Add compiler X-flag to enable self upper bound type inference

^KT-48026 Fixed

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt

@@ -381,6 +381,12 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
     )
     var unrestrictedBuilderInference: Boolean by FreezableVar(false)
 
+    @Argument(
+        value = "-Xself-upper-bound-inference",
+        description = "Support inferring type arguments based on only self upper bounds of the corresponding type parameters"
+    )
+    var selfUpperBoundInference: Boolean by FreezableVar(false)
+
     open fun configureAnalysisFlags(collector: MessageCollector, languageVersion: LanguageVersion): MutableMap<AnalysisFlag<*>, Any> {
         return HashMap<AnalysisFlag<*>, Any>().apply {
             put(AnalysisFlags.skipMetadataVersionCheck, skipMetadataVersionCheck)
@@ -423,6 +429,10 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
                 put(LanguageFeature.UnrestrictedBuilderInference, LanguageFeature.State.ENABLED)
             }
 
+            if (selfUpperBoundInference) {
+                put(LanguageFeature.TypeInferenceOnCallsWithSelfTypes, LanguageFeature.State.ENABLED)
+            }
+
             if (newInference) {
                 put(LanguageFeature.NewInference, LanguageFeature.State.ENABLED)
                 put(LanguageFeature.SamConversionPerArgument, LanguageFeature.State.ENABLED)

compiler/testData/cli/js/jsExtraHelp.out

@@ -81,6 +81,7 @@ where advanced options include:
   -Xread-deserialized-contracts Enable reading of contracts from metadata
   -Xreport-output-files      Report source to output files mapping
   -Xreport-perf              Report detailed performance statistics
+  -Xself-upper-bound-inference Support inferring type arguments based on only self upper bounds of the corresponding type parameters
   -Xskip-metadata-version-check Allow to load classes with bad metadata version and pre-release classes
   -Xskip-prerelease-check    Allow to load pre-release classes
   -Xsuppress-version-warnings Suppress warnings about outdated, inconsistent or experimental language or API versions

compiler/testData/cli/jvm/extraHelp.out

@@ -195,6 +195,7 @@ where advanced options include:
   -Xread-deserialized-contracts Enable reading of contracts from metadata
   -Xreport-output-files      Report source to output files mapping
   -Xreport-perf              Report detailed performance statistics
+  -Xself-upper-bound-inference Support inferring type arguments based on only self upper bounds of the corresponding type parameters
   -Xskip-metadata-version-check Allow to load classes with bad metadata version and pre-release classes
   -Xskip-prerelease-check    Allow to load pre-release classes
   -Xsuppress-version-warnings Suppress warnings about outdated, inconsistent or experimental language or API versions

compiler/testData/cli/jvm/selfUpperBoundInference.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/selfUpperBoundInference.kt
+-d
+$TEMP_DIR$
+-Xself-upper-bound-inference

compiler/testData/cli/jvm/selfUpperBoundInference.kt

@@ -0,0 +1,51 @@
+class Builder<B : Builder<B>> {
+    fun <T : B> test(): T = TODO()
+
+    fun foo() {}
+}
+
+fun testStar(builder: Builder<*>) {
+    builder.test()
+
+    builder
+        .test()
+        .foo()
+}
+
+fun <K : Builder<K>> testTypeParam(builder: Builder<K>) {
+    builder.test()
+
+    builder
+        .test()
+        .foo()
+}
+
+interface BodySpec<B, S : BodySpec<B, S>> {
+    fun <T : S> isEqualTo(expected: B): T
+}
+
+fun test(b: BodySpec<String, *>) {
+    b.isEqualTo("")
+
+    WriterAppender.newBuilder()
+    WriterAppender.Builder1()
+    WriterAppender.intersectTwoSelfTypes()
+}
+
+object WriterAppender {
+    interface Builder2<K : Builder2<K>>
+
+    class Builder1<B : Builder1<B>> {
+        fun asBuilder(): B {
+            return this as B
+        }
+    }
+
+    fun <B : Builder1<B>> newBuilder(): B {
+        return Builder1<B>().asBuilder()
+    }
+
+    fun <B> intersectTwoSelfTypes(): B where B : Builder1<B>, B: Builder2<B> {
+        return Builder1<B>().asBuilder()
+    }
+}

compiler/testData/cli/jvm/selfUpperBoundInference.out

@@ -0,0 +1,4 @@
+compiler/testData/cli/jvm/selfUpperBoundInference.kt:40:25: warning: unchecked cast: WriterAppender.Builder1<B> to B
+            return this as B
+                        ^
+OK

compiler/tests-gen/org/jetbrains/kotlin/cli/CliTestGenerated.java

@@ -756,6 +756,11 @@ public class CliTestGenerated extends AbstractCliTest {
             runTest("compiler/testData/cli/jvm/sanitized-name.clash.args");
         }
 
+        @TestMetadata("selfUpperBoundInference.args")
+        public void testSelfUpperBoundInference() throws Exception {
+            runTest("compiler/testData/cli/jvm/selfUpperBoundInference.args");
+        }
+
         @TestMetadata("signatureClash.args")
         public void testSignatureClash() throws Exception {
             runTest("compiler/testData/cli/jvm/signatureClash.args");