fix: manual_unwrap_or_default

Author: t-webber

clippy_lints/src/manual_unwrap_or_default.rs

@@ -2,7 +2,7 @@ use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::{Arm, Expr, ExprKind, HirId, LangItem, MatchSource, Pat, PatKind, QPath};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::ty::GenericArgKind;
+use rustc_middle::ty::{self, GenericArgKind};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;
 
@@ -152,6 +152,42 @@ fn handle<'tcx>(cx: &LateContext<'tcx>, if_let_or_match: IfLetOrMatch<'tcx>, exp
         && is_default_equivalent(cx, body_none)
         && let Some(receiver) = Sugg::hir_opt(cx, condition).map(Sugg::maybe_par)
     {
+        // We check if the expression is not a None variant
+        if let Some(none_def_id) = cx.tcx.lang_items().option_none_variant() {
+            if let ExprKind::Path(QPath::Resolved(_, path)) = &condition.kind {
+                if let Some(def_id) = path.res.opt_def_id() {
+                    if cx.tcx.parent(def_id) == none_def_id {
+                        return span_lint_and_sugg(
+                            cx,
+                            MANUAL_UNWRAP_OR_DEFAULT,
+                            expr.span,
+                            format!("{expr_name} can be simplified with `.unwrap_or_default()`"),
+                            "replace it with",
+                            format!("{receiver}::</* Type */>.unwrap_or_default()"),
+                            Applicability::HasPlaceholders,
+                        );
+                    }
+                }
+            }
+        }
+
+        // We check if the expression is not a method or function with a unspecified return type
+        if let ExprKind::MethodCall(_, expr, _, _) = &condition.kind {
+            if let ty::Adt(_, substs) = cx.typeck_results().expr_ty(expr).kind() {
+                if let Some(ok_type) = substs.first() {
+                    return span_lint_and_sugg(
+                        cx,
+                        MANUAL_UNWRAP_OR_DEFAULT,
+                        expr.span,
+                        format!("{expr_name} can be simplified with `.unwrap_or_default()`"),
+                        format!("explicit the type {ok_type} and replace your expression with"),
+                        format!("{receiver}.unwrap_or_default()"),
+                        Applicability::Unspecified,
+                    );
+                }
+            }
+        }
+
         // Machine applicable only if there are no comments present
         let applicability = if span_contains_comment(cx.sess().source_map(), expr.span) {
             Applicability::MaybeIncorrect

tests/ui/manual_unwrap_or_default.rs

@@ -132,3 +132,19 @@ fn issue_12928() {
     let y = if let Some(Y(a, _)) = x { a } else { 0 };
     let y = if let Some(Y(a, ..)) = x { a } else { 0 };
 }
+
+//@no-rustfix
+fn issue_12670() {
+    // no auto: type not found
+    #[allow(clippy::match_result_ok)]
+    let _ = if let Some(x) = "1".parse().ok() {
+        x
+    } else {
+        i32::default()
+    };
+    let _ = if let Some(x) = None { x } else { i32::default() };
+    // auto fix with unwrap_or_default
+    let a: Option<i32> = None;
+    let _ = if let Some(x) = a { x } else { i32::default() };
+    let _ = if let Some(x) = Some(99) { x } else { i32::default() };
+}

tests/ui/manual_unwrap_or_default.stderr

@@ -83,5 +83,29 @@ LL | |             _ => 0,
 LL | |         },
    | |_________^ help: replace it with: `(*b).unwrap_or_default()`
 
-error: aborting due to 8 previous errors
+error: if let can be simplified with `.unwrap_or_default()`
+  --> tests/ui/manual_unwrap_or_default.rs:104:30
+   |
+LL |     let _ = if let Some(x) = "1".parse().ok() {
+   |                              ^^^^^^^^^^^ help: explicit the type i32 and replace your expression with: `"1".parse().ok().unwrap_or_default()`
+
+error: if let can be simplified with `.unwrap_or_default()`
+  --> tests/ui/manual_unwrap_or_default.rs:109:13
+   |
+LL |     let _ = if let Some(x) = None { x } else { i32::default() };
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `None::</* Type */>.unwrap_or_default()`
+
+error: if let can be simplified with `.unwrap_or_default()`
+  --> tests/ui/manual_unwrap_or_default.rs:112:13
+   |
+LL |     let _ = if let Some(x) = a { x } else { i32::default() };
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `a.unwrap_or_default()`
+
+error: if let can be simplified with `.unwrap_or_default()`
+  --> tests/ui/manual_unwrap_or_default.rs:113:13
+   |
+LL |     let _ = if let Some(x) = Some(99) { x } else { i32::default() };
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `Some(99).unwrap_or_default()`
+
+error: aborting due to 10 previous errors