Reclassify -Ysemanticdb as -Xsemanticdb, as it is officially supported.

We keep -Ysemanticdb as an alias (an "abbreviation") so that we do
not break all the existing tools that enable that setting.

Author: sjrd

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

@@ -148,7 +148,7 @@ class Compiler {
   def newRun(using Context): Run = {
     reset()
     val rctx =
-      if ctx.settings.Ysemanticdb.value then
+      if ctx.settings.Xsemanticdb.value then
         ctx.addMode(Mode.ReadPositions)
       else
         ctx

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -123,6 +123,7 @@ class ScalaSettings extends Settings.SettingGroup with CommonScalaSettings {
   val XverifySignatures: Setting[Boolean] = BooleanSetting("-Xverify-signatures", "Verify generic signatures in generated bytecode.")
   val XignoreScala2Macros: Setting[Boolean] = BooleanSetting("-Xignore-scala2-macros", "Ignore errors when compiling code that calls Scala2 macros, these will fail at runtime.")
   val XimportSuggestionTimeout: Setting[Int] = IntSetting("-Ximport-suggestion-timeout", "Timeout (in ms) for searching for import suggestions when errors are reported.", 8000)
+  val Xsemanticdb: Setting[Boolean] = BooleanSetting("-Xsemanticdb", "Store information in SemanticDB.").withAbbreviation("-Ysemanticdb")
 
   val XmixinForceForwarders = ChoiceSetting(
     name    = "-Xmixin-force-forwarders",
@@ -183,7 +184,6 @@ class ScalaSettings extends Settings.SettingGroup with CommonScalaSettings {
   val YdumpSbtInc: Setting[Boolean] = BooleanSetting("-Ydump-sbt-inc", "For every compiled foo.scala, output the API representation and dependencies used for sbt incremental compilation in foo.inc, implies -Yforce-sbt-phases.")
   val YcheckAllPatmat: Setting[Boolean] = BooleanSetting("-Ycheck-all-patmat", "Check exhaustivity and redundancy of all pattern matching (used for testing the algorithm).")
   val YretainTrees: Setting[Boolean] = BooleanSetting("-Yretain-trees", "Retain trees for top-level classes, accessible from ClassSymbol#tree")
-  val Ysemanticdb: Setting[Boolean] = BooleanSetting("-Ysemanticdb", "Store information in SemanticDB.")
   val YshowTreeIds: Setting[Boolean] = BooleanSetting("-Yshow-tree-ids", "Uniquely tag all tree nodes in debugging output.")
   val YfromTastyIgnoreList: Setting[List[String]] = MultiStringSetting("-Yfrom-tasty-ignore-list", "file", "List of `tasty` files in jar files that will not be loaded when using -from-tasty")
 

compiler/src/dotty/tools/dotc/semanticdb/ExtractSemanticDB.scala

@@ -35,7 +35,7 @@ class ExtractSemanticDB extends Phase:
   override val phaseName: String = ExtractSemanticDB.name
 
   override def isRunnable(using Context) =
-    super.isRunnable && ctx.settings.Ysemanticdb.value
+    super.isRunnable && ctx.settings.Xsemanticdb.value
 
   // Check not needed since it does not transform trees
   override def isCheckable: Boolean = false

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

@@ -35,7 +35,7 @@ class BootstrappedOnlyCompilationTests extends ParallelTesting {
     aggregateTests(
       compileFilesInDir("tests/bench", defaultOptions),
       compileFilesInDir("tests/pos-macros", defaultOptions),
-      compileFilesInDir("tests/pos-custom-args/semanticdb", defaultOptions.and("-Ysemanticdb")),
+      compileFilesInDir("tests/pos-custom-args/semanticdb", defaultOptions.and("-Xsemanticdb")),
     ).checkCompile()
   }
 

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

@@ -232,7 +232,7 @@ class CompilationTests {
         Properties.compilerInterface, Properties.scalaLibrary, Properties.scalaAsm,
         Properties.dottyInterfaces, Properties.jlineTerminal, Properties.jlineReader,
       ).mkString(File.pathSeparator),
-      Array("-Ycheck-reentrant", "-language:postfixOps", "-Ysemanticdb")
+      Array("-Ycheck-reentrant", "-language:postfixOps", "-Xsemanticdb")
     )
 
     val libraryDirs = List(Paths.get("library/src"), Paths.get("library/src-bootstrapped"))

compiler/test/dotty/tools/dotc/semanticdb/SemanticdbTests.scala

@@ -107,7 +107,7 @@ class SemanticdbTests:
     val exitJava = javac.run(null, null, null, javaArgs:_*)
     assert(exitJava == 0, "java compiler has errors")
     val args = Array(
-      "-Ysemanticdb",
+      "-Xsemanticdb",
       "-d", target.toString,
       "-feature",
       "-deprecation",

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

@@ -17,7 +17,7 @@ object TestConfiguration {
     "-Yno-deep-subtypes",
     "-Yno-double-bindings",
     "-Yforce-sbt-phases",
-    "-Ysemanticdb",
+    "-Xsemanticdb",
     "-Xverify-signatures"
   )
 

docs/docs/contributing/testing.md

@@ -148,7 +148,7 @@ with `with-compiler` in their name.
 
 ### SemanticDB tests
 
-The output of the `extractSemanticDB` phase, enabled with `-Ysemanticdb` is tested with the bootstrapped JUnit test
+The output of the `extractSemanticDB` phase, enabled with `-Xsemanticdb` is tested with the bootstrapped JUnit test
 `dotty.tools.dotc.semanticdb.SemanticdbTests`. It uses source files in `tests/semanticdb/expect` to generate
 two kinds of output file that are compared with "expect files": placement of semanticdb symbol occurrences inline in
 sourcecode (`*.expect.scala`), for human verification by inspection; and secondly metap formatted output which outputs