[ConstraintSystem] Extend solver support for designated types for operators.

Have the constraint solver consider multiple designated types for an
operator. We currently consider the overloads from each in turn,
stopping as soon as we have a solution. As a result, we can still end
up with exponential type checking in some cases if an operator has
more than a single designated type. This still allows us to reduce the
base of that exponent, though, which makes it possible to increase the
number of expressions we can type check successfully in practice.

Author: rudkx

lib/Sema/CSSolver.cpp

@@ -1629,13 +1629,12 @@ static bool isOperatorBindOverload(Constraint *bindOverload) {
 // Given a bind overload constraint for an operator, return the
 // protocol designated as the first place to look for overloads of the
 // operator.
-static NominalTypeDecl *
-getOperatorDesignatedNominalType(Constraint *bindOverload) {
+static ArrayRef<NominalTypeDecl *>
+getOperatorDesignatedNominalTypes(Constraint *bindOverload) {
   auto choice = bindOverload->getOverloadChoice();
   auto *funcDecl = cast<FuncDecl>(choice.getDecl());
   auto *operatorDecl = funcDecl->getOperatorDecl();
-  auto designatedTypes = operatorDecl->getDesignatedNominalTypes();
-  return !designatedTypes.empty() ? designatedTypes[0] : nullptr;
+  return operatorDecl->getDesignatedNominalTypes();
 }
 
 void ConstraintSystem::partitionDisjunction(
@@ -1660,8 +1659,8 @@ void ConstraintSystem::partitionDisjunction(
   SmallVector<unsigned, 4> disabled;
   SmallVector<unsigned, 4> unavailable;
   SmallVector<unsigned, 4> globalScope;
-  SmallVector<unsigned, 4> definedInDesignatedType;
-  SmallVector<unsigned, 4> definedInExtensionOfDesignatedType;
+  SmallVector<SmallVector<unsigned, 4>, 4> definedInDesignatedType;
+  SmallVector<SmallVector<unsigned, 4>, 4> definedInExtensionOfDesignatedType;
   SmallVector<unsigned, 4> everythingElse;
   SmallSet<Constraint *, 16> taken;
 
@@ -1722,28 +1721,43 @@ void ConstraintSystem::partitionDisjunction(
 
   // Now collect the overload choices that are defined within the type
   // that was designated in the operator declaration.
-  auto *designatedNominal = getOperatorDesignatedNominalType(Choices[0]);
-  if (designatedNominal) {
-    forEachChoice(Choices, [&](unsigned index, Constraint *constraint) -> bool {
-        auto *decl = constraint->getOverloadChoice().getDecl();
-        auto *funcDecl = cast<FuncDecl>(decl);
-
-        auto *parentDecl = funcDecl->getParent()->getAsDecl();
-        if (parentDecl == designatedNominal) {
-          definedInDesignatedType.push_back(index);
-          return true;
-        }
+  auto designatedNominalTypes = getOperatorDesignatedNominalTypes(Choices[0]);
+  if (!designatedNominalTypes.empty()) {
+    forEachChoice(
+        Choices, [&](unsigned constraintIndex, Constraint *constraint) -> bool {
+          auto *decl = constraint->getOverloadChoice().getDecl();
+          auto *funcDecl = cast<FuncDecl>(decl);
+
+          auto *parentDecl = funcDecl->getParent()->getAsDecl();
+          for (auto designatedTypeIndex : indices(designatedNominalTypes)) {
+            auto *designatedNominal =
+                designatedNominalTypes[designatedTypeIndex];
+            if (parentDecl == designatedNominal) {
+              if (designatedTypeIndex >= definedInDesignatedType.size())
+                definedInDesignatedType.resize(designatedTypeIndex + 1);
+              auto &constraints = definedInDesignatedType[designatedTypeIndex];
+              constraints.push_back(constraintIndex);
+              return true;
+            }
 
-        if (auto *extensionDecl = dyn_cast<ExtensionDecl>(parentDecl)) {
-          parentDecl = extensionDecl->getExtendedNominal();
-          if (parentDecl == designatedNominal) {
-            definedInExtensionOfDesignatedType.push_back(index);
-            return true;
+            if (auto *extensionDecl = dyn_cast<ExtensionDecl>(parentDecl)) {
+              parentDecl = extensionDecl->getExtendedNominal();
+              if (parentDecl == designatedNominal) {
+                if (designatedTypeIndex >=
+                    definedInExtensionOfDesignatedType.size())
+                  definedInExtensionOfDesignatedType.resize(
+                      designatedTypeIndex + 1);
+
+                auto &constraints =
+                    definedInExtensionOfDesignatedType[designatedTypeIndex];
+                constraints.push_back(constraintIndex);
+                return true;
+              }
+            }
           }
-        }
 
