Sema: Add BindingSet::operator==

This will be used for debugging.

Author: slavapestov

include/swift/Sema/CSBindings.h

@@ -583,44 +583,11 @@ class BindingSet {
 
   static BindingScore formBindingScore(const BindingSet &b);
 
-  /// Compare two sets of bindings, where \c x < y indicates that
-  /// \c x is a better set of bindings that \c y.
-  friend bool operator<(const BindingSet &x, const BindingSet &y) {
-    auto xScore = formBindingScore(x);
-    auto yScore = formBindingScore(y);
+  bool operator==(const BindingSet &other);
 
-    if (xScore < yScore)
-      return true;
-
-    if (yScore < xScore)
-      return false;
-
-    auto xDefaults = x.getNumViableDefaultableBindings();
-    auto yDefaults = y.getNumViableDefaultableBindings();
-
-    // If there is a difference in number of default types,
-    // prioritize bindings with fewer of them.
-    if (xDefaults != yDefaults)
-      return xDefaults < yDefaults;
-
-    // If neither type variable is a "hole" let's check whether
-    // there is a subtype relationship between them and prefer
-    // type variable which represents superclass first in order
-    // for "subtype" type variable to attempt more bindings later.
-    // This is required because algorithm can't currently infer
-    // bindings for subtype transitively through superclass ones.
-    if (!(std::get<0>(xScore) && std::get<0>(yScore))) {
-      if (x.Info.isSubtypeOf(y.getTypeVariable()))
-        return false;
-
-      if (y.Info.isSubtypeOf(x.getTypeVariable()))
-        return true;
-    }
-
-    // As a last resort, let's check if the bindings are
-    // potentially incomplete, and if so, let's de-prioritize them.
-    return x.isPotentiallyIncomplete() < y.isPotentiallyIncomplete();
-  }
+  /// Compare two sets of bindings, where \c this < other indicates that
+  /// \c this is a better set of bindings that \c other.
+  bool operator<(const BindingSet &other);
 
   void dump(llvm::raw_ostream &out, unsigned indent) const;
 

lib/Sema/CSBindings.cpp

@@ -953,6 +953,56 @@ void BindingSet::addLiteralRequirement(Constraint *constraint) {
   Literals.insert({protocol, std::move(literal)});
 }
 
+bool BindingSet::operator==(const BindingSet &other) {
+  if (AdjacentVars != other.AdjacentVars)
+    return false;
+
+  if (Bindings.size() != other.Bindings.size())
+    return false;
+
+  for (auto i : indices(Bindings)) {
+    const auto &x = Bindings[i];
+    const auto &y = other.Bindings[i];
+
+    if (x.BindingType.getPointer() != y.BindingType.getPointer() ||
+        x.Kind != y.Kind)
+      return false;
+  }
+
+  if (Literals.size() != other.Literals.size())
+    return false;
+
+  for (auto pair : Literals) {
+    auto found = other.Literals.find(pair.first);
+    if (found == other.Literals.end())
+      return false;
+
+    const auto &x = pair.second;
+    const auto &y = found->second;
+
+    if (x.Source != y.Source ||
+        x.DefaultType.getPointer() != y.DefaultType.getPointer() ||
+        x.IsDirectRequirement != y.IsDirectRequirement) {
+      return false;
+    }
+  }
+
+  if (Defaults.size() != other.Defaults.size())
+    return false;
+
+  for (auto pair : Defaults) {
+    auto found = other.Defaults.find(pair.first);
+    if (found == other.Defaults.end() ||
+        pair.second != found->second)
+      return false;
+  }
+
+  if (TransitiveProtocols != other.TransitiveProtocols)
+    return false;
+
+  return true;
+}
+
 BindingSet::BindingScore BindingSet::formBindingScore(const BindingSet &b) {
   // If there are no bindings available but this type
   // variable represents a closure - let's consider it
@@ -973,6 +1023,43 @@ BindingSet::BindingScore BindingSet::formBindingScore(const BindingSet &b) {
                          -numNonDefaultableBindings);
 }
 
+bool BindingSet::operator<(const BindingSet &other) {
+  auto xScore = formBindingScore(*this);
+  auto yScore = formBindingScore(other);
+
+  if (xScore < yScore)
+    return true;
+
+  if (yScore < xScore)
+    return false;
+
+  auto xDefaults = getNumViableDefaultableBindings();
+  auto yDefaults = other.getNumViableDefaultableBindings();
+
+  // If there is a difference in number of default types,
+  // prioritize bindings with fewer of them.
+  if (xDefaults != yDefaults)
+    return xDefaults < yDefaults;
+
+  // If neither type variable is a "hole" let's check whether
+  // there is a subtype relationship between them and prefer
+  // type variable which represents superclass first in order
+  // for "subtype" type variable to attempt more bindings later.
+  // This is required because algorithm can't currently infer
+  // bindings for subtype transitively through superclass ones.
+  if (!(std::get<0>(xScore) && std::get<0>(yScore))) {
+    if (Info.isSubtypeOf(other.getTypeVariable()))
+      return false;
+
+    if (other.Info.isSubtypeOf(getTypeVariable()))
+      return true;
+  }
+
+  // As a last resort, let's check if the bindings are
+  // potentially incomplete, and if so, let's de-prioritize them.
+  return isPotentiallyIncomplete() < other.isPotentiallyIncomplete();
+}
+
 std::optional<BindingSet> ConstraintSystem::determineBestBindings(
     llvm::function_ref<void(const BindingSet &)> onCandidate) {
   // Look for potential type variable bindings.