[MsgPack] Use JSON schema boolean resolution rules

[slinder1]

Since YAMLIO generally knows the types ahead of time (since it primarily functions to (de)serialize concrete C++ types) "tag resolution" isn't really a meaningful isssue.

With MsgPackDocument we permit arbitrary documents with arbitrary type nodes, and so the YAML "NO" problem is an issue.

Address this in MsgPackDocument itself to avoid a significant and far-reaching backwards-incompatible change to YAMLIO (although we could still consider tightening things up there in the future). Use the "JSON Schema" for tag resolution where the only literals to resolve to bool by default are "true" and "false".

[llvmbot]

@llvm/pr-subscribers-llvm-binary-utilities

Author: Scott Linder (slinder1)

Changes

Since YAMLIO generally knows the types ahead of time (since it primarily functions to (de)serialize concrete C++ types) "tag resolution" isn't really a meaningful isssue.

With MsgPackDocument we permit arbitrary documents with arbitrary type nodes, and so the YAML "NO" problem is an issue.

Address this in MsgPackDocument itself to avoid a significant and far-reaching backwards-incompatible change to YAMLIO (although we could still consider tightening things up there in the future). Use the "JSON Schema" for tag resolution where the only literals to resolve to bool by default are "true" and "false".

---

Full diff: https://github.com/llvm/llvm-project/pull/170561.diff

2 Files Affected:

• (modified) llvm/lib/BinaryFormat/MsgPackDocumentYAML.cpp (+15-4)
• (modified) llvm/unittests/BinaryFormat/MsgPackDocumentTest.cpp (+74)

diff --git a/llvm/lib/BinaryFormat/MsgPackDocumentYAML.cpp b/llvm/lib/BinaryFormat/MsgPackDocumentYAML.cpp
index 80b421d5f752e..fbf871f709a64 100644
--- a/llvm/lib/BinaryFormat/MsgPackDocumentYAML.cpp
+++ b/llvm/lib/BinaryFormat/MsgPackDocumentYAML.cpp
@@ -29,6 +29,10 @@ struct ScalarDocNode : DocNode {
   StringRef getYAMLTag() const;
 };
 
+bool isJSONSchemaBoolLiteral(StringRef S) {
+  return S == "true" || S == "false";
+}
+
 } // namespace
 
 /// Convert this DocNode to a string, assuming it is scalar.
@@ -84,11 +88,18 @@ StringRef DocNode::fromString(StringRef S, StringRef Tag) {
     *this = getDocument()->getNode();
     return "";
   }
-  if (Tag == "!bool" || Tag == "") {
+  if (Tag == "!bool") {
     *this = getDocument()->getNode(false);
-    StringRef Err = yaml::ScalarTraits<bool>::input(S, nullptr, getBool());
-    if (Err == "" || Tag != "")
-      return Err;
+    return yaml::ScalarTraits<bool>::input(S, nullptr, getBool());
+  }
+  // FIXME: This enforces the "JSON Schema" tag resolution for boolean literals,
+  // defined at https://yaml.org/spec/1.2.2/#json-schema which we adopt because
+  // the more general pre-1.2 resolution includes many common strings (e.g. "n",
+  // "no", "y", "yes", ...). This should be handled at the YAMLTraits level, but
+  // that change would have a much broader impact.
+  if (Tag == "" && isJSONSchemaBoolLiteral(S)) {
+    *this = getDocument()->getNode(S == "true");
+    return "";
   }
   if (Tag == "!float" || Tag == "") {
     *this = getDocument()->getNode(0.0);
diff --git a/llvm/unittests/BinaryFormat/MsgPackDocumentTest.cpp b/llvm/unittests/BinaryFormat/MsgPackDocumentTest.cpp
index 6a6ad7010f629..5aace87cb3b6b 100644
--- a/llvm/unittests/BinaryFormat/MsgPackDocumentTest.cpp
+++ b/llvm/unittests/BinaryFormat/MsgPackDocumentTest.cpp
@@ -420,3 +420,77 @@ TEST(MsgPackDocument, TestInputYAMLMap) {
   ASSERT_EQ(SS.getKind(), Type::String);
   ASSERT_EQ(SS.getString(), "2");
 }
+
+TEST(MsgPackDocument, TestInputYAMLBoolean) {
+  Document Doc;
+  auto GetFirst = [](Document &Doc) { return Doc.getRoot().getArray()[0]; };
+  auto ToYAML = [](Document &Doc) {
+    std::string S;
+    raw_string_ostream OS(S);
+    Doc.toYAML(OS);
+    return S;
+  };
+
+  bool Ok;
+
+  Ok = Doc.fromYAML("- n\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::String);
+  ASSERT_EQ(GetFirst(Doc).getString(), "n");
+  ASSERT_EQ(ToYAML(Doc), "---\n- n\n...\n");
+
+  Ok = Doc.fromYAML("- y\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::String);
+  ASSERT_EQ(GetFirst(Doc).getString(), "y");
+  ASSERT_EQ(ToYAML(Doc), "---\n- y\n...\n");
+
+  Ok = Doc.fromYAML("- no\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::String);
+  ASSERT_EQ(GetFirst(Doc).getString(), "no");
+  ASSERT_EQ(ToYAML(Doc), "---\n- no\n...\n");
+
+  Ok = Doc.fromYAML("- yes\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::String);
+  ASSERT_EQ(GetFirst(Doc).getString(), "yes");
+  ASSERT_EQ(ToYAML(Doc), "---\n- yes\n...\n");
+
+  Ok = Doc.fromYAML("- false\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::Boolean);
+  ASSERT_EQ(GetFirst(Doc).getBool(), false);
+  ASSERT_EQ(ToYAML(Doc), "---\n- false\n...\n");
+
+  Ok = Doc.fromYAML("- true\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::Boolean);
+  ASSERT_EQ(GetFirst(Doc).getBool(), true);
+  ASSERT_EQ(ToYAML(Doc), "---\n- true\n...\n");
+
+  Ok = Doc.fromYAML("- !str false\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::String);
+  ASSERT_EQ(GetFirst(Doc).getString(), "false");
+  ASSERT_EQ(ToYAML(Doc), "---\n- !str 'false'\n...\n");
+
+  Ok = Doc.fromYAML("- !str true\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::String);
+  ASSERT_EQ(GetFirst(Doc).getString(), "true");
+  ASSERT_EQ(ToYAML(Doc), "---\n- !str 'true'\n...\n");
+
+  // FIXME: A fix for these requires changes in YAMLParser/YAMLTraits.
+  Ok = Doc.fromYAML("- \"false\"\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::Boolean);
+  ASSERT_EQ(GetFirst(Doc).getBool(), false);
+  ASSERT_EQ(ToYAML(Doc), "---\n- false\n...\n");
+
+  Ok = Doc.fromYAML("- \"true\"\n");
+  ASSERT_TRUE(Ok);
+  ASSERT_EQ(GetFirst(Doc).getKind(), Type::Boolean);
+  ASSERT_EQ(GetFirst(Doc).getBool(), true);
+  ASSERT_EQ(ToYAML(Doc), "---\n- true\n...\n");
+}

[perlfu]

Can you explain in more detail what fix is required?
Is there a reason it is not part of this PR?

[slinder1]

It requires a change in YAMLParser/YAMLTraits directly and I wanted to avoid the fallout. If we would rather not have a half measure like this I can spend some time trying to understand the YAML issue more directly.