Do not harmonize constant args if their type doesn't affect resType

Fixes the following sample from #9939: ```scala scala> f"${3.14}%.2f rounds to ${3}%d" 1 |f"${3.14}%.2f rounds to ${3}%d" | ^ | type mismatch; | found : Double | required: Int | This location contains code that was inlined from rs$line$2:1 ``` At the moment when StringInterpolation transformation was performed instead of receiving `List(Constant(3.0), Constant(3))` arguments they were: `List(Constant(3.0), Constant(3.0))` (the second one was converted to double because of harmonization). That caused the reported type mismatch. In Scala2 harmonization doesn't happen if the resulting type is fully defined. For f-interp it shouldn't happen too as it's resulting type is a `String`: ```scala def f[A >: Any](args: A*): String = macro ??? ```

Author: dos65

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

@@ -744,7 +744,10 @@ trait Applications extends Compatibility {
  typedArgBuf += seqToRepeated(SeqLiteral(args, elemtpt))
  }
 
- def harmonizeArgs(args: List[TypedArg]): List[Tree] = harmonize(args)
+ def harmonizeArgs(args: List[TypedArg]): List[Tree] =
+ // harmonize args only if resType depends on parameter types
+ if (isFullyDefined(methodType.resType, ForceDegree.none)) args
+ else harmonize(args)
 
  override def appPos: SrcPos = app.srcPos
 

tests/run-macros/f-interpolator-tests.check

@@ -1,6 +1,7 @@
 integer: 5
 string: l
 5, 6, hello
+3.14 rounds to 3
 5
 6
 Bob is 1 years old

tests/run-macros/f-interpolator-tests.scala

@@ -10,6 +10,7 @@ object Test {
  println(f"integer: ${5}%d")
  println(f"string: ${"l"}%s")
  println(f"${5}%s, ${6}%d, ${"hello"}%s")
+ println(f"${3.14}%.2f rounds to ${3}%d")
 
  val x = 5
  println(f"$x%d")

tests/run/i9939.check

@@ -0,0 +1,2 @@
+[3.0, 42]
+[3.0, 42.0]

tests/run/i9939.scala

@@ -0,0 +1,6 @@
+def nonHarmonized[A >: Any](args: A*): String = args.mkString("[", ", ", "]")
+def harmonized[A >: Any](args: A*): List[A] = args.toList
+
+@main def Test =
+ println(nonHarmonized(3.0, 42))
+ println(harmonized(3.0, 42).mkString("[", ", ", "]"))