Show inlined positions with source code

This gives more context to the users on what happen and where the code came from.

Author: nicolasstucki

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

@@ -16,6 +16,8 @@ import scala.annotation.switch
 import scala.collection.mutable
 
 trait MessageRendering {
+  import Highlight.*
+  import Offsets.*
 
   /** Remove ANSI coloring from `str`, useful for getting real length of
     * strings
@@ -25,31 +27,25 @@ trait MessageRendering {
   def stripColor(str: String): String =
     str.replaceAll("\u001b\\[.*?m", "")
 
-  /** When inlining a method call, if there's an error we'd like to get the
-    * outer context and the `pos` at which the call was inlined.
-    *
-    * @return a list of strings with inline locations
-    */
-  def outer(pos: SourcePosition, prefix: String)(using Context): List[String] =
-    if (pos.outer.exists)
-       i"$prefix| This location contains code that was inlined from $pos" ::
-       outer(pos.outer, prefix)
+  /** List of all the inline calls that surround the position */
+  def inlinePosStack(pos: SourcePosition): List[SourcePosition] =
+    if pos.outer != null && pos.outer.exists then pos :: inlinePosStack(pos.outer)
     else Nil
 
   /** Get the sourcelines before and after the position, as well as the offset
     * for rendering line numbers
     *
     * @return (lines before error, lines after error, line numbers offset)
     */
-  def sourceLines(pos: SourcePosition, diagnosticLevel: String)(using Context): (List[String], List[String], Int) = {
+  private def sourceLines(pos: SourcePosition)(using Context, Level, Offset): (List[String], List[String], Int) = {
     assert(pos.exists && pos.source.file.exists)
     var maxLen = Int.MinValue
     def render(offsetAndLine: (Int, String)): String = {
-      val (offset, line) = offsetAndLine
-      val lineNbr = pos.source.offsetToLine(offset)
-      val prefix = s"${lineNbr + 1} |"
+      val (offset1, line) = offsetAndLine
+      val lineNbr = (pos.source.offsetToLine(offset1) + 1).toString
+      val prefix = String.format(s"%${offset - 2}s |", lineNbr)
       maxLen = math.max(maxLen, prefix.length)
-      val lnum = hl(diagnosticLevel)(" " * math.max(0, maxLen - prefix.length) + prefix)
+      val lnum = hl(" " * math.max(0, maxLen - prefix.length - 1) + prefix)
       lnum + line.stripLineEnd
     }
 
@@ -77,23 +73,75 @@ trait MessageRendering {
     )
   }
 
-  /** The column markers aligned under the error */
-  def columnMarker(pos: SourcePosition, offset: Int, diagnosticLevel: String)(using Context): String = {
-    val prefix = " " * (offset - 1)
+  /** Generate box containing the report title
+   *
+   *  ```
+   *  -- Error: source.scala ---------------------
+   *  ```
+   */
+  private def boxTitle(title: String)(using Context, Level, Offset): String =
+    val pageWidth = ctx.settings.pageWidth.value
+    val line = "-" * (pageWidth - title.length - 4)
+    hl(s"-- $title $line")
+
+  /** The position markers aligned under the error
+   *
+   *  ```
+   *    |         ^^^^^
+   *  ```
+   */
+  private def positionMarker(pos: SourcePosition)(using Context, Level, Offset): String = {
     val padding = pos.startColumnPadding
-    val carets = hl(diagnosticLevel) {
+    val carets =
       if (pos.startLine == pos.endLine)
         "^" * math.max(1, pos.endColumn - pos.startColumn)
       else "^"
-    }
-    s"$prefix|$padding$carets"
+    hl(s"$offsetBox$padding$carets")
   }
 
