[YAML] Fix YAML tags appearing before the start of sequence elements

Our existing yaml::Output code writes tags immediately when mapTag is called, without any state handling. This results in tags on sequence elements being written before the element itself. For example, we see this:

SomeArray:     !elem_type
  - key1:         1
    key2:         2 !elem_type2
  - key3:         3
    key4:         4

We should instead see:

SomeArray:
  - !elem_type
    key1:         1
    key2:         2
  - !elem_type2
    key3:         3
    key4:         4

Our reader handles reading properly, so this bug only impacts writing yaml sequences with tagged elements.

As a test for this I've modified the Mach-O yaml encoding to allways apply the !mach-o tag when encoding MachOYAML::Object entries. This results in the !mach-o tag appearing as expected in dumped fat files.

llvm-svn: 274067

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/ObjectYAML/MachOYAML.cpp b/llvm/lib/ObjectYAML/MachOYAML.cpp
index 0a303a6e739..d819e80836c 100644
--- a/llvm/lib/ObjectYAML/MachOYAML.cpp
+++ b/llvm/lib/ObjectYAML/MachOYAML.cpp
@@ -91,8 +91,8 @@ void MappingTraits<MachOYAML::Object>::mapping(IO &IO,
   // For Fat files there will be a different tag so they can be differentiated.
   if (!IO.getContext()) {
     IO.setContext(&Object);
-    IO.mapTag("!mach-o", true);
   }
+  IO.mapTag("!mach-o", true);
   IO.mapRequired("FileHeader", Object.Header);
   IO.mapOptional("LoadCommands", Object.LoadCommands);
   IO.mapOptional("LinkEditData", Object.LinkEdit);