[clang-tools-extra] [libc++] Prevent calling the projection more than three times (PR #66315)

[Louis Dionne via cfe-commits]

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@@ -37,9 +37,10 @@ struct __fn {
     _LIBCPP_ASSERT_UNCATEGORIZED(!bool(std::invoke(__comp, std::invoke(__proj, __high), std::invoke(__proj, __low))),
                                  "Bad bounds passed to std::ranges::clamp");
 
-    if (std::invoke(__comp, std::invoke(__proj, __value), std::invoke(__proj, __low)))
+    auto&& __projected = std::forward<decltype(__projected)>(std::invoke(__proj, __value));
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ldionne wrote:

We don't want to use `std::forward` here, we want to use it in the argument to `std::invoke`.

https://github.com/llvm/llvm-project/pull/66315