[ABI] Use faux mangled names for associated conformances in witness tables

docs/ABI/Mangling.rst

@@ -90,6 +90,9 @@ The following symbolic reference kinds are currently implemented:
    dependent-associated-conformance ::= '\x05' .{4}  // Reference points directly to associated conformance descriptor (NOT IMPLEMENTED)
    dependent-associated-conformance ::= '\x06' .{4}  // Reference points indirectly to associated conformance descriptor (NOT IMPLEMENTED)
 
+   associated-conformance-acceess-function ::= '\x07' .{4}  // Reference points directly to associated conformance access function relative to the protocol
+   associated-conformance-acceess-function ::= '\x08' .{4}  // Reference points directly to associated conformance access function relative to the conforming type
+
 Globals
 ~~~~~~~
 

include/swift/AST/LazyResolver.h

@@ -78,6 +78,10 @@ class LazyResolver {
   /// Mark the given conformance as "used" from the given declaration context.
   virtual void markConformanceUsed(ProtocolConformanceRef conformance,
                                    DeclContext *dc) = 0;
+
+  /// Fill in the signature conformances of the given protocol conformance.
+  virtual void checkConformanceRequirements(
+                                    NormalProtocolConformance *conformance) = 0;
 };
 
 class LazyMemberLoader;

include/swift/Runtime/Metadata.h

@@ -429,7 +429,7 @@ MetadataResponse swift_getAssociatedTypeWitness(
 ///
 /// \param wtable The witness table.
 /// \param conformingType Metadata for the conforming type.
-/// \param assocType Metadata for the sasociated type.
+/// \param assocType Metadata for the associated type.
 /// \param reqBase "Base" requirement used to compute the witness index
 /// \param assocConformance Associated conformance descriptor.
 ///

lib/AST/ProtocolConformance.cpp

@@ -850,6 +850,14 @@ NormalProtocolConformance::getAssociatedConformance(Type assocType,
                                                 LazyResolver *resolver) const {
   assert(assocType->isTypeParameter() &&
          "associated type must be a type parameter");
+
+  // Fill in the signature conformances, if we haven't done so yet.
+  if (getSignatureConformances().empty()) {
+    assocType->getASTContext().getLazyResolver()
+      ->checkConformanceRequirements(
+        const_cast<NormalProtocolConformance *>(this));
+  }
+
   assert(!getSignatureConformances().empty() &&
          "signature conformances not yet computed");
 

lib/IRGen/GenMeta.cpp

@@ -788,15 +788,15 @@ namespace {
           continue;
 
         auto witness = entry.getAssociatedTypeProtocolWitness().Witness;
-        return getDefaultAssociatedConformanceAccessFunction(
-                 AssociatedConformance(Proto, association, requirement),
-                 witness);
+        AssociatedConformance conformance(Proto, association, requirement);
+        defineDefaultAssociatedConformanceAccessFunction(conformance, witness);
+        return IGM.getMangledAssociatedConformance(nullptr, conformance);
       }
 
       return nullptr;
     }
 
-    llvm::Constant *getDefaultAssociatedConformanceAccessFunction(
+    void defineDefaultAssociatedConformanceAccessFunction(
                       AssociatedConformance requirement,
                       ProtocolConformanceRef conformance) {
       auto accessor =
@@ -839,7 +839,7 @@ namespace {
                                                     conformance.getConcrete());
         auto returnValue = conformanceI->getTable(IGF, &associatedTypeMetadata);
         IGF.Builder.CreateRet(returnValue);
-        return accessor;
+        return;
       }
 
       // For an abstract table, emit a reference to the witness table.
@@ -852,7 +852,7 @@ namespace {
             cast<ArchetypeType>(associatedTypeInContext),
             associatedProtocol);
       IGF.Builder.CreateRet(returnValue);
-      return accessor;
+      return;
     }
 
     void addAssociatedTypeNames() {