Merge pull request #22267 from xedin/rdar-47492691

[ConstraintSystem] Decouple `designated types` feature from Swift ver…

Author: xedin

lib/Sema/CSSolver.cpp

@@ -1897,10 +1897,10 @@ Constraint *ConstraintSystem::selectDisjunction() {
   // disjunctions that we may not be able to short-circuit, allowing
   // us to eliminate behavior that is exponential in the number of
   // operators in the expression.
-  if (getASTContext().isSwiftVersionAtLeast(5) ||
-      TC.getLangOpts().SolverEnableOperatorDesignatedTypes)
+  if (TC.getLangOpts().SolverEnableOperatorDesignatedTypes) {
     if (auto *disjunction = selectApplyDisjunction())
       return disjunction;
+  }
 
   if (auto *disjunction = selectBestBindingDisjunction(*this, disjunctions))
     return disjunction;

validation-test/Sema/type_checker_perf/fast/rdar47492691.swift

@@ -0,0 +1,9 @@
+// RUN: %target-typecheck-verify-swift
+// REQUIRES: objc_interop
+
+import CoreGraphics
+import simd
+
+func test(foo: CGFloat, bar: CGFloat) {
+  _ = CGRect(x: 0.0 + 1.0, y: 0.0 + foo, width: 3.0 - 1 - 1 - 1.0, height: bar)
+}