[NFC] add llvm namespace to Optional and None

This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
                     bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".

I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.

Author: etcwilde

include/swift/APIDigester/ModuleAnalyzerNodes.h

@@ -179,7 +179,7 @@ class SDKContext {
   CheckerOptions Opts;
   std::vector<BreakingAttributeInfo> BreakingAttrs;
   // The common version of two ABI/API descriptors under comparison.
-  Optional<uint8_t> CommonVersion;
+  llvm::Optional<uint8_t> CommonVersion;
 public:
   // Define the set of known identifiers.
 #define IDENTIFIER_WITH_NAME(Name, IdStr) StringRef Id_##Name = IdStr;
@@ -231,7 +231,7 @@ class SDKContext {
   const CheckerOptions &getOpts() const { return Opts; }
   bool shouldIgnore(Decl *D, const Decl* Parent = nullptr) const;
   ArrayRef<BreakingAttributeInfo> getBreakingAttributeInfo() const { return BreakingAttrs; }
-  Optional<uint8_t> getFixedBinaryOrder(ValueDecl *VD) const;
+  llvm::Optional<uint8_t> getFixedBinaryOrder(ValueDecl *VD) const;
 
   CompilerInstance &newCompilerInstance() {
     CIs.emplace_back(new CompilerInstance());
@@ -363,7 +363,7 @@ class SDKNodeDecl: public SDKNode {
   // In ABI mode, this field is populated as a user-friendly version of GenericSig.
   // Diagnostic preferes the sugared versions if they differ as well.
   StringRef SugaredGenericSig;
-  Optional<uint8_t> FixedBinaryOrder;
+  llvm::Optional<uint8_t> FixedBinaryOrder;
   PlatformIntroVersion introVersions;
   StringRef ObjCName;
 
@@ -586,11 +586,11 @@ class SDKNodeDeclType: public SDKNodeDecl {
     return InheritsConvenienceInitializers;
   };
 
-  Optional<SDKNodeDeclType*> getSuperclass() const;
+  llvm::Optional<SDKNodeDeclType*> getSuperclass() const;
 
   /// Finding the node through all children, including the inherited ones,
   /// whose printed name matches with the given name.
-  Optional<SDKNodeDecl*> lookupChildByPrintedName(StringRef Name) const;
+  llvm::Optional<SDKNodeDecl*> lookupChildByPrintedName(StringRef Name) const;
   SDKNodeType *getRawValueType() const;
   bool isConformingTo(KnownProtocolKind Kind) const;
   void jsonize(json::Output &out) override;
@@ -684,7 +684,7 @@ class SDKNodeDeclMacro : public SDKNodeDecl {
 class SDKNodeDeclAbstractFunc : public SDKNodeDecl {
   bool IsThrowing;
   bool ReqNewWitnessTableEntry;
-  Optional<uint8_t> SelfIndex;
+  llvm::Optional<uint8_t> SelfIndex;
 
 protected:
   SDKNodeDeclAbstractFunc(SDKNodeInitInfo Info, SDKNodeKind Kind);
@@ -693,7 +693,7 @@ class SDKNodeDeclAbstractFunc : public SDKNodeDecl {
   bool isThrowing() const { return IsThrowing; }
   bool reqNewWitnessTableEntry() const { return ReqNewWitnessTableEntry; }
   uint8_t getSelfIndex() const { return SelfIndex.value(); }
-  Optional<uint8_t> getSelfIndexOptional() const { return SelfIndex; }
+  llvm::Optional<uint8_t> getSelfIndexOptional() const { return SelfIndex; }
   bool hasSelfIndex() const { return SelfIndex.has_value(); }
   static bool classof(const SDKNode *N);
   virtual void jsonize(json::Output &out) override;

include/swift/AST/ASTContext.h

@@ -168,7 +168,7 @@ enum class KnownFoundationEntity {
 
 /// Retrieve the Foundation entity kind for the given Objective-C
 /// entity name.
-Optional<KnownFoundationEntity> getKnownFoundationEntity(StringRef name);
+llvm::Optional<KnownFoundationEntity> getKnownFoundationEntity(StringRef name);
 
