Remove InfixOpBlock

And add a comment on possibly ode types returned from typedApply

Author: odersky

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -96,16 +96,6 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
     override def isEmpty = true
   }
 
-  /** A block arising from a right-associative infix operation, where, e.g.
-   *
-   *     a +: b
-   *
-   *  is expanded to
-   *
-   *     { val x = a; b.+:(x) }
-   */
-  class InfixOpBlock(leftOperand: Tree, rightOp: Tree) extends Block(leftOperand :: Nil, rightOp)
-
   /** A block generated by the XML parser, only treated specially by
    *  `Positioned#checkPos` */
   class XMLBlock(stats: List[Tree], expr: Tree) extends Block(stats, expr)

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

@@ -665,6 +665,10 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
   def argCtx(app: untpd.Tree)(implicit ctx: Context): Context =
     if (untpd.isSelfConstrCall(app)) ctx.thisCallArgContext else ctx
 
+  /** Typecheck application. Result could be an `Apply` node,
+   *  or, if application is an operator assignment, also an `Assign` or
+   *  Block node.
+   */
   def typedApply(tree: untpd.Apply, pt: Type)(implicit ctx: Context): Tree = {
 
     def realApply(implicit ctx: Context): Tree = track("realApply") {

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

@@ -664,12 +664,7 @@ class Typer extends Namer
 
   def typedBlock(tree: untpd.Block, pt: Type)(implicit ctx: Context) = track("typedBlock") {
     val (exprCtx, stats1) = typedBlockStats(tree.stats)
-    val ept =
-      if (tree.isInstanceOf[untpd.InfixOpBlock])
-        // Right-binding infix operations are expanded to InfixBlocks, which may be followed by arguments.
-        // Example: `(a /: bs)(op)` expands to `{ val x = a; bs./:(x) } (op)` where `{...}` is an InfixBlock.
-        pt
-      else pt.notApplied
+    val ept = pt.notApplied
     val expr1 = typedExpr(tree.expr, ept)(exprCtx)
     ensureNoLocalRefs(
       cpy.Block(tree)(stats1, expr1).withType(expr1.tpe), pt, localSyms(stats1))