Auto merge of rust-lang#9002 - andylizi:fix-never-loop, r=Manishearth

Fix false positive for `never_loop` struct expression fields

Fixes rust-lang#9001.

changelog: [`never_loop`]: Now checks for `continue` in struct expression

Author: bors

clippy_lints/src/loops/never_loop.rs

@@ -117,13 +117,20 @@ fn never_loop_expr(expr: &Expr<'_>, main_loop_id: HirId) -> NeverLoopResult {
         | ExprKind::Type(e, _)
         | ExprKind::Field(e, _)
         | ExprKind::AddrOf(_, _, e)
-        | ExprKind::Struct(_, _, Some(e))
         | ExprKind::Repeat(e, _)
         | ExprKind::DropTemps(e) => never_loop_expr(e, main_loop_id),
         ExprKind::Let(let_expr) => never_loop_expr(let_expr.init, main_loop_id),
         ExprKind::Array(es) | ExprKind::MethodCall(_, es, _) | ExprKind::Tup(es) => {
             never_loop_expr_all(&mut es.iter(), main_loop_id)
         },
+        ExprKind::Struct(_, fields, base) => {
+            let fields = never_loop_expr_all(&mut fields.iter().map(|f| f.expr), main_loop_id);
+            if let Some(base) = base {
+                combine_both(fields, never_loop_expr(base, main_loop_id))
+            } else {
+                fields
+            }
+        },
         ExprKind::Call(e, es) => never_loop_expr_all(&mut once(e).chain(es.iter()), main_loop_id),
         ExprKind::Binary(_, e1, e2)
         | ExprKind::Assign(e1, e2, _)
@@ -180,8 +187,7 @@ fn never_loop_expr(expr: &Expr<'_>, main_loop_id: HirId) -> NeverLoopResult {
                 | InlineAsmOperand::SymStatic { .. } => NeverLoopResult::Otherwise,
             })
             .fold(NeverLoopResult::Otherwise, combine_both),
-        ExprKind::Struct(_, _, None)
-        | ExprKind::Yield(_, _)
+        ExprKind::Yield(_, _)
         | ExprKind::Closure(_, _, _, _, _)
         | ExprKind::Path(_)
         | ExprKind::ConstBlock(_)

tests/ui/never_loop.rs

@@ -186,6 +186,23 @@ pub fn test16() {
     }
 }
 
+// Issue #9001: `continue` in struct expression fields
+pub fn test17() {
+    struct Foo {
+        f: (),
+    }
+
+    let mut n = 0;
+    let _ = loop {
+        break Foo {
+            f: if n < 5 {
+                n += 1;
+                continue;
+            },
+        };
+    };
+}
+
 fn main() {
     test1();
     test2();