 /// Retrieve the Swift name for the given Foundation entity, where
 /// "NS" prefix stripping will apply under omit-needless-words.
@@ -343,7 +343,7 @@ class ASTContext final {
   unsigned NumTypoCorrections = 0;
 
   /// Cached mapping from types to their associated tangent spaces.
-  llvm::DenseMap<Type, Optional<TangentSpace>> AutoDiffTangentSpaces;
+  llvm::DenseMap<Type, llvm::Optional<TangentSpace>> AutoDiffTangentSpaces;
 
   /// A cache of derivative function types per configuration.
   llvm::DenseMap<SILAutoDiffDerivativeFunctionKey, CanSILFunctionType>
@@ -804,7 +804,7 @@ class ASTContext final {
   /// SIL analog of \c ASTContext::getClangFunctionType .
   const clang::Type *
   getCanonicalClangFunctionType(
-    ArrayRef<SILParameterInfo> params, Optional<SILResultInfo> result,
+    ArrayRef<SILParameterInfo> params, llvm::Optional<SILResultInfo> result,
     SILFunctionType::Representation trueRep);
 
   /// Instantiates "Impl.Converter" if needed, then translate Swift generic
@@ -1031,22 +1031,22 @@ class ASTContext final {
 
   /// Retrieve the module dependencies for the module with the given name.
   ///
-  Optional<const ModuleDependencyInfo*> getModuleDependencies(
+  llvm::Optional<const ModuleDependencyInfo*> getModuleDependencies(
       StringRef moduleName,
       ModuleDependenciesCache &cache,
       InterfaceSubContextDelegate &delegate,
       bool optionalDependencyLookup = false,
       bool isTestableImport = false,
-      llvm::Optional<std::pair<std::string, swift::ModuleDependencyKind>> dependencyOf = None);
+      llvm::Optional<std::pair<std::string, swift::ModuleDependencyKind>> dependencyOf = llvm::None);
 
   /// Retrieve the module dependencies for the Clang module with the given name.
-  Optional<const ModuleDependencyInfo*> getClangModuleDependencies(
+  llvm::Optional<const ModuleDependencyInfo*> getClangModuleDependencies(
       StringRef moduleName,
       ModuleDependenciesCache &cache,
       InterfaceSubContextDelegate &delegate);
 
   /// Retrieve the module dependencies for the Swift module with the given name.
-  Optional<const ModuleDependencyInfo*> getSwiftModuleDependencies(
+  llvm::Optional<const ModuleDependencyInfo*> getSwiftModuleDependencies(
       StringRef moduleName,
       ModuleDependenciesCache &cache,
       InterfaceSubContextDelegate &delegate);
@@ -1519,7 +1519,7 @@ class ASTContext final {
 private:
   friend Decl;
 
-  Optional<ExternalSourceLocs *> getExternalSourceLocs(const Decl *D);
+  llvm::Optional<ExternalSourceLocs *> getExternalSourceLocs(const Decl *D);
   void setExternalSourceLocs(const Decl *D, ExternalSourceLocs *Locs);
 
   friend TypeBase;

include/swift/AST/ASTDemangler.h

@@ -24,6 +24,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Optional.h"
 #include "swift/AST/Types.h"
 #include "swift/Demangling/Demangler.h"
 #include "swift/Demangling/NamespaceMacros.h"
@@ -126,7 +127,7 @@ class ASTBuilder {
     Demangle::ImplParameterConvention calleeConvention,
     ArrayRef<Demangle::ImplFunctionParam<Type>> params,
     ArrayRef<Demangle::ImplFunctionResult<Type>> results,
-    Optional<Demangle::ImplFunctionResult<Type>> errorResult,
+    llvm::Optional<Demangle::ImplFunctionResult<Type>> errorResult,
     ImplFunctionTypeFlags flags);
 
