Feature request - limit number of lines for an issue to 1

[pinkasey]

Expected Behavior

When a rule finds a warning, the warning never spans more than one line.
If the rule "misbehaves" and reports entity that spans multiple lines -
detekt will narrow the issue to a sub-entity that spans 1 line.

I would put this behaviour under a configuration in detekt-config.yml, something like:
limitIssueToOneLine: true

Current Behavior

Some rules mark entire files, classes, or methods as warning - and you can hardly see in IntelliJ that there are additional warnings on the file/class/method.

Context

This is mostly relevant to the IntelliJ plugin -
There are some rules that mark an entire file/class/method as the issue entity.
e.g MatchingDeclarationName
This makes it impossible to continue working without addressing the warning somehow
(And what if it's a file I'm just visiting, and wasn't planning on modifying? It's all yellow and hard to read).

Example of what I want to prevent:

[pinkasey]

Some additional thoughts:

  entity = when (entity) {
    isFile() -> entity.narrowToFirstLine()
    isClass() -> entity.narrowToClassName()
    isCallExpression() -> entity.narrowToCalledMethodName()
    else -> entity.narrowToFirstWord()
  }

[pinkasey]

Also -
I might find time to contribute here (not sure when I'll be available for it)

If there's a preliminary PR - I can finish it
or I might do the entire PR myself

[arturbosch]

Thanks for the proposal. I tried it and it works great. I will later post a PR for 1.10.0.

[BraisGabin]

But would this apply for detekt or for the intellij plugin?

[arturbosch]

I first tried to only implement it at the intellij plugin.
However due to dependency conflict between compiler and embeddable-compiler this must be implemented in detekt or a library.

My second thought was to introduce a detekt-tooling/detekt-embeddable module which can be consumed by the intellij und sonar plugins with these kind of helpers.

Now I think it makes sense to always report at the identifier not only for classes/objects but also for methods. File related issues can be reported at the package or the first declaration.

I've come up with just extending the Entity class:

        /**
         * Factory function which retrieves all needed information from the PsiElement itself.
         */
        fun from(element: PsiElement, offset: Int = 0): Entity {
            val location = Location.from(element, offset)
            return from(element, location)
        }

        /**
         * Create an entity at the location of the identifier of given named declaration.
         */
        fun atName(element: KtNamedDeclaration): Entity = from(element.nameIdentifier ?: element)

        /**
         * Create an entity at the location of the package, first import or first declaration.
         */
        fun atPackageOrFirstDecl(file: KtFile): Entity = from(
            file.packageDirective ?: file.firstChild ?: file
        )

The last function is new. Issues on functions can use atName.