Gradle kts files are rejected over standard in

[dpassen]

Expected Behavior

I expect ktlint to handle build.gradle.kts files over standard in.

$ <build.gradle.kts ktlint --stdin

Observed Behavior

$ <build.gradle.kts ktlint --log-level=info --stdin
10:37:16.772 [main] INFO com.pinterest.ktlint.internal.KtlintCommandLine - Enable default patterns [**/*.kt, **/*.kts]
<stdin>:1:1: Not a valid Kotlin file (1:1 expecting a top level declaration) (cannot be auto-corrected) ()

Summary error count (descending) by rule:
  Not a valid Kotlin file: 1

Steps to Reproduce

Pass a build.gradle.kts file over standard input.

Your Environment

• Version of ktlint used: 0.48.2
• Relevant parts of the .editorconfig settings: n/a
• Name and version (or code for custom task) of integration used (Gradle plugin, Maven plugin, command line, custom Gradle task): n/a
• Version of Gradle used (if applicable): 8.0.1
• Operating System and version: macOS Ventura 13.2.1

[paul-dingemans]

Given the command you specified, ktlint can not determine whether the code snippet is to be treated as kotlin (.kt) or as kotlin script (.kts).

The first log line is misleading in this case. It actually tells you which patterns will be recognized when scanning files. However when reading from stdin no files are scanned, only stdin is read.

10:37:16.772 [main] INFO com.pinterest.ktlint.internal.KtlintCommandLine - Enable default patterns [**/*.kt, **/*.kts]

Ktlint needs to run the embedded kotlin compiler with a file with either .kt or a .kts extension and it chooses .kt by default. As a result the pre-compiler throws the error:

<stdin>:1:1: Not a valid Kotlin file (1:1 expecting a top level declaration) (cannot be auto-corrected) ()

Possible solutions to be investigated:

• For extension to be specified explicitly when reading from stdin. Either use the current patterns parameter of add a new parameter which indicates that stdin has to be treated as kotlin script
• In case reading from stdin then retry compilation automatically as .kts file in case initial compilation with .kt fails.
• When reading from stdin send the same snippet both as .kt and .kts file to the processing pipeline. Exactly one of the files is expected to raise an compilation error and could be ignored.