Revert "Function to convert OpenOptions to c_int"

[jyn514]

Reverts #76110. This broke Rust's stability guarantees.

Closes #77089.

r? @joshtriplett

[dtolnay]

@bors r+ p=10

[bors]

📌 Commit 15f08d6 has been approved by dtolnay

[jyn514]

@dtolnay is there a way to tell whether a PR breaks stability without eyeballing it or noticing from a bug report after the fact? It would be great to have it as part of the test suite somehow.

[bors]

⌛ Testing commit 15f08d6 with merge c80f5e8ae0e4e51ae34a373092c84cd5f9fbb038...

[bors]

💔 Test failed - checks-actions

[jyn514]

It failed building LLVM, it might be spurious?

  running: "D:/a/rust/rust/citools/clang-rust/bin/clang-cl.exe" "-nologo" "-MT" "-O2" "-Brepro" "-m64" "/Zl" "-D__func__=__FUNCTION__" "-FoD:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\stage1-std\\x86_64-pc-windows-msvc\\release\\build\\compiler_builtins-2a3f11e60d5138ca\\out\\divsc3.o" "-c" "D:\\a\\rust\\rust\\src/llvm-project/compiler-rt\\lib/builtins\\divsc3.c"
  exit code: 0xc0000005

  --- stderr


  error occurred: Command "D:/a/rust/rust/citools/clang-rust/bin/clang-cl.exe" "-nologo" "-MT" "-O2" "-Brepro" "-m64" "/Zl" "-D__func__=__FUNCTION__" "-FoD:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\stage1-std\\x86_64-pc-windows-msvc\\release\\build\\compiler_builtins-2a3f11e60d5138ca\\out\\divsc3.o" "-c" "D:\\a\\rust\\rust\\src/llvm-project/compiler-rt\\lib/builtins\\divsc3.c" with args "clang-cl.exe" did not execute successfully (status code exit code: 0xc0000005).

@bors retry p=10

[bors]

⌛ Testing commit 15f08d6 with merge a6008fa...

[bors]

☀️ Test successful - checks-actions, checks-azure
Approved by: dtolnay
Pushing a6008fa to master...

[joshtriplett]

Interesting; I'd agree with the assessment elsewhere that OpenOptionsExt should really have been sealed, but since it can't be, this is indeed a stability break. I don't think we can do much better than a default implementation that calls unimplemented!() with an appropriate message, here.

[jyn514]

Whatever happens, we should also add a test for the current behavior so this doesn't slip into nightly again.

[joshtriplett]

It occurs to me that we could add another trait, this one sealed, to handle this, rather than extending the existing trait.

(It's unfortunate that we can't just have a platform-specific implementation of From.)