use crate::utils;
use if_chain::if_chain;
use rustc_errors::Applicability;
-use rustc_hir::{def, Arm, Expr, ExprKind, PatKind, QPath};
+use rustc_hir::{def, Arm, Expr, ExprKind, Pat, PatKind, QPath};
use rustc_lint::LintContext;
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::lint::in_external_macro;
declare_clippy_lint! {
/// **What it does:**
- /// Finds patterns that reimplement `Option::unwrap_or`.
+ /// Finds patterns that reimplement `Option::unwrap_or` or `Result::unwrap_or`.
///
/// **Why is this bad?**
/// Concise code helps focusing on behavior instead of boilerplate.
/// ```
pub MANUAL_UNWRAP_OR,
complexity,
- "finds patterns that can be encoded more concisely with `Option::unwrap_or`"
+ "finds patterns that can be encoded more concisely with `Option::unwrap_or` or `Result::unwrap_or`"
}
declare_lint_pass!(ManualUnwrapOr => [MANUAL_UNWRAP_OR]);
if in_external_macro(cx.sess(), expr.span) {
return;
}
- lint_option_unwrap_or_case(cx, expr);
+ lint_manual_unwrap_or(cx, expr);
}
}
-fn lint_option_unwrap_or_case<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
- fn applicable_none_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
+#[derive(Copy, Clone)]
+enum Case {
+ Option,
+ Result,
+}
+
+impl Case {
+ fn unwrap_fn_path(&self) -> &str {
+ match self {
+ Case::Option => "Option::unwrap_or",
+ Case::Result => "Result::unwrap_or",
+ }
+ }
+}
+
+fn lint_manual_unwrap_or<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
+ fn applicable_or_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
if_chain! {
if arms.len() == 2;
if arms.iter().all(|arm| arm.guard.is_none());
- if let Some((idx, none_arm)) = arms.iter().enumerate().find(|(_, arm)|
- if let PatKind::Path(ref qpath) = arm.pat.kind {
- utils::match_qpath(qpath, &utils::paths::OPTION_NONE)
- } else {
- false
+ if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)|
+ match arm.pat.kind {
+ PatKind::Path(ref some_qpath) =>
+ utils::match_qpath(some_qpath, &utils::paths::OPTION_NONE),
+ PatKind::TupleStruct(ref err_qpath, &[Pat { kind: PatKind::Wild, .. }], _) =>
+ utils::match_qpath(err_qpath, &utils::paths::RESULT_ERR),
+ _ => false,
}
);
- let some_arm = &arms[1 - idx];
- if let PatKind::TupleStruct(ref some_qpath, &[some_binding], _) = some_arm.pat.kind;
- if utils::match_qpath(some_qpath, &utils::paths::OPTION_SOME);
- if let PatKind::Binding(_, binding_hir_id, ..) = some_binding.kind;
- if let ExprKind::Path(QPath::Resolved(_, body_path)) = some_arm.body.kind;
+ let unwrap_arm = &arms[1 - idx];
+ if let PatKind::TupleStruct(ref unwrap_qpath, &[unwrap_pat], _) = unwrap_arm.pat.kind;
+ if utils::match_qpath(unwrap_qpath, &utils::paths::OPTION_SOME)
+ || utils::match_qpath(unwrap_qpath, &utils::paths::RESULT_OK);
+ if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind;
+ if let ExprKind::Path(QPath::Resolved(_, body_path)) = unwrap_arm.body.kind;
if let def::Res::Local(body_path_hir_id) = body_path.res;
if body_path_hir_id == binding_hir_id;
- if !utils::usage::contains_return_break_continue_macro(none_arm.body);
+ if !utils::usage::contains_return_break_continue_macro(or_arm.body);
then {
- Some(none_arm)
+ Some(or_arm)
} else {
None
}
if_chain! {
if let ExprKind::Match(scrutinee, match_arms, _) = expr.kind;
