Stop catching Throwable/IIOBE/NPE in the compiler, outside of stack overflow handling (#25832)

Part of #25799

## How much have you relied on LLM-based tools in this contribution?

Not at all

## How was the solution tested?

Covered by existing tests (this is a refactoring)

Author: SolalPirelli

compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala

@@ -662,15 +662,13 @@ trait BCodeHelpers(val backendUtils: BackendUtils)(using ctx: Context) extends B
     import scala.tools.asm.util.CheckClassAdapter
     def wrap(body: => Unit): Unit = {
       try body
-      catch {
-        case ex: Throwable =>
-          report.error(
-            em"""|compiler bug: created invalid generic signature for $sym in ${sym.denot.owner.showFullName}
-                 |signature: $sig
-                 |if this is reproducible, please report bug at https://github.com/scala/scala3/issues
-               """, sym.sourcePos)
-          throw ex
-      }
+      catch case ex: Exception =>
+        report.error(
+          em"""|compiler bug: created invalid generic signature for $sym in ${sym.denot.owner.showFullName}
+               |signature: $sig
+               |if this is reproducible, please report bug at https://github.com/scala/scala3/issues
+             """, sym.sourcePos)
+        throw ex
     }
 
     wrap {

compiler/src/dotty/tools/backend/jvm/ClassfileWriters.scala

@@ -238,7 +238,7 @@ class ClassfileWriters(frontendAccess: PostProcessorFrontendAccess)(using ctx: C
         catch {
           case ex: ClosedByInterruptException =>
             try Files.deleteIfExists(path) // don't leave a empty of half-written classfile around after an interrupt
-            catch { case _: Throwable => () }
+            catch { case _: java.io.IOException => () }
             throw ex
         }
         os.close()

compiler/src/dotty/tools/backend/jvm/CodeGen.scala

@@ -85,10 +85,7 @@ class CodeGen(val backendUtils: BackendUtils, val primitives: ScalaPrimitives, v
         registerGeneratedClass(mainClassNode, isArtifact = false)
         registerGeneratedClass(mirrorClassNode, isArtifact = true)
       catch
-        case ex: InterruptedException => throw ex
-        case ex: CompilationUnit.SuspendException => throw ex
-        case ex: Throwable =>
-          if !ex.isInstanceOf[TypeError] then ex.printStackTrace()
+        case ex: TypeError =>
           report.error(s"Error while emitting ${unit.source}\n${ex.getMessage}", cd.sourcePos)
 
 

compiler/src/dotty/tools/backend/jvm/GeneratedClassHandler.scala

@@ -10,10 +10,8 @@ import dotty.tools.dotc.core.Contexts.*
 import dotty.tools.io.AbstractFile
 import dotty.tools.dotc.profile.ThreadPoolFactory
 
-import scala.util.control.NonFatal
 import dotty.tools.dotc.core.Phases
 import dotty.tools.dotc.core.Decorators.em
-import dotty.tools.dotc.core.Types.IdentityTypeMap.mapCtx
 import dotty.tools.dotc.report
 
 import scala.compiletime.uninitialized
@@ -155,10 +153,10 @@ private[jvm] object GeneratedClassHandler {
           unitInPostProcess.task.value.get.get
         catch
           case _: ClosedByInterruptException => throw new InterruptedException()
-          case NonFatal(t) =>
-            t.printStackTrace()
+          case e: Exception =>
+            e.printStackTrace()
             given Context = ctx
-            report.error(em"unable to write ${unitInPostProcess.sourceFile} $t")
+            report.error(em"unable to write ${unitInPostProcess.sourceFile} $e")
       }
     }
   }

compiler/src/dotty/tools/backend/jvm/GenericSignatureVisitor.scala

@@ -6,7 +6,7 @@ import scala.tools.asm.{ClassReader, Type, Handle }
 import scala.tools.asm.tree.*
 
 import scala.collection.mutable
-import scala.util.control.{NoStackTrace, NonFatal}
+import scala.util.control.NoStackTrace
 import scala.annotation.*
 import scala.jdk.CollectionConverters.*
 import BTypes.InternalName
@@ -47,7 +47,7 @@ abstract class GenericSignatureVisitor(nestedOnly: Boolean) {
 
