[LLVM][ADT] Make scope-exit CTAD-capable

[localspook]

This enables using it like

llvm::scope_exit Cleanup([] { ... });

instead of

auto Cleanup = llvm::make_scope_exit([] { ... });

[llvmbot]

@llvm/pr-subscribers-lldb

@llvm/pr-subscribers-llvm-adt

Author: Victor Chernyakin (localspook)

Changes

This enables using it like

llvm::scope_exit Cleanup = [] { ... };

instead of

auto Cleanup = llvm::make_scope_exit([] { ... });

---

Full diff: https://github.com/llvm/llvm-project/pull/173131.diff

1 Files Affected:

• (modified) llvm/include/llvm/ADT/ScopeExit.h (+3-9)

diff --git a/llvm/include/llvm/ADT/ScopeExit.h b/llvm/include/llvm/ADT/ScopeExit.h
index 2f13fb65d34d8..04b602a69f7e3 100644
--- a/llvm/include/llvm/ADT/ScopeExit.h
+++ b/llvm/include/llvm/ADT/ScopeExit.h
@@ -15,13 +15,9 @@
 #ifndef LLVM_ADT_SCOPEEXIT_H
 #define LLVM_ADT_SCOPEEXIT_H
 
-#include "llvm/Support/Compiler.h"
-
-#include <type_traits>
 #include <utility>
 
 namespace llvm {
-namespace detail {
 
 template <typename Callable> class scope_exit {
   Callable ExitFunction;
@@ -47,17 +43,15 @@ template <typename Callable> class scope_exit {
   }
 };
 
-} // end namespace detail
+template <typename Callable> scope_exit(Callable) -> scope_exit<Callable>;
 
 // Keeps the callable object that is passed in, and execute it at the
 // destruction of the returned object (usually at the scope exit where the
 // returned object is kept).
 //
 // Interface is specified by p0052r2.
-template <typename Callable>
-[[nodiscard]] detail::scope_exit<std::decay_t<Callable>>
-make_scope_exit(Callable &&F) {
-  return detail::scope_exit<std::decay_t<Callable>>(std::forward<Callable>(F));
+template <typename Callable> [[nodiscard]] auto make_scope_exit(Callable &&F) {
+  return scope_exit(std::forward<Callable>(F));
 }
 
 } // end namespace llvm

[kuhar]

Makes sense. Do you also plan to mark make_scope_exit as deprecated in a future PR?

[localspook]

Yes. I'm hoping to do that after I implement a clang-tidy check (something like modernize-use-ctad) that can do the migration automatically (we already have the logic in abseil-cleanup-ctad, but it only works with one particular abseil class right now).