   Type createProtocolCompositionType(ArrayRef<ProtocolDecl *> protocols,
@@ -143,10 +144,10 @@ class ASTBuilder {
                                              ArrayRef<Type> genArgs);
 
   Type createExistentialMetatypeType(Type instance,
-                     Optional<Demangle::ImplMetatypeRepresentation> repr=None);
+                     llvm::Optional<Demangle::ImplMetatypeRepresentation> repr=llvm::None);
 
   Type createMetatypeType(Type instance,
-                     Optional<Demangle::ImplMetatypeRepresentation> repr=None);
+                     llvm::Optional<Demangle::ImplMetatypeRepresentation> repr=llvm::None);
 
   Type createGenericTypeParameterType(unsigned depth, unsigned index);
 
@@ -222,7 +223,7 @@ class ASTBuilder {
     SynthesizedByImporter
   };
 
-  Optional<ForeignModuleKind>
+  llvm::Optional<ForeignModuleKind>
   getForeignModuleKind(NodePointer node);
 
   GenericTypeDecl *findTypeDecl(DeclContext *dc,

include/swift/AST/ASTMangler.h

@@ -18,6 +18,7 @@
 #include "swift/AST/Decl.h"
 #include "swift/AST/FreestandingMacroExpansion.h"
 #include "swift/Basic/TaggedUnion.h"
+#include "llvm/ADT/Optional.h"
 
 namespace clang {
 class NamedDecl;
@@ -254,7 +255,7 @@ class ASTMangler : public Mangler {
   std::string mangleObjCAsyncCompletionHandlerImpl(CanSILFunctionType BlockType,
                                                    CanType ResultType,
                                                    CanGenericSignature Sig,
-                                                   Optional<bool> FlagParamIsZeroOnError,
+                                                   llvm::Optional<bool> FlagParamIsZeroOnError,
                                                    bool predefined);
 
   /// Mangle the derivative function (JVP/VJP), or optionally its vtable entry
@@ -381,7 +382,7 @@ class ASTMangler : public Mangler {
     ClangImporterContext,
   };
 
-  static Optional<SpecialContext>
+  static llvm::Optional<SpecialContext>
   getSpecialManglingContext(const ValueDecl *decl, bool useObjCProtocolNames);
 
   static bool isCXXCFOptionsDefinition(const ValueDecl *decl);

include/swift/AST/ASTPrinter.h

@@ -133,7 +133,7 @@ class ASTPrinter {
   /// Called before printing of a declaration.
   ///
   /// Callers should use callPrintDeclPre().
-  virtual void printDeclPre(const Decl *D, Optional<BracketOptions> Bracket) {}
+  virtual void printDeclPre(const Decl *D, llvm::Optional<BracketOptions> Bracket) {}
   /// Called before printing at the point which would be considered the location
   /// of the declaration (normally the name of the declaration).
   ///
@@ -147,7 +147,7 @@ class ASTPrinter {
   /// Called after finishing printing of a declaration.
   ///
   /// Callers should use callPrintDeclPost().
-  virtual void printDeclPost(const Decl *D, Optional<BracketOptions> Bracket) {}
+  virtual void printDeclPost(const Decl *D, llvm::Optional<BracketOptions> Bracket) {}
 
   /// Called before printing the result type of the declaration. Printer can
   /// replace \p TL to customize the input.
@@ -176,12 +176,12 @@ class ASTPrinter {
   /// Called before printing a synthesized extension.
   virtual void printSynthesizedExtensionPre(const ExtensionDecl *ED,
                                             TypeOrExtensionDecl NTD,
-                                            Optional<BracketOptions> Bracket) {}
+                                            llvm::Optional<BracketOptions> Bracket) {}
 
   /// Called after printing a synthesized extension.
   virtual void printSynthesizedExtensionPost(const ExtensionDecl *ED,
                                              TypeOrExtensionDecl TargetDecl,
-                                             Optional<BracketOptions> Bracket) {
+                                             llvm::Optional<BracketOptions> Bracket) {
   }
 
   /// Called before printing a structured entity.
@@ -304,10 +304,10 @@ class ASTPrinter {
   // MARK: Callback interface wrappers that perform ASTPrinter bookkeeping.
 
