From 200406ce53e9be45b5490836051fbd86e0d8c27e Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 09:50:44 +0200
Subject: [PATCH 01/15] function to check if current compiler is Apple Clang

---
 extension_helpers/_setup_helpers.py | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/extension_helpers/_setup_helpers.py b/extension_helpers/_setup_helpers.py
index 7e766da..95e9edb 100644
--- a/extension_helpers/_setup_helpers.py
+++ b/extension_helpers/_setup_helpers.py
@@ -12,7 +12,7 @@
 from collections import defaultdict
 
 from setuptools import Extension, find_packages
-from setuptools.command.build_ext import new_compiler
+from setuptools.command.build_ext import customize_compiler,new_compiler
 
 from ._utils import import_file, walk_skip_hidden
 
@@ -36,6 +36,29 @@ def get_compiler():
     return new_compiler().compiler_type
 
 
+def check_apple_clang():
+    """
+    Detemines if compiler that will be used to build extension modules is
+    'Apple Clang' (which requires a specific management of OpenMP compilation
+    and linking flags).
+
+    Returns
+    -------
+    apple_clang : bool
+        Indicator whether current compiler is 'Apple Clang'.
+    """
+    try:
+        ccompiler = new_compiler()
+        customize_compiler(ccompiler)
+        compiler_version = subprocess.run(
+            [ccompiler.compiler[0], "--version"], capture_output=True
+        )
+        apple_clang = "Apple clang" in str(compiler_version.stdout)
+    except:
+        apple_clang = False
+    return apple_clang
+
+
 def get_extensions(srcdir='.'):
     """
     Collect all extensions from Cython files and ``setup_package.py`` files.

From b4ea694e5807227b009d215b968ff6e9c7a5a7e1 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 09:51:12 +0200
Subject: [PATCH 02/15] test function checking if current compiler is Apple
 Clang

---
 extension_helpers/tests/test_setup_helpers.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/extension_helpers/tests/test_setup_helpers.py b/extension_helpers/tests/test_setup_helpers.py
index 05fc7ab..dab45f4 100644
--- a/extension_helpers/tests/test_setup_helpers.py
+++ b/extension_helpers/tests/test_setup_helpers.py
@@ -7,7 +7,7 @@
 
 import pytest
 
-from .._setup_helpers import get_compiler, get_extensions
+from .._setup_helpers import check_apple_clang, get_compiler, get_extensions
 from . import cleanup_import, run_setup
 
 extension_helpers_PATH = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..'))  # noqa
@@ -27,6 +27,9 @@ def teardown_module(module):
 def test_get_compiler():
     assert get_compiler() in POSSIBLE_COMPILERS
 
+def test_check_apple_clang():
+    assert check_apple_clang() in [True, False]
+
 
 def _extension_test_package(tmpdir, request, extension_type='c',
                             include_numpy=False):

From 45b198c59c39fb069ac671242f62d349ea6d2b05 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 09:51:43 +0200
Subject: [PATCH 03/15] specific compilation and linking flags for Apple Clang
 compiler

---
 extension_helpers/_openmp_helpers.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index e7376d6..17f35e5 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -22,7 +22,7 @@
 
 from setuptools.command.build_ext import customize_compiler, get_config_var, new_compiler
 
-from ._setup_helpers import get_compiler
+from ._setup_helpers import check_apple_clang, get_compiler
 
 __all__ = ['add_openmp_flags_if_available']
 
@@ -134,8 +134,12 @@ def get_openmp_flags():
             link_flags.append('-L' + lib_path)
             link_flags.append('-Wl,-rpath,' + lib_path)
 
-        compile_flags.append('-fopenmp')
-        link_flags.append('-fopenmp')
+        if not check_apple_clang():
+            compile_flags.append('-fopenmp')
+            link_flags.append('-fopenmp')
+        else:
+            compile_flags.append('-Xpreprocessor -fopenmp')
+            link_flags.append('-lomp')
 
     return {'compiler_flags': compile_flags, 'linker_flags': link_flags}
 

From 40a39fdc7944c3b16b1de70ca33c78e154ed2fad Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 10:28:09 +0200
Subject: [PATCH 04/15] add comment about libomp + refine except statement

---
 extension_helpers/_setup_helpers.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/extension_helpers/_setup_helpers.py b/extension_helpers/_setup_helpers.py
index 95e9edb..ee1b53a 100644
--- a/extension_helpers/_setup_helpers.py
+++ b/extension_helpers/_setup_helpers.py
@@ -41,6 +41,9 @@ def check_apple_clang():
     Detemines if compiler that will be used to build extension modules is
     'Apple Clang' (which requires a specific management of OpenMP compilation
     and linking flags).
+    
+    In addition, it may require that you install `libomp` (e.g. with
+    `brew install libomp`).
 
