Merge pull request #14353 from dotty-staging/fix-i14333

Avoid unnecessary under-constrained implicit searches

Author: odersky

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

@@ -433,15 +433,18 @@ trait Applications extends Compatibility {
 
     protected def init(): Unit = methType match {
       case methType: MethodType =>
-        // apply the result type constraint, unless method type is dependent
         val resultApprox = resultTypeApprox(methType)
-        if (!constrainResult(methRef.symbol, resultApprox, resultType))
-          if (ctx.typerState.isCommittable)
-            // defer the problem until after the application;
-            // it might be healed by an implicit conversion
-            ()
-          else
-            fail(TypeMismatch(methType.resultType, resultType, None))
+        val sym = methRef.symbol
+        if ctx.typerState.isCommittable then
+          // Here we call `resultType` only to accumulate constraints (even if
+          // it fails, we might be able to heal the expression to conform to the
+          // result type) so don't check for views since `viewExists` doesn't
+          // have any side-effect and would only slow the compiler down (cf #14333).
+          NoViewsAllowed.constrainResult(sym, resultApprox, resultType)
+        else if !constrainResult(sym, resultApprox, resultType) then
+          // Here we actually record that this alternative failed so that
+          // overloading resolution might prune it.
+          fail(TypeMismatch(methType.resultType, resultType, None))
 
         // match all arguments with corresponding formal parameters
         matchArgs(orderedArgs, methType.paramInfos, 0)