Remove lazy member loading re-entrancy guards

Effectively revert #28907. The request evaluator will also catch re-entrancy here, and those cycles can be broken with NameLookupFlags::IgnoreNewExtensions.

Author: CodaFi

include/swift/AST/DeclContext.h

@@ -681,18 +681,9 @@ enum class IterableDeclContextKind : uint8_t {
 /// Note that an iterable declaration context must inherit from both
 /// \c IterableDeclContext and \c DeclContext.
 class IterableDeclContext {
-  enum LazyMembers : unsigned {
-    Present = 1 << 0,
-
-    /// Lazy member loading has a variety of feedback loops that need to
-    /// switch to pseudo-empty-member behaviour to avoid infinite recursion;
-    /// we use this flag to control them.
-    InProgress = 1 << 1,
-  };
-
   /// The first declaration in this context along with a bit indicating whether
   /// the members of this context will be lazily produced.
-  mutable llvm::PointerIntPair<Decl *, 2, LazyMembers> FirstDeclAndLazyMembers;
+  mutable llvm::PointerIntPair<Decl *, 1, bool> FirstDeclAndLazyMembers;
 
   /// The last declaration in this context, used for efficient insertion,
   /// along with the kind of iterable declaration context.
@@ -780,20 +771,7 @@ class IterableDeclContext {
 
   /// Check whether there are lazily-loaded members.
   bool hasLazyMembers() const {
-    return FirstDeclAndLazyMembers.getInt() & LazyMembers::Present;
-  }
-
-  bool isLoadingLazyMembers() {
-    return FirstDeclAndLazyMembers.getInt() & LazyMembers::InProgress;
-  }
-
-  void setLoadingLazyMembers(bool inProgress) {
-    LazyMembers status = FirstDeclAndLazyMembers.getInt();
-    if (inProgress)
-      status = LazyMembers(status | LazyMembers::InProgress);
-    else
-      status = LazyMembers(status & ~LazyMembers::InProgress);
-    FirstDeclAndLazyMembers.setInt(status);
+    return FirstDeclAndLazyMembers.getInt();
   }
 
   /// Setup the loader for lazily-loaded members.

lib/AST/DeclContext.cpp

@@ -798,8 +798,7 @@ void IterableDeclContext::setMemberLoader(LazyMemberLoader *loader,
 
   ASTContext &ctx = getASTContext();
   auto contextInfo = ctx.getOrCreateLazyIterableContextData(this, loader);
-  auto lazyMembers = FirstDeclAndLazyMembers.getInt() | LazyMembers::Present;
-  FirstDeclAndLazyMembers.setInt(LazyMembers(lazyMembers));
+  FirstDeclAndLazyMembers.setInt(true);
   contextInfo->memberData = contextData;
 
   ++NumLazyIterableDeclContexts;
@@ -855,12 +854,11 @@ void IterableDeclContext::loadAllMembers() const {
     return;
 
   // Don't try to load all members re-entrant-ly.
-  auto contextInfo = ctx.getOrCreateLazyIterableContextData(this,
-    /*lazyLoader=*/nullptr);
-  auto lazyMembers = FirstDeclAndLazyMembers.getInt() & ~LazyMembers::Present;
-  FirstDeclAndLazyMembers.setInt(LazyMembers(lazyMembers));
+  FirstDeclAndLazyMembers.setInt(false);
 
   const Decl *container = getDecl();
+  auto contextInfo = ctx.getOrCreateLazyIterableContextData(this,
+    /*lazyLoader=*/nullptr);
   contextInfo->loader->loadAllMembers(const_cast<Decl *>(container),
                                       contextInfo->memberData);
 

lib/AST/NameLookup.cpp

@@ -1148,11 +1148,9 @@ populateLookupTableEntryFromLazyIDCLoader(ASTContext &ctx,
                                           MemberLookupTable &LookupTable,
                                           DeclBaseName name,
                                           IterableDeclContext *IDC) {
-  IDC->setLoadingLazyMembers(true);
   auto ci = ctx.getOrCreateLazyIterableContextData(IDC,
                                                    /*lazyLoader=*/nullptr);
   if (auto res = ci->loader->loadNamedMembers(IDC, name, ci->memberData)) {
-    IDC->setLoadingLazyMembers(false);
     if (auto s = ctx.Stats) {
       ++s->getFrontendCounters().NamedLazyMemberLoadSuccessCount;
     }
@@ -1161,7 +1159,6 @@ populateLookupTableEntryFromLazyIDCLoader(ASTContext &ctx,
     }
     return false;
   } else {
-    IDC->setLoadingLazyMembers(false);
     if (auto s = ctx.Stats) {
       ++s->getFrontendCounters().NamedLazyMemberLoadFailureCount;
     }
@@ -1285,7 +1282,6 @@ DirectLookupRequest::evaluate(Evaluator &evaluator,
                           << useNamedLazyMemberLoading
                           << "\n");
 
-
   decl->prepareLookupTable();
 
   auto tryCacheLookup =