[CSStep] Clearly present an initial state of the component step, listing type variables, their possible bindings, and next attempt.

Author: Amritpan Kaur

lib/Sema/CSBindings.cpp

@@ -735,7 +735,8 @@ BindingSet::BindingScore BindingSet::formBindingScore(const BindingSet &b) {
                          -numNonDefaultableBindings);
 }
 
-Optional<BindingSet> ConstraintSystem::determineBestBindings() {
+Optional<BindingSet>
+ConstraintSystem::determineBestBindings() {
   // Look for potential type variable bindings.
   Optional<BindingSet> bestBindings;
   llvm::SmallDenseMap<TypeVariableType *, BindingSet> cache;

lib/Sema/CSStep.cpp

@@ -343,7 +343,13 @@ StepResult ComponentStep::take(bool prevFailed) {
   /// Try to figure out what this step is going to be,
   /// after the scope has been established.
   auto *disjunction = CS.selectDisjunction();
-  auto bestBindings = CS.determineBestBindings();
+  const bool isSolverStep = !IsSingle;
+  auto bestBindings = CS.determineBestBindings(isSolverStep);
+  if (isSolverStep) {
+    auto &log = getDebugLogger();
+    log << ")" << '\n';
+    log.indent(0);
+  }
 
   if (CS.shouldAttemptFixes()) {
     if ((bestBindings &&
@@ -478,23 +484,6 @@ StepResult ComponentStep::finalize(bool isSuccess) {
 
 void TypeVariableStep::setup() {
   ++CS.solverState->NumTypeVariablesBound;
-  if (CS.isDebugMode()) {
-    PrintOptions PO;
-    PO.PrintTypesForDebugging = true;
-    auto &log = getDebugLogger();
-
-    auto initialBindings = Producer.getCurrentBindings();
-    log << "Initial bindings: ";
-    interleave(
-        initialBindings.begin(), initialBindings.end(),
-        [&](const Binding &binding) {
-          log << TypeVar->getString(PO)
-              << " := " << binding.BindingType->getString(PO);
-        },
-        [&log] { log << ", "; });
-
-    log << '\n';
-  }
 }
 
 bool TypeVariableStep::attempt(const TypeVariableBinding &choice) {

lib/Sema/CSStep.h

@@ -482,7 +482,7 @@ class ComponentStep final : public SolverStep {
                    Type(typeVar).print(log, PO);
                  },
                  [&] {
-                   log << ' ';
+                   log << ", ";
                  });
       log << "])" << '\n';