[llvm] [Support] Consolidate runOnNewStack (NFC) (PR #160816)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/160816

This patch consolidates two implementations of runOnNewStack with
"if constexpr".


>From fdb626a047a7ee4b6147af81372c1f34e45b4275 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Wed, 10 Sep 2025 20:27:23 -0700
Subject: [PATCH] [Support] Consolidate runOnNewStack (NFC)

This patch consolidates two implementations of runOnNewStack with
"if constexpr".
---
 llvm/include/llvm/Support/ProgramStack.h | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/llvm/include/llvm/Support/ProgramStack.h b/llvm/include/llvm/Support/ProgramStack.h
index 0dd8235b90c06..13729a2990588 100644
--- a/llvm/include/llvm/Support/ProgramStack.h
+++ b/llvm/include/llvm/Support/ProgramStack.h
@@ -46,17 +46,15 @@ LLVM_ABI unsigned getDefaultStackSize();
 LLVM_ABI void runOnNewStack(unsigned StackSize, function_ref<void()> Fn);
 
 template <typename R, typename... Ts>
-std::enable_if_t<!std::is_same_v<R, void>, R>
-runOnNewStack(unsigned StackSize, function_ref<R(Ts...)> Fn, Ts &&...Args) {
-  std::optional<R> Ret;
-  runOnNewStack(StackSize, [&]() { Ret = Fn(std::forward<Ts>(Args)...); });
-  return std::move(*Ret);
-}
-
-template <typename... Ts>
-void runOnNewStack(unsigned StackSize, function_ref<void(Ts...)> Fn,
+auto runOnNewStack(unsigned StackSize, function_ref<R(Ts...)> Fn,
                    Ts &&...Args) {
-  runOnNewStack(StackSize, [&]() { Fn(std::forward<Ts>(Args)...); });
+  if constexpr (std::is_same_v<R, void>) {
+    runOnNewStack(StackSize, [&]() { Fn(std::forward<Ts>(Args)...); });
+  } else {
+    std::optional<R> Ret;
+    runOnNewStack(StackSize, [&]() { Ret = Fn(std::forward<Ts>(Args)...); });
+    return std::move(*Ret);
+  }
 }
 
 } // namespace llvm