Fix KotlinProjectExtension.targets import on Kotlin 1.7.20

[Goooler]

See #5163 (comment)

[codecov]

Codecov Report

Merging #5381 (faf099e) into main (7eab480) will increase coverage by 0.27%.
The diff coverage is 81.25%.

❗ Current head faf099e differs from pull request most recent head d99c88d. Consider uploading reports for the commit d99c88d to get more accurate results

@@             Coverage Diff              @@
##               main    #5381      +/-   ##
============================================
+ Coverage     85.84%   86.11%   +0.27%     
+ Complexity     3722     3643      -79     
============================================
  Files           513      515       +2     
  Lines         12023    12085      +62     
  Branches       2227     2161      -66     
============================================
+ Hits          10321    10407      +86     
+ Misses          611      609       -2     
+ Partials       1091     1069      -22     

Impacted Files	Coverage Δ
...in/io/gitlab/arturbosch/detekt/api/SplitPattern.kt	100.00% <ø> (+7.40%)	⬆️
...gitlab/arturbosch/detekt/core/config/BaseConfig.kt	90.32% <0.00%> (-6.35%)	⬇️
...t/generator/collection/RuleSetProviderCollector.kt	78.31% <0.00%> (-0.96%)	⬇️
...detekt/rules/bugs/DuplicateCaseInWhenExpression.kt	100.00% <ø> (ø)
...ab/arturbosch/detekt/rules/bugs/MissingWhenCase.kt	92.85% <ø> (ø)
...rturbosch/detekt/rules/bugs/RedundantElseInWhen.kt	100.00% <ø> (+7.69%)	⬆️
.../arturbosch/detekt/rules/style/CanBeNonNullable.kt	73.20% <ø> (ø)
...tlab/arturbosch/detekt/rules/style/UseDataClass.kt	79.72% <0.00%> (-1.36%)	⬇️
...bosch/detekt/rules/complexity/LabeledExpression.kt	86.20% <50.00%> (ø)
.../arturbosch/detekt/rules/style/AlsoCouldBeApply.kt	56.25% <56.25%> (ø)
... and 53 more

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[Goooler]

@cortinico What will be the min Kotlin version requirement of Detekt 1.22, if it running under Kotlin 1.7.20, this PR would be a broken change?

[cortinico]

@cortinico What will be the min Kotlin version requirement of Detekt 1.22, if it running under Kotlin 1.7.20, this PR would be a broken change?

That's a non trivial question as it depends on the Kotlin version used by Gradle (as this is part of the Gradle plugin). I don't recall what's the status in the ecosystem, but we can't enforce 1.7.20 on all of our users. @3flex do you recall if this is safe to land or do we need to revert it?

[Goooler]

If not, I'll address a compatible commit with Goooler#3.

[Goooler]

I just see the declaration of KotlinProjectExtension.targets has changed from

// 1.7.10
val KotlinProjectExtension.targets: Iterable<KotlinTarget>
    get() = when (this) {
        is KotlinSingleTargetExtension -> listOf(this.target)
        is KotlinMultiplatformExtension -> targets
        else -> error("Unexpected 'kotlin' extension $this")
    }

to

// 1.7.20
val KotlinProjectExtension.targets: Iterable<KotlinTarget>
    get() = when (this) {
        is KotlinSingleTargetExtension<*> -> listOf(this.target)
        is KotlinMultiplatformExtension -> targets
        else -> error("Unexpected 'kotlin' extension $this")
    }

there is an type argument added on KotlinSingleTargetExtension:

abstract class KotlinSingleTargetExtension<TARGET : KotlinTarget>(project: Project) : KotlinProjectExtension(project) {
    abstract val target: TARGET

    fun target(body: Action<TARGET>) = body.execute(target)
}

[Goooler]

We can fix this broken change like Goooler@bb81a27?

[Goooler]

And the other solution is using KotlinJvmProjectExtension's target directly like Goooler@c6b9550, but I'd prefer to merge DetektJvm into DetektMultiplatform to unify task configurations.

[3flex]

I had a look at this and there's no need to use that function there. So I've opened #5383 to remove it which should avoid any compatibility issues.