
pub(crate) fn check(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
let ty = cx.typeck_results().expr_ty(ex).peel_refs();
let adt_def = match ty.kind() {
ty::Adt(adt_def, _)
if adt_def.is_enum()
&& !(is_type_diagnostic_item(cx, ty, sym::Option) || is_type_diagnostic_item(cx, ty, sym::Result)) =>
{
adt_def
},
_ => return,
};
// First pass - check for violation, but don't do much book-keeping because this is hopefully
// the uncommon case, and the book-keeping is slightly expensive.
let mut wildcard_span = None;
let mut wildcard_ident = None;
let mut has_non_wild = false;
for arm in arms {
match peel_hir_pat_refs(arm.pat).0.kind {
PatKind::Wild => wildcard_span = Some(arm.pat.span),
PatKind::Binding(_, _, ident, None) => {
wildcard_span = Some(arm.pat.span);
wildcard_ident = Some(ident);
},
_ => has_non_wild = true,
}
}
let wildcard_span = match wildcard_span {
Some(x) if has_non_wild => x,
_ => return,
};
// Accumulate the variants which should be put in place of the wildcard because they're not
// already covered.
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();
let mut path_prefix = CommonPrefixSearcher::None;
for arm in arms {
// Guards mean that this case probably isn't exhaustively covered. Technically
// this is incorrect, as we should really check whether each variant is exhaustively
// covered by the set of guards that cover it, but that's really hard to do.
recurse_or_patterns(arm.pat, |pat| {
let path = match &peel_hir_pat_refs(pat).0.kind {
PatKind::Path(path) => {
#[allow(clippy::match_same_arms)]
let id = match cx.qpath_res(path, pat.hir_id) {
Res::Def(
DefKind::Const | DefKind::ConstParam | DefKind::AnonConst | DefKind::InlineConst,
_,
) => return,
Res::Def(_, id) => id,
_ => return,
};
if arm.guard.is_none() {
missing_variants.retain(|e| e.ctor_def_id != Some(id));
}
path
},
PatKind::TupleStruct(path, patterns, ..) => {
if let Some(id) = cx.qpath_res(path, pat.hir_id).opt_def_id() {
if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p)) {
missing_variants.retain(|e| e.ctor_def_id != Some(id));
}
}
path
},
PatKind::Struct(path, patterns, ..) => {
if let Some(id) = cx.qpath_res(path, pat.hir_id).opt_def_id() {
if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p.pat)) {
missing_variants.retain(|e| e.def_id != id);
}
}
path
},
_ => return,
};
match path {
QPath::Resolved(_, path) => path_prefix.with_path(path.segments),
QPath::TypeRelative(
Ty {
kind: TyKind::Path(QPath::Resolved(_, path)),
..
},
_,
) => path_prefix.with_prefix(path.segments),
_ => (),
}
});
}
let format_suggestion = |variant: &VariantDef| {
format!(
"{}{}{}{}",
if let Some(ident) = wildcard_ident {
format!("{} @ ", ident.name)
} else {
String::new()
},
if let CommonPrefixSearcher::Path(path_prefix) = path_prefix {
let mut s = String::new();
for seg in path_prefix {
s.push_str(seg.ident.as_str());
s.push_str("::");
}
s
} else {
let mut s = cx.tcx.def_path_str(adt_def.did);
s.push_str("::");
s
},
variant.name,
match variant.ctor_kind {
CtorKind::Fn if variant.fields.len() == 1 => "(_)",
CtorKind::Fn => "(..)",
CtorKind::Const => "",
CtorKind::Fictive => "{ .. }",
}
)
};
match missing_variants.as_slice() {
[] => (),
[x] if !adt_def.is_variant_list_non_exhaustive() && !has_hidden => span_lint_and_sugg(
cx,
MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
wildcard_span,
"wildcard matches only a single variant and will also match any future added variants",
"try this",
format_suggestion(x),
Applicability::MaybeIncorrect,
),
variants => {
let mut suggestions: Vec<_> = variants.iter().copied().map(format_suggestion).collect();
