Add language feature for extended main convention

- suspend
- parameterless

 #KT-17679 Fixed
 #KT-26574 Fixed

compiler/frontend/src/org/jetbrains/kotlin/idea/MainFunctionDetector.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.idea
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.name.FqName
@@ -138,6 +139,8 @@ class MainFunctionDetector {
             }
         }
 
+        if (descriptor.isSuspend && !languageVersionSettings.supportsFeature(LanguageFeature.ExtendedMainConvention)) return false
+
         if (checkReturnType && !isMainReturnType(descriptor)) return false
 
         if (DescriptorUtils.isTopLevelDeclaration(descriptor)) return true
@@ -173,17 +176,17 @@ class MainFunctionDetector {
     private fun findMainFunction(declarations: List<KtDeclaration>) =
         declarations.filterIsInstance<KtNamedFunction>().find { isMain(it) }
 
-    companion object {
-        private fun isParameterNumberSuitsForMain(
-            parametersCount: Int,
-            isTopLevel: Boolean,
-            allowParameterless: Boolean
-        ) = when (parametersCount) {
-            1 -> true
-            0 -> isTopLevel && allowParameterless
-            else -> false
-        }
+    private fun isParameterNumberSuitsForMain(
+        parametersCount: Int,
+        isTopLevel: Boolean,
+        allowParameterless: Boolean
+    ) = when (parametersCount) {
+        1 -> true
+        0 -> isTopLevel && allowParameterless && languageVersionSettings.supportsFeature(LanguageFeature.ExtendedMainConvention)
+        else -> false
+    }
 
+    companion object {
         private fun isMainReturnType(descriptor: FunctionDescriptor): Boolean {
             val returnType = descriptor.returnType
             return returnType != null && KotlinBuiltIns.isUnit(returnType)

compiler/testData/codegen/bytecodeListing/main/parameterlessMain.kt

@@ -0,0 +1,3 @@
+// WITH_RUNTIME
+
+fun main() {}

compiler/testData/codegen/bytecodeListing/main/parameterlessMain.txt

@@ -0,0 +1,5 @@
+@kotlin.Metadata
+public final class ParameterlessMainKt {
+    public final static method main(): void
+    public synthetic static method main(p0: java.lang.String[]): void
+}

compiler/testData/codegen/bytecodeListing/main/parameterlessMain_before.kt

@@ -0,0 +1,4 @@
+// !LANGUAGE: -ExtendedMainConvention
+// WITH_RUNTIME
+
+fun main() {}

compiler/testData/codegen/bytecodeListing/main/parameterlessMain_before.txt

@@ -0,0 +1,4 @@
+@kotlin.Metadata
+public final class ParameterlessMain_beforeKt {
+    public final static method main(): void
+}

compiler/testData/codegen/bytecodeListing/main/suspendMain.kt

@@ -0,0 +1,3 @@
+// WITH_RUNTIME
+
+suspend fun main(args: Array<String>) {}

compiler/testData/codegen/bytecodeListing/main/suspendMain.txt

@@ -0,0 +1,12 @@
+@kotlin.Metadata
+synthetic final class SuspendMainKt$$$main {
+    private final field args: java.lang.String[]
+    synthetic method <init>(p0: java.lang.String[]): void
+    public synthetic final method invoke(p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+public final class SuspendMainKt {
+    public final static @org.jetbrains.annotations.Nullable method main(@org.jetbrains.annotations.NotNull p0: java.lang.String[], @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.Continuation): java.lang.Object
+    public synthetic static method main(p0: java.lang.String[]): void
+}

compiler/testData/codegen/bytecodeListing/main/suspendMain_before.kt

@@ -0,0 +1,4 @@
+// !LANGUAGE: -ExtendedMainConvention -ReleaseCoroutines
+// WITH_RUNTIME
+
+suspend fun main(args: Array<String>) {}

compiler/testData/codegen/bytecodeListing/main/suspendMain_before.txt

@@ -0,0 +1,4 @@
+@kotlin.Metadata
+public final class SuspendMain_beforeKt {
+    public final static @org.jetbrains.annotations.Nullable method main(@org.jetbrains.annotations.NotNull p0: java.lang.String[], @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.experimental.Continuation): java.lang.Object
+}

compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.kt

@@ -0,0 +1,7 @@
+// !LANGUAGE: -ExtendedMainConvention
+
+// FILE: a.kt
+<!CONFLICTING_OVERLOADS!>fun main()<!> {}
+
+// FILE: b.kt
+<!CONFLICTING_OVERLOADS!>fun main()<!> {}

compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.txt

@@ -0,0 +1,4 @@
+package
+
+public fun main(): kotlin.Unit
+public fun main(): kotlin.Unit

compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.kt

@@ -0,0 +1,7 @@
+// !LANGUAGE: -ExtendedMainConvention
+
+// FILE: a.kt
+<!CONFLICTING_OVERLOADS!>suspend fun main(<!UNUSED_PARAMETER!>args<!>: Array<String>)<!> {}
+
+// FILE: b.kt
+<!CONFLICTING_OVERLOADS!>suspend fun main(<!UNUSED_PARAMETER!>args<!>: Array<String>)<!> {}

compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.txt

@@ -0,0 +1,4 @@
+package
+
+public suspend fun main(/*0*/ args: kotlin.Array<kotlin.String>): kotlin.Unit
+public suspend fun main(/*0*/ args: kotlin.Array<kotlin.String>): kotlin.Unit

