[libc-commits] [libc] [libc] Implement `CMPLX` for clang < 12 (PR #157096)

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https://github.com/c8ef created https://github.com/llvm/llvm-project/pull/157096

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>From ffb7b6cafcf957c84b0f94718c1a973283a49c4a Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Fri, 5 Sep 2025 20:51:27 +0800
Subject: [PATCH] buildin complex only available for clang >= 12

---
 .../include/llvm-libc-macros/complex-macros.h | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/libc/include/llvm-libc-macros/complex-macros.h b/libc/include/llvm-libc-macros/complex-macros.h
index d98c6fdb306c8..5ea272a2e7482 100644
--- a/libc/include/llvm-libc-macros/complex-macros.h
+++ b/libc/include/llvm-libc-macros/complex-macros.h
@@ -22,21 +22,26 @@
 
 // TODO: Add imaginary macros once GCC or Clang support _Imaginary builtin-type.
 
-#define CMPLX(x, y) __builtin_complex((double)(x), (double)(y))
-#define CMPLXF(x, y) __builtin_complex((float)(x), (float)(y))
-#define CMPLXL(x, y) __builtin_complex((long double)(x), (long double)(y))
+#if !defined(__clang__) || (__clang_major__ >= 12)
+#define __CMPLX(r, i, t) (__builtin_complex((t)(r), (t)(i)))
+#else
+#define __CMPLX(r, i, t) ((_Complex t){(t)(r), (t)(i)})
+#endif
+
+#define CMPLX(r, i) __CMPLX(r, i, double)
+#define CMPLXF(r, i) __CMPLX(r, i, float)
+#define CMPLXL(r, i) __CMPLX(r, i, long double)
 
 #ifdef LIBC_TYPES_HAS_CFLOAT16
 #if !defined(__clang__) || (__clang_major__ >= 22 && __clang_minor__ > 0)
-#define CMPLXF16(x, y) __builtin_complex((_Float16)(x), (_Float16)(y))
+#define CMPLXF16(r, i) __CMPLX(r, i, _Float16)
 #else
-#define CMPLXF16(x, y)                                                         \
-  ((complex _Float16)(__builtin_complex((float)(x), (float)(y))))
+#define CMPLXF16(r, i) ((complex _Float16)(__CMPLX(r, i, float)))
 #endif
 #endif // LIBC_TYPES_HAS_CFLOAT16
 
 #ifdef LIBC_TYPES_HAS_CFLOAT128
-#define CMPLXF128(x, y) __builtin_complex((float128)(x), (float128)(y))
+#define CMPLXF128(r, i) __CMPLX(r, i, float128)
 #endif // LIBC_TYPES_HAS_CFLOAT128
 
 #endif // __STDC_NO_COMPLEX__