Full file path not being fed to SWC CLI

[riyavsinha]

I have a file packages/xpackage/server/src/tests/y-test.ts, which I am trying to compile with the swc_rule.

Problem
The compiled output file is empty.

Configuration

swc(
  name = "y_test_swc",
  srcs = ["y-test.ts"],
  source_maps = True,
  swcrc = "//packages/xpackage:.swcrc",
)

Possible Cause
Current subcommand being run by swc_rule:

SUBCOMMAND: # //packages/xpackage/server/src/tests:y_test_swc [action 'Transpiling with swc //packages/xpackage/server/src/tests:y_test_swc [swc packages/xpackage/server/src/tests/y-test.ts]', configuration: 2dbb605ac0825292323b7a4585cb36cd7762af7e47ba3ff3f3e09310b3ca4246, execution platform: @local_config_platform//:host]
(cd /private/var/tmp/_bazel_riyavsinha/903eebc477abc3a7df81d5ec7291fe86/execroot/workspace_name && \
  exec env - \
    SWC_BINARY_PATH=external/swc_darwin-x64/swc.darwin-x64.node \
  bazel-out/darwin-opt-exec-2B5CBBC6/bin/external/aspect_rules_swc/swc/_cli_launcher.sh --source-maps true --config-file packages/xpackage/.swcrc server/src/tests/y-test.ts --out-file bazel-out/darwin-fastbuild/bin/packages/xpackage/server/src/tests/y-test.js --no-swcrc -q)

Because the input file is being given as server/src/tests/y-test.ts instead of packages/xpackage/server/src/tests/y-test.ts (the packages/xpackage stripped away), maybe the file is not being recognized/input to swc in the first place, and so it outputs a blank file?

(There is also no error thrown for this, and only by opening the compiled file can you see that it is blank, though this may be an issue with swc?)

[alexeagle]

--out-file bazel-out/darwin-fastbuild/bin/packages/xpackage/server/src/tests/y-test.js looks right.

What's in your .swcrc?

[riyavsinha]

SWCRC:

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": false,
      "decorators": true,
      "dynamicImport": false
    },
    "transform": {
      "legacyDecorator": true,
      "decoratorMetadata": true
    },
    "target": "es2016"
  },
  "module": {
    "type": "commonjs",
    "strict": false,
    "strictMode": true,
    "lazy": false,
    "noInterop": false
  },
  "sourceMaps": true
}

[riyavsinha]

Oh interesting, removing the swcrc attribute makes it compile with the correct input file:

Config:

swc(
  name = "cron_test_swc",
  srcs = ["cron-test.ts"],
  source_maps = True,
)

Subcommand run:

SUBCOMMAND: # //packages/xpackage/server/src/tests:y_test_swc [action 'Transpiling with swc //packages/xpackage/server/src/tests:y_test_swc [swc packages/xpackage/server/src/tests/y-test.ts]', configuration: 2dbb605ac0825292323b7a4585cb36cd7762af7e47ba3ff3f3e09310b3ca4246, execution platform: @local_config_platform//:host]
(cd /private/var/tmp/_bazel_riyavsinha/903eebc477abc3a7df81d5ec7291fe86/execroot/workspace_name && \
  exec env - \
    SWC_BINARY_PATH=external/swc_darwin-x64/swc.darwin-x64.node \
  bazel-out/darwin-opt-exec-2B5CBBC6/bin/external/aspect_rules_swc/swc/_cli_launcher.sh --source-maps true packages/xpackage/server/src/tests/y-test.ts --out-file bazel-out/darwin-fastbuild/bin/packages/xpackage/server/src/tests/y-test.js --no-swcrc -q)

Not fully sure what part of the swcrc is contributing to this yet

[riyavsinha]

I tried moving my .swcrc to the workspace root, which produced this command, which looks more correct:

SUBCOMMAND: # //packages/xpackage/server/src/tests:y_test_swc [action 'Transpiling with swc //packages/xpackage/server/src/tests:y_test_swc [swc packages/xpackage/server/src/tests/y-test.ts]', configuration: 2dbb605ac0825292323b7a4585cb36cd7762af7e47ba3ff3f3e09310b3ca4246, execution platform: @local_config_platform//:host]
(cd /private/var/tmp/_bazel_riyavsinha/903eebc477abc3a7df81d5ec7291fe86/execroot/workspace_name && \
  exec env - \
    SWC_BINARY_PATH=external/swc_darwin-x64/swc.darwin-x64.node \
  bazel-out/darwin-opt-exec-2B5CBBC6/bin/external/aspect_rules_swc/swc/_cli_launcher.sh --source-maps true --config-file .swcrc packages/xpackage/server/src/tests/y-test.ts --out-file bazel-out/darwin-fastbuild/bin/packages/xpackage/server/src/tests/y-test.js --no-swcrc -q)

ERROR: /Users/riyavsinha/Projects/workspace_name/packages/xpackage/server/src/tests/BUILD:20:4: Transpiling with swc //packages/xpackage/server/src/tests:y_test_swc [swc packages/xpackage/server/src/tests/y-test.ts] failed: (Exit 1): _cli_launcher.sh failed: error executing command bazel-out/darwin-opt-exec-2B5CBBC6/bin/external/aspect_rules_swc/swc/_cli_launcher.sh --source-maps true --config-file .swcrc packages/xpackage/server/src/tests/y-test.ts --out-file ... (remaining 3 argument(s) skipped)

So, because the .swcrc is now in the root, it looks like it passes the correct full path to the CLI packages/xpackage/server/src/tests/y-test.ts.

(The error comes from //:.swcrc being passed to the CLI as .swcrc, which it doesn't like for some reason)

[riyavsinha]

This is probably happening because of the "relativizing" of paths:
https://github.com/aspect-build/rules_swc/blob/main/swc/private/swc.bzl#L83

[alexeagle]

Yeah I agree, swc behavior changes based on the config file path. I'm not sure if that's actually desirable or if it ought to change upstream.

[riyavsinha]

Hm, so the path relativizing in this repo's rule is not the cause?

In my initial custom swc rule I believe it worked without modifying paths in the rule implementation:

args.add("--config-file", ctx.file.swcrc.path)
args.add_all([src.path for src in ctx.files.srcs])

[alexeagle]

@gregmagolan added that comment

# Pass in the swcrc config if it is set; if it is
# then source paths are expected to be relative to the swcrc directory

But yeah, it seems broken to me as-is.

[gregmagolan]

Odd, I had trouble with it initially with the full path when passing an swcrc file and had to make it relative to work. Something change upstream?