[clang] [C++23] [CLANG] Adding C++23 constexpr math functions: fmin and frexp. (PR #88978)

[Hubert Tong via cfe-commits]

================
@@ -0,0 +1,38 @@
+// RUN: %clang_cc1 -DWIN -verify -std=c++23 -fsyntax-only  %s
+// RUN: %clang_cc1 -verify -std=c++23 -fsyntax-only  %s
+
+// expected-no-diagnostics
+
+
+#ifdef WIN
+#define INFINITY ((float)(1e+300 * 1e+300))
+#define NAN      (-(float)(INFINITY * 0.0F))
+#else
+#define NAN (__builtin_nanf(""))
+#define INFINITY (__builtin_inff())
+#endif
+
+int main() {
+    int i;
+
+    // fmin
+    static_assert(__builtin_fmin(15.24, 1.3) == 1.3, "");
+    static_assert(__builtin_fmin(-0.0, +0.0) == -0.0, "");
+    static_assert(__builtin_fmin(+0.0, -0.0) == -0.0, "");
----------------
hubert-reinterpretcast wrote:

... also, optional `static_assert` message should be removed if not used in a helpful manner.

Example (please apply to other lines too):
```suggestion
    static_assert(is_same_val<__builtin_fmin(-0.0, +0.0), -0.0>);
    static_assert(is_same_val<__builtin_fmin(+0.0, -0.0), -0.0>);
```

https://github.com/llvm/llvm-project/pull/88978