Dont lint on match pattern-binding

Fixes #9347

Technically it is possible to have a blank match-pattern that does
nothing, and we fail to lint. But its easier to be safe than sorry here.

clippy_lints/src/question_mark.rs

@@ -123,7 +123,7 @@ fn check_if_let_some_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr:
         if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else }) = higher::IfLet::hir(cx, expr);
         if !is_else_clause(cx.tcx, expr);
         if let PatKind::TupleStruct(ref path1, [field], None) = let_pat.kind;
-        if let PatKind::Binding(annot, bind_id, ident, _) = field.kind;
+        if let PatKind::Binding(annot, bind_id, ident, None) = field.kind;
         let caller_ty = cx.typeck_results().expr_ty(let_expr);
         let if_block = IfBlockType::IfLet(path1, caller_ty, ident.name, let_expr, if_then, if_else);
         if (is_early_return(sym::Option, cx, &if_block) && path_to_local_id(peel_blocks(if_then), bind_id))

tests/ui/question_mark.fixed

@@ -207,4 +207,19 @@ fn option_map() -> Option<bool> {
     }
 }
 
+pub struct PatternedError {
+    flag: bool,
+}
+
+// No warning
+fn pattern() -> Result<(), PatternedError> {
+    let res = Ok(());
+
+    if let Err(err @ PatternedError { flag: true }) = res {
+        return Err(err);
+    }
+
+    res
+}
+
 fn main() {}

tests/ui/question_mark.rs

@@ -243,4 +243,19 @@ fn option_map() -> Option<bool> {
     }
 }
 
+pub struct PatternedError {
+    flag: bool,
+}
+
+// No warning
+fn pattern() -> Result<(), PatternedError> {
+    let res = Ok(());
+
+    if let Err(err @ PatternedError { flag: true }) = res {
+        return Err(err);
+    }
+
+    res
+}
+
 fn main() {}