More doc

[Cherry-picked 3c873cf]

Author: som-snytt

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

@@ -236,7 +236,7 @@ private sealed trait WarningSettings:
     "patterns",
     default = List(),
     descr =
-      s"""Configure compiler warnings.
+    raw"""Configure compiler warnings.
          |Syntax: -Wconf:<filters>:<action>,<filters>:<action>,...
          |multiple <filters> are combined with &, i.e., <filter>&...&<filter>
          |
@@ -257,6 +257,9 @@ private sealed trait WarningSettings:
          |  - Source location: src=regex
          |    The regex is evaluated against the full source path.
          |
+         |  - Origin of warning: origin=regex
+         |    The regex must match the full name (`package.Class.method`) of the deprecated entity.
+         |
          |In verbose warning mode the compiler prints matching filters for warnings.
          |Verbose mode can be enabled globally using `-Wconf:any:verbose`, or locally
          |using the @nowarn annotation (example: `@nowarn("v") def test = try 1`).
@@ -276,6 +279,7 @@ private sealed trait WarningSettings:
          |Examples:
          |  - change every warning into an error: -Wconf:any:error
          |  - silence deprecations: -Wconf:cat=deprecation:s
+         |  - silence a deprecation: -Wconf:origin=java\.lang\.Thread\.getId:s
          |  - silence warnings in src_managed directory: -Wconf:src=src_managed/.*:s
          |
          |Note: on the command-line you might need to quote configurations containing `*` or `&`

compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala

@@ -15,7 +15,7 @@ import util.{ SourcePosition, NoSourcePosition }
 import util.Chars.{ LF, CR, FF, SU }
 import scala.annotation.switch
 
-import scala.collection.mutable
+import scala.collection.mutable.StringBuilder
 
 trait MessageRendering {
   import Highlight.*
@@ -209,22 +209,27 @@ trait MessageRendering {
     sb.toString
   }
 
-  private def appendFilterHelp(dia: Diagnostic, sb: mutable.StringBuilder): Unit =
-    import dia.*
+  private def appendFilterHelp(dia: Diagnostic, sb: StringBuilder): Unit =
+    import dia.msg
     val hasId = msg.errorId.errorNumber >= 0
-    val category = dia match {
-      case _: UncheckedWarning => "unchecked"
-      case _: DeprecationWarning => "deprecation"
-      case _: FeatureWarning => "feature"
-      case _ => ""
-    }
-    if (hasId || category.nonEmpty)
-      sb.append(EOL).append("Matching filters for @nowarn or -Wconf:")
-      if (hasId)
-        sb.append(EOL).append("  - id=E").append(msg.errorId.errorNumber)
-        sb.append(EOL).append("  - name=").append(msg.errorId.productPrefix.stripSuffix("ID"))
-      if (category.nonEmpty)
-        sb.append(EOL).append("  - cat=").append(category)
+    val (category, origin) = dia match
+      case _: UncheckedWarning => ("unchecked", "")
+      case w: DeprecationWarning => ("deprecation", w.origin)
+      case _: FeatureWarning => ("feature", "")
+      case _ => ("", "")
+    var entitled = false
+    def addHelp(what: String)(value: String): Unit =
+      if !entitled then
+        sb.append(EOL).append("Matching filters for @nowarn or -Wconf:")
+        entitled = true
+      sb.append(EOL).append("  - ").append(what).append(value)
+    if hasId then
+      addHelp("id=E")(msg.errorId.errorNumber.toString)
+      addHelp("name=")(msg.errorId.productPrefix.stripSuffix("ID"))
+    if category.nonEmpty then
+      addHelp("cat=")(category)
+    if origin.nonEmpty then
+      addHelp("origin=")(origin)
 
   /** The whole message rendered from `msg` */
   def messageAndPos(dia: Diagnostic)(using Context): String = {
@@ -236,7 +241,7 @@ trait MessageRendering {
       else 0
     given Level = Level(level)
     given Offset = Offset(maxLineNumber.toString.length + 2)
-    val sb = mutable.StringBuilder()
+    val sb = StringBuilder()
     val posString = posStr(pos, msg, diagnosticLevel(dia))
     if (posString.nonEmpty) sb.append(posString).append(EOL)
     if (pos.exists) {

tests/warn/deprecated-origin-verbose.check

@@ -0,0 +1,14 @@
+-- Deprecation Warning: tests/warn/deprecated-origin-verbose.scala:12:18 -----------------------------------------------
+12 |  class D extends C // warn
+   |                  ^
+   |                  class C in package p is deprecated since 1.0: Old style
+Matching filters for @nowarn or -Wconf:
+  - cat=deprecation
+  - origin=p.C
+-- Deprecation Warning: tests/warn/deprecated-origin-verbose.scala:13:20 -----------------------------------------------
+13 |  class Oil extends Crude // warn
+   |                    ^^^^^
+   |                    class Crude in package p is deprecated since 1.0: Bad style
+Matching filters for @nowarn or -Wconf:
+  - cat=deprecation
+  - origin=p.Crude

tests/warn/deprecated-origin-verbose.scala

@@ -0,0 +1,15 @@
+//> using options -deprecation -Wconf:any:verbose
+
+package p:
+  @deprecated("Old style", since="1.0")
+  class C
+  @deprecated("Bad style", since="1.0")
+  class Crude
+
+package q:
+  import annotation.*
+  import p.*
+  class D extends C // warn
+  class Oil extends Crude // warn
+  @nowarn("""origin=p\.Crude""")
+  class Language extends Crude // nowarn obvs