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 {
"wildcard match will also match any future added variants"
};
span_lint_and_sugg(
cx,
WILDCARD_ENUM_MATCH_ARM,
wildcard_span,
message,
"try this",
suggestions.join(" | "),
Applicability::MaybeIncorrect,
);
},
};
}
enum CommonPrefixSearcher<'a> {
None,
Path(&'a [PathSegment<'a>]),
Mixed,
}
impl<'a> CommonPrefixSearcher<'a> {
fn with_path(&mut self, path: &'a [PathSegment<'a>]) {
match path {
[path @ .., _] => self.with_prefix(path),
[] => (),
}
}
fn with_prefix(&mut self, path: &'a [PathSegment<'a>]) {
match self {
Self::None => *self = Self::Path(path),
Self::Path(self_path)
if path
.iter()
.map(|p| p.ident.name)
.eq(self_path.iter().map(|p| p.ident.name)) => {},
Self::Path(_) => *self = Self::Mixed,
Self::Mixed => (),
}
}
}
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_unstable(attrs)
}

200
clippy_lints/src/matches/mod.rs
View File

@ -1,29 +1,26 @@
use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_help, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::{indent_of, snippet, snippet_block, snippet_opt, snippet_with_applicability};
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::{
get_parent_expr, is_lang_ctor, is_refutable, is_wild, meets_msrv, msrvs, path_to_local_id, peel_blocks,
peel_hir_pat_refs, recurse_or_patterns, strip_pat_refs,
strip_pat_refs,
};
use core::iter::once;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{
self as hir, Arm, BindingAnnotation, BorrowKind, Expr, ExprKind, Local, MatchSource, Mutability, Node, Pat,
PatKind, PathSegment, QPath, TyKind,
Arm, BindingAnnotation, BorrowKind, Expr, ExprKind, Local, MatchSource, Mutability, Node, Pat, PatKind, QPath,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::{self, VariantDef};
use rustc_middle::ty;
use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::sym;
mod match_bool;
mod match_like_matches;
mod match_same_arms;
mod match_wild_enum;
mod match_wild_err_arm;
mod overlapping_arms;
mod redundant_pattern_match;
@ -629,7 +626,7 @@ impl<'tcx> LateLintPass<'tcx> for Matches {
match_bool::check(cx, ex, arms, expr);
overlapping_arms::check(cx, ex, arms);
match_wild_err_arm::check(cx, ex, arms);
check_wild_enum_match(cx, ex, arms);
match_wild_enum::check(cx, ex, arms);
check_match_as_ref(cx, ex, arms, expr);
check_wild_in_or_pats(cx, arms);
@ -705,193 +702,6 @@ impl<'tcx> LateLintPass<'tcx> for Matches {
extract_msrv_attr!(LateContext);
}
enum CommonPrefixSearcher<'a> {
None,
Path(&'a [PathSegment<'a>]),
Mixed,
}
impl<'a> CommonPrefixSearcher<'a> {
fn with_path(&mut self, path: &'a [PathSegment<'a>]) {
match path {
[path @ .., _] => self.with_prefix(path),
[] => (),
}
}
fn with_prefix(&mut self, path: &'a [PathSegment<'a>]) {
match self {
Self::None => *self = Self::Path(path),
Self::Path(self_path)
if path
.iter()
.map(|p| p.ident.name)
.eq(self_path.iter().map(|p| p.ident.name)) => {},
Self::Path(_) => *self = Self::Mixed,
Self::Mixed => (),
}
}
}
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_unstable(attrs)
}
#[allow(clippy::too_many_lines)]
fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
let ty = cx.typeck_results().expr_ty(ex).peel_refs();
let adt_def = match ty.kind() {
ty::Adt(adt_def, _)
if adt_def.is_enum()
&& !(is_type_diagnostic_item(cx, ty, sym::Option) || is_type_diagnostic_item(cx, ty, sym::Result)) =>
{
adt_def
},
_ => return,
};
// First pass - check for violation, but don't do much book-keeping because this is hopefully
// the uncommon case, and the book-keeping is slightly expensive.
