import scala.reflect.mirror._

object Test extends App {
  def f[T](a: T, b: T) = {
    reify(a.toString + b)
    reify(a + b.toString)
  }
}

reifying = 
a.toString().+(b)
Apply(Select(Apply(Select(Ident(newTermName("a")), newTermName("toString")), List()), newTermName("$plus")), List(Ident(newTermName("b"))))
reifee is located at: source-C:\Projects\Kepler\sandbox\Test.scala,line-5,offset=105
prefix = scala.reflect.`package`.mirror
[calculate phase]
[reshape phase]
[metalevels phase]
[interlude]
symbol table = <empty>
reifee = 
a.toString().+(b)
Apply(Select(Apply(Select(Ident(newTermName("a")), newTermName("toString")), List()), newTermName("$plus")), List(Ident(newTermName("b"))))
[reify phase]
Free term: value a(value)
splicing T
launching implicit search for scala.reflect.`package`.mirror.TypeTag[T]
reifying = T
prefix = scala.reflect.`package`.mirror
splicing T
splicing has been cancelled: spliceTypesEnabled = false
Free type: type T (type)
Filling in: type T (type)
reified = {
  val $mr: scala.reflect.`package`.mirror.type = scala.reflect.`package`.mirror;
  val free$T1 = $mr.newFreeType("T", $mr.TypeBounds($mr.staticClass("scala.Nothing").asTypeConstructor, $mr.staticClass("scala.Any").asTypeConstructor), $mr.TypeTag[T](null, null), 8208L, "defined by f in Test.scala:4:9");
  $mr.TypeTag[T]($mr.TypeRef($mr.NoPrefix, free$T1, scala.collection.immutable.List.apply()), Predef.this.classOf[Object])
}
implicit search has produced a result: {
  val $mr: reflect.mirror.type = scala.reflect.`package`.mirror;
  val free$T1: $mr.Symbol = $mr.newFreeType("T", $mr.TypeBounds.apply($mr.staticClass("scala.Nothing").asTypeConstructor, $mr.staticClass("scala.Any").asTypeConstructor), $mr.TypeTag.apply[T](null, null), 8208L, "defined by f in Test.scala:4:9");
  $mr.TypeTag.apply[T]($mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil), classOf[java.lang.Object])
}
inlined the splicee: $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil)
Free term: value b(value)
splicing T
cache hit: $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil)
Filling in: type T (type)
Filling in: value a (value)
Filling in: value b (value)
reified = {
  val $mr: scala.reflect.`package`.mirror.type = scala.reflect.`package`.mirror;
  val free$T1: $mr.Symbol = $mr.newFreeType("T", $mr.TypeBounds.apply($mr.staticClass("scala.Nothing").asTypeConstructor, $mr.staticClass("scala.Any").asTypeConstructor), $mr.TypeTag.apply[T](null, null), 8208L, "defined by f in Test.scala:4:9");
  val free$a1 = $mr.newFreeTerm("a", $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil), a, 17592186052608L, "defined by f in Test.scala:4:12");
  val free$b1 = $mr.newFreeTerm("b", $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil), b, 17592186052608L, "defined by f in Test.scala:4:18");
  $mr.Expr[String]($mr.Apply($mr.Select($mr.Apply($mr.Select($mr.Ident(free$a1), $mr.newTermName("toString")), scala.collection.immutable.List.apply()), $mr.newTermName("$plus")), scala.collection.immutable.List.apply($mr.Ident(free$b1))))($mr.TypeTag[String]($mr.staticClass("java.lang.String").asTypeConstructor, Predef.this.classOf[String]))
}
reifying = 
scala.this.Predef.any2stringadd(a).+(b.toString())
Apply(Select(Apply(Select(Select(This(newTypeName("scala")), newTermName("Predef")), newTermName("any2stringadd")), List(Ident(newTermName("a")))), newTermName("$plus")), List(Apply(Select(Ident(newTermName("b")), newTermName("toString")), List())))
reifee is located at: source-C:\Projects\Kepler\sandbox\Test.scala,line-6,offset=122
prefix = scala.reflect.`package`.mirror
[calculate phase]
[reshape phase]
[metalevels phase]
[interlude]
symbol table = <empty>
reifee = 
scala.this.Predef.any2stringadd(a).+(b.toString())
Apply(Select(Apply(Select(Select(This(newTypeName("scala")), newTermName("Predef")), newTermName("any2stringadd")), List(Ident(newTermName("a")))), newTermName("$plus")), List(Apply(Select(Ident(newTermName("b")), newTermName("toString")), List())))
[reify phase]
This for package scala, reified as This
Free term: value a(value)
splicing T
cache hit: $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil)
Free term: value b(value)
splicing T
cache hit: $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil)
Filling in: value a (value)
Filling in: value b (value)
reified = {
  val $mr: scala.reflect.`package`.mirror.type = scala.reflect.`package`.mirror;
  val free$a2 = $mr.newFreeTerm("a", $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil), a, 17592186052608L, "defined by f in Test.scala:4:12");
  val free$b2 = $mr.newFreeTerm("b", $mr.TypeRef.apply($mr.NoPrefix, free$T1, immutable.this.Nil), b, 17592186052608L, "defined by f in Test.scala:4:18");
  $mr.Expr[String]($mr.Apply($mr.Select($mr.Apply($mr.Select($mr.Select($mr.This($mr.staticModule("scala").moduleClass), $mr.newTermName("Predef")), $mr.newTermName("any2stringadd")), scala.collection.immutable.List.apply($mr.Ident(free$a2))), $mr.newTermName("$plus")), scala.collection.immutable.List.apply($mr.Apply($mr.Select($mr.Ident(free$b2), $mr.newTermName("toString")), scala.collection.immutable.List.apply()))))($mr.ConcreteTypeTag[String]($mr.staticClass("java.lang.String").asTypeConstructor, Predef.this.classOf[String]))
}

Test.scala:6: error: Cannot materialize Expr because:
scala.reflect.internal.Types$TypeError: not found: value free$T1
    reify(a + b.toString)
         ^
one error found