     Returns
     -------
@@ -54,7 +57,7 @@ def check_apple_clang():
             [ccompiler.compiler[0], "--version"], capture_output=True
         )
         apple_clang = "Apple clang" in str(compiler_version.stdout)
-    except:
+    except Exception:
         apple_clang = False
     return apple_clang
 

From ac7644e5ce30903022163118273d2767ed5c88fd Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 13:55:33 +0200
Subject: [PATCH 05/15] specific warning message for Apple Clang users +
 specific OpenMP include and lib path (if not aleady setup) for Apple Clang

---
 extension_helpers/_openmp_helpers.py | 30 ++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 17f35e5..6a14d57 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -19,6 +19,7 @@
 import datetime
 import tempfile
 import subprocess
+import textwrap
 
 from setuptools.command.build_ext import customize_compiler, get_config_var, new_compiler
 
@@ -138,8 +139,37 @@ def get_openmp_flags():
             compile_flags.append('-fopenmp')
             link_flags.append('-fopenmp')
         else:
+            msg = textwrap.dedent(
+                """\
+                You are using Apple Clang compiler.
+
+                Your system should be prepared:
+                1. You should have specfically installed OpenMP,
+                   for instance by running `brew install libomp`.
+                2. OpenMP source and library should be findable by the compiler.
+
+                By default, OpenMP source and library will be looked in
+                `/usr/local/opt/libomp/include` and `/usr/local/opt/libomp/lib`
+                respectively.
+
+                To use specific OpenMP source and library paths, you can setup
+                the following environment variables `CFLAGS` and `LDFLAGS`
+                before any compilation/installation, e.g.
+                ```
+                export CFLAGS="-I/usr/local/opt/libomp/include"
+                export LDFLAGS="-L/usr/local/opt/libomp/lib"
+                ```
+                """
+            )
+            log.warn(msg)
             compile_flags.append('-Xpreprocessor -fopenmp')
+            if not 'CFLAG' in os.environ and \
+                os.path.dir('/usr/local/opt/libomp/include'):
+                compile_flags.append('-I/usr/local/opt/libomp/include')
             link_flags.append('-lomp')
+            if not 'LDFLAG' in os.environ and \
+                os.path.dir('/usr/local/opt/libomp/lib'):
+                compile_flags.append('-I/usr/local/opt/libomp/lib')
 
     return {'compiler_flags': compile_flags, 'linker_flags': link_flags}
 

From 401d869f3dc5c6a47b99ecb564ebf7ab71dfef45 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 13:57:35 +0200
Subject: [PATCH 06/15] fix typo in dir check

---
 extension_helpers/_openmp_helpers.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 6a14d57..025c449 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -164,11 +164,11 @@ def get_openmp_flags():
             log.warn(msg)
             compile_flags.append('-Xpreprocessor -fopenmp')
             if not 'CFLAG' in os.environ and \
-                os.path.dir('/usr/local/opt/libomp/include'):
+                os.path.isdir('/usr/local/opt/libomp/include'):
                 compile_flags.append('-I/usr/local/opt/libomp/include')
             link_flags.append('-lomp')
             if not 'LDFLAG' in os.environ and \
-                os.path.dir('/usr/local/opt/libomp/lib'):
+                os.path.isdir('/usr/local/opt/libomp/lib'):
                 compile_flags.append('-I/usr/local/opt/libomp/lib')
 
     return {'compiler_flags': compile_flags, 'linker_flags': link_flags}

From ad2b191f58c39768e3173476a2373041fd58fc0c Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 14:03:42 +0200
Subject: [PATCH 07/15] add preargs instead of postargs to compile command
 (because '-Xprocessor -fopenmp' not undertood by Apple Clang as postargs but
 ok as preargs)

---
 extension_helpers/_openmp_helpers.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 025c449..f309bd1 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -223,12 +223,12 @@ def check_openmp_support(openmp_flags=None):
 
             # Compile, test program
             ccompiler.compile(['test_openmp.c'], output_dir='objects',
-                              extra_postargs=compile_flags)
+                              extra_preargs=compile_flags)
 
             # Link test program
             objects = glob.glob(os.path.join('objects', '*' + ccompiler.obj_extension))
             ccompiler.link_executable(objects, 'test_openmp',
-                                      extra_postargs=link_flags)
+                                      extra_preargs=link_flags)
 
             # Run test program
             output = subprocess.check_output('./test_openmp')

From 31de7ec1f57981a63afbfd75f8668c61b72bd36c Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 14:10:00 +0200
Subject: [PATCH 08/15] fix typo regarding link_flags

