Add lint for redundant pattern matching for explicit return boolean
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CYBAI
parent
dae7abb16b
commit
3b7c88888b
@ -11,6 +11,8 @@
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use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use crate::rustc::{declare_tool_lint, lint_array};
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use crate::rustc::hir::*;
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use crate::syntax::ptr::P;
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use crate::syntax::ast::LitKind;
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use crate::utils::{match_qpath, paths, snippet, span_lint_and_then};
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use crate::rustc_errors::Applicability;
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@ -58,46 +60,164 @@ impl LintPass for Pass {
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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#[allow(clippy::similar_names)]
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if let ExprKind::Match(ref op, ref arms, MatchSource::IfLetDesugar { .. }) = expr.node {
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if arms[0].pats.len() == 1 {
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let good_method = match arms[0].pats[0].node {
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PatKind::TupleStruct(ref path, ref pats, _) if pats.len() == 1 => {
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if let PatKind::Wild = pats[0].node {
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if match_qpath(path, &paths::RESULT_OK) {
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"is_ok()"
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} else if match_qpath(path, &paths::RESULT_ERR) {
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"is_err()"
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} else if match_qpath(path, &paths::OPTION_SOME) {
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"is_some()"
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} else {
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return;
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}
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} else {
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return;
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}
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},
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PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => "is_none()",
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_ => return,
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};
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span_lint_and_then(
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cx,
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IF_LET_REDUNDANT_PATTERN_MATCHING,
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arms[0].pats[0].span,
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&format!("redundant pattern matching, consider using `{}`", good_method),
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|db| {
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let span = expr.span.to(op.span);
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db.span_suggestion_with_applicability(
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span,
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"try this",
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format!("if {}.{}", snippet(cx, op.span, "_"), good_method),
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Applicability::MachineApplicable, // snippet
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);
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},
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);
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if let ExprKind::Match(ref op, ref arms, ref match_source) = expr.node {
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match match_source {
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MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
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MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms),
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_ => return,
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}
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}
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}
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}
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fn find_sugg_for_if_let<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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expr: &'tcx Expr,
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op: &P<Expr>,
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arms: &HirVec<Arm>
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) {
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if arms[0].pats.len() == 1 {
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let good_method = match arms[0].pats[0].node {
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PatKind::TupleStruct(ref path, ref pats, _) if pats.len() == 1 => {
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if let PatKind::Wild = pats[0].node {
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if match_qpath(path, &paths::RESULT_OK) {
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"is_ok()"
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} else if match_qpath(path, &paths::RESULT_ERR) {
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"is_err()"
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} else if match_qpath(path, &paths::OPTION_SOME) {
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"is_some()"
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} else {
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return;
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}
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} else {
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return;
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}
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},
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PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => "is_none()",
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_ => return,
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};
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span_lint_and_then(
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cx,
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IF_LET_REDUNDANT_PATTERN_MATCHING,
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arms[0].pats[0].span,
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&format!("redundant pattern matching, consider using `{}`", good_method),
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|db| {
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let span = expr.span.to(op.span);
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db.span_suggestion_with_applicability(
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span,
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"try this",
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format!("if {}.{}", snippet(cx, op.span, "_"), good_method),
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Applicability::MachineApplicable, // snippet
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);
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},
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);
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} else {
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return;
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}
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}
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fn find_sugg_for_match<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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expr: &'tcx Expr,
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op: &P<Expr>,
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arms: &HirVec<Arm>
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) {
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if arms.len() == 2 {
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let node_pair = (&arms[0].pats[0].node, &arms[1].pats[0].node);
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let found_good_method = match node_pair {
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(
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PatKind::TupleStruct(ref path_left, ref pats_left, _),
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PatKind::TupleStruct(ref path_right, ref pats_right, _)
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) if pats_left.len() == 1 && pats_right.len() == 1 => {
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if let (PatKind::Wild, PatKind::Wild) = (&pats_left[0].node, &pats_right[0].node) {
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find_good_method_for_match(
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arms,
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path_left,
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path_right,
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&paths::RESULT_OK,
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&paths::RESULT_ERR,
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"is_ok()",
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"is_err()"
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)
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} else {
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None
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}
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},
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(
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PatKind::TupleStruct(ref path_left, ref pats, _),
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PatKind::Path(ref path_right)
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) | (
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PatKind::Path(ref path_left),
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PatKind::TupleStruct(ref path_right, ref pats, _)
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) if pats.len() == 1 => {
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if let PatKind::Wild = pats[0].node {
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find_good_method_for_match(
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arms,
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path_left,
