如何在 GDB 中漂亮地打印 Rust 哈希图?

Question

这是一个简单的 Rust 示例，其中包含我在 GDB 中运行的Vec和HashMap：

use std::collections::HashMap;
fn main() {
let v = vec!["Mon", "Tue", "Wed"];
println!("{:?}", v);
let mut h = HashMap::new();
h.insert(1,"Jan");
h.insert(2,"Feb");
h.insert(3,"Mar");
h.insert(4,"Apr");
println!("{:?}", h);
}

当我查看Vec时，它是漂亮的印刷，而HashMap则不是：

bash$ rust-gdb target/debug/test_hashmap
GNU gdb (GDB) 8.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from target/debug/test_hashmap...done.
(gdb) b 12
Breakpoint 1 at 0xa056: file src/main.rs, line 12.
(gdb) r
Starting program: /home/john/proj/test_hashmap/target/debug/test_hashmap 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
["Mon", "Tue", "Wed"]
Breakpoint 1, test_hashmap::main () at src/main.rs:12
12          println!("{:?}", h);
(gdb) p v
$1 = Vec<&str>(len: 3, cap: 3) = {"Mon", "Tue", "Wed"}
(gdb) p h
$2 = HashMap<i32, &str, std::collections::hash::map::RandomState> = {hash_builder = RandomState = {k0 = 12919411587537124140, 
k1 = 836420561220520453}, table = RawTable<i32, &str> = {capacity_mask = 31, size = 4, hashes = TaggedHashUintPtr = {
Unique<usize> = {pointer = NonZero<*const usize> = {0x7ffff6c1c400}, _marker = PhantomData<usize>}}, 
marker = PhantomData<(i32, &str)>}, resize_policy = DefaultResizePolicy}
(gdb) info pretty-printer
global pretty-printers:
builtin
mpx_bound128
objfile /home/john/proj/test_hashmap/target/debug/test_hashmap pretty-printers:
rust_pretty_printer_lookup_function
(gdb) n
{1: "Jan", 4: "Apr", 3: "Mar", 2: "Feb"}
13      }
(gdb) 

程序可以看到HashMap(并打印其值正常(，但我在 GDB 中看不到这些值。Rust漂亮的打印机似乎已启用Vec因为它打印得很好。

如何在常规 GDB 中获取HashMap键和值？

Answer 1

目前无法为HashMap漂亮地打印键值项。

存在请求此功能的未决问题。

Answer 2

如果合并此 PR，将启用漂亮的打印BTreeMap。

BTreeMap 和 HashMap API 都是相似的。因此，您可以替换HashMap和BTreeMap进行调试。

Answer 3

你可以使用 rust-gdb/rust-lldb，它可以漂亮地打印 HashMap 的键值项。