SI-8608 f interpolator emits constant strings

When invoking `format` is obviated by a lack of
formatting fields, then just degenerate to an
unenhanced constant string.

This means it doesn't cost anything to use
f"$$ordinary" in place of "$ordinary", which
may cause warnings under -Xlint.

Note that certain format literals, in particular
for line separator %n, are not actually literals and
can't be replaced at compile time.

1 files changed, 15 insertions, 0 deletions

diff --git a/test/files/run/t8608-no-format.scala b/test/files/run/t8608-no-format.scala
new file mode 100644
index 0000000000..71c369a7ea
--- /dev/null
+++ b/test/files/run/t8608-no-format.scala
@@ -0,0 +1,15 @@
+
+import scala.tools.partest.JavapTest
+
+object Test extends JavapTest {
+  def code = """
+    |f"hello, world"
+    |:javap -prv -
+  """.stripMargin
+
+  // no format
+  override def yah(res: Seq[String]) = {
+    // note: avoid the word "information"
+    res forall (!_.contains("StringOps.format"))
+  }
+}