Improve log messages when failing to compile with daemon

Instead of letting `compileWithDaemon` return null, allow it to throw
exceptions so that the caller can catch those exceptions and log clearer
messages on why it failed.

^KT-31602 In progress

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/compilerRunner/GradleKotlinCompilerWork.kt

@@ -18,10 +18,10 @@ import org.jetbrains.kotlin.gradle.report.*
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompilerExecutionStrategy
 import org.jetbrains.kotlin.gradle.tasks.cleanOutputsAndLocalState
 import org.jetbrains.kotlin.gradle.tasks.throwGradleExceptionIfError
-import org.jetbrains.kotlin.gradle.utils.stackTraceAsString
 import org.jetbrains.kotlin.incremental.ChangedFiles
 import org.jetbrains.kotlin.incremental.ClasspathChanges
 import org.jetbrains.kotlin.incremental.IncrementalModuleInfo
+import org.jetbrains.kotlin.util.suffixIfNot
 import org.slf4j.LoggerFactory
 import java.io.*
 import java.net.URLClassLoader
@@ -147,12 +147,14 @@ internal class GradleKotlinCompilerWork @Inject constructor(
         }
 
         if (compilerExecutionStrategy == KotlinCompilerExecutionStrategy.DAEMON) {
-            val daemonExitCode = compileWithDaemon(messageCollector)
+            try {
-
+                return compileWithDaemon(messageCollector) to KotlinCompilerExecutionStrategy.DAEMON
-            if (daemonExitCode != null) {
+            } catch (e: Throwable) {
-                return daemonExitCode to KotlinCompilerExecutionStrategy.DAEMON
+                log.warn(
-            } else {
+                    "Failed to compile with Kotlin daemon: ${e.stackTraceToString().suffixIfNot("\n")}" +
-                log.warn("Could not connect to kotlin daemon. Using fallback strategy.")
+                            "Using fallback strategy: Compile without Kotlin daemon\n" +
+                            "Try ./gradlew --stop if this issue persists."
+                )
             }
         }
 
@@ -164,13 +166,12 @@ internal class GradleKotlinCompilerWork @Inject constructor(
         }
     }
 
-    private fun compileWithDaemon(messageCollector: MessageCollector): ExitCode? {
+    private fun compileWithDaemon(messageCollector: MessageCollector): ExitCode {
         val isDebugEnabled = log.isDebugEnabled || System.getProperty("kotlin.daemon.debug.log")?.toBoolean() ?: true
         val daemonMessageCollector =
             if (isDebugEnabled) messageCollector else MessageCollector.NONE
         val connection =
             metrics.measure(BuildTime.CONNECT_TO_DAEMON) {
-                try {
                 GradleCompilerRunner.getDaemonConnectionImpl(
                     clientIsAliveFlagFile,
                     sessionFlagFile,
@@ -179,20 +180,7 @@ internal class GradleKotlinCompilerWork @Inject constructor(
                     isDebugEnabled = isDebugEnabled,
                     daemonJvmArgs = daemonJvmArgs
                 )
-                } catch (e: Throwable) {
+            } ?: throw RuntimeException(COULD_NOT_CONNECT_TO_DAEMON_MESSAGE) // TODO: Add root cause
-                    log.error("Caught an exception trying to connect to Kotlin Daemon:")
-                    log.error(e.stackTraceAsString())
-                    null
-                }
-            }
-        if (connection == null) {
-            if (isIncremental) {
-                log.warn("Could not perform incremental compilation: $COULD_NOT_CONNECT_TO_DAEMON_MESSAGE")
-            } else {
-                log.warn(COULD_NOT_CONNECT_TO_DAEMON_MESSAGE)
-            }
-            return null
-        }
 
         val (daemon, sessionId) = connection
 
@@ -218,10 +206,8 @@ internal class GradleKotlinCompilerWork @Inject constructor(
             exitCodeFromProcessExitCode(log, res.get())
         } catch (e: Throwable) {
             bufferingMessageCollector.flush(messageCollector)
-            log.error("Compilation with Kotlin compile daemon was not successful")
+            throw e
-            log.error(e.stackTraceAsString())
+        } finally {
-            null
-        }
             // todo: can we clear cache on the end of session?
             // often source of the NoSuchObjectException and UnmarshalException, probably caused by the failed/crashed/exited daemon
             // TODO: implement a proper logic to avoid remote calls in such cases
@@ -232,6 +218,7 @@ internal class GradleKotlinCompilerWork @Inject constructor(
             } catch (e: RemoteException) {
                 log.warn("Unable to clear jar cache after compilation, maybe daemon is already down: $e")
             }
+        }
         log.logFinish(KotlinCompilerExecutionStrategy.DAEMON)
         return exitCode
     }