    /// Make a callback to printDeclPre(), performing any necessary bookkeeping.
-  void callPrintDeclPre(const Decl *D, Optional<BracketOptions> Bracket);
+  void callPrintDeclPre(const Decl *D, llvm::Optional<BracketOptions> Bracket);
 
   /// Make a callback to printDeclPost(), performing any necessary bookkeeping.
-  void callPrintDeclPost(const Decl *D, Optional<BracketOptions> Bracket) {
+  void callPrintDeclPost(const Decl *D, llvm::Optional<BracketOptions> Bracket) {
     printDeclPost(D, Bracket);
   }
 

include/swift/AST/ASTScope.h

@@ -39,6 +39,7 @@
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Optional.h"
 
 /// In case there's a bug in the ASTScope lookup system, suggest that the user
 /// try disabling it.
@@ -152,7 +153,7 @@ class ASTScopeImpl : public ASTAllocated<ASTScopeImpl> {
   /// Child scopes, sorted by source range.
   Children storedChildren;
 
-  mutable Optional<CharSourceRange> cachedCharSourceRange;
+  mutable llvm::Optional<CharSourceRange> cachedCharSourceRange;
 
 #pragma mark - constructor / destructor
 public:
@@ -922,11 +923,11 @@ class AbstractPatternEntryScope : public ASTScopeImpl {
 
 class PatternEntryDeclScope final : public AbstractPatternEntryScope {
   const bool isLocalBinding;
-  Optional<SourceLoc> endLoc;
+  llvm::Optional<SourceLoc> endLoc;
 
 public:
   PatternEntryDeclScope(PatternBindingDecl *pbDecl, unsigned entryIndex,
-                        bool isLocalBinding, Optional<SourceLoc> endLoc)
+                        bool isLocalBinding, llvm::Optional<SourceLoc> endLoc)
       : AbstractPatternEntryScope(pbDecl, entryIndex),
         isLocalBinding(isLocalBinding), endLoc(endLoc) {}
   virtual ~PatternEntryDeclScope() {}

include/swift/AST/ASTTypeIDZone.def

@@ -62,9 +62,9 @@ SWIFT_TYPEID_NAMED(NamedPattern *, NamedPattern)
 SWIFT_TYPEID_NAMED(NominalTypeDecl *, NominalTypeDecl)
 SWIFT_TYPEID_NAMED(OpaqueTypeDecl *, OpaqueTypeDecl)
 SWIFT_TYPEID_NAMED(OperatorDecl *, OperatorDecl)
-SWIFT_TYPEID_NAMED(Optional<PropertyWrapperLValueness>,
+SWIFT_TYPEID_NAMED(llvm::Optional<PropertyWrapperLValueness>,
                    PropertyWrapperLValueness)
-SWIFT_TYPEID_NAMED(Optional<PropertyWrapperMutability>,
+SWIFT_TYPEID_NAMED(llvm::Optional<PropertyWrapperMutability>,
                    PropertyWrapperMutability)
 SWIFT_TYPEID_NAMED(ParamDecl *, ParamDecl)
 SWIFT_TYPEID_NAMED(PatternBindingEntry *, PatternBindingEntry)

include/swift/AST/ASTTypeIDs.h

@@ -19,6 +19,7 @@
 
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/TypeID.h"
+#include "llvm/ADT/Optional.h"
 
 namespace swift {
 

include/swift/AST/ASTWalker.h

@@ -51,13 +51,13 @@ struct ReferenceMetaData {
   bool isImplicitCtorType = false;
 
