Rollup merge of #23307 - michaelwoerister:lldb-vec-pp-bug, r=alexcrichton

Fixes #22656. Also adds a nice pretty printer for `Vec`.

src/test/debuginfo/issue22656.rs

@@ -0,0 +1,57 @@
+// Copyright 2013-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+
+// This test makes sure that the LLDB pretty printer does not throw an exception
+// when trying to handle a Vec<> or anything else that contains zero-sized
+// fields.
+
+// min-lldb-version: 310
+// ignore-gdb
+// ignore-tidy-linelength
+
+// compile-flags:-g
+
+// === LLDB TESTS ==================================================================================
+// lldb-command:run
+
+// lldb-command:print v
+// lldb-check:[...]$0 = vec![1, 2, 3]
+// lldb-command:print zs
+// lldb-check:[...]$1 = StructWithZeroSizedField { x: ZeroSizedStruct, y: 123, z: ZeroSizedStruct, w: 456 }
+// lldb-command:continue
+
+#![allow(unused_variables)]
+#![allow(dead_code)]
+#![omit_gdb_pretty_printer_section]
+
+struct ZeroSizedStruct;
+
+struct StructWithZeroSizedField {
+    x: ZeroSizedStruct,
+    y: u32,
+    z: ZeroSizedStruct,
+    w: u64
+}
+
+fn main() {
+    let v = vec![1,2,3];
+
+    let zs = StructWithZeroSizedField {
+        x: ZeroSizedStruct,
+        y: 123,
+        z: ZeroSizedStruct,
+        w: 456
+    };
+
+    zzz(); // #break
+}
+
+fn zzz() { () }