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path_right,
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&paths::OPTION_SOME,
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&paths::OPTION_NONE,
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"is_some()",
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"is_none()"
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)
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} else {
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None
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}
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},
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_ => None,
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};
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if let Some(good_method) = found_good_method {
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span_lint_and_then(
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cx,
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IF_LET_REDUNDANT_PATTERN_MATCHING,
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expr.span,
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&format!("redundant pattern matching, consider using `{}`", good_method),
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|db| {
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let span = expr.span.to(op.span);
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db.span_suggestion_with_applicability(
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span,
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"try this",
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format!("{}.{}", snippet(cx, op.span, "_"), good_method),
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Applicability::MachineApplicable, // snippet
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);
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},
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);
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}
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} else {
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return;
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}
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}
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fn find_good_method_for_match<'a>(
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arms: &HirVec<Arm>,
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path_left: &QPath,
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path_right: &QPath,
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expected_left: &[&str],
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expected_right: &[&str],
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should_be_left: &'a str,
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should_be_right: &'a str
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) -> Option<&'a str> {
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let body_node_pair = if match_qpath(path_left, expected_left) && match_qpath(path_right, expected_right) {
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(&(*arms[0].body).node, &(*arms[1].body).node)
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} else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
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(&(*arms[1].body).node, &(*arms[0].body).node)
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} else {
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return None;
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};
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match body_node_pair {
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(ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => {
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match (&lit_left.node, &lit_right.node) {
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(LitKind::Bool(true), LitKind::Bool(false)) => Some(should_be_left),
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(LitKind::Bool(false), LitKind::Bool(true)) => Some(should_be_right),
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_ => None,
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}
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},
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_ => None,
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}
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}
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@ -42,4 +42,34 @@ fn main() {
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if let Ok(x) = Ok::<i32,i32>(42) {
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println!("{}", x);
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}
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match Ok::<i32, i32>(42) {
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Ok(_) => true,
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Err(_) => false,
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};
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match Ok::<i32, i32>(42) {
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Ok(_) => false,
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Err(_) => true,
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};
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match Err::<i32, i32>(42) {
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Ok(_) => false,
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Err(_) => true,
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};
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match Err::<i32, i32>(42) {
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Ok(_) => true,
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Err(_) => false,
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};
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match Some(42) {
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Some(_) => true,
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None => false,
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};
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match None::<()> {
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Some(_) => false,
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None => true,
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};
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}
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@ -30,5 +30,59 @@ error: redundant pattern matching, consider using `is_some()`
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28 | | }
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| |_____- help: try this: `if Some(42).is_some()`
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error: aborting due to 4 previous errors
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error: redundant pattern matching, consider using `is_ok()`
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--> $DIR/if_let_redundant_pattern_matching.rs:46:5
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46 | / match Ok::<i32, i32>(42) {
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47 | | Ok(_) => true,
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48 | | Err(_) => false,
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49 | | };
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| |_____^ help: try this: `Ok::<i32, i32>(42).is_ok()`
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error: redundant pattern matching, consider using `is_err()`
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--> $DIR/if_let_redundant_pattern_matching.rs:51:5
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51 | / match Ok::<i32, i32>(42) {
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52 | | Ok(_) => false,
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53 | | Err(_) => true,
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54 | | };
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| |_____^ help: try this: `Ok::<i32, i32>(42).is_err()`
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error: redundant pattern matching, consider using `is_err()`
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--> $DIR/if_let_redundant_pattern_matching.rs:56:5
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56 | / match Err::<i32, i32>(42) {
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57 | | Ok(_) => false,
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58 | | Err(_) => true,
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59 | | };
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| |_____^ help: try this: `Err::<i32, i32>(42).is_err()`
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error: redundant pattern matching, consider using `is_ok()`
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--> $DIR/if_let_redundant_pattern_matching.rs:61:5
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61 | / match Err::<i32, i32>(42) {
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62 | | Ok(_) => true,
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63 | | Err(_) => false,
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64 | | };
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| |_____^ help: try this: `Err::<i32, i32>(42).is_ok()`
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error: redundant pattern matching, consider using `is_some()`
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--> $DIR/if_let_redundant_pattern_matching.rs:66:5
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66 | / match Some(42) {
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67 | | Some(_) => true,
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68 | | None => false,
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69 | | };
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| |_____^ help: try this: `Some(42).is_some()`
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error: redundant pattern matching, consider using `is_none()`
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--> $DIR/if_let_redundant_pattern_matching.rs:71:5
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71 | / match None::<()> {
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72 | | Some(_) => false,
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73 | | None => true,
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74 | | };
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| |_____^ help: try this: `None::<()>.is_none()`
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error: aborting due to 10 previous errors
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