[clang] [HIP] Fix return type in __clang_hip_cmath.h (PR #139697)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Juan Manuel Martinez Caamaño (jmmartinez)

<details>
<summary>Changes</summary>

Before, some functions like `isgreater(double, double)` would return a `double` instead of a `bool`.

I've stumbled upon this bug while trying to adapt [`External/CUDA/cmath.cu`](https://github.com/llvm/llvm-test-suite/blob/main/External/CUDA/cmath.cu) to HIP.

```
/_llvm-test-suite/External/HIP/../CUDA/math_h.cu:617:20: error: static assertion failed due to requirement 'std::is_same<double, bool>::value':
617 |     static_assert((std::is_same<decltype(isgreater((float)0, (double)0)), bool>::value), "");
```

---
Full diff: https://github.com/llvm/llvm-project/pull/139697.diff


1 Files Affected:

- (modified) clang/lib/Headers/__clang_hip_cmath.h (+7-6) 


``````````diff
diff --git a/clang/lib/Headers/__clang_hip_cmath.h b/clang/lib/Headers/__clang_hip_cmath.h
index 7d982ad9af7ee..8039d0e12d7c9 100644
--- a/clang/lib/Headers/__clang_hip_cmath.h
+++ b/clang/lib/Headers/__clang_hip_cmath.h
@@ -464,12 +464,13 @@ class __promote : public __promote_imp<_A1, _A2, _A3> {};
 #if __cplusplus >= 201103L
 #define __HIP_OVERLOAD2(__retty, __fn)                                         \
   template <typename __T1, typename __T2>                                      \
-  __DEVICE__ __CONSTEXPR__ typename __hip_enable_if<                           \
-      __hip::is_arithmetic<__T1>::value && __hip::is_arithmetic<__T2>::value,  \
-      typename __hip::__promote<__T1, __T2>::type>::type                       \
-  __fn(__T1 __x, __T2 __y) {                                                   \
-    typedef typename __hip::__promote<__T1, __T2>::type __result_type;         \
-    return __fn((__result_type)__x, (__result_type)__y);                       \
+  __DEVICE__ __CONSTEXPR__                                                     \
+      typename __hip_enable_if<__hip::is_arithmetic<__T1>::value &&            \
+                                   __hip::is_arithmetic<__T2>::value,          \
+                               __retty>::type                                  \
+      __fn(__T1 __x, __T2 __y) {                                               \
+    typedef typename __hip::__promote<__T1, __T2>::type __arg_type;            \
+    return __fn((__arg_type)__x, (__arg_type)__y);                             \
   }
 #else
 #define __HIP_OVERLOAD2(__retty, __fn)                                         \

``````````

</details>


https://github.com/llvm/llvm-project/pull/139697