No BTreeMap BTreeSet debug visualizers for lldb / macOS

[alcroito]

It would be great if rust / lldb / codelldb (vscode) shipped with lldb visualizers / synthetic debug providers for BTreeSet and BTreeMap.

There exists a similar issue for Windows / natvis at #90520 , but not for lldb / macOS.

I guess the gdb providers https://github.com/rust-lang/rust/blob/1.69.0/src/etc/gdb_providers.py#L242 need to be ported for

https://github.com/rust-lang/rust/blob/1.69.0/src/etc/lldb_providers.py

[jyn514]

This isn't specific to macOS, right? LLDB also has the same issue on linux and windows?

[alcroito]

This isn't specific to macOS, right? LLDB also has the same issue on linux and windows?

I believe so, yes.

[werifu]

The hardest challenge to support this feature is the fact that lldb lacks the ability to print enum correctly, while BTreeMap.root has a type of Option<Root<K, V>> . After this commit [lldb] Add basic support to Rust enums in TypeSystemClang , lldb could print enum in Rust. But the latest release llvm 17.0.6 still does not contain this code.

When this feature is release, pretty print for BTreeMap and BTreeSet can be easily implemented by providing SynthesisProvider just like HashMap and HashSet and I'm willing to do this work. Please let me know when it's ready.

Related issue: #79530

Actually, codelldb supports presenting content of an enum value, I guess it is because of RustEnum which generates an FFI type enum in https://github.com/vadimcn/codelldb/blob/master/adapter/scripts/codelldb/codelldb.py
So it should be possible to support BTreeMap and BTreeSet now by adding synthesis providers in rust.py. But now I find it hard to build that project on my mac, I may do this work when I can successfully run codelldb...

[ede1998]

I got something working on Linux. Don't have macOS to cross test it though:

https://github.com/ede1998/btreemap-debug/compare/27851762d6a33e21223c5e811f1688a8bf20f9f7..master

Planning to turn it into a proper PR in the next few days.

It works on the terminal with rust-lldb (or my adaption for testing at least) and in VSCode with codelldb and some custom init commands to inject my changes.

Output on command line

-> 27       println!("{movie_reviews:?}");
   28   }
   29
   30   /*
(lldb) p movie_reviews
(alloc::collections::btree::map::BTreeMap<&str, &str, alloc::alloc::Global>) size=12 {
  [0] = {
    0 = "A" {
      [0] = 'A'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [1] = {
    0 = "B" {
      [0] = 'B'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [2] = {
    0 = "C" {
      [0] = 'C'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [3] = {
    0 = "D" {
      [0] = 'D'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [4] = {
    0 = "E" {
      [0] = 'E'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [5] = {
    0 = "F" {
      [0] = 'F'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [6] = {
    0 = "G" {
      [0] = 'G'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [7] = {
    0 = "H" {
      [0] = 'H'
    }
    1 = "value" {
      [0] = 'v'
      [1] = 'a'
      [2] = 'l'
      [3] = 'u'
      [4] = 'e'
    }
  }
  [8] = {
    0 = "Office Space" {
      [0] = 'O'
      [1] = 'f'
      [2] = 'f'
      [3] = 'i'
      [4] = 'c'
      [5] = 'e'
      [6] = ' '
      [7] = 'S'
      [8] = 'p'
      [9] = 'a'
      [10] = 'c'
      [11] = 'e'
    }
    1 = "Deals with real issues in the workplace." {
      [0] = 'D'
      [1] = 'e'
      [2] = 'a'
      [3] = 'l'
      [4] = 's'
      [5] = ' '
      [6] = 'w'
      [7] = 'i'
      [8] = 't'
      [9] = 'h'
      [10] = ' '
      [11] = 'r'
      [12] = 'e'
      [13] = 'a'
      [14] = 'l'
      [15] = ' '
      [16] = 'i'
      [17] = 's'
      [18] = 's'
      [19] = 'u'
      [20] = 'e'
      [21] = 's'
      [22] = ' '
      [23] = 'i'
      [24] = 'n'
      [25] = ' '
      [26] = 't'
      [27] = 'h'
      [28] = 'e'
      [29] = ' '
      [30] = 'w'
      [31] = 'o'
      [32] = 'r'
      [33] = 'k'
      [34] = 'p'
      [35] = 'l'
      [36] = 'a'
      [37] = 'c'
      [38] = 'e'
      [39] = '.'
    }
  }
  [9] = {
    0 = "Pulp Fiction" {
      [0] = 'P'
      [1] = 'u'
      [2] = 'l'
      [3] = 'p'
      [4] = ' '
      [5] = 'F'
      [6] = 'i'
      [7] = 'c'
      [8] = 't'
      [9] = 'i'
      [10] = 'o'
      [11] = 'n'
    }
    1 = "Masterpiece." {
      [0] = 'M'
      [1] = 'a'
      [2] = 's'
      [3] = 't'
      [4] = 'e'
      [5] = 'r'
      [6] = 'p'
      [7] = 'i'
      [8] = 'e'
      [9] = 'c'
      [10] = 'e'
      [11] = '.'
    }
  }
  [10] = {
    0 = "The Blues Brothers" {
      [0] = 'T'
      [1] = 'h'
      [2] = 'e'
      [3] = ' '
      [4] = 'B'
      [5] = 'l'
      [6] = 'u'
      [7] = 'e'
      [8] = 's'
      [9] = ' '
      [10] = 'B'
      [11] = 'r'
      [12] = 'o'
      [13] = 't'
      [14] = 'h'
      [15] = 'e'
      [16] = 'r'
      [17] = 's'
    }
    1 = "Eye lyked it a lot." {
      [0] = 'E'
      [1] = 'y'
      [2] = 'e'
      [3] = ' '
      [4] = 'l'
      [5] = 'y'
      [6] = 'k'
      [7] = 'e'
      [8] = 'd'
      [9] = ' '
      [10] = 'i'
      [11] = 't'
      [12] = ' '
      [13] = 'a'
      [14] = ' '
      [15] = 'l'
      [16] = 'o'
      [17] = 't'
      [18] = '.'
    }
  }
  [11] = {
    0 = "The Godfather" {
      [0] = 'T'
      [1] = 'h'
      [2] = 'e'
      [3] = ' '
      [4] = 'G'
      [5] = 'o'
      [6] = 'd'
      [7] = 'f'
      [8] = 'a'
      [9] = 't'
      [10] = 'h'
      [11] = 'e'
      [12] = 'r'
    }
    1 = "Very enjoyable." {
      [0] = 'V'
      [1] = 'e'
      [2] = 'r'
      [3] = 'y'
      [4] = ' '
      [5] = 'e'
      [6] = 'n'
      [7] = 'j'
      [8] = 'o'
      [9] = 'y'
      [10] = 'a'
      [11] = 'b'
      [12] = 'l'
      [13] = 'e'
      [14] = '.'
    }
  }
}

The output on the command line is a bit lengthy but it should be the same as with a HashMap and rust-lldb (except ordering).