Use adjusted pos when rendering diagnostic

The previous code was unclear about what pos to adjust.

The diagnostic pos yields an innermost "user pos"
which is adjusted at EOF.

The inline stack is already filtered by position for rendering.

Author: som-snytt

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

@@ -250,16 +250,8 @@ trait MessageRendering {
    *  usually we intend to test `contains` or `coincidesWith`.
    *
    */
-  def messageAndPos(dia: Diagnostic)(using Context): String = {
-    import dia.*
-    val pos1 = pos.nonInlined
-    val inlineStack = pos.inlinePosStack.filterNot(_.contains(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 = StringBuilder()
+  def messageAndPos(dia: Diagnostic)(using Context): String =
+    // adjust a pos at EOF if preceded by newline
     def adjust(pos: SourcePosition): SourcePosition =
       if pos.span.isSynthetic
       && pos.span.isZeroExtent
@@ -270,53 +262,57 @@ trait MessageRendering {
         pos.withSpan(pos.span.shift(-1))
       else
         pos
-    val adjusted = adjust(pos)
-    val posString = posStr(adjusted, msg, diagnosticLevel(dia))
-    if (posString.nonEmpty) sb.append(posString).append(EOL)
-    if (pos.exists) {
-      if (pos1.exists && pos1.source.file.exists) {
-        val readjusted =
-          if pos1 == pos then adjusted
-          else adjust(pos1)
-        val (srcBefore, srcAfter, offset) = sourceLines(readjusted)
-        val marker = positionMarker(readjusted)
-        val err = errorMsg(readjusted, 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
-            sb.append(EOL).append(newBox(soft = true))
-            sb.append(EOL).append(offsetBox).append(i"This location contains code that was inlined from $pos")
-            if inlinedPos.source.file.exists then
-              val (srcBefore, srcAfter, _) = sourceLines(inlinedPos)
-              val marker = positionMarker(inlinedPos)
-              sb.append(EOL).append((srcBefore ::: marker :: srcAfter).mkString(EOL))
-          sb.append(EOL).append(endBox)
-      }
-      else sb.append(msg.message)
-    }
+    val msg = dia.msg
+    val pos = dia.pos
+    val pos1 = adjust(pos.nonInlined) // innermost pos contained by call.pos
+    val outermost = pos.outermost // call.pos
+    val inlineStack = pos.inlinePosStack.filterNot(outermost.contains(_))
+    given Level = Level(dia.level)
+    given Offset =
+      val maxLineNumber =
+        if pos.exists then (pos1 :: inlineStack).map(_.endLine).max + 1
+        else 0
+      Offset(maxLineNumber.toString.length + 2)
+    val sb = StringBuilder()
+    val posString = posStr(pos1, msg, diagnosticLevel(dia))
+    if posString.nonEmpty then sb.append(posString).append(EOL)
+    if pos.exists && pos1.exists && pos1.source.file.exists then
+      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 do
+          sb.append(EOL).append(newBox(soft = true))
+          sb.append(EOL).append(offsetBox).append(i"This location contains code that was inlined from $pos")
+          if inlinedPos.source.file.exists then
+            val (srcBefore, srcAfter, _) = sourceLines(inlinedPos)
+            val marker = positionMarker(inlinedPos)
+            sb.append(EOL).append((srcBefore ::: marker :: srcAfter).mkString(EOL))
+        sb.append(EOL).append(endBox)
+      end if
     else sb.append(msg.message)
-    if (dia.isVerbose)
+    if dia.isVerbose then
       appendFilterHelp(dia, sb)
 
     if Diagnostic.shouldExplain(dia) then
       sb.append(EOL).append(newBox())
       sb.append(EOL).append(offsetBox).append(" Explanation (enabled by `-explain`)")
       sb.append(EOL).append(newBox(soft = true))
-      dia.msg.explanation.split(raw"\R").foreach { line =>
+      dia.msg.explanation.split(raw"\R").foreach: line =>
         sb.append(EOL).append(offsetBox).append(if line.isEmpty then "" else " ").append(line)
-      }
       sb.append(EOL).append(endBox)
     else if dia.msg.canExplain then
       sb.append(EOL).append(offsetBox)
       sb.append(EOL).append(offsetBox).append(" longer explanation available when compiling with `-explain`")
 
     sb.toString
-  }
+  end messageAndPos
 
-  private  def hl(str: String)(using Context, Level): String =
+  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

tests/neg/i23815.check

@@ -4,6 +4,6 @@
   |  ':' or '{' expected, but 'end of statement' found
   |  Nested package statements that are not at the beginning of the file require braces or ':' with an indented body.
 -- [E040] Syntax Error: tests/neg/i23815.scala:9:8 ---------------------------------------------------------------------
- 9 |// error
-   |        ^
-   |        '}' expected, but eof found
+9 |// error
+  |        ^
+  |        '}' expected, but eof found