Use highlighting in explanation classes

Author: felixmulder

src/dotty/tools/dotc/reporting/Examples.scala

@@ -3,6 +3,7 @@ package dotc
 package reporting
 
 import dotc.core.Contexts.Context
+import dotc.printing.SyntaxHighlighting._
 
 object ErrorExplanations {
   import dotc.ast.Trees._
@@ -36,32 +37,40 @@ object ErrorExplanations {
         case Block(Nil, untpd.EmptyTree) => "{}"
         case _ => tryBody.show
       }
-      s"""|Explanation:
-          |============
-          |A try expression should be followed by some mechanism to handle any exceptions
-          |thrown. Typically a `catch` expression follows the `try` and pattern matches
-          |on any expected exceptions. For example:
-          |
-          |try $tryString catch {
-          | case t: Throwable => ???
-          |}
-          |
-          |It is also possible to follow a `try` immediately by a finally - letting the
-          |exception propagate - but still allowing for some clean up in `finally`:
-          |
-          |try $tryString finally {
-          | // perform your cleanup here!
-          |}""".stripMargin
+
+      val code1 =
+        s"""|try $tryString catch {
+            |  case t: Throwable => ???
+            |}""".stripMargin
+
+      val code2 =
+        s"""|try $tryString finally {
+            |  // perform your cleanup here!
+            |}""".stripMargin
+
+      hl"""|Explanation:
+           |============
+           |A ${"try"} expression should be followed by some mechanism to handle any exceptions
+           |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
+           |on any expected exceptions. For example:
+           |
+           |$code1
+           |
+           |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
+           |exception propagate - but still allowing for some clean up in ${"finally"}:
+           |
+           |$code2
+           """.stripMargin
     }
   }
 
   case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
     val msg =
-      "`catch` block does not contain a valid expression, try adding a case like - `case e: Exception =>` to the block"
+      hl"""The ${"catch"} block does not contain a valid expression, try adding a case like - `${"case e: Exception =>"}` to the block"""
   }
 
   case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
     val msg =
-      "A try without `catch` or `finally` is equivalent to putting its body in a block; no exceptions are handled."
+      hl"""A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting its body in a block; no exceptions are handled."""
   }
 }