Merge pull request #1416 from boostorg/1412pt2

Check all of special functions can be included under same conditions

Author: mborland

test/Jamfile.v2

@@ -203,6 +203,7 @@ test-suite special_fun :
    [ run git_issue_1247.cpp ]
    [ run git_issue_1308.cpp /boost/test//boost_unit_test_framework ]
    [ run git_issue_1412.cpp ]
+   [ run git_issue_1412_pt_2.cpp ]
    [ run special_functions_test.cpp /boost/test//boost_unit_test_framework  ]
    [ run test_airy.cpp test_instances//test_instances pch_light /boost/test//boost_unit_test_framework  ]
    [ run test_bessel_j.cpp test_instances//test_instances pch_light /boost/test//boost_unit_test_framework  ]

test/git_issue_1412_pt_2.cpp

@@ -0,0 +1,26 @@
+//  Copyright Matt Borland 2026
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Regression test for https://github.com/boostorg/math/issues/1412
+//
+// Part 2: Test all of #include <boost/math/special_functions.hpp> as that is what libc++ is going to use
+
+#define BOOST_MATH_NO_EXCEPTIONS
+
+// Claim the <iomanip> include guard so any later #include <iomanip> expands to nothing and std::setprecision is unavailable.
+// The original reproducer with _SSTREAM broke <complex> which is outside our purview.
+#define _LIBCPP_IOMANIP        // libc++
+#define _GLIBCXX_IOMANIP 1     // libstdc++
+
+#include "compile_test/instantiate.hpp"
+
+int main(int argc, char* [])
+{
+    if (argc > 10000)
+    {
+        instantiate(double(0));
+        instantiate_mixed(double(0));
+    }
+}