+  /** The horizontal line with the given offset
+   *
+   *  ```
+   *    |
+   *  ```
+   */
+  private def offsetBox(using Context, Level, Offset): String =
+    val prefix = " " * (offset - 1)
+    hl(s"$prefix|")
+
+  /** The end of a box section
+   *
+   *  ```
+   *    |---------------
+   *  ```
+   *  Or if there `soft` is true,
+   *  ```
+   *    |···············
+   *  ```
+   */
+  private def newBox(soft: Boolean = false)(using Context, Level, Offset): String =
+    val pageWidth = ctx.settings.pageWidth.value
+    val prefix = " " * (offset - 1)
+    val line = (if soft then "·" else "-") * (pageWidth - offset)
+    hl(s"$prefix|$line")
+
+  /** The end of a box section
+   *
+   *  ```
+   *    ·----------------
+   *  ```
+   */
+  private def endBox(using Context, Level, Offset): String =
+    val pageWidth = ctx.settings.pageWidth.value
+    val prefix = " " * (offset - 1)
+    val line = "-" * (pageWidth - offset)
+    hl(s"${prefix}·$line")
+
   /** The error message (`msg`) aligned under `pos`
     *
     * @return aligned error message
     */
-  def errorMsg(pos: SourcePosition, msg: String, offset: Int)(using Context): String = {
+  private def errorMsg(pos: SourcePosition, msg: String)(using Context, Level, Offset): String = {
     val padding = msg.linesIterator.foldLeft(pos.startColumnPadding) { (pad, line) =>
       val lineLength = stripColor(line).length
       val maxPad = math.max(0, ctx.settings.pageWidth.value - offset - lineLength) - offset
@@ -103,35 +151,35 @@ trait MessageRendering {
     }
 
     msg.linesIterator
-      .map { line => " " * (offset - 1) + "|" + (if line.isEmpty then "" else padding + line) }
+      .map { line => offsetBox + (if line.isEmpty then "" else padding + line) }
       .mkString(EOL)
   }
 
   /** The source file path, line and column numbers from the given SourcePosition */
-  def posFileStr(pos: SourcePosition): String =
+  protected def posFileStr(pos: SourcePosition): String =
     val path = pos.source.file.path
     if pos.exists then s"$path:${pos.line + 1}:${pos.column}" else path
 
   /** The separator between errors containing the source file and error type
     *
     * @return separator containing error location and kind
     */
-  def posStr(pos: SourcePosition, diagnosticLevel: String, message: Message)(using Context): String =
-    if (pos.source != NoSourcePosition.source) hl(diagnosticLevel)({
-      val fileAndPos = posFileStr(pos.nonInlined)
-      val file = if fileAndPos.isEmpty || fileAndPos.endsWith(" ") then fileAndPos else s"$fileAndPos "
+  private def posStr(pos: SourcePosition, message: Message, diagnosticString: String)(using Context, Level, Offset): String =
+    if (pos.source != NoSourcePosition.source) hl({
+      val realPos = pos.nonInlined
+      val fileAndPos = posFileStr(realPos)
       val errId =
         if (message.errorId ne ErrorMessageID.NoExplanationID) {
           val errorNumber = message.errorId.errorNumber
           s"[E${"0" * (3 - errorNumber.toString.length) + errorNumber}] "
         } else ""
       val kind =
-        if (message.kind == "") diagnosticLevel
-        else s"${message.kind} $diagnosticLevel"
-      val prefix = s"-- ${errId}${kind}: $file"
-
-      prefix +
-        ("-" * math.max(ctx.settings.pageWidth.value - stripColor(prefix).length, 0))
+        if (message.kind == "") diagnosticString
+        else s"${message.kind} $diagnosticString"
+      val title =
+        if fileAndPos.isEmpty then s"$errId$kind:" // this happens in dotty.tools.repl.ScriptedTests // TODO add name of source or remove `:` (and update test files)
+        else s"$errId$kind: $fileAndPos"
+      boxTitle(title)
     }) else ""
 
   /** Explanation rendered under "Explanation" header */
@@ -146,7 +194,7 @@ trait MessageRendering {
     sb.toString
   }
 
