Revert "[CSSimplify] Don't enable OneWayBindParam for result builder transf…"

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -10879,7 +10879,8 @@ bool ConstraintSystem::resolveClosure(TypeVariableType *typeVar,
   // type as seen in the body of the closure and the external parameter
   // type.
   bool oneWayConstraints =
-      getASTContext().LangOpts.hasFeature(Feature::OneWayClosureParameters);
+    getASTContext().LangOpts.hasFeature(Feature::OneWayClosureParameters) ||
+    resultBuilderType;
 
   auto *paramList = closure->getParameters();
   SmallVector<AnyFunctionType::Param, 4> parameters;

test/Constraints/result_builder_diags.swift

@@ -622,7 +622,7 @@ func wrapperifyInfer<T, U>(_ cond: Bool, @WrapperBuilder body: (U) -> T) -> T {
 }
 
 let intValue = 17
-_ = wrapperifyInfer(true) { x in // Ok
+wrapperifyInfer(true) { x in // expected-error{{unable to infer type of a closure parameter 'x' in the current context}}
   intValue + x
 }
 
@@ -1000,17 +1000,3 @@ func test_requirement_failure_in_buildBlock() {
     }
   }
 }
-
-func test_partially_resolved_closure_params() {
-  struct S<T> {
-    var a: String = ""
-  }
-
-  func test<T>(@TupleBuilder _: (S<T>) -> T) { // expected-note {{in call to function 'test'}}
-  }
-
-  test { // expected-error {{generic parameter 'T' could not be inferred}}
-    $0.a
-    42
-  }
-}