Merge pull request #85357 from slavapestov/workaround-rdar160649141

IRGen: Terrible workaround for problem in searchNominalTypeMetadata()

Author: slavapestov

lib/IRGen/Fulfillment.cpp

@@ -380,7 +380,24 @@ bool FulfillmentMap::searchNominalTypeMetadata(IRGenModule &IGM,
 
   for (unsigned reqtIndex : indices(requirements.getRequirements())) {
     auto requirement = requirements.getRequirements()[reqtIndex];
-    auto arg = requirement.getTypeParameter().subst(subs)->getCanonicalType();
+
+    // FIXME: The correct fix is to pass down the substitution map's
+    // output generic signature and reduce the result of subst() with
+    // this signature before forming the lookup key.
+    //
+    // Once that's fixed, change the below back to this:
+    // auto arg = requirement.getTypeParameter().subst(subs)->getCanonicalType();
+
+    auto arg = requirement.getTypeParameter().subst(
+      QuerySubstitutionMap{subs},
+      [&](InFlightSubstitution &IFS, Type origType, ProtocolDecl *proto)
+            -> ProtocolConformanceRef {
+        auto substType = origType.subst(IFS);
+        if (substType->isTypeParameter())
+          return ProtocolConformanceRef::forAbstract(substType, proto);
+
+        return subs.lookupConformance(origType->getCanonicalType(), proto);
+      })->getCanonicalType();
 
     // Skip uninteresting type arguments.
     if (!keys.hasInterestingType(arg))

test/IRGen/fulfillment_map_key_equality.swift

@@ -0,0 +1,44 @@
+// RUN: %target-swift-frontend -emit-ir %s -enable-library-evolution | %FileCheck %s
+
+// FIXME: We just need to adjust the check line below, there's no inherent
+// reason for this not to be tested on wasm.
+// UNSUPPORTED: CPU=wasm32
+
+// rdar://160649141
+
+public protocol P1 {}
+
+public protocol P2 {
+  associatedtype A1
+}
+
+public protocol P5 {
+  associatedtype A2: P2
+}
+
+public protocol P3 where A4.A1 == A3.A2.A1 {
+  associatedtype A3: P5
+  associatedtype A4: P2
+
+  var x: Int { get }
+}
+
+public protocol P6: P3 {}
+
+public protocol P4 {
+  associatedtype A4: P2
+}
+
+public struct G1<A1>: P2 {}
+
+public struct G2<A2: P2>: P5  {}
+
+public struct G3<T: P6 & P4>: P3 where T.A4.A1: P1 {
+  public typealias A4 = G1<T.A3.A2.A1>
+  public typealias A3 = G2<T.A3.A2>
+
+  // Make sure this witness thunk doesn't have any additional bogus parameters.
+
+  // CHECK-LABEL: define internal swiftcc i64 @"$s28fulfillment_map_key_equality2G3VyxGAA2P3A2aEP1xSivgTW"(ptr noalias swiftself captures(none) %0, ptr %Self, ptr %SelfWitnessTable) {{.*}} {
+  public var x: Int { fatalError() }
+}