javac diagnostics wrapper

Wrapper around javac to output diagnostics in an easily-configurable way.

How to Build

./gradlew assemble

will generate build/libs/javac-diagnostics-wrapper-all.jar.

How to Use

Simply use instead of your usual javac command.

Instead of

javac [flags] File1.java File2.java

(where [flags] is a placeholder for 0 or more actual javac flags you're using)

use

java \
    -cp /path/to/javac-diagnostics-wrapper-all.jar \
    io.github.wmdietl.diagnostics.json.lsp.Main \
    [flags] File1.java File2.java

(where [flags] is a placeholder for 0 or more actual javac flags you're using)

There are currently two supported output formats:

• io.github.wmdietl.diagnostics.json.lsp.Main produces output in the LSP JSON format.
• io.github.wmdietl.diagnostics.json.javac.Main produces output in a JSON format directly corresponding to the javac diagnostics.

Examples

Normal compilation of a file with errors, using the javac format:

java \
    -cp /path/to/javac-diagnostics-wrapper-all.jar \
    io.github.wmdietl.diagnostics.json.javac.Main \
    File1.java

results in

{
  "diagnostics": [
    {
      "fileUri": "file:///.../File1.java",
      "kind": "ERROR",
      "position": 29,
      "startPosition": 29,
      "endPosition": 30,
      "lineNumber": 2,
      "columnNumber": 16,
      "code": "compiler.err.prob.found.req",
      "message": "incompatible types: int cannot be converted to java.lang.String"
    },
    {
      "fileUri": "file:///.../File1.java",
      "kind": "ERROR",
      "position": 64,
      "startPosition": 64,
      "endPosition": 69,
      "lineNumber": 4,
      "columnNumber": 16,
      "code": "compiler.err.prob.found.req",
      "message": "incompatible types: unexpected return value"
    }
  ]
}

Compilation of a file using the Checker Framework, using the LSP format:

java \
    -cp /path/to/javac-diagnostics-wrapper-all.jar \
    io.github.wmdietl.diagnostics.json.lsp.Main \
    -classpath /path/to/checker-framework/checker/dist/checker.jar \
    -processor org.checkerframework.checker.nullness.NullnessChecker \
    File2.java

results in:

[
  {
    "uri": "file://.../File2.java",
    "diagnostics": [
      {
        "range": {
          "start": {
            "line": 12,
            "character": 14
          },
          "end": {
            "line": 12,
            "character": 16
          }
        },
        "severity": 1,
        "code": "compiler.err.proc.messager",
        "source": "Main",
        "message": "[argument.type.incompatible] incompatible types in argument.\n  found   : @Initialized @Nullable InputStream\n  required: @Initialized @NonNull InputStream"
      }
    ]
  }
]

How to Develop

To format the source code, run ./gradlew spotlessApply.

Acknowledgements

• Compiler API guide
• Checker Framework language server