Backport "Move tests/init from neg to warn" to LTS (#20809)

Backports #19241 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -208,6 +208,7 @@ class CompilationTests {
     implicit val testGroup: TestGroup = TestGroup("checkInit")
     val options = defaultOptions.and("-Ysafe-init", "-Xfatal-warnings")
     compileFilesInDir("tests/init/neg", options).checkExpectedErrors()
+    compileFilesInDir("tests/init/warn", defaultOptions.and("-Ysafe-init")).checkWarnings()
     compileFilesInDir("tests/init/pos", options).checkCompile()
     compileFilesInDir("tests/init/crash", options.without("-Xfatal-warnings")).checkCompile()
 

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -755,7 +755,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     end maybeFailureMessage
 
     def getWarnMapAndExpectedCount(files: Seq[JFile]): (HashMap[String, Integer], Int) =
-      val comment = raw"//( *)warn".r
+      val comment = raw"//( *)(nopos-)?warn".r
       val map = new HashMap[String, Integer]()
       var count = 0
       def bump(key: String): Unit =
@@ -766,8 +766,11 @@ trait ParallelTesting extends RunnerOrchestration { self =>
       files.filter(isSourceFile).foreach { file =>
         Using(Source.fromFile(file, StandardCharsets.UTF_8.name)) { source =>
           source.getLines.zipWithIndex.foreach { case (line, lineNbr) =>
-            comment.findAllMatchIn(line).foreach { _ =>
-              bump(s"${file.getPath}:${lineNbr+1}")
+            comment.findAllMatchIn(line).foreach { m =>
+              m.group(2) match
+                case "nopos-" =>
+                  bump("nopos")
+                case _ => bump(s"${file.getPath}:${lineNbr+1}")
             }
           }
         }.get
@@ -788,7 +791,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
           val key = s"${relativize(srcpos.source.file.toString())}:${srcpos.line + 1}"
           if !seenAt(key) then unexpected += key
         else
-          unpositioned += relativize(srcpos.source.file.toString())
+          if(!seenAt("nopos")) unpositioned += relativize(srcpos.source.file.toString())
 
       reporterWarnings.foreach(sawDiagnostic)
 

tests/init/neg/early-promote2.scala

@@ -4,6 +4,6 @@ abstract class AbstractFile {
 }
 
 class RemoteFile(url: String) extends AbstractFile {
-	val localFile: String = s"${url.##}.tmp"  // error: usage of `localFile` before it's initialized
+	val localFile: String = s"${url.##}.tmp"  // warn: usage of `localFile` before it's initialized
 	def name: String = localFile
 }

tests/init/neg/i12544.scala

@@ -1,5 +1,5 @@
 class Foo {
   val self = this
   val x = self.n
-  val n = 10       // error
+  val n = 10       // warn
 }

tests/init/neg/inner9.scala

@@ -6,7 +6,7 @@ object A:
 
 class B:
   val a = A(this)
-  val a2 = A.foo(this)   // error
+  val a2 = A.foo(this)   // warn
   val a3 = A.bar(this)
 
 // test receiver is ThisRef
@@ -20,7 +20,7 @@ object O:
 
   class B:
     val a = A(this)
-    val a2 = A.foo(this)   // error
+    val a2 = A.foo(this)   // warn
     val a3 = A.bar(this)
 
   val b = new B
@@ -38,7 +38,7 @@ class M(n: N):
 
   class B:
     val a = A(this)
-    val a2 = A.foo(this)   // error
+    val a2 = A.foo(this)   // warn
     val a3 = A.bar(this)
 end M