New tests and fix

Author: Wojtechnology

compiler/src/dotty/tools/dotc/transform/localopt/StringInterpolatorOpt.scala

@@ -32,15 +32,29 @@ class StringInterpolatorOpt extends MiniPhase {
     }
   }
 
+  private object StringContextIdent {
+    def unapply(tree: Ident)(implicit ctx: Context): Option[Ident] = {
+      if (tree.symbol.eq(defn.StringContextModule)) Some(tree) else None
+    }
+  }
+
+  private object StringContextApply {
+    def unapply(tree: Select)(implicit ctx: Context): Option[Select] = {
+      tree match {
+        case Select(StringContextIdent(_), _)
+          if tree.symbol.eq(defn.StringContextModule_apply) => Some(tree)
+        case _ => None
+      }
+    }
+  }
+
   /** Matches an s or raw string interpolator */
   private object SOrRawInterpolator {
     def unapply(tree: Tree)(implicit ctx: Context): Option[(List[Literal], List[Tree])] = {
       if (tree.symbol.eq(defn.StringContextRaw) || tree.symbol.eq(defn.StringContextS)) {
         tree match {
-          case Apply(Select(Apply(strContextApply, List(Literals(strs))), _),
-          List(SeqLiteral(elems, _)))
-            if strContextApply.symbol.eq(defn.StringContextModule_apply) &&
-              elems.length == strs.length - 1 =>
+          case Apply(Select(Apply(StringContextApply(_), List(Literals(strs))), _),
+          List(SeqLiteral(elems, _))) if elems.length == strs.length - 1 =>
             Some(strs, elems)
           case _ => None
         }

tests/run/interpolation-opt.check

@@ -7,4 +7,6 @@ a1two3.0b
 
 Hello World
 Side effect!
-Hello World
+Foo Bar
+Side effect n2!
+Titi Toto

tests/run/interpolation-opt.scala

@@ -22,5 +22,8 @@ object Test extends App {
   println(StringContext(foo, bar).s(" "))
 
   def myStringContext= { println("Side effect!"); StringContext }
-  println(myStringContext(foo, bar).s(" ")) // this shouldn't be optimised away
+  println(myStringContext("Foo", "Bar").s(" ")) // this shouldn't be optimised away
+
+  // this shouldn't be optimised away
+  println({ println("Side effect n2!"); StringContext }.apply("Titi", "Toto").s(" "))
 }