let ty = cx.typeck_results().expr_ty(scrutinee);
- if utils::is_type_diagnostic_item(cx, ty, sym!(option_type));
- if let Some(none_arm) = applicable_none_arm(match_arms);
+ if let Some(case) = if utils::is_type_diagnostic_item(cx, ty, sym!(option_type)) {
+ Some(Case::Option)
+ } else if utils::is_type_diagnostic_item(cx, ty, sym!(result_type)) {
+ Some(Case::Result)
+ } else {
+ None
+ };
+ if let Some(or_arm) = applicable_or_arm(match_arms);
if let Some(scrutinee_snippet) = utils::snippet_opt(cx, scrutinee.span);
- if let Some(none_body_snippet) = utils::snippet_opt(cx, none_arm.body.span);
+ if let Some(or_body_snippet) = utils::snippet_opt(cx, or_arm.body.span);
if let Some(indent) = utils::indent_of(cx, expr.span);
- if constant_simple(cx, cx.typeck_results(), none_arm.body).is_some();
+ if constant_simple(cx, cx.typeck_results(), or_arm.body).is_some();
then {
- let reindented_none_body =
- utils::reindent_multiline(none_body_snippet.into(), true, Some(indent));
+ let reindented_or_body =
+ utils::reindent_multiline(or_body_snippet.into(), true, Some(indent));
+ let wrap_in_parens = !matches!(scrutinee, Expr { kind: ExprKind::Call(..), .. });
+ let l_paren = if wrap_in_parens { "(" } else { "" };
+ let r_paren = if wrap_in_parens { ")" } else { "" };
utils::span_lint_and_sugg(
cx,
MANUAL_UNWRAP_OR, expr.span,
- "this pattern reimplements `Option::unwrap_or`",
+ &format!("this pattern reimplements `{}`", case.unwrap_fn_path()),
"replace with",
format!(
- "{}.unwrap_or({})",
+ "{}{}{}.unwrap_or({})",
+ l_paren,
scrutinee_snippet,
- reindented_none_body,
+ r_paren,
+ reindented_or_body,
),
Applicability::MachineApplicable,
);
LL | | };
| |_____^ help: replace with: `Some("Bob").unwrap_or("Alice")`
-error: aborting due to 5 previous errors
+error: this pattern reimplements `Result::unwrap_or`
+ --> $DIR/manual_unwrap_or.rs:85:5
+ |
+LL | / match Ok(1) as Result<i32, &str> {
+LL | | Ok(i) => i,
+LL | | Err(_) => 42,
+LL | | };
+ | |_____^ help: replace with: `(Ok(1) as Result<i32, &str>).unwrap_or(42)`
+
+error: this pattern reimplements `Result::unwrap_or`
+ --> $DIR/manual_unwrap_or.rs:91:5
+ |
+LL | / match Ok(1) as Result<i32, &str> {
+LL | | Err(_) => 42,
+LL | | Ok(i) => i,
+LL | | };
+ | |_____^ help: replace with: `(Ok(1) as Result<i32, &str>).unwrap_or(42)`
+
+error: this pattern reimplements `Result::unwrap_or`
+ --> $DIR/manual_unwrap_or.rs:97:5
+ |
+LL | / match Ok(1) as Result<i32, &str> {
+LL | | Ok(i) => i,
+LL | | Err(_) => 1 + 42,
+LL | | };
+ | |_____^ help: replace with: `(Ok(1) as Result<i32, &str>).unwrap_or(1 + 42)`
+
+error: this pattern reimplements `Result::unwrap_or`
+ --> $DIR/manual_unwrap_or.rs:104:5
+ |
+LL | / match Ok(1) as Result<i32, &str> {
+LL | | Ok(i) => i,
+LL | | Err(_) => {
+LL | | 42 + 42
+... |
+LL | | }
+LL | | };
+ | |_____^
+ |
+help: replace with
+ |
+LL | (Ok(1) as Result<i32, &str>).unwrap_or({
+LL | 42 + 42
+LL | + 42 + 42 + 42
+LL | + 42 + 42 + 42
+LL | });
+ |
+
+error: this pattern reimplements `Result::unwrap_or`
+ --> $DIR/manual_unwrap_or.rs:114:5
+ |
+LL | / match Ok("Bob") as Result<&str, &str> {
+LL | | Ok(i) => i,
+LL | | Err(_) => "Alice",
+LL | | };
+ | |_____^ help: replace with: `(Ok("Bob") as Result<&str, &str>).unwrap_or("Alice")`
+
+error: aborting due to 10 previous errors