-        return false;
-      });
+          return false;
+        });
   }
 
   // Gather the remaining options.
@@ -1762,8 +1776,19 @@ void ConstraintSystem::partitionDisjunction(
   };
 
   // Now create the partitioning based on what was collected.
-  appendPartition(definedInDesignatedType);
-  appendPartition(definedInExtensionOfDesignatedType);
+
+  // First we'll add partitions for each of the overloads we found in
+  // types that were designated as part of the operator declaration.
+  for (auto designatedTypeIndex : indices(designatedNominalTypes)) {
+    if (designatedTypeIndex < definedInDesignatedType.size()) {
+      auto &primary = definedInDesignatedType[designatedTypeIndex];
+      appendPartition(primary);
+    }
+    if (designatedTypeIndex < definedInExtensionOfDesignatedType.size()) {
+      auto &secondary = definedInExtensionOfDesignatedType[designatedTypeIndex];
+      appendPartition(secondary);
+    }
+  }
   appendPartition(everythingElse);
   appendPartition(globalScope);
   appendPartition(unavailable);

stdlib/public/core/Policy.swift

@@ -422,15 +422,15 @@ infix operator &>> : BitwiseShiftPrecedence, FixedWidthInteger
 
 infix operator   * : MultiplicationPrecedence, Numeric
 infix operator  &* : MultiplicationPrecedence, FixedWidthInteger
-infix operator   / : MultiplicationPrecedence, BinaryInteger
+infix operator   / : MultiplicationPrecedence, BinaryInteger, FloatingPoint
 infix operator   % : MultiplicationPrecedence, BinaryInteger
 infix operator   & : MultiplicationPrecedence, BinaryInteger
 
 // "Additive"
 
-infix operator   + : AdditionPrecedence, Numeric
+infix operator   + : AdditionPrecedence, Numeric, String, Strideable
 infix operator  &+ : AdditionPrecedence, FixedWidthInteger
-infix operator   - : AdditionPrecedence, Numeric
+infix operator   - : AdditionPrecedence, Numeric, Strideable
 infix operator  &- : AdditionPrecedence, FixedWidthInteger
 infix operator   | : AdditionPrecedence, BinaryInteger
 infix operator   ^ : AdditionPrecedence, BinaryInteger
@@ -482,9 +482,9 @@ infix operator   *= : AssignmentPrecedence, Numeric
 infix operator  &*= : AssignmentPrecedence, FixedWidthInteger
 infix operator   /= : AssignmentPrecedence, BinaryInteger
 infix operator   %= : AssignmentPrecedence, BinaryInteger
-infix operator   += : AssignmentPrecedence, Numeric
+infix operator   += : AssignmentPrecedence, Numeric, String, Strideable
 infix operator  &+= : AssignmentPrecedence, FixedWidthInteger
-infix operator   -= : AssignmentPrecedence, Numeric
+infix operator   -= : AssignmentPrecedence, Numeric, Strideable
 infix operator  &-= : AssignmentPrecedence, FixedWidthInteger
 infix operator  <<= : AssignmentPrecedence, BinaryInteger
 infix operator &<<= : AssignmentPrecedence, FixedWidthInteger

validation-test/Sema/type_checker_perf/slow/rdar17170728.swift renamed to validation-test/Sema/type_checker_perf/fast/rdar17170728.swift

@@ -1,11 +1,10 @@
-// RUN: %target-typecheck-verify-swift -solver-expression-time-threshold=1
+// RUN: %target-typecheck-verify-swift -solver-expression-time-threshold=1 -swift-version 5 -solver-disable-shrink -disable-constraint-solver-performance-hacks -solver-enable-operator-designated-types
 // REQUIRES: tools-release,no_asserts
 
 let i: Int? = 1
 let j: Int?
 let k: Int? = 2
 
 let _ = [i, j, k].reduce(0 as Int?) {
-  // expected-error@-1 {{reasonable time}}
   $0 != nil && $1 != nil ? $0! + $1! : ($0 != nil ? $0! : ($1 != nil ? $1! : nil))
 }