-  def appendFilterHelp(dia: Diagnostic, sb: mutable.StringBuilder): Unit =
+  private def appendFilterHelp(dia: Diagnostic, sb: mutable.StringBuilder): Unit =
     import dia._
     val hasId = msg.errorId.errorNumber >= 0
     val category = dia match {
@@ -166,17 +214,34 @@ trait MessageRendering {
   /** The whole message rendered from `msg` */
   def messageAndPos(dia: Diagnostic)(using Context): String = {
     import dia._
-    val levelString = diagnosticLevel(dia)
+    val pos1 = pos.nonInlined
+    val inlineStack = inlinePosStack(pos).filter(_ != pos1)
+    val maxLineNumber =
+      if pos.exists then (pos1 :: inlineStack).map(_.endLine).max + 1
+      else 0
+    given Level = Level(level)
+    given Offset = Offset(maxLineNumber.toString.length + 2)
     val sb = mutable.StringBuilder()
-    val posString = posStr(pos, levelString, msg)
+    val posString = posStr(pos, msg, diagnosticLevel(dia))
     if (posString.nonEmpty) sb.append(posString).append(EOL)
     if (pos.exists) {
       val pos1 = pos.nonInlined
       if (pos1.exists && pos1.source.file.exists) {
-        val (srcBefore, srcAfter, offset) = sourceLines(pos1, levelString)
-        val marker = columnMarker(pos1, offset, levelString)
-        val err = errorMsg(pos1, msg.message, offset)
-        sb.append((srcBefore ::: marker :: err :: outer(pos, " " * (offset - 1)) ::: srcAfter).mkString(EOL))
+        val (srcBefore, srcAfter, offset) = sourceLines(pos1)
+        val marker = positionMarker(pos1)
+        val err = errorMsg(pos1, msg.message)
+        sb.append((srcBefore ::: marker :: err :: srcAfter).mkString(EOL))
+
+        if inlineStack.nonEmpty then
+          sb.append(EOL).append(newBox())
+          sb.append(EOL).append(offsetBox).append(i"Inline stack trace")
+          for inlinedPos <- inlineStack if inlinedPos != pos1 do
+            val (srcBefore, srcAfter, offset) = sourceLines(inlinedPos)
+            val marker = positionMarker(inlinedPos)
+            sb.append(EOL).append(newBox(soft = true))
+            sb.append(EOL).append(offsetBox).append(i"This location contains code that was inlined from $pos")
+            sb.append(EOL).append((srcBefore ::: marker :: srcAfter).mkString(EOL))
+          sb.append(EOL).append(endBox)
       }
       else sb.append(msg.message)
     }
@@ -186,15 +251,13 @@ trait MessageRendering {
     sb.toString
   }
 
-  def hl(diagnosticLevel: String)(str: String)(using Context): String = diagnosticLevel match {
-    case "Info" => Blue(str).show
-    case "Error" => Red(str).show
-    case _ =>
-      assert(diagnosticLevel.contains("Warning"))
-      Yellow(str).show
-  }
+  private  def hl(str: String)(using Context, Level): String =
+    summon[Level].value match
+      case interfaces.Diagnostic.ERROR   => Red(str).show
+      case interfaces.Diagnostic.WARNING => Yellow(str).show
+      case interfaces.Diagnostic.INFO    => Blue(str).show
 
-  def diagnosticLevel(dia: Diagnostic): String =
+  private def diagnosticLevel(dia: Diagnostic): String =
     dia match {
       case dia: FeatureWarning => "Feature Warning"
       case dia: DeprecationWarning => "Deprecation Warning"
@@ -205,4 +268,28 @@ trait MessageRendering {
         case interfaces.Diagnostic.WARNING => "Warning"
         case interfaces.Diagnostic.INFO    => "Info"
     }
+
+}
+
+private object Highlight {
+  opaque type Level = Int
+  extension (level: Level) def value: Int = level
+  object Level:
+    def apply(level: Int): Level = level
+}
+
+/** Size of the left offset added by the box
+ *
+ *  ```
+ *  -- Error: ... ------------
+ *  4 |  foo
+ *    |  ^^^
+ *  ^^^ // size of this offset
+ *  ```
+ */
+private object Offsets {
+  opaque type Offset = Int
+  def offset(using o: Offset): Int = o
+  object Offset:
+    def apply(level: Int): Offset = level
 }

compiler/src/dotty/tools/dotc/transform/Splicer.scala

@@ -49,7 +49,7 @@ object Splicer {
           val oldContextClassLoader = Thread.currentThread().getContextClassLoader
           Thread.currentThread().setContextClassLoader(classLoader)
           try {
-            val interpreter = new Interpreter(spliceExpansionPos, classLoader)
+            val interpreter = new Interpreter(splicePos, classLoader)
 
