-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,
-};
-use core::iter::once;
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::{is_wild, meets_msrv, msrvs};
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,
-};
+use rustc_hir::{Arm, Expr, ExprKind, Local, MatchSource, 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 infalliable_detructuring_match;
+mod match_as_ref;
mod match_bool;
mod match_like_matches;
+mod match_ref_pats;
mod match_same_arms;
+mod match_single_binding;
+mod match_wild_enum;
mod match_wild_err_arm;
mod overlapping_arms;
mod redundant_pattern_match;
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);
- check_match_as_ref(cx, ex, arms, expr);
+ match_wild_enum::check(cx, ex, arms);
+ match_as_ref::check(cx, ex, arms, expr);
check_wild_in_or_pats(cx, arms);
if self.infallible_destructuring_match_linted {
self.infallible_destructuring_match_linted = false;
} else {
- check_match_single_binding(cx, ex, arms, expr);
+ match_single_binding::check(cx, ex, arms, expr);
}
}
if let ExprKind::Match(ex, arms, _) = expr.kind {
- check_match_ref_pats(cx, ex, arms.iter().map(|el| el.pat), expr);
+ match_ref_pats::check(cx, ex, arms.iter().map(|el| el.pat), expr);
}
}
fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'_>) {
- if_chain! {
- if !local.span.from_expansion();
- if let Some(expr) = local.init;
- if let ExprKind::Match(target, arms, MatchSource::Normal) = expr.kind;
- if arms.len() == 1 && arms[0].guard.is_none();
- if let PatKind::TupleStruct(
- QPath::Resolved(None, variant_name), args, _) = arms[0].pat.kind;
- if args.len() == 1;
- if let PatKind::Binding(_, arg, ..) = strip_pat_refs(&args[0]).kind;
- let body = peel_blocks(arms[0].body);
- if path_to_local_id(body, arg);
-
- then {
- let mut applicability = Applicability::MachineApplicable;
- self.infallible_destructuring_match_linted = true;
- span_lint_and_sugg(
- cx,
- INFALLIBLE_DESTRUCTURING_MATCH,
- local.span,
- "you seem to be trying to use `match` to destructure a single infallible pattern. \
- Consider using `let`",
- "try this",
- format!(
- "let {}({}) = {};",
- snippet_with_applicability(cx, variant_name.span, "..", &mut applicability),
- snippet_with_applicability(cx, local.pat.span, "..", &mut applicability),
- snippet_with_applicability(cx, target.span, "..", &mut applicability),
- ),
- applicability,
- );
- }
- }
+ self.infallible_destructuring_match_linted |= infalliable_detructuring_match::check(cx, local);
}
fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
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,
- I: Clone + Iterator<Item = &'a Pat<'b>>,
-{
- if !has_multiple_ref_pats(pats.clone()) {
- return;
- }
-
- let (first_sugg, msg, title);
- let span = ex.span.source_callsite();
- if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = ex.kind {
- first_sugg = once((span, Sugg::hir_with_macro_callsite(cx, inner, "..").to_string()));
- msg = "try";
- title = "you don't need to add `&` to both the expression and the patterns";
- } else {
- first_sugg = once((span, Sugg::hir_with_macro_callsite(cx, ex, "..").deref().to_string()));
- msg = "instead of prefixing all patterns with `&`, you can dereference the expression";
- title = "you don't need to add `&` to all patterns";
- }
-
- let remaining_suggs = pats.filter_map(|pat| {
- if let PatKind::Ref(refp, _) = pat.kind {
- Some((pat.span, snippet(cx, refp.span, "..").to_string()))
- } else {
- None
- }
- });
-
- span_lint_and_then(cx, MATCH_REF_PATS, expr.span, title, |diag| {
- if !expr.span.from_expansion() {
- multispan_sugg(diag, msg, first_sugg.chain(remaining_suggs));
- }
- });
-}
-
-fn check_match_as_ref(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
- if arms.len() == 2 && arms[0].guard.is_none() && arms[1].guard.is_none() {
- let arm_ref: Option<BindingAnnotation> = if is_none_arm(cx, &arms[0]) {
