fix KT-10064 Regression: Error with multiple main functions within a single package

#KT-10064 Fixed

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

@@ -80,13 +80,19 @@ public class MainFunctionDetector {
             return false;
         }
 
-        FunctionDescriptor functionDescriptor = getFunctionDescriptor.fun(function);
+        return isMain(getFunctionDescriptor.fun(function));
+    }
+
+    public static boolean isMain(@NotNull DeclarationDescriptor descriptor) {
+        if (!(descriptor instanceof FunctionDescriptor)) return false;
+
+        FunctionDescriptor functionDescriptor = (FunctionDescriptor) descriptor;
         if (!getJVMFunctionName(functionDescriptor).equals("main")) {
             return false;
         }
 
         List<ValueParameterDescriptor> parameters = functionDescriptor.getValueParameters();
-        if (parameters.size() != 1) return false;
+        if (parameters.size() != 1 || !functionDescriptor.getTypeParameters().isEmpty()) return false;
 
         ValueParameterDescriptor parameter = parameters.get(0);
         KotlinType parameterType = parameter.getType();

compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorToSourceUtils.kt

@@ -17,16 +17,17 @@
 package org.jetbrains.kotlin.resolve
 
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.DECLARATION
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.SYNTHESIZED
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptorWithSource
+import org.jetbrains.kotlin.descriptors.PropertyAccessorDescriptor
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
-import org.jetbrains.kotlin.idea.MainFunctionDetector
 import org.jetbrains.kotlin.psi.KtAnnotationEntry
 import org.jetbrains.kotlin.psi.KtFile
-import org.jetbrains.kotlin.psi.KtNamedFunction
 import org.jetbrains.kotlin.resolve.source.getPsi
-import java.util.ArrayList
+import java.util.*
 
 public object DescriptorToSourceUtils {
     private fun collectEffectiveReferencedDescriptors(result: MutableList<DeclarationDescriptor>, descriptor: DeclarationDescriptor) {
@@ -80,16 +81,6 @@ public object DescriptorToSourceUtils {
         return declaration.getContainingFile() as? KtFile
     }
 
-    @JvmStatic
-    public fun isTopLevelMainFunction(declarationDescriptor: DeclarationDescriptor, mainFunctionDetector: MainFunctionDetector): Boolean {
-        if (declarationDescriptor !is FunctionDescriptor ||
-            !DescriptorUtils.isTopLevelDeclaration(declarationDescriptor) ||
-            declarationDescriptor.name.asString() != "main") return false
-
-        val element = descriptorToDeclaration(declarationDescriptor)
-        return element is KtNamedFunction && mainFunctionDetector.isMain(element)
-    }
-
     private fun findTopLevelParent(declarationDescriptor: DeclarationDescriptor): DeclarationDescriptor? {
         var descriptor: DeclarationDescriptor? = declarationDescriptor
         if (declarationDescriptor is PropertyAccessorDescriptor) {

compiler/frontend/src/org/jetbrains/kotlin/resolve/OverloadResolver.java

@@ -36,7 +36,6 @@ import static org.jetbrains.kotlin.resolve.DescriptorUtils.getFqName;
 public class OverloadResolver {
     @NotNull private final BindingTrace trace;
     @NotNull private final OverloadFilter overloadFilter;
-    @NotNull private final MainFunctionDetector mainFunctionDetector;
 
     public OverloadResolver(
             @NotNull BindingTrace trace,
@@ -44,8 +43,6 @@ public class OverloadResolver {
     ) {
         this.trace = trace;
         this.overloadFilter = overloadFilter;
-
-        mainFunctionDetector = new MainFunctionDetector(trace.getBindingContext());
     }
 
     public void process(@NotNull BodiesResolveContext c) {
@@ -160,7 +157,7 @@ public class OverloadResolver {
     }
 
     @NotNull
-    private Set<Pair<KtDeclaration, CallableMemberDescriptor>> findRedeclarations(@NotNull Collection<? extends CallableMemberDescriptor> members) {
+    private static Set<Pair<KtDeclaration, CallableMemberDescriptor>> findRedeclarations(@NotNull Collection<? extends CallableMemberDescriptor> members) {
         Set<Pair<KtDeclaration, CallableMemberDescriptor>> redeclarations = Sets.newLinkedHashSet();
         for (CallableMemberDescriptor member : members) {
             for (CallableMemberDescriptor member2 : members) {
@@ -195,13 +192,15 @@ public class OverloadResolver {
                member.getContainingDeclaration().getContainingDeclaration().equals(member2.getContainingDeclaration().getContainingDeclaration());
     }
 
-    private boolean isTopLevelMainInDifferentFiles(@NotNull CallableMemberDescriptor member, @NotNull CallableMemberDescriptor member2) {
-        if (!DescriptorToSourceUtils.isTopLevelMainFunction(member, mainFunctionDetector) ||
-            !DescriptorToSourceUtils.isTopLevelMainFunction(member2, mainFunctionDetector)) {
+    private static boolean isTopLevelMainInDifferentFiles(@NotNull CallableMemberDescriptor member, @NotNull CallableMemberDescriptor member2) {
+        if (!MainFunctionDetector.isMain(member) ||
+            !MainFunctionDetector.isMain(member2)) {
             return false;
         }
 
-        return DescriptorToSourceUtils.getContainingFile(member) != DescriptorToSourceUtils.getContainingFile(member2);
+        KtFile file = DescriptorToSourceUtils.getContainingFile(member);
+        KtFile file2 = DescriptorToSourceUtils.getContainingFile(member2);
+        return file == null || file2 == null || file != file2;
     }
 
     private void reportRedeclarations(@NotNull String functionContainer,

jps-plugin/test/org/jetbrains/kotlin/jps/build/ExperimentalIncrementalJpsTestGenerated.java

@@ -395,6 +395,12 @@ public class ExperimentalIncrementalJpsTestGenerated extends AbstractExperimenta
             doTest(fileName);
         }
 
+        @TestMetadata("mainRedeclaration")
+        public void testMainRedeclaration() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/incremental/pureKotlin/mainRedeclaration/");
+            doTest(fileName);
+        }
+
         @TestMetadata("moveClass")
         public void testMoveClass() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/incremental/pureKotlin/moveClass/");

jps-plugin/test/org/jetbrains/kotlin/jps/build/IncrementalJpsTestGenerated.java

@@ -395,6 +395,12 @@ public class IncrementalJpsTestGenerated extends AbstractIncrementalJpsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("mainRedeclaration")
+        public void testMainRedeclaration() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/incremental/pureKotlin/mainRedeclaration/");
+            doTest(fileName);
+        }
+
         @TestMetadata("moveClass")
         public void testMoveClass() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("jps-plugin/testData/incremental/pureKotlin/moveClass/");

jps-plugin/testData/incremental/pureKotlin/mainRedeclaration/a.kt

@@ -0,0 +1,3 @@
+package foo
+
+fun main(args: Array<String>) = println("a")

jps-plugin/testData/incremental/pureKotlin/mainRedeclaration/a.kt.new

@@ -0,0 +1,3 @@
+package foo
+
+fun main(args: Array<String>) = println("A")

jps-plugin/testData/incremental/pureKotlin/mainRedeclaration/b.kt

@@ -0,0 +1,3 @@
+package foo
+
+fun main(args: Array<String>) = println("b")

jps-plugin/testData/incremental/pureKotlin/mainRedeclaration/build.log

@@ -0,0 +1,7 @@
+Cleaning output files:
+out/production/module/META-INF/module.kotlin_module
+out/production/module/foo/AKt.class
+End of files
+Compiling files:
+src/a.kt
+End of files