More thorough retry of constraints which may succeed now that fixes are allowed.

Author: gregomni

lib/Sema/ConstraintSystem.cpp

@@ -2045,8 +2045,14 @@ bool ConstraintSystem::salvage(SmallVectorImpl<Solution> &viable, Expr *expr) {
     SolverState state(expr, *this, FreeTypeVariableBinding::Disallow);
     state.recordFixes = true;
 
-    if (failedConstraint && simplifyConstraint(*failedConstraint) == SolutionKind::Solved)
+    // Retry all inactive and failed constraints
+    if (failedConstraint) {
+      addUnsolvedConstraint(failedConstraint);
       failedConstraint = nullptr;
+    }
+    ActiveConstraints.splice(ActiveConstraints.end(), InactiveConstraints);
+    for (auto &constraint : ActiveConstraints)
+      constraint.setActive(true);
 
     // Solve the system.
     solve(viable);