[llvm] [NFC][YAML] Add `IO::error()` (PR #123475)

[Vitaly Buka via llvm-commits]

https://github.com/vitalybuka updated https://github.com/llvm/llvm-project/pull/123475

>From e696bc48465e52ba4f98bb6c3edfb132139fa3c2 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka at google.com>
Date: Sat, 18 Jan 2025 12:23:12 -0800
Subject: [PATCH] [NFC][YAML] Add `IO::error()`

Pull Request: https://github.com/llvm/llvm-project/pull/123475
---
 llvm/include/llvm/Support/YAMLTraits.h | 4 +++-
 llvm/lib/Support/YAMLTraits.cpp        | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/llvm/include/llvm/Support/YAMLTraits.h b/llvm/include/llvm/Support/YAMLTraits.h
index eca26e90845bf6..e707a445012b51 100644
--- a/llvm/include/llvm/Support/YAMLTraits.h
+++ b/llvm/include/llvm/Support/YAMLTraits.h
@@ -819,6 +819,7 @@ class IO {
   virtual NodeKind getNodeKind() = 0;
 
   virtual void setError(const Twine &) = 0;
+  virtual std::error_code error() = 0;
   virtual void setAllowUnknownKeys(bool Allow);
 
   template <typename T>
@@ -1448,7 +1449,7 @@ class Input : public IO {
   ~Input() override;
 
   // Check if there was an syntax or semantic error during parsing.
-  std::error_code error();
+  std::error_code error() override;
 
 private:
   bool outputting() const override;
@@ -1631,6 +1632,7 @@ class Output : public IO {
   void scalarTag(std::string &) override;
   NodeKind getNodeKind() override;
   void setError(const Twine &message) override;
+  std::error_code error() override;
   bool canElideEmptySequence() override;
 
   // These are only used by operator<<. They could be private
diff --git a/llvm/lib/Support/YAMLTraits.cpp b/llvm/lib/Support/YAMLTraits.cpp
index f326422138488c..28642e004c4f43 100644
--- a/llvm/lib/Support/YAMLTraits.cpp
+++ b/llvm/lib/Support/YAMLTraits.cpp
@@ -750,6 +750,8 @@ void Output::scalarTag(std::string &Tag) {
 void Output::setError(const Twine &message) {
 }
 
+std::error_code Output::error() { return {}; }
+
 bool Output::canElideEmptySequence() {
   // Normally, with an optional key/value where the value is an empty sequence,
   // the whole key/value can be not written.  But, that produces wrong yaml