Allow ktlint invocations without matching sources

[liutikas]

Expected Behavior

We use Gradle to invoke ktlint via a custom task. We pass in src/**/*.kt !src/**/test-data/**/*.kt !src/**/external/**/*.kt for what files we want to analyze. We create these tasks regardless if there is a matching kt file in the project, so that we don't have to do I/O during Gradle configuration. We have some project that have no matching files. 0.46 and older versions of ktlint, these invocations would just work.

example full command

/ssd/ssd5/androidx-main/prebuilts/jdk/jdk11/linux-x86/bin/java -Dfile.encoding=UTF-8 -Duser.country=US -Duser.language=en -Duser.variant -cp /ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/0.47.0/ktlint-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-baseline/0.47.0/ktlint-reporter-baseline-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-checkstyle/0.47.0/ktlint-reporter-checkstyle-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-json/0.47.0/ktlint-reporter-json-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-format/0.47.0/ktlint-reporter-format-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-html/0.47.0/ktlint-reporter-html-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-plain/0.47.0/ktlint-reporter-plain-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-reporter-sarif/0.47.0/ktlint-reporter-sarif-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-ruleset-experimental/0.47.0/ktlint-ruleset-experimental-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-ruleset-standard/0.47.0/ktlint-ruleset-standard-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-ruleset-test/0.47.0/ktlint-ruleset-test-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/pinterest/ktlint/ktlint-core/0.47.0/ktlint-core-0.47.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-compiler-embeddable/1.7.10/kotlin-compiler-embeddable-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/com/github/shyiko/klob/klob/0.2.1/klob-0.2.1.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/info/picocli/picocli/4.6.3/picocli-4.6.3.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/ch/qos/logback/logback-classic/1.2.11/logback-classic-1.2.11.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/io/github/microutils/kotlin-logging-jvm/2.1.21/kotlin-logging-jvm-2.1.21.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-stdlib-jdk8/1.7.10/kotlin-stdlib-jdk8-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/ec4j/core/ec4j-core/0.3.0/ec4j-core-0.3.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/io/github/detekt/sarif4k/sarif4k/0.0.1/sarif4k-0.0.1.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-reflect/1.7.10/kotlin-reflect-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-stdlib-jdk7/1.7.10/kotlin-stdlib-jdk7-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlinx/kotlinx-serialization-json-jvm/1.1.0/kotlinx-serialization-json-jvm-1.1.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlinx/kotlinx-serialization-core-jvm/1.1.0/kotlinx-serialization-core-jvm-1.1.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-stdlib/1.7.10/kotlin-stdlib-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-script-runtime/1.7.10/kotlin-script-runtime-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-daemon-embeddable/1.7.10/kotlin-daemon-embeddable-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/intellij/deps/trove4j/1.0.20200330/trove4j-1.0.20200330.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/net/java/dev/jna/jna/5.6.0/jna-5.6.0.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/ch/qos/logback/logback-core/1.2.11/logback-core-1.2.11.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/slf4j/slf4j-api/1.7.32/slf4j-api-1.7.32.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/kotlin/kotlin-stdlib-common/1.7.10/kotlin-stdlib-common-1.7.10.jar:/ssd/ssd5/androidx-main/prebuilts/androidx/external/org/jetbrains/annotations/13.0/annotations-13.0.jar com.pinterest.ktlint.Main --android --reporter=plain --reporter=checkstyle,output=../../../../out/androidx/appsearch/appsearch-platform-storage/build/reports/ktlint/ktlint-checkstyle-report.xml src/**/*.kt !src/**/test-data/**/*.kt !src/**/external/**/*.kt

Observed Behavior

Starting with ktlint 0.47, it just exits with

14:41:03.584 [main] ERROR com.pinterest.ktlint.internal.KtlintCommandLine - No files matched [src/**/*.kt, !src/**/test-data/**/*.kt, !src/**/external/**/*.kt]

Steps to Reproduce

Call ktlint with arguments that have no matching files.

Your Environment

• Version of ktlint used: 0.47
• Operating System and version: Linux

If we do not want this behavior by default, ideally there is a flag to tell ktlint to skip running if there are no matching files.

[paul-dingemans]

This is a regression bug. The warning will stay after the fix but it should just exit with status code zero.

[liutikas]

Could we please add a flag to not warn about it? We'd really like to avoid polluting stdout.

[paul-dingemans]

Could we please add a flag to not warn about it? We'd really like to avoid polluting stdout.

I do not want to introduce a flag to surpress this specific warning. Ktlint already has to many obscure flags and options which do hinder development.

I will think about a possibility to suppress all warnings. Currently it is already possibly to influence the log level by setting flag --debug or --trace. Maybe I should replace those option with a new option --log-level=<level>. Setting that flag to --log-level=error would result in only displaying log messages at error (or higher) level and thus suppressing all warning, info, debug and trace messages. But this will not be released in the bugfix release 0.47.1.