[patch] std::polar requires non-negative rho

[Jonathan Wakely]

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4383.html#2459

Voted into the WP in Lenexa.

Tested powerpc64le-linux, comitted to trunk.

commit 9bf3b9ea20334711ecdced656323f69959521a82
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Wed May 13 14:18:03 2015 +0100

    	* include/std/complex (polar): Check for negative rho (LWG 2459).

diff --git a/libstdc++-v3/include/std/complex b/libstdc++-v3/include/std/complex
index 585683c..f2a6cf9 100644
--- a/libstdc++-v3/include/std/complex
+++ b/libstdc++-v3/include/std/complex
@@ -667,7 +667,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp>
     inline complex<_Tp>
     polar(const _Tp& __rho, const _Tp& __theta)
-    { return complex<_Tp>(__rho * cos(__theta), __rho * sin(__theta)); }
+    {
+      _GLIBCXX_DEBUG_ASSERT( __rho >= 0 );
+      return complex<_Tp>(__rho * cos(__theta), __rho * sin(__theta));
+    }
 
   template<typename _Tp>
     inline complex<_Tp>