FunSpec.overriding does not handle internal methods correctly

[Leland-Takamine]

Repro Steps

git clone git@github.com:Leland-Takamine/kotlinpoet-repro.git
cd kotlinpoet-repro
./gradlew :build
# Build fails

Explanation

Method to be overridden

class Foo {
    internal abstract fun myMethod()
}

Overriding method generated via FunSpec.overriding(...)

class FooImpl : Foo() {
  override fun myMethod$repro(): Unit = throw UnsupportedOperationException()
}

Notice that the generated method includes the $repro suffix. This is due to the fact that Kotlin mangles the names of internal methods.

Possible Solution

KotlinPoet should inspect the Kotlin metadata to use the original method name for overriding.

[Leland-Takamine]

@tyvsmith @kurtisnelson

[ZacSweers]

Heavily discussed in #236

[Egorand]

@Leland-Takamine KotlinPoet does work with Kotlin metadata but through different API, please refer to https://github.com/square/kotlinpoet/blob/master/kotlinpoet-metadata-specs/README.md and https://github.com/square/kotlinpoet/blob/master/kotlinpoet-metadata/README.md.

We should probably deprecate existing introspection API since they don't work well with Kotlin.

[ZacSweers]

+1 on deprecating the existing. It's a straight port from javapoet but is wrong often enough to be untrustworthy

[ZacSweers]

Folding this into #236 since it's basically a duplicate of the discussion there.