   /// When non-none, this is a custom attribute reference.
-  Optional<std::pair<const CustomAttr *, Decl *>> CustomAttrRef;
+  llvm::Optional<std::pair<const CustomAttr *, Decl *>> CustomAttrRef;
 
   ReferenceMetaData(
       SemaReferenceKind Kind, llvm::Optional<AccessKind> AccKind,
       bool isImplicit = false,
-      Optional<std::pair<const CustomAttr *, Decl *>> customAttrRef
-        = None
+      llvm::Optional<std::pair<const CustomAttr *, Decl *>> customAttrRef
+        = llvm::None
   ) : Kind(Kind), AccKind(AccKind), isImplicit(isImplicit),
       CustomAttrRef(customAttrRef) {}
 };
@@ -319,7 +319,7 @@ class ASTWalker {
   template <typename T>
   struct PreWalkResult {
     PreWalkAction Action;
-    Optional<T> Value;
+    llvm::Optional<T> Value;
 
     template <typename U,
               typename std::enable_if<std::is_convertible<U, T>::value>::type
@@ -353,7 +353,7 @@ class ASTWalker {
           Value(std::move(Result.Value)) {}
 
     PreWalkResult(_Detail::StopWalkAction)
-        : Action(PreWalkAction::Stop), Value(None) {}
+        : Action(PreWalkAction::Stop), Value(llvm::None) {}
   };
 
   /// Do not construct directly, use \c Action::<action> instead.
@@ -364,7 +364,7 @@ class ASTWalker {
   template <typename T>
   struct PostWalkResult {
     PostWalkAction Action;
-    Optional<T> Value;
+    llvm::Optional<T> Value;
 
     template <typename U,
               typename std::enable_if<std::is_convertible<U, T>::value>::type
@@ -392,7 +392,7 @@ class ASTWalker {
           Value(std::move(Result.Value)) {}
 
     PostWalkResult(_Detail::StopWalkAction)
-        : Action(PostWalkAction::Stop), Value(None) {}
+        : Action(PostWalkAction::Stop), Value(llvm::None) {}
   };
 
   /// This method is called when first visiting an expression

include/swift/AST/AbstractSourceFileDepGraphFactory.h

@@ -17,6 +17,7 @@
 #include "swift/AST/DeclContext.h"
 #include "swift/AST/FineGrainedDependencies.h"
 #include "llvm/Support/VirtualOutputBackend.h"
+#include "llvm/ADT/Optional.h"
 
 namespace swift {
 class DiagnosticEngine;
@@ -90,26 +91,26 @@ class AbstractSourceFileDepGraphFactory {
   /// represent some \c Decl defined in this source file. \param key the
   /// interface key of the pair
   void addADefinedDecl(const DependencyKey &key,
-                       Optional<Fingerprint> fingerprint);
+                       llvm::Optional<Fingerprint> fingerprint);
 
   void addAUsedDecl(const DependencyKey &def, const DependencyKey &use);
 
   /// Add an external dependency node to the graph. If the provided fingerprint
   /// is not \c None, it is added to the def key.
   void addAnExternalDependency(const DependencyKey &def,
                                const DependencyKey &use,
-                               Optional<Fingerprint> dependencyFingerprint);
+                               llvm::Optional<Fingerprint> dependencyFingerprint);
 
-  static Optional<Fingerprint>
+  static llvm::Optional<Fingerprint>
   getFingerprintIfAny(std::pair<const NominalTypeDecl *, const ValueDecl *>) {
-    return None;
+    return llvm::None;
   }
 
-  static Optional<Fingerprint> getFingerprintIfAny(const Decl *d) {
+  static llvm::Optional<Fingerprint> getFingerprintIfAny(const Decl *d) {
     if (const auto *idc = dyn_cast<IterableDeclContext>(d)) {
       return idc->getBodyFingerprint();
     }
-    return None;
+    return llvm::None;
   }
 };