Don't read file content to see if file is Kotlin-compiled if we have cached attribute but don't have complete data

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/IDEKotlinBinaryClassCache.kt

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.idea.caches
 
+import com.intellij.ide.highlighter.JavaClassFileType
 import com.intellij.openapi.components.ServiceManager
 import com.intellij.openapi.util.Key
 import com.intellij.openapi.vfs.VirtualFile
@@ -28,6 +29,21 @@ object IDEKotlinBinaryClassCache {
     data class KotlinBinaryHeaderData(val classHeader: KotlinClassHeader, val classId: ClassId)
     data class KotlinBinaryData(val isKotlinBinary: Boolean, val timestamp: Long, val headerData: KotlinBinaryHeaderData?)
 
+    /**
+     * Checks if this file is a compiled Kotlin class file (not necessarily ABI-compatible with the current plugin)
+     */
+    fun isKotlinJvmCompiledFile(file: VirtualFile): Boolean {
+        if (file.extension != JavaClassFileType.INSTANCE!!.defaultExtension) {
+            return false
+        }
+
+        val cached = getKotlinBinaryFromCache(file)
+        if (cached != null) {
+            return cached.isKotlinBinary
+        }
+        return getKotlinBinaryClass(file) != null
+    }
+
     fun getKotlinBinaryClass(file: VirtualFile, fileContent: ByteArray? = null): KotlinJvmBinaryClass? {
         val cached = getKotlinBinaryFromCache(file)
         if (cached != null && !cached.isKotlinBinary) {

idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/classFile/ClassFileDecompilerUtil.kt

@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.idea.decompiler.classFile
 
-import com.intellij.ide.highlighter.JavaClassFileType
 import com.intellij.openapi.components.ServiceManager
 import com.intellij.openapi.util.Key
 import com.intellij.openapi.vfs.VirtualFile
@@ -36,22 +35,11 @@ val KOTLIN_COMPILED_FILE_ATTRIBUTE: String = "kotlin-compiled-file".apply {
 
 val KEY = Key.create<IsKotlinBinary>(KOTLIN_COMPILED_FILE_ATTRIBUTE)
 
-/**
- * Checks if this file is a compiled Kotlin class file (not necessarily ABI-compatible with the current plugin)
- */
-fun isKotlinJvmCompiledFile(file: VirtualFile): Boolean {
-    if (file.extension != JavaClassFileType.INSTANCE!!.defaultExtension) {
-        return false
-    }
-
-    return IDEKotlinBinaryClassCache.getKotlinBinaryClassHeaderData(file) != null
-}
-
 /**
  * Checks if this file is a compiled Kotlin class file ABI-compatible with the current plugin
  */
 fun isKotlinWithCompatibleAbiVersion(file: VirtualFile): Boolean {
-    if (!isKotlinJvmCompiledFile(file)) return false
+    if (!IDEKotlinBinaryClassCache.isKotlinJvmCompiledFile(file)) return false
 
     val kotlinClass = IDEKotlinBinaryClassCache.getKotlinBinaryClassHeaderData(file)
     return kotlinClass != null && kotlinClass.classHeader.metadataVersion.isCompatible()
@@ -62,7 +50,7 @@ fun isKotlinWithCompatibleAbiVersion(file: VirtualFile): Boolean {
  * which should NOT be decompiled (and, as a result, shown under the library in the Project view, be searchable via Find class, etc.)
  */
 fun isKotlinInternalCompiledFile(file: VirtualFile): Boolean {
-    if (!isKotlinJvmCompiledFile(file)) {
+    if (!IDEKotlinBinaryClassCache.isKotlinJvmCompiledFile(file)) {
         return false
     }
 

idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/classFile/KotlinClassFileDecompiler.kt

@@ -41,7 +41,7 @@ import org.jetbrains.kotlin.types.isFlexible
 class KotlinClassFileDecompiler : ClassFileDecompilers.Full() {
     private val stubBuilder = KotlinClsStubBuilder()
 
-    override fun accepts(file: VirtualFile) = isKotlinJvmCompiledFile(file)
+    override fun accepts(file: VirtualFile) = IDEKotlinBinaryClassCache.isKotlinJvmCompiledFile(file)
 
     override fun getStubBuilder() = stubBuilder