[java] improves mandatory module path detection; more package accessibility tests

java/java-impl/src/com/intellij/psi/impl/JavaPlatformModuleSystem.kt

@@ -13,8 +13,9 @@ import com.intellij.codeInsight.intention.IntentionAction
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.module.Module
 import com.intellij.openapi.project.Project
+import com.intellij.openapi.roots.JdkOrderEntry
+import com.intellij.openapi.roots.ModuleRootManager
 import com.intellij.openapi.roots.ProjectFileIndex
-import com.intellij.openapi.vfs.jrt.JrtFileSystem
 import com.intellij.psi.*
 import com.intellij.psi.impl.light.LightJavaModule
 import com.intellij.psi.impl.source.PsiJavaModuleReference
@@ -81,14 +82,24 @@ class JavaPlatformModuleSystem : JavaModuleSystemEx {
         return null
       }
 
-      if (useModule == null && targetModule.containingFile?.virtualFile?.fileSystem !is JrtFileSystem) {
-        return null  // a target is not on the mandatory module path
-      }
-
       val targetName = targetModule.name
       val useName = useModule?.name ?: "ALL-UNNAMED"
       val module = place.virtualFile?.let { ProjectFileIndex.getInstance(place.project).getModuleForFile(it) }
 
+      if (useModule == null) {
+        val origin = targetModule.containingFile?.virtualFile
+        if (origin == null || module == null || ModuleRootManager.getInstance(module).fileIndex.getOrderEntryForFile(origin) !is JdkOrderEntry) {
+          return null  // a target is not on the mandatory module path
+        }
+
+        val root = PsiJavaModuleReference.resolve(place, "java.se", false)
+        if (!(root == null || JavaModuleGraphUtil.reads(root, targetModule) || inAddedModules(module, targetName))) {
+          return if (quick) ERR else ErrorWithFixes(
+            JavaErrorMessages.message("module.access.not.in.graph", packageName, targetName),
+            listOf(AddModulesOptionFix(module, targetName)))
+        }
+      }
+
       if (!(targetModule is LightJavaModule ||
             JavaModuleGraphUtil.exports(targetModule, packageName, useModule) ||
             module != null && inAddedExports(module, targetName, packageName, useName))) {
@@ -105,16 +116,7 @@ class JavaPlatformModuleSystem : JavaModuleSystemEx {
         }
       }
 
-      if (useModule == null) {
-        if (!targetName.startsWith("java.")) return null
-        val root = PsiJavaModuleReference.resolve(place, "java.se", false)
-        if (root == null || JavaModuleGraphUtil.reads(root, targetModule)) return null
-        if (module != null && inAddedModules(module, targetName)) return null
-        val fixes = if (quick || module == null) emptyList() else listOf(AddModulesOptionFix(module, targetName))
-        return if (quick) ERR else ErrorWithFixes(JavaErrorMessages.message("module.access.not.in.graph", packageName, targetName), fixes)
-      }
-
-      if (!(targetName == PsiJavaModule.JAVA_BASE || JavaModuleGraphUtil.reads(useModule, targetModule))) {
+      if (useModule != null && !(targetName == PsiJavaModule.JAVA_BASE || JavaModuleGraphUtil.reads(useModule, targetModule))) {
         return when {
           quick -> ERR
           PsiNameHelper.isValidModuleName(targetName, useModule) -> ErrorWithFixes(

java/java-tests/testSrc/com/intellij/java/codeInsight/completion/ModuleCompletionTest.kt

@@ -32,7 +32,8 @@ class ModuleCompletionTest : LightJava9ModulesCodeInsightFixtureTestCase() {
   fun testStatementsUnambiguous() = complete("module M { requires X; ex<caret> }", "module M { requires X; exports <caret> }")
 
   fun testRequiresBare() =
-    variants("module M { requires <caret>", "transitive", "static", "M2", "java.base", "lib.multi.release", "lib.named", "lib.auto", "lib.claimed")
+    variants("module M { requires <caret>",
+             "transitive", "static", "M2", "java.base", "java.se", "javax.doomed", "lib.multi.release", "lib.named", "lib.auto", "lib.claimed")
   fun testRequiresTransitive() = complete("module M { requires tr<caret> }", "module M { requires transitive <caret> }")
   fun testRequiresSimpleName() = complete("module M { requires M<caret> }", "module M { requires M2;<caret> }")
   fun testRequiresQualifiedName() = complete("module M { requires lib.m<caret> }", "module M { requires lib.multi.release;<caret> }")
@@ -42,7 +43,8 @@ class ModuleCompletionTest : LightJava9ModulesCodeInsightFixtureTestCase() {
   fun testExportsQualified() = variants("module M { exports pkg.<caret> }", "main", "other", "empty")
   fun testExportsQualifiedUnambiguous() = complete("module M { exports pkg.o<caret> }", "module M { exports pkg.other.<caret> }")
   fun testExportsTo() = complete("module M { exports pkg.other <caret> }", "module M { exports pkg.other to <caret> }")
-  fun testExportsToList() = variants("module M { exports pkg.other to <caret> }", "M2", "java.base", "lib.multi.release", "lib.named")
+  fun testExportsToList() =
+    variants("module M { exports pkg.other to <caret> }", "M2", "java.base", "java.se", "javax.doomed", "lib.multi.release", "lib.named")
   fun testExportsToUnambiguous() = complete("module M { exports pkg.other to M<caret> }", "module M { exports pkg.other to M2<caret> }")
 
   fun testUsesPrefixed() = complete("module M { uses p<caret> }", "module M { uses pkg.<caret> }")

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/ModuleHighlightingTest.kt

@@ -295,6 +295,25 @@ class ModuleHighlightingTest : LightJava9ModulesCodeInsightFixtureTestCase() {
     highlight("test.java", checkFileText, checkFileInTests)
   }
 
+  fun testPrivateJdkPackage() {
+    addFile("module-info.java", "module M { }")
+    highlight("test.java", """
+        import <error descr="Package 'jdk.internal' is declared in module 'java.base', which does not export it to module 'M'">jdk.internal</error>.*;
+        """.trimIndent())
+  }
+
+  fun testPrivateJdkPackageFromUnnamed() {
+    highlight("test.java", """
+        import <error descr="Package 'jdk.internal' is declared in module 'java.base', which does not export it to the unnamed module">jdk.internal</error>.*;
+        """.trimIndent())
+  }
+
+  fun testNonRootJdkModule() {
+    highlight("test.java", """
+        import <error descr="Package 'javax.doomed' is declared in module 'javax.doomed', which is not in the module graph">javax.doomed</error>.*;
+        """.trimIndent())
+  }
+
   fun testLinearModuleGraphBug() {
     addFile("module-info.java", "module M6 { requires M7; }", M6)
     addFile("module-info.java", "module M7 { }", M7)