Moshi: Inline function with reified type parameter in @JsonClass breaks codegen on >= 1.9.0

[mannodermaus]

The following model class definition fails with Moshi 1.9.0 and above:

@JsonClass(generateAdapter = true)
data class Model(@Json(name = "id") val id: String) {
    inline fun <reified T> inlineMethod(named: String): T? = null
}

The fields on the class & the body of its inline function are irrelevant - instead, it seems like the presence of the reified keyword will cause Moshi's codegen to fail with the following message:

e: [kapt] An exception occurred: java.util.NoSuchElementException: Key 0 is missing in the map.
    at kotlin.collections.MapsKt__MapWithDefaultKt.getOrImplicitDefaultNullable(MapWithDefault.kt:24)
    at kotlin.collections.MapsKt__MapsKt.getValue(Maps.kt:294)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toFunSpec(KotlinPoetMetadataSpecs.kt:543)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.access$toFunSpec(KotlinPoetMetadataSpecs.kt:1)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs$toTypeSpec$26.invoke(KotlinPoetMetadataSpecs.kt:429)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs$toTypeSpec$26.invoke(KotlinPoetMetadataSpecs.kt)
    at kotlin.sequences.TransformingSequence$iterator$1.next(Sequences.kt:172)
    at com.squareup.kotlinpoet.TypeSpec$Builder.addFunctions(TypeSpec.kt:786)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toTypeSpec(KotlinPoetMetadataSpecs.kt:403)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toTypeSpec(KotlinPoetMetadataSpecs.kt:173)
    at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toTypeSpec$default(KotlinPoetMetadataSpecs.kt:171)
    at com.squareup.moshi.kotlin.codegen.MetadataKt.targetType(metadata.kt:153)
    at com.squareup.moshi.kotlin.codegen.JsonClassCodegenProcessor.adapterGenerator(JsonClassCodegenProcessor.kt:133)
    at com.squareup.moshi.kotlin.codegen.JsonClassCodegenProcessor.process(JsonClassCodegenProcessor.kt:107)
    at org.jetbrains.kotlin.kapt3.base.incremental.IncrementalProcessor.process(incrementalProcessors.kt)
(More kapt stuff below this line...)

On 1.8.0, code generation and compilation are successful.

As a workaround, the reified inline fun can be defined outside of the model class, as an extension function:

@JsonClass(generateAdapter = true)
data class Model(@Json(name = "id") val id: String)

// This works
inline fun <reified T> Model.inlineMethod(named: String): T? = null

[ZacSweers]

Can you try the master snapshot and 1.9.1? We fixed an issue around type
variables last week.

On Wed, Nov 6, 2019 at 4:03 AM Marcel Schnelle [e-mail]
wrote:

The following model class definition fails with Moshi 1.9.0 and above:

@JsonClass(generateAdapter = true)data class Model(@Json(name = "id") val id: String) {
inline fun inlineMethod(named: String): T? = null
}

The fields on the class & the body of its inline function are irrelevant -
instead, it seems like the presence of the reified keyword will cause
Moshi's codegen to fail with the following message:

e: [kapt] An exception occurred: java.util.NoSuchElementException: Key 0 is missing in the map.
at kotlin.collections.MapsKt__MapWithDefaultKt.getOrImplicitDefaultNullable(MapWithDefault.kt:24)
at kotlin.collections.MapsKt__MapsKt.getValue(Maps.kt:294)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toFunSpec(KotlinPoetMetadataSpecs.kt:543)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.access$toFunSpec(KotlinPoetMetadataSpecs.kt:1)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs$toTypeSpec$26.invoke(KotlinPoetMetadataSpecs.kt:429)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs$toTypeSpec$26.invoke(KotlinPoetMetadataSpecs.kt)
at kotlin.sequences.TransformingSequence$iterator$1.next(Sequences.kt:172)
at com.squareup.kotlinpoet.TypeSpec$Builder.addFunctions(TypeSpec.kt:786)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toTypeSpec(KotlinPoetMetadataSpecs.kt:403)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toTypeSpec(KotlinPoetMetadataSpecs.kt:173)
at com.squareup.moshi.kotlinpoet.metadata.specs.KotlinPoetMetadataSpecs.toTypeSpec$default(KotlinPoetMetadataSpecs.kt:171)
at com.squareup.moshi.kotlin.codegen.MetadataKt.targetType(metadata.kt:153)
at com.squareup.moshi.kotlin.codegen.JsonClassCodegenProcessor.adapterGenerator(JsonClassCodegenProcessor.kt:133)
at com.squareup.moshi.kotlin.codegen.JsonClassCodegenProcessor.process(JsonClassCodegenProcessor.kt:107)
at org.jetbrains.kotlin.kapt3.base.incremental.IncrementalProcessor.process(incrementalProcessors.kt)
(More kapt stuff below this line...)

On 1.8.0, code generation and compilation are successful.

As a workaround, the reified inline fun can be defined outside of the
model class, as an extension function:

@JsonClass(generateAdapter = true)data class Model(@Json(name = "id") val id: String)
// This worksinline fun Model.inlineMethod(named: String): T? = null

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[mannodermaus]

Neither 1.9.1 nor the latest 1.10.0-SNAPSHOT seem to change anything about the failure, unfortunately. The stack trace is unchanged compared to the error using 1.9.0 as well.

[DanielClayton]

I'm also seeing something similar with the out variance annotation:

@JsonClass(generateAdapter = true)
data class NodeGlobalApiResponse<out T>

This was working in 1.8.0, but in 1.9.1 I'm getting a compile-time error:
Type parameter T is declared as 'out' but occurs in 'invariant' position in type JsonAdapter<NodeGlobalApiResponse<T>>

[ZacSweers]

@mannodermaus since this is a KotlinPoet issue, do you mind filing there? We'll need to start there

@DanielClayton yours looks like a separate issue. Can you please post a separate issue with the full stacktrace? Also whether or not you tested the current master snapshot

[mannodermaus]

@ZacSweers Thanks! I raised it on KotlinPoet as https://github.com/square/kotlinpoet/issues/829.

[ZacSweers]

@DanielClayton I've extracted your issue to a separate issue in #1009 and opened a PR for it in #1010.

[mannodermaus]

I can confirm that the latest 1.10.0-SNAPSHOT resolves this issue. As soon as 1.9.2 hits jcenter, I will upgrade to that version. Thank you for the quick turnaround!