[llvm] Replace deprecated aligned_storage with aligned byte array

[marcauberer]

std::aligned_storage is deprecated with C++23, see here.

This replaces the usages of std::aligned_storage within llvm (only one in ADT and one in Support) with an aligned std::byte array.
I will provide patches for other subcomponents as well.

[llvmbot]

@llvm/pr-subscribers-llvm-adt

Author: Marc Auberer (marcauberer)

Changes

std::aligned_storage is deprecated with C++23, see here.

This replaces the usages of std::aligned_storage within llvm (only one in ADT and one in Support) with an aligned std::byte array.
I will provide patches for other subcomponents as well.

---

Full diff: https://github.com/llvm/llvm-project/pull/94169.diff

2 Files Affected:

• (modified) llvm/include/llvm/ADT/FunctionExtras.h (+1-2)
• (modified) llvm/lib/Support/PrettyStackTrace.cpp (+2-4)

diff --git a/llvm/include/llvm/ADT/FunctionExtras.h b/llvm/include/llvm/ADT/FunctionExtras.h
index c0bc30c7450fe..49e0e8ab0db40 100644
--- a/llvm/include/llvm/ADT/FunctionExtras.h
+++ b/llvm/include/llvm/ADT/FunctionExtras.h
@@ -161,8 +161,7 @@ template <typename ReturnT, typename... ParamTs> class UniqueFunctionBase {
     // provide three pointers worth of storage here.
     // This is mutable as an inlined `const unique_function<void() const>` may
     // still modify its own mutable members.
-    mutable std::aligned_storage_t<InlineStorageSize, alignof(void *)>
-        InlineStorage;
+    alignas(void *) mutable std::byte InlineStorage[InlineStorageSize];
   } StorageUnion;
 
   // A compressed pointer to either our dispatching callback or our table of
diff --git a/llvm/lib/Support/PrettyStackTrace.cpp b/llvm/lib/Support/PrettyStackTrace.cpp
index f9f1b8a419b82..7c6d84d3697db 100644
--- a/llvm/lib/Support/PrettyStackTrace.cpp
+++ b/llvm/lib/Support/PrettyStackTrace.cpp
@@ -143,10 +143,8 @@ static void setCrashLogMessage(const char *msg) {
 
 #ifdef __APPLE__
 using CrashHandlerString = SmallString<2048>;
-using CrashHandlerStringStorage =
-    std::aligned_storage<sizeof(CrashHandlerString),
-                         alignof(CrashHandlerString)>::type;
-static CrashHandlerStringStorage crashHandlerStringStorage;
+using CrashHandlerStringStorage = std::byte[sizeof(CrashHandlerString)];
+alignas(CrashHandlerString) static CrashHandlerStringStorage crashHandlerStringStorage;
 #endif
 
 /// This callback is run if a fatal signal is delivered to the process, it

[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Marc Auberer (marcauberer)

Changes

std::aligned_storage is deprecated with C++23, see here.

This replaces the usages of std::aligned_storage within llvm (only one in ADT and one in Support) with an aligned std::byte array.
I will provide patches for other subcomponents as well.

---

Full diff: https://github.com/llvm/llvm-project/pull/94169.diff

2 Files Affected:

• (modified) llvm/include/llvm/ADT/FunctionExtras.h (+1-2)
• (modified) llvm/lib/Support/PrettyStackTrace.cpp (+2-4)

diff --git a/llvm/include/llvm/ADT/FunctionExtras.h b/llvm/include/llvm/ADT/FunctionExtras.h
index c0bc30c7450fe..49e0e8ab0db40 100644
--- a/llvm/include/llvm/ADT/FunctionExtras.h
+++ b/llvm/include/llvm/ADT/FunctionExtras.h
@@ -161,8 +161,7 @@ template <typename ReturnT, typename... ParamTs> class UniqueFunctionBase {
     // provide three pointers worth of storage here.
     // This is mutable as an inlined `const unique_function<void() const>` may
     // still modify its own mutable members.
-    mutable std::aligned_storage_t<InlineStorageSize, alignof(void *)>
-        InlineStorage;
+    alignas(void *) mutable std::byte InlineStorage[InlineStorageSize];
   } StorageUnion;
 
   // A compressed pointer to either our dispatching callback or our table of
diff --git a/llvm/lib/Support/PrettyStackTrace.cpp b/llvm/lib/Support/PrettyStackTrace.cpp
index f9f1b8a419b82..7c6d84d3697db 100644
--- a/llvm/lib/Support/PrettyStackTrace.cpp
+++ b/llvm/lib/Support/PrettyStackTrace.cpp
@@ -143,10 +143,8 @@ static void setCrashLogMessage(const char *msg) {
 
 #ifdef __APPLE__
 using CrashHandlerString = SmallString<2048>;
-using CrashHandlerStringStorage =
-    std::aligned_storage<sizeof(CrashHandlerString),
-                         alignof(CrashHandlerString)>::type;
-static CrashHandlerStringStorage crashHandlerStringStorage;
+using CrashHandlerStringStorage = std::byte[sizeof(CrashHandlerString)];
+alignas(CrashHandlerString) static CrashHandlerStringStorage crashHandlerStringStorage;
 #endif
 
 /// This callback is run if a fatal signal is delivered to the process, it

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[tschuett]

Why? We are not even close to C++20?

[marcauberer]

Why? We are not even close to C++20?

As these are in headers, which are transitively included by users (which potentially use C++23). So they will get the deprecation warnings as well.

[dwblaikie]

SGTM