Improve highlight of decl

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -444,6 +444,12 @@ object Contexts {
     def useColors: Boolean =
       base.settings.color.value == "always"
 
+    def withColors: FreshContext =
+      fresh.setSetting(ctx.settings.color, "always")
+
+    def withoutColors: FreshContext =
+      fresh.setSetting(ctx.settings.color, "never")
+
     /** Is the explicit nulls option set? */
     def explicitNulls: Boolean = base.settings.YexplicitNulls.value
 

compiler/src/dotty/tools/dotc/inlines/Inlines.scala

@@ -381,8 +381,7 @@ object Inlines:
 
     /** Expand call to scala.compiletime.codeOf */
     def codeOf(arg: Tree, pos: SrcPos)(using Context): Tree =
-      val ctx1 = ctx.fresh.setSetting(ctx.settings.color, "never")
-      Literal(Constant(arg.show(using ctx1))).withSpan(pos.span)
+      Literal(Constant(arg.show(using ctx.withoutColors))).withSpan(pos.span)
   end Intrinsics
 
   /** Produces an inlined version of `call` via its `inlined` method.

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

@@ -1504,7 +1504,7 @@ class MissingArgument(pname: Name, methString: String)(using Context)
 class MissingArgumentList(method: String, sym: Symbol)(using Context)
   extends TypeMsg(MissingArgumentListID) {
   def msg(using Context) =
-    val symDcl = if sym.exists then "\n\n  " + sym.showDcl else ""
+    val symDcl = if sym.exists then "\n\n  " + hl(sym.showDcl(using ctx.withoutColors)) else ""
     i"missing argument list for $method$symDcl"
   def explain(using Context) = {
     i"""Unapplied methods are only converted to functions when a function type is expected."""

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -3080,7 +3080,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
       lazy val ConstantCode: Printer[Constant] = new Printer[Constant]:
         def show(const: Constant): String =
-          const.show(using ctx.fresh.setSetting(ctx.settings.color, "never"))
+          const.show(using ctx.withoutColors)
 
       lazy val ConstantStructure: Printer[Constant] = new Printer[Constant]:
         def show(const: Constant): String =

compiler/test/dotty/tools/dotc/printing/SyntaxHighlightingTests.scala

@@ -12,8 +12,7 @@ class SyntaxHighlightingTests extends DottyTest {
   import SyntaxHighlighting._
 
   private def test(source: String, expected: String): Unit = {
-    val testCtx = ctx.fresh.setSetting(ctx.settings.color, "always")
-    val highlighted = SyntaxHighlighting.highlight(source)(using testCtx)
+    val highlighted = SyntaxHighlighting.highlight(source)(using ctx.withColors)
       .replace(NoColor,         ">")
       .replace(CommentColor,    "<C|")
       .replace(KeywordColor,    "<K|")

compiler/test/dotty/tools/dotc/reporting/ErrorMessagesTest.scala

@@ -12,7 +12,7 @@ trait ErrorMessagesTest extends DottyTest {
   protected def newContext = {
     val rep = new StoreReporter(null)
               with UniqueMessagePositions with HideNonSensicalMessages
-    initialCtx.setReporter(rep).setSetting(ctx.settings.color, "never")
+    initialCtx.setReporter(rep).withoutColors
   }
 
   class Report(messages: List[Message], ictx: Context) {