[AST] Remove respectOriginallyDefinedIn parameter from mangleAnyDecl

This was always set to `true` except for USR mangling, where we already
have it set to `false` for IDE USRs. The other clients were:

- AutoDiff, which is just using the resulting string as a dictionary
key, so don't seem to have any preference.
- The ClangImporter, which always overrides `@_originallyDefinedIn`
anyway.

include/swift/AST/ASTMangler.h

@@ -398,8 +398,7 @@ public:
   std::string mangleTypeAsContextUSR(const NominalTypeDecl *type);
 
   void appendAnyDecl(const ValueDecl *Decl);
-  std::string mangleAnyDecl(const ValueDecl *Decl, bool prefix,
-                            bool respectOriginallyDefinedIn = false);
+  std::string mangleAnyDecl(const ValueDecl *decl, bool addPrefix);
   std::string mangleDeclAsUSR(const ValueDecl *Decl, StringRef USRPrefix);
 
   std::string mangleAccessorEntityAsUSR(AccessorKind kind,

lib/APIDigester/ModuleAnalyzerNodes.cpp

@@ -1120,8 +1120,7 @@ static StringRef calculateMangledName(SDKContext &Ctx, ValueDecl *VD) {
     return Ctx.buffer(attr->Name);
   }
   Mangle::ASTMangler NewMangler(VD->getASTContext());
-  return Ctx.buffer(NewMangler.mangleAnyDecl(VD, true,
-                                    /*bool respectOriginallyDefinedIn*/true));
+  return Ctx.buffer(NewMangler.mangleAnyDecl(VD, /*addPrefix*/ true));
 }
 
 static StringRef calculateLocation(SDKContext &SDKCtx, Decl *D) {

lib/AST/ASTMangler.cpp

@@ -993,31 +993,28 @@ void ASTMangler::appendAnyDecl(const ValueDecl *Decl) {
   }
 }
 
-std::string
-ASTMangler::mangleAnyDecl(const ValueDecl *Decl,
-                          bool prefix,
-                          bool respectOriginallyDefinedIn) {
+std::string ASTMangler::mangleAnyDecl(const ValueDecl *decl, bool addPrefix) {
   DWARFMangling = true;
-  RespectOriginallyDefinedIn = respectOriginallyDefinedIn;
-  if (prefix) {
+  if (addPrefix) {
     beginMangling();
   } else {
     beginManglingWithoutPrefix();
   }
   llvm::SaveAndRestore<bool> allowUnnamedRAII(AllowNamelessEntities, true);
 
-  appendAnyDecl(Decl);
+  appendAnyDecl(decl);
 
   // We have a custom prefix, so finalize() won't verify for us. If we're not
   // in invalid code (coming from an IDE caller) verify manually.
-  if (CONDITIONAL_ASSERT_enabled() && !prefix && !Decl->isInvalid())
+  if (CONDITIONAL_ASSERT_enabled() && !addPrefix && !decl->isInvalid())
     verify(Storage.str(), Flavor);
   return finalize();
 }
 
 std::string ASTMangler::mangleDeclAsUSR(const ValueDecl *Decl,
                                         StringRef USRPrefix) {
-  return (llvm::Twine(USRPrefix) + mangleAnyDecl(Decl, false)).str();
+  return (llvm::Twine(USRPrefix) + mangleAnyDecl(Decl, /*addPrefix*/ false))
+      .str();
 }
 
 std::string ASTMangler::mangleAccessorEntityAsUSR(AccessorKind kind,

lib/AST/ASTPrinter.cpp

@@ -1348,9 +1348,9 @@ void PrintAST::printAttributes(const Decl *D) {
   if (Options.PrintSyntheticSILGenName
         && !D->getAttrs().hasAttribute<SILGenNameAttr>()) {
     if (canPrintSyntheticSILGenName(D)) {
-      auto mangledName = Mangle::ASTMangler(D->getASTContext())
-                            .mangleAnyDecl(cast<ValueDecl>(D), /*prefix=*/true,
-                                           /*respectOriginallyDefinedIn=*/true);
+      auto mangledName =
+          Mangle::ASTMangler(D->getASTContext())
+              .mangleAnyDecl(cast<ValueDecl>(D), /*addPrefix*/ true);
       Printer.printAttrName("@_silgen_name");
       Printer << "(";
       Printer.printEscapedStringLiteral(mangledName);

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -155,8 +155,7 @@ static std::string getMangledNameString(const Decl *D) {
   if (!VD)
     return std::string();
   Mangle::ASTMangler mangler(VD->getASTContext());
-  return mangler.mangleAnyDecl(VD, /*prefix=*/true,
-                               /*respectOriginallyDefinedIn=*/true);
+  return mangler.mangleAnyDecl(VD, /*addPrefix*/ true);
 }
 
 static std::string getTypeString(const ValueDecl *VD) {