Systematic treatment of result types of dependent methods

We approximate dependencies to parameters by Wildcards. This was already
done in one place, is now done in other places as well, instead of doing nothing for
dependent methods.

1 files changed, 10 insertions, 14 deletions

diff --git a/compiler/src/dotty/tools/dotc/typer/Applications.scala b/compiler/src/dotty/tools/dotc/typer/Applications.scala
index e9df12b42..bca44997d 100644
--- a/compiler/src/dotty/tools/dotc/typer/Applications.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Applications.scala
@@ -213,16 +213,14 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
     protected def init() = methType match {
       case methType: MethodType =>
         // apply the result type constraint, unless method type is dependent
-        if (!methType.isDependent) {
-          val savedConstraint = ctx.typerState.constraint
-          if (!constrainResult(methType.resultType, resultType))
-            if (ctx.typerState.isCommittable)
-              // defer the problem until after the application;
-              // it might be healed by an implicit conversion
-              assert(ctx.typerState.constraint eq savedConstraint)
-            else
-              fail(err.typeMismatchMsg(methType.resultType, resultType))
-        }
+        val savedConstraint = ctx.typerState.constraint
+        if (!constrainResult(methType.resultTypeApprox, resultType))
+          if (ctx.typerState.isCommittable)
+            // defer the problem until after the application;
+            // it might be healed by an implicit conversion
+            assert(ctx.typerState.constraint eq savedConstraint)
+          else
+            fail(err.typeMismatchMsg(methType.resultType, resultType))
         // match all arguments with corresponding formal parameters
         matchArgs(orderedArgs, methType.paramTypes, 0)
       case _ =>
@@ -1100,10 +1098,8 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
 
     /** Drop any implicit parameter section */
     def stripImplicit(tp: Type): Type = tp match {
-      case mt: ImplicitMethodType if !mt.isDependent =>
-        mt.resultType
-          // todo: make sure implicit method types are not dependent?
-          // but check test case in /tests/pos/depmet_implicit_chaining_zw.scala
+      case mt: ImplicitMethodType =>
+        mt.resultTypeApprox
       case pt: PolyType =>
         pt.derivedPolyType(pt.paramNames, pt.paramBounds, stripImplicit(pt.resultType))
       case _ =>