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

@@ -25,15 +25,9 @@ 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.exists then pos :: inlinePosStack(pos.outer)
     else Nil
 
   /** Get the sourcelines before and after the position, as well as the offset
@@ -173,10 +167,18 @@ trait MessageRendering {
     if (pos.exists) {
       val pos1 = pos.nonInlined
       if (pos1.exists && pos1.source.file.exists) {
+        // Print error message at inline position
         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))
+        sb.append((srcBefore ::: marker :: err :: srcAfter).mkString(EOL))
+        // print inline stack trace
+        for inlinedPos <- inlinePosStack(pos) do
+          val (srcBefore, srcAfter, offset) = sourceLines(inlinedPos, levelString)
+          val marker = columnMarker(inlinedPos, offset, levelString)
+          val prefix = " " * (offset - 1)
+          sb.append((i"\nThis location contains code that was inlined from $pos" :: srcBefore ::: marker :: srcAfter).mkString(EOL))
+
       }
       else sb.append(msg.message)
     }

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 +3,7 @@ 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$1:1
+This location contains code that was inlined from rs$line$1:1
+1 | import scala.quoted._; inline def myMacro[T]: Unit = ${ myMacroImpl[T] }; def myMacroImpl[T](using Quotes): Expr[Unit] = '{}; println(myMacro[Int])
+  |                                                                                                                                       ^^^^^^^^^^^^
 1 error found

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

@@ -4,4 +4,6 @@
   |  ^
   |  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
+This location contains code that was inlined from Test_2.scala:6
+6 |  f // error
+  |  ^

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

@@ -4,4 +4,6 @@
   |  ^
   |  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
+This location contains code that was inlined from Test_2.scala:5
+5 |  f // error
+  |  ^

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

@@ -4,4 +4,6 @@
   |  ^
   |  NoMatchingImplicits
   |  no implicit values were found that match type A
-  | This location contains code that was inlined from Test_2.scala:3
+This location contains code that was inlined from Test_2.scala:3
+3 |  f // error
+  |  ^

tests/neg-macros/i11386.check

@@ -3,11 +3,19 @@
 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
+This location contains code that was inlined from Test_2.scala:6
+6 |    dummy(0) // error
+  |          ^
+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
+This location contains code that was inlined from Test_2.scala:8
+8 |    dummy(int2String(0)) // error
+  |          ^^^^^^^^^^^^^
+This location contains code that was inlined from Test_2.scala:8
+7 |    notNull(i)
+  |    ^^^^^^^^^^

tests/neg-macros/i13991.check

@@ -0,0 +1,11 @@
+
+-- Error: tests/neg-macros/i13991/Test_2.scala:6:5 ---------------------------------------------------------------------
+6 |     v2  // error
+  |     ^^
+  |     Error
+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)