Sema: Banish UnboundGenericType from the constraint system

These should have been opened already, and the logic in
simplifyConstraint(), matchTypes(), etc is just going to do
undefined things if they end up there, so let's guard
against it happening.

Author: slavapestov

lib/IDE/CodeCompletionResultType.cpp

@@ -395,7 +395,8 @@ static TypeRelation calculateTypeRelation(Type Ty, Type ExpectedTy,
 
   // Equality/Conversion of GenericTypeParameterType won't account for
   // requirements – ignore them
-  if (!Ty->hasTypeParameter() && !ExpectedTy->hasTypeParameter()) {
+  if (!Ty->hasTypeParameter() && !ExpectedTy->hasTypeParameter() &&
+      !Ty->hasUnboundGenericType() && !ExpectedTy->hasUnboundGenericType()) {
     if (Ty->isEqual(ExpectedTy))
       return TypeRelation::Convertible;
     bool isAny = false;

lib/Sema/Constraint.cpp

@@ -47,6 +47,10 @@ Constraint::Constraint(ConstraintKind kind, ArrayRef<Constraint *> constraints,
                           getTypeVariablesBuffer().begin());
 }
 
+static bool isAdmissibleType(Type type) {
+  return !type->hasUnboundGenericType();
+}
+
 Constraint::Constraint(ConstraintKind Kind, Type First, Type Second,
                        ConstraintLocator *locator,
                        SmallPtrSetImpl<TypeVariableType *> &typeVars)
@@ -55,6 +59,9 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second,
       IsFavored(false), IsIsolated(false),
       NumTypeVariables(typeVars.size()), Types{First, Second, Type()},
       Locator(locator) {
+  ASSERT(isAdmissibleType(First));
+  ASSERT(isAdmissibleType(Second));
+
   switch (Kind) {
   case ConstraintKind::Bind:
   case ConstraintKind::Equal:
@@ -84,11 +91,9 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second,
   case ConstraintKind::SameShape:
   case ConstraintKind::MaterializePackExpansion:
   case ConstraintKind::LValueObject:
-    assert(!First.isNull());
-    assert(!Second.isNull());
     break;
   case ConstraintKind::DynamicCallableApplicableFunction:
-    assert(First->is<FunctionType>()
+    ASSERT(First->is<FunctionType>()
            && "The left-hand side type should be a function type");
     break;
 
@@ -99,8 +104,6 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second,
 
   case ConstraintKind::Defaultable:
   case ConstraintKind::FallbackType:
-    assert(!First.isNull());
-    assert(!Second.isNull());
     break;
 
   case ConstraintKind::BindOverload:
@@ -136,6 +139,10 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second, Type Third,
       IsFavored(false), IsIsolated(false),
       NumTypeVariables(typeVars.size()), Types{First, Second, Third},
       Locator(locator) {
+  ASSERT(isAdmissibleType(First));
+  ASSERT(isAdmissibleType(Second));
+  ASSERT(isAdmissibleType(Third));
+
   switch (Kind) {
   case ConstraintKind::Bind:
   case ConstraintKind::Equal:
@@ -180,9 +187,6 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second, Type Third,
 
   case ConstraintKind::KeyPath:
   case ConstraintKind::KeyPathApplication:
-    assert(!First.isNull());
-    assert(!Second.isNull());
-    assert(!Third.isNull());
     break;
   }
 
@@ -256,8 +260,8 @@ Constraint::Constraint(ConstraintKind kind,
       RememberChoice(false), IsFavored(false), IsIsolated(false),
       NumTypeVariables(typeVars.size()), Types{first, second, Type()},
       Locator(locator) {
-  assert(!first.isNull());
-  assert(!second.isNull());
+  ASSERT(isAdmissibleType(first));
+  ASSERT(isAdmissibleType(second));
   std::copy(typeVars.begin(), typeVars.end(), getTypeVariablesBuffer().begin());
 }
 
@@ -269,8 +273,8 @@ Constraint::Constraint(ConstraintKind kind, ConstraintFix *fix, Type first,
       IsFavored(false), IsIsolated(false),
       NumTypeVariables(typeVars.size()), Types{first, second, Type()},
       Locator(locator) {
-  assert(!first.isNull());
-  assert(!second.isNull());
+  ASSERT(isAdmissibleType(first));
+  ASSERT(isAdmissibleType(second));
   std::copy(typeVars.begin(), typeVars.end(), getTypeVariablesBuffer().begin());
   if (fix)
     *getTrailingObjects<ConstraintFix *>() = fix;
@@ -297,8 +301,8 @@ Constraint::Constraint(FunctionType *appliedFn, Type calleeType,
       HasRestriction(false), IsActive(false), IsDisabled(false),
       IsDisabledForPerformance(false), RememberChoice(false), IsFavored(false),
       IsIsolated(false), NumTypeVariables(typeVars.size()), Locator(locator) {
-  assert(appliedFn);
-  assert(calleeType);
+  ASSERT(isAdmissibleType(appliedFn));
+  ASSERT(isAdmissibleType(calleeType));
   assert(trailingClosureMatching >= 0 && trailingClosureMatching <= 2);
   assert(useDC);