let mut wildcard_span = None;
let mut wildcard_ident = None;
let mut has_non_wild = false;
for arm in arms {
match peel_hir_pat_refs(arm.pat).0.kind {
PatKind::Wild => wildcard_span = Some(arm.pat.span),
PatKind::Binding(_, _, ident, None) => {
wildcard_span = Some(arm.pat.span);
wildcard_ident = Some(ident);
},
_ => has_non_wild = true,
}
}
let wildcard_span = match wildcard_span {
Some(x) if has_non_wild => x,
_ => return,
};
// Accumulate the variants which should be put in place of the wildcard because they're not
// already covered.
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();
let mut path_prefix = CommonPrefixSearcher::None;
for arm in arms {
// Guards mean that this case probably isn't exhaustively covered. Technically
// this is incorrect, as we should really check whether each variant is exhaustively
// covered by the set of guards that cover it, but that's really hard to do.
recurse_or_patterns(arm.pat, |pat| {
let path = match &peel_hir_pat_refs(pat).0.kind {
PatKind::Path(path) => {
#[allow(clippy::match_same_arms)]
let id = match cx.qpath_res(path, pat.hir_id) {
Res::Def(
DefKind::Const | DefKind::ConstParam | DefKind::AnonConst | DefKind::InlineConst,
_,
) => return,
Res::Def(_, id) => id,
_ => return,
};
if arm.guard.is_none() {
missing_variants.retain(|e| e.ctor_def_id != Some(id));
}
path
},
PatKind::TupleStruct(path, patterns, ..) => {
if let Some(id) = cx.qpath_res(path, pat.hir_id).opt_def_id() {
if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p)) {
missing_variants.retain(|e| e.ctor_def_id != Some(id));
}
}
path
},
PatKind::Struct(path, patterns, ..) => {
if let Some(id) = cx.qpath_res(path, pat.hir_id).opt_def_id() {
if arm.guard.is_none() && patterns.iter().all(|p| !is_refutable(cx, p.pat)) {
missing_variants.retain(|e| e.def_id != id);
}
}
path
},
_ => return,
};
match path {
QPath::Resolved(_, path) => path_prefix.with_path(path.segments),
QPath::TypeRelative(
hir::Ty {
kind: TyKind::Path(QPath::Resolved(_, path)),
..
},
_,
) => path_prefix.with_prefix(path.segments),
_ => (),
}
});
}
let format_suggestion = |variant: &VariantDef| {
format!(
"{}{}{}{}",
if let Some(ident) = wildcard_ident {
format!("{} @ ", ident.name)
} else {
String::new()
},
if let CommonPrefixSearcher::Path(path_prefix) = path_prefix {
let mut s = String::new();
for seg in path_prefix {
s.push_str(seg.ident.as_str());
s.push_str("::");
}
s
} else {
let mut s = cx.tcx.def_path_str(adt_def.did);
s.push_str("::");
s
},
variant.name,
match variant.ctor_kind {
CtorKind::Fn if variant.fields.len() == 1 => "(_)",
CtorKind::Fn => "(..)",
CtorKind::Const => "",
CtorKind::Fictive => "{ .. }",
}
)
};
match missing_variants.as_slice() {
[] => (),
[x] if !adt_def.is_variant_list_non_exhaustive() && !has_hidden => span_lint_and_sugg(
cx,
MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
wildcard_span,
"wildcard matches only a single variant and will also match any future added variants",
"try this",
format_suggestion(x),
Applicability::MaybeIncorrect,
),
variants => {
let mut suggestions: Vec<_> = variants.iter().copied().map(format_suggestion).collect();
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 {
"wildcard match will also match any future added variants"
};
span_lint_and_sugg(
cx,
WILDCARD_ENUM_MATCH_ARM,
wildcard_span,
message,
"try this",
suggestions.join(" | "),
Applicability::MaybeIncorrect,
);
},
};
}
fn check_match_ref_pats<'a, 'b, I>(cx: &LateContext<'_>, ex: &Expr<'_>, pats: I, expr: &Expr<'_>)
where
'b: 'a,