Stale compilation diagnostics

[harpocrates]

This project is using Scala 2.12.17, with a manually constructed Bloop config. This same config and same project have been working completely fine, but just now I ran into a case of Metals reporting stale compilation diagnostics. Conveniently, I did not have any other working changes - this was almost just a fresh pull of a project that compiles. The sequence of steps I took

1. move a file MyClass.scala from org.pkg1 to org.pkg1.nested (I dragged the file across folders reflecting the package structure)
2. I asked Metals to show me the refactor it was proposing and then accepted it. The refactor did the following (which seems right to me):
   • updated the package header line in MyClass.scala
   • added some import org.pkg1.nested.MyClass imports in two places where MyClass was being used and previously imported via import org.pkg1._
3. I saved MyClass.scala which was currently open. Then, when I saw the diagnostics in problems pane did not go away, I ran save all and saved the other two files where imports had been changed.

This is when I noticed that the problems in the diagnostics pane were showing something wrong: they were both pointing to the newly added import lines and they both said:

object MyClass is not a member of package org.pkg1.nested.MyClass

Here's an excerpt from bsp.trace.json which shows a number of small compile requests came in:

Redacted BSP logs

// I re-opened the project here, but I think it was previously compiling.

[Trace - 01:45:01 PM] Sending request 'buildTarget/compile - (20)'
Params: {
  "targets": [
    {
      "uri": "..."
    }
  ],
  "originId": "METALS-$e0a3f881-c18f-4134-bb81-e588d979062a",
  "arguments": [
    "--best-effort"
  ]
}

[Trace - 01:45:01 PM] Received notification 'build/publishDiagnostics'
// Just an expected warning about something unused

[Trace - 01:45:01 PM] Received response 'buildTarget/compile - (20)' in 325ms
Result: {
  "originId": "METALS-$e0a3f881-c18f-4134-bb81-e588d979062a",
  "statusCode": 1
}

[Trace - 01:45:32 PM] Sending request 'buildTarget/compile - (25)'
Params: {
  "targets": [
    {
      "uri": "..."
    }
  ],
  "originId": "METALS-$69ee1c10-b105-47b5-bb07-8c0ddd2b90a3",
  "arguments": [
    "--best-effort"
  ]
}


[Trace - 01:45:32 PM] Received notification 'build/taskStart'
Params: {
  "taskId": {
    "id": "1"
  },
  "eventTime": 1750614332419,
  "message": "Compiling MyProject (3 Scala sources)",
  "dataKind": "compile-task",
  "data": {
    "target": {
      "uri": "..."
    }
  }
}

// ... lots of `taskProgress`% updates


[Trace - 01:45:36 PM] Received notification 'build/logMessage'
Params: {
  "type": 3,
  "message": "sbt-api: Unhandled method type class MyClass in package pkg1"
}

// This error also normally shows up when compiling the project. Not sure if it is related. A bit surprising to see the old package...
[Trace - 01:45:36 PM] Received notification 'build/logMessage'
Params: {
  "type": 3,
  "message": "sbt-api: Unhandled method type class MyClass in package pkg1"
}

// ... lots of `taskProgress` % updates

[Trace - 01:45:36 PM] Received notification 'build/taskProgress'
// Compiling MyProject (100%)

[Trace - 01:45:37 PM] Received notification 'build/taskFinish'
Params: {
  "taskId": {
    "id": "1"
  },
  "eventTime": 1750614337336,
  "message": "Compiled \u0027MyProject\u0027",
  "status": 1,
  "dataKind": "compile-report",
  "data": {
    "target": {
      "uri": "..."
    },
    "originId": "METALS-$69ee1c10-b105-47b5-bb07-8c0ddd2b90a3",
    "errors": 0,
    "warnings": 0,
    "isNoOp": false,
    "isLastCycle": true,
    "clientDir": "file:///tmp/MyProject_repl2/MyProject/bloop-bsp-clients-classes/classes-Metals-tXzjuzmoRhCar8MfQrhzWg\u003d\u003d/",
    "analysisOut": "file:///tmp/MyProject_repl2/MyProject/MyProject-analysis.bin"
  }
}

[Trace - 01:45:37 PM] Received response 'buildTarget/compile - (25)' in 5027ms
Result: {
  "originId": "METALS-$69ee1c10-b105-47b5-bb07-8c0ddd2b90a3",
  "statusCode": 1
}
Error: null


[Trace - 01:45:37 PM] Sending request 'buildTarget/compile - (28)'
Params: {
  "targets": [
    {
      "uri": "..."
    }
  ],
  "originId": "METALS-$5c41feef-467b-4254-8916-2831592d1db9",
  "arguments": [
    "--best-effort"
  ]
}

[Trace - 01:45:37 PM] Received response 'buildTarget/compile - (28)' in 194ms
Result: {
  "originId": "METALS-$5c41feef-467b-4254-8916-2831592d1db9",
  "statusCode": 1
}
Error: null

[Trace - 01:45:40 PM] Sending request 'buildTarget/compile - (31)'
Params: {
  "targets": [
    {
      "uri": "..."
    }
  ],
  "originId": "METALS-$e54189e3-5953-4138-a54d-f0cce98c7c4c",
  "arguments": [
    "--best-effort"
  ]
}

[Trace - 01:45:41 PM] Received notification 'build/taskStart'
Params: {
  "taskId": {
    "id": "2"
  },
  "eventTime": 1750614341102,
  "message": "Compiling MyProject (2 Scala sources)",
  "dataKind": "compile-task",
  "data": {
    "target": {
      "uri": "..."
    }
  }
}

