Fix #6027: Use argument span for inlined type parameters

Author: nicolasstucki

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

@@ -211,6 +211,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
    */
   private val paramBinding = new mutable.HashMap[Name, Type]
 
+  /** A map from parameter names of the inlineable method to spans of the actual arguments */
   private val paramSpan = new mutable.HashMap[Name, Span]
 
   /** A map from references to (type and value) parameters of the inlineable method
@@ -273,6 +274,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
   private def computeParamBindings(tp: Type, targs: List[Tree], argss: List[List[Tree]]): Unit = tp match {
     case tp: PolyType =>
       (tp.paramNames, targs).zipped.foreach { (name, arg) =>
+        paramSpan(name) = arg.span
         paramBinding(name) = arg.tpe.stripTypeVar
       }
       computeParamBindings(tp.resultType, Nil, argss)
@@ -446,7 +448,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
             case Some(t) if tree.isTerm && t.isSingleton =>
               singleton(t.dealias).withSpan(paramSpan(tree.name))
             case Some(t) if tree.isType =>
-              TypeTree(t).withSpan(tree.span)
+              TypeTree(t).withSpan(paramSpan(tree.name))
             case _ => tree
           }
         case tree => tree

tests/run/tasty-macro-positions.check

@@ -26,11 +26,11 @@ quoted_2.scala:[345..358]
 ("abc": scala.Predef.String)
 quoted_2.scala:[369..383]
 _root_.scala.StringContext.apply(("abc", "": scala.<repeated>[scala#Predef.String])).s(("def": scala.<repeated>[scala.Any]))
-quoted_2.scala:[201..202]
+quoted_2.scala:[426..427]
 T
-quoted_2.scala:[201..202]
+quoted_2.scala:[438..444]
 scala.Predef.String
-quoted_2.scala:[201..202]
+quoted_2.scala:[455..460]
 "abc"
-quoted_2.scala:[201..202]
+quoted_2.scala:[471..472]
 U

tests/run/tasty-macro-positions/quoted_2.scala

@@ -27,12 +27,10 @@ object Test {
     type T
     type U = "abc"
 
-    fun3[T] // ERROR
-    fun3[String] // ERROR
-    fun3["abc"] // ERROR
-    fun3[U] // ERROR
+    fun3[T]
+    fun3[String]
+    fun3["abc"]
+    fun3[U]
   }
-  // FIXME all the lines marked as ERROR have the wrong position on the three of the argument.
-  // they all have as source file this file but the span of `'[T]` in `fun3`.
-  // see #6027
+
 }