Fix another crash found when analyzing rustc

crates/ra_hir/src/expr.rs

@@ -831,18 +831,18 @@ impl ExprCollector {
                     p.field_pat_list().expect("every struct should have a field list");
                 let mut fields: Vec<_> = field_pat_list
                     .bind_pats()
-                    .map(|bind_pat| {
+                    .filter_map(|bind_pat| {
                         let ast_pat = ast::Pat::cast(bind_pat.syntax()).expect("bind pat is a pat");
                         let pat = self.collect_pat(ast_pat);
-                        let name = bind_pat.name().expect("bind pat has a name").as_name();
+                        let name = bind_pat.name()?.as_name();
-                        FieldPat { name, pat }
+                        Some(FieldPat { name, pat })
                     })
                     .collect();
-                let iter = field_pat_list.field_pats().map(|f| {
+                let iter = field_pat_list.field_pats().filter_map(|f| {
-                    let ast_pat = f.pat().expect("field pat always contains a pattern");
+                    let ast_pat = f.pat()?;
                     let pat = self.collect_pat(ast_pat);
-                    let name = f.name().expect("field pats always have a name").as_name();
+                    let name = f.name()?.as_name();
-                    FieldPat { name, pat }
+                    Some(FieldPat { name, pat })
                 });
                 fields.extend(iter);
 

crates/ra_hir/src/ty/snapshots/tests__infer_std_crash_4.snap

@@ -0,0 +1,16 @@
+---
+created: "2019-02-09T19:55:39.712470520Z"
+creator: insta@0.6.1
+source: crates/ra_hir/src/ty/tests.rs
+expression: "&result"
+---
+[25; 110) '{     ...   } }': ()
+[31; 108) 'match ...     }': ()
+[37; 42) '*self': [unknown]
+[38; 42) 'self': [unknown]
+[53; 95) 'Borrow...), ..}': [unknown]
+[74; 77) 'box': [unknown]
+[78; 87) 'Primitive': [unknown]
+[88; 89) 'p': [unknown]
+[99; 101) '{}': ()
+

crates/ra_hir/src/ty/tests.rs

@@ -678,6 +678,21 @@ pub fn compute() {
     );
 }
 
+#[test]
+fn infer_std_crash_4() {
+    // taken from rustc
+    check_inference(
+        "infer_std_crash_4",
+        r#"
+pub fn primitive_type() {
+    match *self {
+        BorrowedRef { type_: box Primitive(p), ..} => {},
+    }
+}
+"#,
+    );
+}
+
 fn infer(content: &str) -> String {
     let (db, _, file_id) = MockDatabase::with_single_file(content);
     let source_file = db.parse(file_id);