GSB: Remove checkConformanceConstraints()

Author: slavapestov

include/swift/AST/GenericSignatureBuilder.h

@@ -723,12 +723,6 @@ class GenericSignatureBuilder {
                             TypeArrayView<GenericTypeParamType> genericParams,
                             EquivalenceClass *equivClass);
 
-  /// Check conformance constraints within the equivalence class of the
-  /// given potential archetype.
-  void checkConformanceConstraints(
-                            TypeArrayView<GenericTypeParamType> genericParams,
-                            EquivalenceClass *equivClass);
-
   /// Check same-type constraints within the equivalence class of the
   /// given potential archetype.
   void checkSameTypeConstraints(

lib/AST/GenericSignatureBuilder.cpp

@@ -2828,6 +2828,7 @@ static void concretizeNestedTypeFromConcreteParent(
   assert(parentEquiv->conformsTo.count(proto) > 0 &&
          "No conformance requirement");
   const RequirementSource *parentConcreteSource = nullptr;
+
   for (const auto &constraint : parentEquiv->conformsTo.find(proto)->second) {
     if (!isSuperclassConstrained) {
       if (constraint.source->kind == RequirementSource::Concrete) {
@@ -5796,16 +5797,24 @@ static void expandSameTypeConstraints(GenericSignatureBuilder &builder,
       bool alreadyFound = false;
       const RequirementSource *conformsSource = nullptr;
       for (const auto &constraint : conforms.second) {
-        if (constraint.source->getAffectedType()->isEqual(dependentType)) {
+        bool derivedViaConcrete = false;
+
+        auto *minimal = constraint.source->getMinimalConformanceSource(
+            builder, constraint.getSubjectDependentType({ }), proto,
+            derivedViaConcrete);
+
+        if (minimal == nullptr || derivedViaConcrete)
+          continue;
+
+        if (minimal->getAffectedType()->isEqual(dependentType)) {
           alreadyFound = true;
           break;
         }
 
         // Capture the source for later use, skipping
         if (!conformsSource &&
-            constraint.source->kind
-              != RequirementSource::RequirementSignatureSelf)
-          conformsSource = constraint.source;
+            minimal->kind != RequirementSource::RequirementSignatureSelf)
+          conformsSource = minimal;
       }
 
       if (alreadyFound) continue;
@@ -6382,9 +6391,7 @@ GenericSignatureBuilder::finalize(TypeArrayView<GenericTypeParamType> genericPar
         equivClass.recursiveSuperclassType = true;
       }
     }
-
-    checkConformanceConstraints(genericParams, &equivClass);
-  };
+  }
 
   if (!Impl->ExplicitSameTypeRequirements.empty()) {
     // FIXME: Expand all conformance requirements. This is expensive :(
@@ -6855,18 +6862,6 @@ static bool isRedundantlyInheritableObjCProtocol(
   return true;
 }
 
-void GenericSignatureBuilder::checkConformanceConstraints(
-                          TypeArrayView<GenericTypeParamType> genericParams,
-                          EquivalenceClass *equivClass) {
-  for (auto &entry : equivClass->conformsTo) {
-    // Remove self-derived constraints.
-    assert(!entry.second.empty() && "No constraints to work with?");
-
-    // Remove any self-derived constraints.
-    removeSelfDerived(*this, entry.second, entry.first);
-  }
-}
-
 void GenericSignatureBuilder::diagnoseRedundantRequirements() const {
   for (const auto &req : Impl->ExplicitRequirements) {
     auto *source = req.getSource();

test/Generics/sr14580.swift

@@ -0,0 +1,32 @@
+// RUN: %target-typecheck-verify-swift
+// RUN: %target-swift-frontend -typecheck -debug-generic-signatures %s 2>&1 | %FileCheck %s
+
+public protocol ScalarProtocol: ScalarMultiplicative where Self == Scalar {
+}
+
+public protocol ScalarMultiplicative {
+  associatedtype Scalar: ScalarProtocol
+}
+
+public protocol MapReduceArithmetic: ScalarMultiplicative, Collection where Element: ScalarMultiplicative {}
+
+public protocol Tensor: MapReduceArithmetic where Element == Scalar {
+}
+
+// FIXME: The same-type requirement canonicalization still produces bugus results here, but
+// at least we don't crash.
+
+// CHECK-LABEL: Requirement signature: <Self where Self : Tensor, Self == Self.Float16Components.Model, Self.Element == Double, Self.Float16Components : ColorComponents, Self.Float32Components : ColorComponents, Self.Float16Components.Element == Double, Self.Float16Components.Model == Self.Float32Components.Model, Self.Float32Components.Element == Double, Self.Float32Components.Indices == Self.Float32Components.Indices.SubSequence, Self.Float32Components.SubSequence == Self.Float32Components.SubSequence.SubSequence, Self.Float32Components.Indices.Indices == Self.Float32Components.Indices.Indices.SubSequence, Self.Float32Components.SubSequence.Indices == Self.Float32Components.SubSequence.Indices.SubSequence, Self.Float32Components.SubSequence.Indices.Indices == Self.Float32Components.SubSequence.Indices.Indices.SubSequence>
+public protocol ColorModel: Tensor where Scalar == Double {
+  associatedtype Float16Components: ColorComponents where Float16Components.Model == Self, Float16Components.Scalar == Double
+  associatedtype Float32Components: ColorComponents where Float32Components.Model == Self, Float32Components.Scalar == Double
+}
+
+public protocol ColorComponents: Tensor {
+  associatedtype Model: ColorModel
+}
+
+extension Double : ScalarMultiplicative {}
+extension Double : ScalarProtocol {
+  public typealias Scalar = Self
+}