- is_ref_some_arm(cx, &arms[1])
- } else if is_none_arm(cx, &arms[1]) {
- is_ref_some_arm(cx, &arms[0])
- } else {
- None
- };
- if let Some(rb) = arm_ref {
- let suggestion = if rb == BindingAnnotation::Ref {
- "as_ref"
- } else {
- "as_mut"
- };
-
- let output_ty = cx.typeck_results().expr_ty(expr);
- let input_ty = cx.typeck_results().expr_ty(ex);
-
- let cast = if_chain! {
- if let ty::Adt(_, substs) = input_ty.kind();
- let input_ty = substs.type_at(0);
- if let ty::Adt(_, substs) = output_ty.kind();
- let output_ty = substs.type_at(0);
- if let ty::Ref(_, output_ty, _) = *output_ty.kind();
- if input_ty != output_ty;
- then {
- ".map(|x| x as _)"
- } else {
- ""
- }
- };
-
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- MATCH_AS_REF,
- expr.span,
- &format!("use `{}()` instead", suggestion),
- "try this",
- format!(
- "{}.{}(){}",
- snippet_with_applicability(cx, ex.span, "_", &mut applicability),
- suggestion,
- cast,
- ),
- applicability,
- );
- }
- }
-}
-
fn check_wild_in_or_pats(cx: &LateContext<'_>, arms: &[Arm<'_>]) {
for arm in arms {
if let PatKind::Or(fields) = arm.pat.kind {
}
}
}
-
-#[allow(clippy::too_many_lines)]
-fn check_match_single_binding<'a>(cx: &LateContext<'a>, ex: &Expr<'a>, arms: &[Arm<'_>], expr: &Expr<'_>) {
- if expr.span.from_expansion() || arms.len() != 1 || is_refutable(cx, arms[0].pat) {
- return;
- }
-
- // HACK:
- // This is a hack to deal with arms that are excluded by macros like `#[cfg]`. It is only used here
- // to prevent false positives as there is currently no better way to detect if code was excluded by
- // a macro. See PR #6435
- if_chain! {
- if let Some(match_snippet) = snippet_opt(cx, expr.span);
- if let Some(arm_snippet) = snippet_opt(cx, arms[0].span);
- if let Some(ex_snippet) = snippet_opt(cx, ex.span);
- let rest_snippet = match_snippet.replace(&arm_snippet, "").replace(&ex_snippet, "");
- if rest_snippet.contains("=>");
- then {
- // The code it self contains another thick arrow "=>"
- // -> Either another arm or a comment
- return;
- }
- }
-
- let matched_vars = ex.span;
- let bind_names = arms[0].pat.span;
- let match_body = peel_blocks(arms[0].body);
- let mut snippet_body = if match_body.span.from_expansion() {
- Sugg::hir_with_macro_callsite(cx, match_body, "..").to_string()
- } else {
- snippet_block(cx, match_body.span, "..", Some(expr.span)).to_string()
- };
-
- // Do we need to add ';' to suggestion ?
- match match_body.kind {
- ExprKind::Block(block, _) => {
- // macro + expr_ty(body) == ()
- if block.span.from_expansion() && cx.typeck_results().expr_ty(match_body).is_unit() {
- snippet_body.push(';');
- }
- },
- _ => {
- // expr_ty(body) == ()
- if cx.typeck_results().expr_ty(match_body).is_unit() {
- snippet_body.push(';');
- }
- },
- }
-
- let mut applicability = Applicability::MaybeIncorrect;
- match arms[0].pat.kind {
- PatKind::Binding(..) | PatKind::Tuple(_, _) | PatKind::Struct(..) => {
- // If this match is in a local (`let`) stmt
- let (target_span, sugg) = if let Some(parent_let_node) = opt_parent_let(cx, ex) {
- (
- parent_let_node.span,
- format!(
- "let {} = {};\n{}let {} = {};",
- snippet_with_applicability(cx, bind_names, "..", &mut applicability),
- snippet_with_applicability(cx, matched_vars, "..", &mut applicability),
- " ".repeat(indent_of(cx, expr.span).unwrap_or(0)),
- snippet_with_applicability(cx, parent_let_node.pat.span, "..", &mut applicability),
- snippet_body
- ),
- )
- } else {
- // If we are in closure, we need curly braces around suggestion
- let mut indent = " ".repeat(indent_of(cx, ex.span).unwrap_or(0));
- let (mut cbrace_start, mut cbrace_end) = ("".to_string(), "".to_string());
- if let Some(parent_expr) = get_parent_expr(cx, expr) {
- if let ExprKind::Closure(..) = parent_expr.kind {
- cbrace_end = format!("\n{}}}", indent);
