Makefile generator creates misplaced build artifacts for dependencies outside of `binding.gyp` root dir

[clavin]

A binding.gyp with dependencies that live outside of its directory will create misplaced artifacts with the makefile generator (usually, on mac & linux). The dependency will be resolved to a relative path with parent directory segments (../../*) and those get joined as-is to the build directory (./build/../../*), resulting in build files outside of the build directory. This result may confuse other tooling too, unfortunately.

For example, the following code in the makefile generator produces a path like ./build/../../node_modules/node-addon-api/node_addon_api.target.mk:

gyp-next/pylib/gyp/generator/make.py

Lines 2433 to 2436 in 732b09e

	if options.generator_output:
	output_file = os.path.join(
	options.depth, options.generator_output, base_path, base_name
	)

Motivating example

I have a multi-workspace project set up like this:

• super/ (root)
  • package.json (defines "workspaces")
  • workspaces/
    • native/
      • package.json
      • binding.gyp

super has no dependencies, and native only depends on node-gyp and node-addon-api. Note that in this setup, npm hoists node-addon-gyp to the root node_modules/.

node-addon-api recommends adding it as a dependency in binding.gyp:

# super/workspaces/native/binding.gyp
{
    "targets": [{
        "target_name": "native",
        "sources": ["module.cc"],
        "dependencies": ["<!(node -p \"require('node-addon-api').targets\"):node_addon_api"]
    }]
}

After running node-gyp rebuild, we end up with some mysterious build artifacts:

• super/ (root)
  • node_modules/ ... (real, created by npm)
  • workspaces/
    • node_modules/ (not real, created by gyp)
      • node-addon-api/
        • node_addon_api_except_all.target.mk
        • node_addon_api_except.target.mk
        • node_addon_api_maybe.target.mk
        • node_addon_api.target.mk
        • node_addon_api.Makefile

A real issue that this causes is npm list failing:

$ npm ls

super@0.0.1 /[...]/super
├─┬ native@0.0.1 -> ./workspaces/native
│ ├── bindings@1.5.0
│ ├── node-addon-api@ invalid: "^8.5.0" from workspaces/native
│ └── node-gyp@12.1.0
└── node-addon-api@8.5.0 extraneous

npm error code ELSPROBLEMS
npm error extraneous: node-addon-api@8.5.0 /[...]/node_modules/node-addon-api
npm error invalid: node-addon-api@ /[...]/workspaces/node_modules/node-addon-api

# exit code 1

We also see some misplaced files within the build directory too:

• super/workspaces/native/build/
  • node_modules/ (should be within Release/obj.target/)
    • node-addon-api/
      • node_addon_api.stamp
  • Release/ ...

I haven't found these artifacts to cause issues, but I am highlighting them because they share the same root cause.