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -15936,11 +15936,21 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMainInvalid.kt");
             }
 
+            @TestMetadata("RedeclarationParameterlessMain_before.kt")
+            public void testRedeclarationParameterlessMain_before() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.kt");
+            }
+
             @TestMetadata("RedeclarationSuspendMainInMultiFile.kt")
             public void testRedeclarationSuspendMainInMultiFile() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile.kt");
             }
 
+            @TestMetadata("RedeclarationSuspendMainInMultiFile_before.kt")
+            public void testRedeclarationSuspendMainInMultiFile_before() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.kt");
+            }
+
             @TestMetadata("Redeclarations.kt")
             public void testRedeclarations() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/redeclarations/Redeclarations.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -15936,11 +15936,21 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMainInvalid.kt");
             }
 
+            @TestMetadata("RedeclarationParameterlessMain_before.kt")
+            public void testRedeclarationParameterlessMain_before() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.kt");
+            }
+
             @TestMetadata("RedeclarationSuspendMainInMultiFile.kt")
             public void testRedeclarationSuspendMainInMultiFile() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile.kt");
             }
 
+            @TestMetadata("RedeclarationSuspendMainInMultiFile_before.kt")
+            public void testRedeclarationSuspendMainInMultiFile_before() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.kt");
+            }
+
             @TestMetadata("Redeclarations.kt")
             public void testRedeclarations() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/redeclarations/Redeclarations.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeListingTestGenerated.java

@@ -320,6 +320,39 @@ public class BytecodeListingTestGenerated extends AbstractBytecodeListingTest {
         }
     }
 
+    @TestMetadata("compiler/testData/codegen/bytecodeListing/main")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Main extends AbstractBytecodeListingTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, TargetBackend.ANY, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInMain() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/bytecodeListing/main"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("parameterlessMain.kt")
+        public void testParameterlessMain() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeListing/main/parameterlessMain.kt");
+        }
+
+        @TestMetadata("parameterlessMain_before.kt")
+        public void testParameterlessMain_before() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeListing/main/parameterlessMain_before.kt");
+        }
+
+        @TestMetadata("suspendMain.kt")
+        public void testSuspendMain() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeListing/main/suspendMain.kt");
+        }
+
+        @TestMetadata("suspendMain_before.kt")
+        public void testSuspendMain_before() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeListing/main/suspendMain_before.kt");
+        }
+    }
+
     @TestMetadata("compiler/testData/codegen/bytecodeListing/multiplatform")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -88,6 +88,7 @@ enum class LanguageFeature(
     DslMarkerOnFunctionTypeReceiver(KOTLIN_1_4, kind = BUG_FIX),
     ProhibitErroneousExpressionsInAnnotationsWithUseSiteTargets(KOTLIN_1_3, kind = BUG_FIX),
     NewCapturedReceiverFieldNamingConvention(KOTLIN_1_3, kind = BUG_FIX),
+    ExtendedMainConvention(KOTLIN_1_3),
 
     RestrictReturnStatementTarget(KOTLIN_1_4, kind = BUG_FIX),
     NoConstantValueAttributeForNonConstVals(KOTLIN_1_4, kind = BUG_FIX),

idea/tests/org/jetbrains/kotlin/idea/run/RunConfigurationTest.kt

@@ -39,6 +39,7 @@ import org.jetbrains.kotlin.idea.stubindex.KotlinTopLevelFunctionFqnNameIndex
 import org.jetbrains.kotlin.idea.test.ConfigLibraryUtil
 import org.jetbrains.kotlin.idea.test.KotlinCodeInsightTestCase
 import org.jetbrains.kotlin.idea.test.PluginTestCaseBase.*
+import org.jetbrains.kotlin.idea.test.configureLanguageAndApiVersion
 import org.jetbrains.kotlin.idea.util.application.runWriteAction
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.allChildren
@@ -55,6 +56,9 @@ class RunConfigurationTest: KotlinCodeInsightTestCase() {
 
     fun testMainInTest() {
         val createResult = configureModule(moduleDirPath("module"), getTestProject().baseDir!!)
+        configureLanguageAndApiVersion(
+            createResult.module.project, createResult.module, LanguageVersionSettingsImpl.DEFAULT.languageVersion.versionString
+        )
         ConfigLibraryUtil.configureKotlinRuntimeAndSdk(createResult.module, addJdk(testRootDisposable, ::mockJdk))
 
         val runConfiguration = createConfigurationFromMain("some.main")