- // Fix body indent due to the closure
- indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
- cbrace_start = format!("{{\n{}", indent);
- }
- }
- // If the parent is already an arm, and the body is another match statement,
- // we need curly braces around suggestion
- let parent_node_id = cx.tcx.hir().get_parent_node(expr.hir_id);
- if let Node::Arm(arm) = &cx.tcx.hir().get(parent_node_id) {
- if let ExprKind::Match(..) = arm.body.kind {
- cbrace_end = format!("\n{}}}", indent);
- // Fix body indent due to the match
- indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
- cbrace_start = format!("{{\n{}", indent);
- }
- }
- (
- expr.span,
- format!(
- "{}let {} = {};\n{}{}{}",
- cbrace_start,
- snippet_with_applicability(cx, bind_names, "..", &mut applicability),
- snippet_with_applicability(cx, matched_vars, "..", &mut applicability),
- indent,
- snippet_body,
- cbrace_end
- ),
- )
- };
- span_lint_and_sugg(
- cx,
- MATCH_SINGLE_BINDING,
- target_span,
- "this match could be written as a `let` statement",
- "consider using `let` statement",
- sugg,
- applicability,
- );
- },
- PatKind::Wild => {
- if ex.can_have_side_effects() {
- let indent = " ".repeat(indent_of(cx, expr.span).unwrap_or(0));
- let sugg = format!(
- "{};\n{}{}",
- snippet_with_applicability(cx, ex.span, "..", &mut applicability),
- indent,
- snippet_body
- );
- span_lint_and_sugg(
- cx,
- MATCH_SINGLE_BINDING,
- expr.span,
- "this match could be replaced by its scrutinee and body",
- "consider using the scrutinee and body instead",
- sugg,
- applicability,
- );
- } else {
- span_lint_and_sugg(
- cx,
- MATCH_SINGLE_BINDING,
- expr.span,
- "this match could be replaced by its body itself",
- "consider using the match body instead",
- snippet_body,
- Applicability::MachineApplicable,
- );
- }
- },
- _ => (),
- }
-}
-
-/// Returns true if the `ex` match expression is in a local (`let`) statement
-fn opt_parent_let<'a>(cx: &LateContext<'a>, ex: &Expr<'a>) -> Option<&'a Local<'a>> {
- let map = &cx.tcx.hir();
- if_chain! {
- if let Some(Node::Expr(parent_arm_expr)) = map.find(map.get_parent_node(ex.hir_id));
- if let Some(Node::Local(parent_let_expr)) = map.find(map.get_parent_node(parent_arm_expr.hir_id));
- then {
- return Some(parent_let_expr);
- }
- }
- None
-}
-
-// Checks if arm has the form `None => None`
-fn is_none_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
- matches!(arm.pat.kind, PatKind::Path(ref qpath) if is_lang_ctor(cx, qpath, OptionNone))
-}
-
-// Checks if arm has the form `Some(ref v) => Some(v)` (checks for `ref` and `ref mut`)
-fn is_ref_some_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> Option<BindingAnnotation> {
- if_chain! {
- if let PatKind::TupleStruct(ref qpath, [first_pat, ..], _) = arm.pat.kind;
- if is_lang_ctor(cx, qpath, OptionSome);
- if let PatKind::Binding(rb, .., ident, _) = first_pat.kind;
- if rb == BindingAnnotation::Ref || rb == BindingAnnotation::RefMut;
- if let ExprKind::Call(e, args) = peel_blocks(arm.body).kind;
- if let ExprKind::Path(ref some_path) = e.kind;
- if is_lang_ctor(cx, some_path, OptionSome) && args.len() == 1;
- if let ExprKind::Path(QPath::Resolved(_, path2)) = args[0].kind;
- if path2.segments.len() == 1 && ident.name == path2.segments[0].ident.name;
- then {
- return Some(rb)
- }
- }
- None
-}
-
-fn has_multiple_ref_pats<'a, 'b, I>(pats: I) -> bool
-where
- 'b: 'a,
- I: Iterator<Item = &'a Pat<'b>>,
-{
- let mut ref_count = 0;
- for opt in pats.map(|pat| match pat.kind {
- PatKind::Ref(..) => Some(true), // &-patterns
- PatKind::Wild => Some(false), // an "anything" wildcard is also fine
- _ => None, // any other pattern is not fine
- }) {
- if let Some(inner) = opt {
- if inner {
- ref_count += 1;
- }
- } else {
- return false;
- }
- }
- ref_count > 1
-}
projects / rust.git / blobdiff