             // Some parts of the macro are evaluated during the unpickling performed in quotedExprToTree
             val interpretedExpr = interpreter.interpret[Quotes => scala.quoted.Expr[Any]](tree)

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -853,7 +853,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
           evidence.tpe match
             case fail: Implicits.SearchFailureType =>
               val msg = evTyper.missingArgMsg(evidence, tpt.tpe, "")
-              errorTree(tpt, em"$msg")
+              errorTree(call, em"$msg")
             case _ =>
               evidence
         return searchImplicit(callTypeArgs.head)

compiler/test-resources/repl/i9227

@@ -3,5 +3,4 @@ scala> import scala.quoted._; inline def myMacro[T]: Unit = ${ myMacroImpl[T] };
 1 | import scala.quoted._; inline def myMacro[T]: Unit = ${ myMacroImpl[T] }; def myMacroImpl[T](using Quotes): Expr[Unit] = '{}; println(myMacro[Int])
   |                                                                                                                                       ^^^^^^^^^^^^
   |      Cannot call macro method myMacroImpl defined in the same source file
-  | This location contains code that was inlined from rs$line$1:1
 1 error found

tests/neg-macros/delegate-match-1.check

@@ -4,4 +4,3 @@
   |  ^
   |  AmbiguousImplicits
   |  both value a1 in class Test1 and value a2 in class Test1 match type A
-  | This location contains code that was inlined from Test_2.scala:6

tests/neg-macros/delegate-match-2.check

@@ -4,4 +4,3 @@
   |  ^
   |  DivergingImplicit
   |  method a1 in class Test produces a diverging implicit search when trying to match type A
-  | This location contains code that was inlined from Test_2.scala:5

tests/neg-macros/delegate-match-3.check

@@ -4,4 +4,3 @@
   |  ^
   |  NoMatchingImplicits
   |  no implicit values were found that match type A
-  | This location contains code that was inlined from Test_2.scala:3

tests/neg-macros/i11386.check

@@ -3,11 +3,21 @@
 6 |    dummy(0) // error
   |          ^
   |          test
-  | This location contains code that was inlined from Test_2.scala:6
-  | This location contains code that was inlined from Macro_1.scala:7
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |·····················································································································
+  |This location contains code that was inlined from Test_2.scala:6
+7 |    notNull(i)
+  |    ^^^^^^^^^^
+  ·---------------------------------------------------------------------------------------------------------------------
 -- Error: tests/neg-macros/i11386/Test_2.scala:8:20 --------------------------------------------------------------------
 8 |    dummy(int2String(0)) // error
   |          ^^^^^^^^^^^^^
   |          test
-  | This location contains code that was inlined from Test_2.scala:8
-  | This location contains code that was inlined from Macro_1.scala:7
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |·····················································································································
+  |This location contains code that was inlined from Test_2.scala:8
+7 |    notNull(i)
+  |    ^^^^^^^^^^
+  ·---------------------------------------------------------------------------------------------------------------------

tests/neg-macros/i13991.check

@@ -0,0 +1,16 @@
+
+-- Error: tests/neg-macros/i13991/Test_2.scala:6:5 ---------------------------------------------------------------------
+6 |     v2  // error
+  |     ^^
+  |     Error
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |·····················································································································
+  |This location contains code that was inlined from Test_2.scala:3
+3 |     inline def v2 = InlineMac.sample("foo")
+  |                                      ^^^^^
+  |·····················································································································
+  |This location contains code that was inlined from Test_2.scala:3
+3 |     inline def v2 = InlineMac.sample("foo")
+  |                     ^^^^^^^^^^^^^^^^^^^^^^^
+  ·---------------------------------------------------------------------------------------------------------------------

tests/neg-macros/i13991/Macro_1.scala

@@ -0,0 +1,10 @@
+import scala.quoted.*
+
+object InlineMac:
+
+  inline def sample(inline expr: String): Int =
+    ${ sampleImpl('expr) }
+
+  def sampleImpl(expr: Expr[String])(using Quotes): Expr[Int] =
+      import quotes.reflect.*
+      report.errorAndAbort("Error", expr)