Print recompilation reasons in build report

compiler/daemon/src/org/jetbrains/kotlin/daemon/report/RemoteICReporter.kt

@@ -34,6 +34,7 @@ internal class RemoteICReporter(
         CompilationResultCategory.IC_COMPILE_ITERATION.code in compilationOptions.requestedCompilationResults
     private val shouldReportICLog = CompilationResultCategory.IC_LOG.code in compilationOptions.requestedCompilationResults
     private val icLogLines = arrayListOf<String>()
+    private val recompilationReason = HashMap<File, String>()
 
     override fun report(message: () -> String) {
         reportImpl(isMessageVerbose = false, message = message)
@@ -64,9 +65,18 @@ internal class RemoteICReporter(
         }
         if (shouldReportICLog && incremental) {
             icLogLines.add("Compile iteration:")
-            sourceFiles.relativePaths(rootDir).forEach {
-                icLogLines.add("  $it")
+            sourceFiles.relativePaths(rootDir).forEach { file ->
+                val reason = recompilationReason[file]?.let { " <- $it" } ?: ""
+                icLogLines.add("  $file$reason")
             }
+            recompilationReason.clear()
+        }
+    }
+
+    override fun reportMarkDirty(affectedFiles: Iterable<File>, reason: String) {
+        super.reportMarkDirty(affectedFiles, reason)
+        if (shouldReportICLog) {
+            affectedFiles.forEach { recompilationReason[it] = reason }
         }
     }
 

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/DirtyFilesContainer.kt

@@ -18,10 +18,13 @@ class DirtyFilesContainer(
     fun toMutableList(): MutableList<File> =
         ArrayList(myDirtyFiles)
 
-    fun add(files: Iterable<File>) {
+    fun add(files: Iterable<File>, reason: String?) {
         val existingKotlinFiles = files.filter { it.isKotlinFile(sourceFilesExtensions) }
         if (existingKotlinFiles.isNotEmpty()) {
             myDirtyFiles.addAll(existingKotlinFiles)
+            if (reason != null) {
+                reporter.reportMarkDirty(existingKotlinFiles, reason)
+            }
         }
     }
 
@@ -29,7 +32,8 @@ class DirtyFilesContainer(
         if (lookupSymbols.isEmpty()) return
 
         val dirtyFilesFromLookups = mapLookupSymbolsToFiles(caches.lookupCache, lookupSymbols, reporter)
-        add(dirtyFilesFromLookups)
+        // reason is null, because files are reported in mapLookupSymbolsToFiles
+        add(dirtyFilesFromLookups, reason = null)
     }
 
     fun addByDirtyClasses(dirtyClassesFqNames: Collection<FqName>) {
@@ -43,6 +47,7 @@ class DirtyFilesContainer(
         }
         val dirtyFilesFromFqNames =
             mapClassesFqNamesToFiles(listOf(caches.platformCache), fqNamesWithSubtypes, reporter)
-        add(dirtyFilesFromFqNames)
+        // reason is null, because files are reported in mapClassesFqNamesToFiles
+        add(dirtyFilesFromFqNames, reason = null)
     }
 }

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCompilerRunner.kt

@@ -139,16 +139,16 @@ abstract class IncrementalCompilerRunner<
     protected abstract fun calculateSourcesToCompile(caches: CacheManager, changedFiles: ChangedFiles.Known, args: Args): CompilationMode
 
     protected fun initDirtyFiles(dirtyFiles: DirtyFilesContainer, changedFiles: ChangedFiles.Known) {
-        dirtyFiles.add(changedFiles.modified)
-        dirtyFiles.add(changedFiles.removed)
+        dirtyFiles.add(changedFiles.modified, "was modified since last time")
+        dirtyFiles.add(changedFiles.removed, "was removed since last time")
 
         if (dirtySourcesSinceLastTimeFile.exists()) {
             val files = dirtySourcesSinceLastTimeFile.readLines().map(::File)
             if (files.isNotEmpty()) {
-                reporter.report { "Source files added since last compilation: ${reporter.pathsAsString(files)}" }
+                reporter.reportVerbose { "Source files added since last compilation: ${reporter.pathsAsString(files)}" }
             }
 
-            dirtyFiles.add(files)
+            dirtyFiles.add(files, "was not compiled last time")
         }
     }