Revert "Unconditionally Record Type Body Fingerprints"

This reverts commit cdd54f1.

Author: CodaFi

include/swift/AST/DeclContext.h

@@ -881,6 +881,8 @@ class IterableDeclContext {
   /// available.
   Optional<Fingerprint> getBodyFingerprint() const;
 
+  bool areTokensHashedForThisBodyInsteadOfInterfaceHash() const;
+
 private:
   /// Add a member to the list for iteration purposes, but do not notify the
   /// subclass that we have done so.

lib/AST/DeclContext.cpp

@@ -1032,6 +1032,11 @@ Optional<Fingerprint> IterableDeclContext::getBodyFingerprint() const {
       .fingerprint;
 }
 
+bool IterableDeclContext::areTokensHashedForThisBodyInsteadOfInterfaceHash()
+    const {
+  return true;
+}
+
 /// Return the DeclContext to compare when checking private access in
 /// Swift 4 mode. The context returned is the type declaration if the context
 /// and the type declaration are in the same file, otherwise it is the types

lib/Parse/ParseDecl.cpp

@@ -4751,9 +4751,12 @@ Parser::parseDeclList(SourceLoc LBLoc, SourceLoc &RBLoc, Diag<> ErrorDiag,
 
   // If we're hashing the type body separately, record the curly braces but
   // nothing inside for the interface hash.
-  llvm::SaveAndRestore<Optional<llvm::MD5>> MemberHashingScope{CurrentTokenHash, llvm::MD5()};
-  recordTokenHash("{");
-  recordTokenHash("}");
+  Optional<llvm::SaveAndRestore<Optional<llvm::MD5>>> MemberHashingScope;
+  if (IDC->areTokensHashedForThisBodyInsteadOfInterfaceHash()) {
+    recordTokenHash("{");
+    recordTokenHash("}");
+    MemberHashingScope.emplace(CurrentTokenHash, llvm::MD5());
+  }
 
   std::vector<Decl *> decls;
   ParserStatus Status;
@@ -4785,7 +4788,8 @@ Parser::parseDeclList(SourceLoc LBLoc, SourceLoc &RBLoc, Diag<> ErrorDiag,
     hadError = true;
 
   llvm::MD5::MD5Result result;
-  CurrentTokenHash->final(result);
+  auto declListHash = MemberHashingScope ? *CurrentTokenHash : llvm::MD5();
+  declListHash.final(result);
   return std::make_pair(decls, Fingerprint{std::move(result)});
 }