From b21d9d307b5fdb1e423d786f9899757b42957b07 Mon Sep 17 00:00:00 2001
From: xphoniex <xphoniex@users.noreply.github.com>
Date: Tue, 6 Sep 2022 04:38:29 +0000
Subject: [PATCH] Suggest `unwrap_or_default` when closure returns
`"".to_string`
Signed-off-by: xphoniex <xphoniex@users.noreply.github.com>
---
.../src/methods/unwrap_or_else_default.rs | 24 +++++++++++++++++--
tests/ui/unwrap_or_else_default.fixed | 3 +++
tests/ui/unwrap_or_else_default.rs | 3 +++
tests/ui/unwrap_or_else_default.stderr | 8 ++++++-
4 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/clippy_lints/src/methods/unwrap_or_else_default.rs b/clippy_lints/src/methods/unwrap_or_else_default.rs
index f3af281d6ca..d3630b7d08e 100644
--- a/clippy_lints/src/methods/unwrap_or_else_default.rs
+++ b/clippy_lints/src/methods/unwrap_or_else_default.rs
@@ -5,10 +5,11 @@ use clippy_utils::{
diagnostics::span_lint_and_sugg, is_default_equivalent_call, source::snippet_with_applicability,
ty::is_type_diagnostic_item,
};
+use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
-use rustc_span::sym;
+use rustc_span::{sym, symbol};
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
@@ -25,7 +26,7 @@ pub(super) fn check<'tcx>(
if_chain! {
if is_option || is_result;
- if is_default_equivalent_call(cx, u_arg);
+ if closure_body_returns_empty_to_string(cx, u_arg) || is_default_equivalent_call(cx, u_arg);
then {
let mut applicability = Applicability::MachineApplicable;
@@ -44,3 +45,22 @@ pub(super) fn check<'tcx>(
}
}
}
+
+fn closure_body_returns_empty_to_string(cx: &LateContext<'_>, e: &hir::Expr<'_>) -> bool {
+ if let hir::ExprKind::Closure(&hir::Closure { body, .. }) = e.kind {
+ let body = cx.tcx.hir().body(body);
+
+ if body.params.is_empty()
+ && let hir::Expr{ kind, .. } = &body.value
+ && let hir::ExprKind::MethodCall(hir::PathSegment {ident, ..}, [self_arg], _) = kind
+ && ident == &symbol::Ident::from_str("to_string")
+ && let hir::Expr{ kind, .. } = self_arg
+ && let hir::ExprKind::Lit(lit) = kind
+ && let LitKind::Str(symbol::kw::Empty, _) = lit.node
+ {
+ return true;
+ }
+ }
+
+ false
+}
diff --git a/tests/ui/unwrap_or_else_default.fixed b/tests/ui/unwrap_or_else_default.fixed
index c2b9bd2c881..84f779569ff 100644
--- a/tests/ui/unwrap_or_else_default.fixed
+++ b/tests/ui/unwrap_or_else_default.fixed
@@ -69,6 +69,9 @@ fn unwrap_or_else_default() {
let with_default_type: Option<Vec<u64>> = None;
with_default_type.unwrap_or_default();
+
+ let empty_string = None::<String>;
+ empty_string.unwrap_or_default();
}
fn main() {}
diff --git a/tests/ui/unwrap_or_else_default.rs b/tests/ui/unwrap_or_else_default.rs
index d55664990ae..1735bd5808e 100644
--- a/tests/ui/unwrap_or_else_default.rs
+++ b/tests/ui/unwrap_or_else_default.rs
@@ -69,6 +69,9 @@ fn unwrap_or_else_default() {
let with_default_type: Option<Vec<u64>> = None;
with_default_type.unwrap_or_else(Vec::new);
+
+ let empty_string = None::<String>;
+ empty_string.unwrap_or_else(|| "".to_string());
}
fn main() {}
diff --git a/tests/ui/unwrap_or_else_default.stderr b/tests/ui/unwrap_or_else_default.stderr
index 53e31d85edf..d2b9212223f 100644
--- a/tests/ui/unwrap_or_else_default.stderr
+++ b/tests/ui/unwrap_or_else_default.stderr
@@ -30,5 +30,11 @@ error: use of `.unwrap_or_else(..)` to construct default value
LL | with_default_type.unwrap_or_else(Vec::new);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `with_default_type.unwrap_or_default()`
-error: aborting due to 5 previous errors
+error: use of `.unwrap_or_else(..)` to construct default value
+ --> $DIR/unwrap_or_else_default.rs:74:5
+ |
+LL | empty_string.unwrap_or_else(|| "".to_string());
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `empty_string.unwrap_or_default()`
+
+error: aborting due to 6 previous errors