Merge pull request #17402 from adrian-prantl/archetypes-removal

Author: swift-ci

docs/ABI/Mangling.rst

@@ -467,7 +467,6 @@ Types
 
   assoc-type-list ::= assoc-type-name '_' assoc-type-name*
 
-  archetype ::= context 'Qq' INDEX           // archetype+context (DWARF only)
   archetype ::= associated-type
 
   associated-type ::= substitution

lib/AST/ASTMangler.cpp

@@ -886,49 +886,8 @@ void ASTMangler::appendType(Type type) {
       return appendImplFunctionType(cast<SILFunctionType>(tybase));
 
       // type ::= archetype
-    case TypeKind::Archetype: {
-      auto *archetype = cast<ArchetypeType>(tybase);
-
-      assert(false && DWARFMangling && "Cannot mangle free-standing archetypes");
-
-      // Mangle the associated type of a parent archetype.
-      if (auto parent = archetype->getParent()) {
-        assert(archetype->getAssocType()
-               && "child archetype has no associated type?!");
-
-        if (tryMangleSubstitution(archetype))
-          return;
-        appendType(parent);
-        appendIdentifier(archetype->getName().str());
-        appendOperator("Qa");
-        addSubstitution(archetype);
-        return;
-      }
-
-      // archetype ::= 'Q' <index>             # archetype with depth=0, index=N
-      // archetype ::= 'Qd' <index> <index>    # archetype with depth=M+1, index=N
-      // Mangle generic parameter archetypes.
-
-      // Find the archetype information.
-      const DeclContext *DC = DeclCtx;
-      auto GTPT = archetype->getInterfaceType()->castTo<GenericTypeParamType>();
-
-      // The DWARF output created by Swift is intentionally flat,
-      // therefore archetypes are emitted with their DeclContext if
-      // they appear at the top level of a type.
-      DWARFMangling = false;
-      while (DC && DC->isGenericContext()) {
-        if (DC->isInnermostContextGeneric() &&
-            DC->getGenericParamsOfContext()->getDepth() == GTPT->getDepth())
-          break;
-        DC = DC->getParent();
-      }
-      assert(DC && "no decl context for archetype found");
-      if (!DC) return;
-      appendContext(DC);
-      DWARFMangling = true;
-      return appendOperator("Qq", Index(GTPT->getIndex()));
-    }
+    case TypeKind::Archetype:
+      llvm_unreachable("Cannot mangle free-standing archetypes");
 
     case TypeKind::DynamicSelf: {
       auto dynamicSelf = cast<DynamicSelfType>(tybase);