Auto merge of rust-lang#10707 - y21:redudant_pattern_matching_rest_pat, r=Manishearth

check for `..` pattern in `redundant_pattern_matching`

The `redundant_pattern_matching` lint currently checks for `if let Some(_) = ...`, but not for `if let Some(..) = ...`.
This PR makes sure to also check for the `..` pattern in tuple structs.
It also found one such instance in clippy itself so that shows it's worth checking for this pattern as well 😅

changelog: [`redundant_pattern_matching`]: check for `..` pattern in tuple structs

Author: bors

clippy_lints/src/indexing_slicing.rs

@@ -170,7 +170,7 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
                         return;
                     }
                     // Index is a constant uint.
-                    if let Some(..) = constant(cx, cx.typeck_results(), index) {
+                    if constant(cx, cx.typeck_results(), index).is_some() {
                         // Let rustc's `const_err` lint handle constant `usize` indexing on arrays.
                         return;
                     }

clippy_lints/src/matches/redundant_pattern_match.rs

@@ -63,8 +63,11 @@ fn find_sugg_for_if_let<'tcx>(
     // Determine which function should be used, and the type contained by the corresponding
     // variant.
     let (good_method, inner_ty) = match check_pat.kind {
-        PatKind::TupleStruct(ref qpath, [sub_pat], _) => {
-            if let PatKind::Wild = sub_pat.kind {
+        PatKind::TupleStruct(ref qpath, args, rest) => {
+            let is_wildcard = matches!(args.first().map(|p| &p.kind), Some(PatKind::Wild));
+            let is_rest = matches!((args, rest.as_opt_usize()), ([], Some(_)));
+
+            if is_wildcard || is_rest {
                 let res = cx.typeck_results().qpath_res(qpath, check_pat.hir_id);
                 let Some(id) = res.opt_def_id().map(|ctor_id| cx.tcx.parent(ctor_id)) else { return };
                 let lang_items = cx.tcx.lang_items();

tests/ui/redundant_pattern_matching_option.fixed

@@ -54,6 +54,8 @@ fn main() {
     } else {
         3
     };
+
+    if gen_opt().is_some() {}
 }
 
 fn gen_opt() -> Option<()> {

tests/ui/redundant_pattern_matching_option.rs

@@ -63,6 +63,8 @@ fn main() {
     } else {
         3
     };
+
+    if let Some(..) = gen_opt() {}
 }
 
 fn gen_opt() -> Option<()> {

tests/ui/redundant_pattern_matching_option.stderr

@@ -89,31 +89,37 @@ LL |     } else if let None = gen_opt() {
    |            -------^^^^------------ help: try this: `if gen_opt().is_none()`
 
 error: redundant pattern matching, consider using `is_some()`
-  --> $DIR/redundant_pattern_matching_option.rs:80:12
+  --> $DIR/redundant_pattern_matching_option.rs:67:12
+   |
+LL |     if let Some(..) = gen_opt() {}
+   |     -------^^^^^^^^------------ help: try this: `if gen_opt().is_some()`
+
+error: redundant pattern matching, consider using `is_some()`
+  --> $DIR/redundant_pattern_matching_option.rs:82:12
    |
 LL |     if let Some(_) = Some(42) {}
    |     -------^^^^^^^----------- help: try this: `if Some(42).is_some()`
 
 error: redundant pattern matching, consider using `is_none()`
-  --> $DIR/redundant_pattern_matching_option.rs:82:12
+  --> $DIR/redundant_pattern_matching_option.rs:84:12
    |
 LL |     if let None = None::<()> {}
    |     -------^^^^------------- help: try this: `if None::<()>.is_none()`
 
 error: redundant pattern matching, consider using `is_some()`
-  --> $DIR/redundant_pattern_matching_option.rs:84:15
+  --> $DIR/redundant_pattern_matching_option.rs:86:15
    |
 LL |     while let Some(_) = Some(42) {}
    |     ----------^^^^^^^----------- help: try this: `while Some(42).is_some()`
 
 error: redundant pattern matching, consider using `is_none()`
-  --> $DIR/redundant_pattern_matching_option.rs:86:15
+  --> $DIR/redundant_pattern_matching_option.rs:88:15
    |
 LL |     while let None = None::<()> {}
    |     ----------^^^^------------- help: try this: `while None::<()>.is_none()`
 
 error: redundant pattern matching, consider using `is_some()`
-  --> $DIR/redundant_pattern_matching_option.rs:88:5
+  --> $DIR/redundant_pattern_matching_option.rs:90:5
    |
 LL | /     match Some(42) {
 LL | |         Some(_) => true,
@@ -122,7 +128,7 @@ LL | |     };
    | |_____^ help: try this: `Some(42).is_some()`
 
 error: redundant pattern matching, consider using `is_none()`
-  --> $DIR/redundant_pattern_matching_option.rs:93:5
+  --> $DIR/redundant_pattern_matching_option.rs:95:5
    |
 LL | /     match None::<()> {
 LL | |         Some(_) => false,
@@ -131,16 +137,16 @@ LL | |     };
    | |_____^ help: try this: `None::<()>.is_none()`
 
 error: redundant pattern matching, consider using `is_none()`
-  --> $DIR/redundant_pattern_matching_option.rs:101:12
+  --> $DIR/redundant_pattern_matching_option.rs:103:12
    |
 LL |     if let None = *(&None::<()>) {}
    |     -------^^^^----------------- help: try this: `if (&None::<()>).is_none()`
 
 error: redundant pattern matching, consider using `is_none()`
-  --> $DIR/redundant_pattern_matching_option.rs:102:12
+  --> $DIR/redundant_pattern_matching_option.rs:104:12
    |
 LL |     if let None = *&None::<()> {}
    |     -------^^^^--------------- help: try this: `if (&None::<()>).is_none()`
 
-error: aborting due to 21 previous errors
+error: aborting due to 22 previous errors