License check breaks if file has no package declaration

[chrisbanes]

I got the following exception:

Step 'licenseHeader' found problem in 'src/main/java/me/banes/chris/tivi/extensions/PreferenceExtensions.kt':
Unable to find delimiter regex ^package 
java.lang.IllegalArgumentException: Unable to find delimiter regex ^package 
        at com.diffplug.spotless.generic.LicenseHeaderStep.format(LicenseHeaderStep.java:88)
        at com.diffplug.spotless.FormatterStepImpl$Standard.format(FormatterStepImpl.java:78)
        at com.diffplug.spotless.FormatterStep$Strict.format(FormatterStep.java:76)
        at com.diffplug.spotless.Formatter.compute(Formatter.java:230)
        at com.diffplug.spotless.Formatter.isClean(Formatter.java:167)
        at com.diffplug.gradle.spotless.SpotlessTask.check(SpotlessTask.java:216)
        at com.diffplug.gradle.spotless.SpotlessTask.performAction(SpotlessTask.java:172)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)

[jbduncan]

@chrisbanes I think I understand the cause of your exception.

IIUC, Spotless needs a way of identifying what counts as the 'top' of a source file so that it can reliably put the specified license header just above. By default, we look for the substring "package" to identify the top of Kotlin files. However, it seems in your case that you have a Kotlin file that doesn't start with "package", so Spotless cannot find the 'top' of the file.

It occurs to me that we don't provide a licenseHeader(String, String) overload for Kotlin files that would allow one to swap out the 'top' of a given Kotlin file with a given substring instead of "package"...

[jbduncan]

Note: I've just edited my previous comment for clarity.

[nedtwigg]

We do provide a way to specify the start of the file manually. The easiest workaround is to avoid the default package. If you don't want to change that, then you have to provide the regex yourself, e.g. something like licenseHeaderFile('license.txt', '^(package|//startfile)') if you want to use the //startfile comment to signify the start of the file. Without a package declaration, it's very difficult to find a regex that will work in the general case. Files might start with imports, comments, a class declaration, etc.

[jbduncan]

We do provide a way to specify the start of the file manually.

Oops, I missed that. Thanks for correcting me @nedtwigg. 😜

[chrisbanes]

The default package is used a lot more in Kotlin files, since you can have extensions methods, etc. Thanks though, licenseHeaderFile('license.txt', '^(package|//startfile)') works well.

[nedtwigg]

Is it required to use the default package in Kotlin, or just more convenient? If it's required, maybe we should update our docs to include this tip.

[chrisbanes]

It's more convenience

[nedtwigg]

Roger. I'll close this for now. If enough future users bump into this same issue, maybe we'll put the //startfile workaround into the docs.