// ... lots of `taskProgress`% updates

[Trace - 01:45:41 PM] Received notification 'build/publishDiagnostics'
Params: {
  "textDocument": {
    "uri": "File1.scala"
  },
  "buildTarget": {
    "uri": "..."
  },
  "originId": "METALS-$e54189e3-5953-4138-a54d-f0cce98c7c4c",
  "diagnostics": [
    {
      "range": {
        ...
      },
      "severity": 1,
      "source": "bloop",
      "message": "object MyClass is not a member of package org.pkg1.nested.MyClass",
      "data": {
        "actions": []
      }
    }
  ],
  "reset": true
}

[Trace - 01:45:41 PM] Received notification 'build/publishDiagnostics'
Params: {
  "textDocument": {
    "uri": "File2.scala"
  },
  "buildTarget": {
    "uri": "..."
  },
  "originId": "METALS-$e54189e3-5953-4138-a54d-f0cce98c7c4c",
  "diagnostics": [
    {
      "range": {
        ...
      },
      "severity": 1,
      "source": "bloop",
      "message": "object MyClass is not a member of package org.pkg1.nested.MyClass",
      "data": {
        "actions": []
      }
    }
  ],
  "reset": true
}

[Trace - 01:45:43 PM] Received notification 'build/taskFinish'
Params: {
  "taskId": {
    "id": "2"
  },
  "eventTime": 1750614343071,
  "message": "Compiled \u0027MyProject\u0027",
  "status": 2,
  "dataKind": "compile-report",
  "data": {
    "target": {
      "uri": "..."
    },
    "originId": "METALS-$e54189e3-5953-4138-a54d-f0cce98c7c4c",
    "errors": 2,
    "warnings": 0,
    "isNoOp": false,
    "isLastCycle": true
  }
}


[Trace - 01:45:43 PM] Received response 'buildTarget/compile - (31)' in 2103ms
Result: {
  "originId": "METALS-$e54189e3-5953-4138-a54d-f0cce98c7c4c",
  "statusCode": 2
}
Error: null

[Trace - 01:45:43 PM] Sending request 'buildTarget/compile - (34)'
Params: {
  "targets": [
    {
      "uri": "..."
    }
  ],
  "originId": "METALS-$135b5282-b7e0-4d97-9cbd-07f4ea1e4db4",
  "arguments": [
    "--best-effort"
  ]
}

[Trace - 01:45:43 PM] Received notification 'build/taskStart'
Params: {
  "taskId": {
    "id": "3"
  },
  "eventTime": 1750614343178,
  "message": "Compiling MyProject (2 Scala sources)",
  "dataKind": "compile-task",
  "data": {
    "target": {
      "uri": "..."
    }
  }
}

[Trace - 01:45:43 PM] Received notification 'build/publishDiagnostics'
Params: {
  "textDocument": {
    "uri": "File1.scala"
  },
  "buildTarget": {
    "uri": "..."
  },
  "originId": "METALS-$135b5282-b7e0-4d97-9cbd-07f4ea1e4db4",
  "diagnostics": [
    {
      "range": {
        "start": {
          "line": 16,
          "character": 0
        },
        "end": {
          "line": 16,
          "character": 77
        }
      },
      "severity": 1,
      "source": "bloop",
      "message": "object MyClass is not a member of package org.pkg1.nested.MyClass",
      "data": {
        "actions": []
      }
    }
  ],
  "reset": true
}


[Trace - 01:45:43 PM] Received notification 'build/publishDiagnostics'
Params: {
  "textDocument": {
    "uri": "File2.Simulate.scala"
  },
  "buildTarget": {
    "uri": "..."
  },
  "originId": "METALS-$135b5282-b7e0-4d97-9cbd-07f4ea1e4db4",
  "diagnostics": [
    {
      "range": {
        "start": {
          "line": 23,
          "character": 0
        },
        "end": {
          "line": 23,
          "character": 77
        }
      },
      "severity": 1,
      "source": "bloop",
      "message": "object MyClass is not a member of package org.pkg1.nested.MyClass",
      "data": {
        "actions": []
      }
    }
  ],
  "reset": true
}

[Trace - 01:45:45 PM] Received notification 'build/taskFinish'
Params: {
  "taskId": {
    "id": "3"
  },
  "eventTime": 1750614345132,
  "message": "Compiled \u0027MyProject\u0027",
  "status": 2,
  "dataKind": "compile-report",
  "data": {
    "target": {
      "uri": "..."
    },
    "originId": "METALS-$135b5282-b7e0-4d97-9cbd-07f4ea1e4db4",
    "errors": 2,
    "warnings": 0,
    "isNoOp": false,
    "isLastCycle": true
  }
}


[Trace - 01:45:45 PM] Received response 'buildTarget/compile - (34)' in 2043ms
Result: {
  "originId": "METALS-$135b5282-b7e0-4d97-9cbd-07f4ea1e4db4",
  "statusCode": 2
}
Error: null

I'm not sure whether it is expected or not given that the latest compilation did not succeed, but the source hashes in the analysis.bin file do not match what I get manually computing the hashes for the 3 files that changed... I've stowed away the entire output directory for safe-keeping.

One other complicating factor: there is a second Bloop client also connected for this same project, but it has not been issuing any build requests. Only requests it would've been making are workspace/buildTargets calls (just as a healthcheck for the connection working).

[tgodzik]

I've seen cases like this and last time it was caused by Bloop sending the old file to compile, which was no longer present. Zinc was not happy about that. I think it might be something similar. I usually turn on verbose mode in metals or run bloop --verbose for those cases. We might be sending to zinc wrong files to compile, maybe one of the older files (should have been fixed but maybe I haven't handled all paths)

It could also be a zinc issue being unearthed which normally don't pop up in less heavy usage.

[tgodzik]

This was the last PR touching a similar thing https://github.com/scalacenter/bloop/pull/2490/files

I might also have a reproduction from tapir, that I can take a look. It might be a totally different though