[GSB] Consistently use nested type name match constraints.

lib/AST/GenericSignatureBuilder.cpp

@@ -2100,7 +2100,9 @@ TypeDecl *EquivalenceClass::lookupNestedType(
   // Infer same-type constraints among same-named associated type anchors.
   if (assocTypeAnchors.size() > 1) {
     auto anchorType = getAnchor(builder, builder.getGenericParams());
-    auto inferredSource = FloatingRequirementSource::forInferred(nullptr);
+    auto inferredSource =
+      FloatingRequirementSource::forNestedTypeNameMatch(
+        assocTypeAnchors.front()->getName());
     for (auto assocType : assocTypeAnchors) {
       if (assocType == bestAssocType) continue;
 
@@ -4732,7 +4734,8 @@ void GenericSignatureBuilder::addedNestedType(PotentialArchetype *nestedPA) {
   if (allNested.size() > 1) {
     auto firstPA = allNested.front();
     auto inferredSource =
-      FloatingRequirementSource::forInferred(nullptr);
+      FloatingRequirementSource::forNestedTypeNameMatch(
+        nestedPA->getNestedName());
 
     addSameTypeRequirement(firstPA, nestedPA, inferredSource,
                            UnresolvedHandlingKind::GenerateConstraints);

test/Generics/Inputs/rdar48049725_other.swift

@@ -0,0 +1,17 @@
+public protocol P1 {
+  associatedtype A1: SomeClass
+}
+
+public protocol P4: P2 where A2: P1 {}
+
+
+public class SomeClass { }
+
+protocol P5 {
+  associatedtype A3: P4
+}
+
+struct Foo {
+  static func f<T: P5>(_: T) {
+  }
+}

test/Generics/rdar48049725.swift

@@ -0,0 +1,16 @@
+// RUN: %target-swift-frontend -primary-file %s -emit-ir %S/Inputs/rdar48049725_other.swift | %FileCheck %s
+public protocol P3 {
+  associatedtype A1: SomeClass
+}
+
+
+public protocol P2 {
+  associatedtype A2: P3
+}
+
+
+func test<T: P5>(value: T) {
+  // Ensure that we get the right generic signature for Foo.f
+  // CHECK: call swiftcc void @"$s12rdar480497253FooV1fyyxAA2P5RzlFZ"
+  Foo.f(value)
+}

test/Generics/requirement_inference.swift

@@ -154,12 +154,11 @@ protocol P10 {
 }
 
 // CHECK-LABEL: sameTypeConcrete1@
-// CHECK: Canonical generic signature: <τ_0_0 where τ_0_0 : P10, τ_0_0 : P9, τ_0_0.A == X3, τ_0_0.A == X3, τ_0_0.B == Int, τ_0_0.C == Int>
+// CHECK: Canonical generic signature: <τ_0_0 where τ_0_0 : P10, τ_0_0 : P9, τ_0_0.A == X3, τ_0_0.B == Int, τ_0_0.C == Int>
 func sameTypeConcrete1<T : P9 & P10>(_: T) where T.A == X3, T.C == T.B, T.C == Int { }
 
 // CHECK-LABEL: sameTypeConcrete2@
 // CHECK: Canonical generic signature: <τ_0_0 where τ_0_0 : P10, τ_0_0 : P9, τ_0_0.B == X3, τ_0_0.C == X3>
-// FIXME: Should have τ_0_0.A == τ_0_0.A
 func sameTypeConcrete2<T : P9 & P10>(_: T) where T.B : X3, T.C == T.B, T.C == X3 { }
 // expected-warning@-1{{redundant superclass constraint 'T.B' : 'X3'}}
 // expected-note@-2{{same-type constraint 'T.C' == 'X3' written here}}
@@ -402,7 +401,7 @@ protocol P30 {
 protocol P31 { }
 
 // CHECK-LABEL: .sameTypeNameMatch1@
-// CHECK: Generic signature: <T where T : P29, T : P30, T.X : P31, T.X == T.X>
+// CHECK: Generic signature: <T where T : P29, T : P30, T.X : P31>
 func sameTypeNameMatch1<T: P29 & P30>(_: T) where T.X: P31 { }
 
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