added DisableToStringGeneration annotation

README.md

@@ -44,6 +44,15 @@ mutating data can affect the results of `equals` and `hashCode` over time, which
 unexpected. For this reason, `@ArrayContentBased` should only be used in very performance-sensitive
 APIs.
 
+### Disable `toString` generation
+
+You can disable `toString` generation on per-class basis with `DisableToStringGeneration`
+annotation.
+
+Generated `toString` implementations add to the string pool, and can't be removed by optimizers like
+`R8` due to the general widely-used nature of toString. For this reason it is desirable in some
+contexts to skip `toString` and only generate `equals` and `hashCode` for internal value types.
+
 ### Annotation
 By default, the `dev.drewhamilton.poko.Poko` annotation is used to mark classes for Poko generation.
 If you prefer, you can create a different annotation and supply it to the Gradle  plugin.

poko-annotations/api/poko-annotations.api

@@ -4,6 +4,9 @@ public abstract interface annotation class dev/drewhamilton/poko/ArrayContentBas
 public abstract interface annotation class dev/drewhamilton/poko/ArrayContentSupport : java/lang/annotation/Annotation {
 }
 
+public abstract interface annotation class dev/drewhamilton/poko/DisableToStringGeneration : java/lang/annotation/Annotation {
+}
+
 public abstract interface annotation class dev/drewhamilton/poko/Poko : java/lang/annotation/Annotation {
 }
 

poko-annotations/src/commonMain/kotlin/dev/drewhamilton/poko/DisableToStringGeneration.kt

@@ -0,0 +1,8 @@
+package dev.drewhamilton.poko
+
+/**
+ * Declares that a [Poko] class will not have [Any.toString] method generated.
+ */
+@Retention(AnnotationRetention.SOURCE)
+@Target(AnnotationTarget.CLASS)
+public annotation class DisableToStringGeneration

poko-compiler-plugin/src/main/kotlin/dev/drewhamilton/poko/ir/PokoMembersTransformer.kt

@@ -56,14 +56,15 @@ internal class PokoMembersTransformer(
                         )
                     }
 
-                    declaration.isToString() -> declaration.convertToGenerated { properties ->
-                        generateToStringMethodBody(
-                            irClass = declarationParent,
-                            functionDeclaration = declaration,
-                            classProperties = properties,
-                            messageCollector = messageCollector,
-                        )
-                    }
+                    declaration.isToString() && !declarationParent.hasDisableToStringGenerationAnnotation() ->
+                        declaration.convertToGenerated { properties ->
+                            generateToStringMethodBody(
+                                irClass = declarationParent,
+                                functionDeclaration = declaration,
+                                classProperties = properties,
+                                messageCollector = messageCollector,
+                            )
+                        }
                 }
             }
         }
@@ -72,7 +73,7 @@ internal class PokoMembersTransformer(
     }
 
     private fun IrClass.isPokoClass(): Boolean = when {
-        !hasAnnotation(pokoAnnotationName.asSingleFqName()) -> {
+        !hasPokoClassAnnotation() -> {
             messageCollector.log("Not Poko class")
             false
         }
@@ -173,4 +174,8 @@ internal class PokoMembersTransformer(
             parent = this@mutateWithNewDispatchReceiverParameterForParentClass
         }
     }
+
+    private fun IrClass.hasPokoClassAnnotation(): Boolean {
+        return hasAnnotation(pokoAnnotationName.asSingleFqName())
+    }
 }

poko-compiler-plugin/src/main/kotlin/dev/drewhamilton/poko/ir/functionGeneration.kt

@@ -134,3 +134,11 @@ internal fun IrClassSymbol.createArrayType(): IrSimpleType {
     }
     return createType(hasQuestionMark = false, arguments = typeArguments)
 }
+
+private val disableToStringGenerationnAnnotationFqName = ClassId(
+    FqName("dev.drewhamilton.poko"),
+    Name.identifier("DisableToStringGeneration"),
+).asSingleFqName()
+
+internal fun IrClass.hasDisableToStringGenerationAnnotation(): Boolean =
+    hasAnnotation(disableToStringGenerationnAnnotationFqName)

poko-compiler-plugin/src/test/kotlin/dev/drewhamilton/poko/PokoCompilerPluginTest.kt

@@ -3,8 +3,10 @@ package dev.drewhamilton.poko
 import assertk.all
 import assertk.assertThat
 import assertk.assertions.contains
-import assertk.assertions.doesNotContain
 import assertk.assertions.isEqualTo
+import assertk.assertions.isNotEqualTo
+import assertk.assertions.prop
+import assertk.assertions.startsWith
 import com.google.testing.junit.testparameterinjector.TestParameter
 import com.google.testing.junit.testparameterinjector.TestParameterInjector
 import com.tschuchort.compiletesting.KotlinCompilation
@@ -32,10 +34,42 @@ class PokoCompilerPluginTest(
 
     //region Primitives
     @Test fun `compilation of valid class succeeds`() {
-        testCompilation("api/Primitives")
+        testCompilation("api/Primitives") { result ->
+            val testClass = result.classLoader.loadClass("api.Primitives")
+            val primaryTestInstance = testClass.declaredConstructors[0].newInstance(
+                "a", 1f, 2.0, 3L, 4, 5.toShort(), 6.toByte(), true
+            )
+            val cloneOfPrimaryTestInstance = testClass.declaredConstructors[0].newInstance(
+                "a", 1f, 2.0, 3L, 4, 5.toShort(), 6.toByte(), true
+            )
+            val otherTestInstance = testClass.declaredConstructors[0].newInstance(
+                "b", 8f, 9.0, 11L, 4, 9.toShort(), 1.toByte(), false
+            )
+
+            assertThat(primaryTestInstance).all {
+                prop(Any::toString).isEqualTo("Primitives(string=a, float=1.0, double=2.0, long=3, int=4, short=5, byte=6, boolean=true)")
+                prop(Any::hashCode).isNotEqualTo(System.identityHashCode(primaryTestInstance))
+
+                isEqualTo(primaryTestInstance)
+                isEqualTo(cloneOfPrimaryTestInstance)
+                isNotEqualTo(otherTestInstance)
+            }
+        }
+    }
+    //endregion
+
+    //region ToStringGenerationDisabled
+    @Test fun `compilation of valid class with disabled to string generation succeeds`() {
+        testCompilation("api/ToStringGenerationDisabled") { result ->
+            val testClass = result.classLoader.loadClass("api.ToStringGenerationDisabled")
+            val testInstance = testClass.declaredConstructors[0].newInstance("hello world")
+            // note @ at the end of assumed toString value, it indicates that default toString was used
+            assertThat(testInstance.toString()).startsWith("api.ToStringGenerationDisabled@")
+        }
     }
     //endregion
 
+
     //region data class
     @Test fun `compilation of data class fails`() {
         testCompilation(

poko-compiler-plugin/src/test/resources/api/ToStringGenerationDisabled.kt

@@ -0,0 +1,9 @@
+package api
+
+import dev.drewhamilton.poko.DisableToStringGeneration
+import dev.drewhamilton.poko.Poko
+
+@DisableToStringGeneration
+@Poko class ToStringGenerationDisabled(
+    val argument: String
+)