[Support] add move operations to raw_ostream

[s-mx]

Copy constructor/operator= were explicitly deleted. Hence, move constructor/operator= were left implicitly deleted. This patch declares them by default and allows the following code to be compiled.

raw_fd_ostream openStream(StringRef Path) {
std::error_code EC;
raw_fd_ostream OS(Path, EC);
// handle errors here
return std::move(OS);
}

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[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Sabianin Maksim (s-mx)

Changes

Copy constructor/operator= were explicitly deleted. Hence, move constructor/operator= were left implicitly deleted. This patch declares them by default and allows the following code to be compiled.

raw_fd_ostream openStream(StringRef Path) {
std::error_code EC;
raw_fd_ostream OS(Path, EC);
// handle errors here
return std::move(OS);
}

---

Full diff: https://github.com/llvm/llvm-project/pull/85134.diff

1 Files Affected:

• (modified) llvm/include/llvm/Support/raw_ostream.h (+2)

diff --git a/llvm/include/llvm/Support/raw_ostream.h b/llvm/include/llvm/Support/raw_ostream.h
index 696290a5d99cf5..de6d6f1e0b006c 100644
--- a/llvm/include/llvm/Support/raw_ostream.h
+++ b/llvm/include/llvm/Support/raw_ostream.h
@@ -143,6 +143,8 @@ class raw_ostream {
 
   raw_ostream(const raw_ostream &) = delete;
   void operator=(const raw_ostream &) = delete;
+  raw_ostream(raw_ostream &&) = default;
+  raw_ostream &operator=(raw_ostream &&) = default;
 
   virtual ~raw_ostream();
 

[s-mx]

My initial desire was to add move operations to raw_fd_ostream. However, I've just realised that my patch is insufficient for that and I need to do it more careful and raw_fd_ostream should have a concrete implementation instead of default one.

[dwblaikie]

this'll need unit test coverage too, fwiw