From 30ba38c0e847c22a8448417cde7c304809eac15a Mon Sep 17 00:00:00 2001
From: Charles Harris <charlesr.harris@gmail.com>
Date: Sun, 19 Dec 2021 16:03:37 -0700
Subject: [PATCH] REV: Revert pull request #20464 from charris/backport-20354

This reverts commit 1d1f0440771, reversing changes made to 157ee4f58d6.

The backport was in error, as there is no C++ in NumPy 1.21.x. The
change caused problems with the manylinux1 compiler, which is not
C++11 compatible.
---
 numpy/core/setup.py | 36 +++++++-----------------------------
 1 file changed, 7 insertions(+), 29 deletions(-)

diff --git a/numpy/core/setup.py b/numpy/core/setup.py
index ae8081d1b92b..b03e9f99005e 100644
--- a/numpy/core/setup.py
+++ b/numpy/core/setup.py
@@ -654,38 +654,16 @@ def get_mathlib_info(*args):
         # but we cannot use add_installed_pkg_config here either, so we only
         # update the substitution dictionary during npymath build
         config_cmd = config.get_config_cmd()
+
         # Check that the toolchain works, to fail early if it doesn't
         # (avoid late errors with MATHLIB which are confusing if the
         # compiler does not work).
-        for lang, test_code, note in (
-            ('c', 'int main(void) { return 0;}', ''),
-            ('c++', (
-                    'int main(void)'
-                    '{ auto x = 0.0; return static_cast<int>(x); }'
-                ), (
-                    'note: A compiler with support for C++11 language '
-                    'features is required.'
-                )
-             ),
-        ):
-            is_cpp = lang == 'c++'
-            if is_cpp:
-                # this a workround to get rid of invalid c++ flags
-                # without doing big changes to config.
-                # c tested first, compiler should be here
-                bk_c = config_cmd.compiler
-                config_cmd.compiler = bk_c.cxx_compiler()
-            st = config_cmd.try_link(test_code, lang=lang)
-            if not st:
-                # rerun the failing command in verbose mode
-                config_cmd.compiler.verbose = True
-                config_cmd.try_link(test_code, lang=lang)
-                raise RuntimeError(
-                    f"Broken toolchain: cannot link a simple {lang.upper()} "
-                    f"program. {note}"
-                )
-            if is_cpp:
-                config_cmd.compiler = bk_c
+        st = config_cmd.try_link('int main(void) { return 0;}')
+        if not st:
+            # rerun the failing command in verbose mode
+            config_cmd.compiler.verbose = True
+            config_cmd.try_link('int main(void) { return 0;}')
+            raise RuntimeError("Broken toolchain: cannot link a simple C program")
         mlibs = check_mathlib(config_cmd)
 
         posix_mlib = ' '.join(['-l%s' % l for l in mlibs])