     @inline def safely(f: => Unit): Unit = try f catch {
       case Aborted =>
-      case NonFatal(e) => raiseError(s"Exception thrown during signature parsing", sig, Some(e))
+      case e: Exception => raiseError(s"Exception thrown during signature parsing", sig, Some(e))
     }
 
     private def current = {

compiler/src/dotty/tools/backend/jvm/PostProcessor.scala

@@ -49,7 +49,7 @@ class PostProcessor(val frontendAccess: PostProcessorFrontendAccess,
         case e: java.lang.RuntimeException if e.getMessage != null && e.getMessage.contains("too large!") =>
           report.error(em"Could not write class $internalName because it exceeds JVM code size limits. ${e.getMessage}")
           null
-        case ex: Throwable =>
+        case ex: Exception =>
           if frontendAccess.compilerSettings.debug then ex.printStackTrace()
           report.error(em"Error while emitting $internalName\n${ex.getMessage}")
           null

compiler/src/dotty/tools/debug/ExpressionCompilerBridge.scala

@@ -1,7 +1,6 @@
 package dotty.tools.debug
 
 import java.nio.file.Path
-import scala.util.control.NonFatal
 import dotty.tools.dotc.core.Contexts.Context
 import dotty.tools.dotc.Driver
 
@@ -29,6 +28,6 @@ class ExpressionCompilerBridge:
       driver.process(args, reporter)
       !reporter.hasErrors
     catch
-      case NonFatal(cause) =>
+      case cause: Exception =>
         cause.printStackTrace()
         throw cause

compiler/src/dotty/tools/dotc/Driver.scala

@@ -11,7 +11,6 @@ import reporting.*
 import core.Decorators.*
 import util.chaining.*
 
-import scala.util.control.NonFatal
 import fromtasty.{TASTYCompiler, TastyFileUtil}
 
 /** Run the Dotty compiler.
@@ -39,13 +38,13 @@ class Driver {
       catch
         case ex: FatalError =>
           report.error(ex.getMessage) // signals that we should fail compilation.
-        case ex: Throwable if ctx.usedBestEffortTasty =>
+        case ex: Exception if ctx.usedBestEffortTasty =>
           report.bestEffortError(ex, "Some best-effort tasty files were not able to be read.")
           throw ex
         case ex: TypeError if !runOrNull.enrichedErrorMessage =>
           println(runOrNull.enrichErrorMessage(s"${ex.toMessage} while compiling ${files.map(_.path).mkString(", ")}"))
           throw ex
-        case ex: Throwable if !runOrNull.enrichedErrorMessage =>
+        case ex: Exception if !runOrNull.enrichedErrorMessage =>
           println(runOrNull.enrichErrorMessage(s"Exception while compiling ${files.map(_.path).mkString(", ")}"))
           throw ex
     ctx.reporter
@@ -215,10 +214,6 @@ class Driver {
   }
 
   def main(args: Array[String]): Unit = {
-    // Preload scala.util.control.NonFatal. Otherwise, when trying to catch a StackOverflowError,
-    // we may try to load it but fail with another StackOverflowError and lose the original exception,
-    // see <https://groups.google.com/forum/#!topic/scala-user/kte6nak-zPM>.
-    val _ = NonFatal
     sys.exit(if (process(args).hasErrors) 1 else 0)
   }
 }

compiler/src/dotty/tools/dotc/Run.scala

@@ -31,7 +31,6 @@ import java.io.{BufferedWriter, OutputStreamWriter}
 import java.nio.charset.StandardCharsets
 
 import scala.collection.mutable, mutable.ListBuffer
-import scala.util.control.NonFatal
 import scala.io.Codec
 
 import Run.Progress
@@ -323,7 +322,7 @@ extends ImplicitRunInfo, ConstraintRunInfo, cc.CaptureRunInfo {
 
   def compile(files: List[AbstractFile]): Unit =
     try compileSources(files.map(runContext.getSource(_)))
-    catch case NonFatal(ex) if !this.enrichedErrorMessage =>
+    catch case ex: Exception if !this.enrichedErrorMessage =>
       val files1 = if units.isEmpty then files else units.map(_.source.file)
       report.echo(this.enrichErrorMessage(s"exception occurred while compiling ${files1.map(_.path)}"))
       throw ex

compiler/src/dotty/tools/dotc/classpath/DirectoryClassPath.scala

@@ -14,7 +14,6 @@ import PlainFile.toPlainFile
 
 import scala.jdk.CollectionConverters.*
 import scala.collection.immutable.ArraySeq
-import scala.util.control.NonFatal
 
 /**
  * A trait allowing to look for classpath entries in directories. It provides common logic for
@@ -134,7 +133,7 @@ object JrtClassPath {
           val ctSym = Paths.get(Properties.javaHome).resolve("lib").resolve("ct.sym")
           if (Files.notExists(ctSym)) None
           else Some(new CtSymClassPath(ctSym, v.toInt))
-        catch case NonFatal(_) => None
+        catch case _: Exception => None
       case _ =>
         try Some(new JrtClassPath(FileSystems.getFileSystem(URI.create("jrt:/"))))
         catch case _: ProviderNotFoundException | _: FileSystemNotFoundException => None