Avoid race condition in Reporter errorsBuilder

scex-core/src/main/scala/com/avsystem/scex/compiler/ScexCompiler.scala

@@ -70,8 +70,7 @@ trait ScexCompiler extends LoggingUtils {
 
     def displayPrompt(): Unit = {}
 
-    override def reset(): Unit = {
-      super.reset()
+    def clearErrors(): Unit = {
       errorsBuilder.clear()
     }
   }
@@ -221,9 +220,11 @@ trait ScexCompiler extends LoggingUtils {
 
   protected final def withGlobal[T](code: ScexGlobal => T): T = underLock {
     reporter.reset()
+    reporter.clearErrors()
     val global = this.global
     val result = try code(global) finally {
       reporter.reset()
+      reporter.clearErrors()
     }
     result
   }
@@ -241,6 +242,7 @@ trait ScexCompiler extends LoggingUtils {
     val classfileDirectory = classLoader.classfileDirectory
 
     reporter.reset()
+    reporter.clearErrors()
 
     logger.debug(s"Compiling source file ${sourceFile.path} to $classfileDirectory:\n${new String(sourceFile.content)}")
 

scex-core/src/main/scala/com/avsystem/scex/compiler/presentation/ScexPresentationCompiler.scala

@@ -50,9 +50,11 @@ trait ScexPresentationCompiler extends ScexCompiler { compiler =>
 
   protected final def withIGlobal[T](code: IGlobal => T) = underLock {
     reporter.reset()
+    reporter.clearErrors()
     val global = compiler.global
     val result = try code(global) finally {
       reporter.reset()
+      reporter.clearErrors()
     }
     result
   }

scex-core/src/test/scala/com/avsystem/scex/compiler/MultipleEvaluationsTest.scala

@@ -0,0 +1,29 @@
+package com.avsystem.scex.compiler
+
+import com.avsystem.scex.compiler.presentation.TypeCompletionPrefixTest.Root
+import com.avsystem.scex.japi.{DefaultJavaScexCompiler, JavaScexCompiler}
+import com.avsystem.scex.util.SimpleContext
+import org.scalatest.funsuite.AnyFunSuite
+
+final class MultipleEvaluationsTest extends AnyFunSuite with CompilationTest {
+  override protected def createCompiler: JavaScexCompiler = {
+    val settings = new ScexSettings
+    settings.classfileDirectory.value = "testClassfileCache"
+
+    // for some reason enabling this setting fixes validation
+    settings.noGetterAdapters.value = false
+    new DefaultJavaScexCompiler(settings)
+  }
+
+  private val completer = compiler.getCompleter[SimpleContext[Root], Any](
+    createProfile(Nil),
+    template = false,
+    header = "",
+  )
+
+  test("Multiple evaluations of invalid expressions should always fail") {
+    (0 until 1000)
+      .map(i => s"invalidExpression $i") //added to avoid hitting the cache
+      .foreach(expr => if (completer.getErrors(expr).isEmpty) fail(s"Expression $expr should not compile"))
+  }
+}