DefaultNodes is nil when generate_ide_files is called

[leidegre]

I primarily use VS Code and wanted to write an IDE generation script that sets isDefault for build tasks marked as such.

{
  "type": "process",
  "label": "game (win64-msvc-debug-default)",
  "command": "tundra2.exe",
  "group":       {
    "kind": "build",
    "isDefault": true // want to add this based on Default "..." hints from my units.lua files
  },
  "problemMatcher": [
    "$msCompile"
  ],
  "args": [
    "win64-msvc-debug-default",
    "game"
  ]
}

Couldn't find the information in the arguments provided to generate_ide_files so I went digging and found that DefaultNodes is nil here:

https://github.com/deplinenoise/tundra/blob/e48e03bbd8a193889337d25b42cfbd64c64c1c33/scripts/tundra/boot.lua#L142

I'm going to assume this table was meant to include the nodes that are set with Default "unit". These can be found in the node_bindings table. For example, this will print the default nodes.

for _, v in ipairs(node_bindings) do
  for _, default_node in pairs(v.DefaultNodes) do
    print(default_node.annotation)
  end
end

Now, the "signature" generate_ide_files(config_tuples, default_names, raw_nodes, env, hints, ide_script) hints that just the names was meant to be provided at some point but since parameter default_names isn't actually used by any IDE generation code I could find and DAG nodes don't have unit names, I'd like to suggest this change:

local default_nodes = {}
for _, v in ipairs(node_bindings) do
  for _, default_node in pairs(v.DefaultNodes) do
    default_nodes[#default_nodes + 1] = default_node
  end
end

-- Pass the build tuples directly to the generator and let it write
-- files.
nodegen.generate_ide_files(build_tuples, default_nodes, raw_nodes, env, raw_data.IdeGenerationHints, ide_script)

And also change default_names to default_nodes in all instances of generate_ide_files. You then test DAG nodes in your ide generation script against this table to tell if a node is a default unit or not.

[leidegre]

I can write up a PR for this if it makes sense.

Should we pass default_nodes as an array or should we pass it as a lookup table where the DAG nodes are keys for ease of use? GIven that I only have this use case atm I'm biased toward the latter.

i.e.

local default_nodes = {}
for _, v in ipairs(node_bindings) do
  for _, default_node in pairs(v.DefaultNodes) do
    default_nodes[default_node] = true
  end
end

[leidegre]

I made a Gist with my vscode generator for completeness sake, it's using the change above that I have made to my local Tundra installation. This line uses the default_nodes to lookup a DAG node to tell if it's a default build unit.

[deplinenoise]

I think this makes sense to add. I vaguely remember doing something like this back in the day for Visual Studio, to mark certain things as being part of the default build, but it wasn't useful or something and I never completed it.

A lookup table probably makes sense if you want to PR this, there's a utility function that makes a LUT from an array.

[leidegre]

Perfect, I'm traveling without a computer for a couple of weeks but I'll put together a PR when I'm back.