libstdc++: Fix -Wnarrowing in <complex> [PR116991]

When _GLIBCXX_USE_C99_COMPLEX_ARC is undefined we use the generic
__complex_acos function template for _Float32 etc. and that gives a
-Wnarrowing warning:

complex:2043: warning: ISO C++ does not allow converting to '_Float32' from 'long double' with greater conversion rank [-Wnarrowing]

Use a cast to do the conversion so that it doesn't warn.

libstdc++-v3/ChangeLog:

	PR libstdc++/116991
	* include/std/complex (__complex_acos): Cast literal to
	destination type.

diff --git a/libstdc++-v3/include/std/complex b/libstdc++-v3/include/std/complex
index 5bc6618f7de0a4404ba958e24bd8f2461abfdf52..eb89e3a8bcfba5fdb696e3ebf22babdae8143d7c 100644 (file)
--- a/libstdc++-v3/include/std/complex
+++ b/libstdc++-v3/include/std/complex
@@ -2040,7 +2040,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __complex_acos(const std::complex<_Tp>& __z)
     {
       const std::complex<_Tp> __t = std::asin(__z);
-      const _Tp __pi_2 = 1.5707963267948966192313216916397514L;
+      const _Tp __pi_2 = (_Tp) 1.5707963267948966192313216916397514L;
       return std::complex<_Tp>(__pi_2 - __t.real(), -__t.imag());
     }