---
 extension_helpers/_openmp_helpers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index f309bd1..a302bca 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -169,7 +169,7 @@ def get_openmp_flags():
             link_flags.append('-lomp')
             if not 'LDFLAG' in os.environ and \
                 os.path.isdir('/usr/local/opt/libomp/lib'):
-                compile_flags.append('-I/usr/local/opt/libomp/lib')
+                link_flags.append('-L/usr/local/opt/libomp/lib')
 
     return {'compiler_flags': compile_flags, 'linker_flags': link_flags}
 

From 094b820e2c0845b6c2086b0c8d083e8922aaf2d2 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 16:56:22 +0200
Subject: [PATCH 09/15] fix typo

---
 extension_helpers/_openmp_helpers.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index a302bca..f538cc1 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -163,11 +163,11 @@ def get_openmp_flags():
             )
             log.warn(msg)
             compile_flags.append('-Xpreprocessor -fopenmp')
-            if not 'CFLAG' in os.environ and \
+            if not 'CFLAGS' in os.environ and \
                 os.path.isdir('/usr/local/opt/libomp/include'):
                 compile_flags.append('-I/usr/local/opt/libomp/include')
             link_flags.append('-lomp')
-            if not 'LDFLAG' in os.environ and \
+            if not 'LDFLAGS' in os.environ and \
                 os.path.isdir('/usr/local/opt/libomp/lib'):
                 link_flags.append('-L/usr/local/opt/libomp/lib')
 

From dcca6d79a89cbcab2d3d52bbe17b71d4a446c4f1 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 17:08:38 +0200
Subject: [PATCH 10/15] account for potential CXXFLAGS env variable

---
 extension_helpers/_openmp_helpers.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index f538cc1..6a5c410 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -130,6 +130,10 @@ def get_openmp_flags():
         if include_path:
             compile_flags.append('-I' + include_path)
 
+        include_path = _get_flag_value_from_var('-I', 'CXXFLAGS')
+        if include_path:
+            compile_flags.append('-I' + include_path)
+
         lib_path = _get_flag_value_from_var('-L', 'LDFLAGS')
         if lib_path:
             link_flags.append('-L' + lib_path)
@@ -153,8 +157,8 @@ def get_openmp_flags():
                 respectively.
 
                 To use specific OpenMP source and library paths, you can setup
-                the following environment variables `CFLAGS` and `LDFLAGS`
-                before any compilation/installation, e.g.
+                the following environment variables `CFLAGS` (or `CXXFLAGS`)
+                and `LDFLAGS` before any compilation/installation, e.g.
                 ```
                 export CFLAGS="-I/usr/local/opt/libomp/include"
                 export LDFLAGS="-L/usr/local/opt/libomp/lib"
@@ -163,7 +167,7 @@ def get_openmp_flags():
             )
             log.warn(msg)
             compile_flags.append('-Xpreprocessor -fopenmp')
-            if not 'CFLAGS' in os.environ and \
+            if not 'CFLAGS' in os.environ and not 'CXXFLAGS' in os.environ and \
                 os.path.isdir('/usr/local/opt/libomp/include'):
                 compile_flags.append('-I/usr/local/opt/libomp/include')
             link_flags.append('-lomp')

From e4c01f861c15a2fd188de3b697239271177eb335 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Fri, 1 Apr 2022 17:33:00 +0200
Subject: [PATCH 11/15] modify _get_flag_value_from_var to return list of
 extracted flags if corresponding environment variable contains one or more

---
 extension_helpers/_openmp_helpers.py          | 24 +++++++++++++++----
 .../tests/test_openmp_helpers.py              | 17 ++++++++++++-
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 6a5c410..9d3d2b4 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -61,6 +61,12 @@ def _get_flag_value_from_var(flag, var, delim=' '):
         The environment variable to extract the flag from, e.g. CFLAGS or LDFLAGS.
     delim : str, optional
         The delimiter separating flags inside the environment variable
+    
+    Returns
+    -------
+    extracted_flags : None|list
+        List of flags starting with flag extracted from var  environment
+        variable.
 
     Examples
     --------
@@ -98,10 +104,15 @@ def _get_flag_value_from_var(flag, var, delim=' '):
             return None
 
     # Extract flag from {var:value}
+    extracted_flags = []
     if flags:
         for item in flags.split(delim):
             if item.startswith(flag):
-                return item[flag_length:]
+                extracted_flags.append(item[flag_length:])
+    if len(extracted_flags) > 0:
+        return extracted_flags
+    else:
+        return None
 
 
 def get_openmp_flags():
@@ -128,16 +139,19 @@ def get_openmp_flags():
 
         include_path = _get_flag_value_from_var('-I', 'CFLAGS')
         if include_path:
-            compile_flags.append('-I' + include_path)
+            for _ in include_path:
+                compile_flags.append('-I' + _)
 
         include_path = _get_flag_value_from_var('-I', 'CXXFLAGS')
         if include_path:
-            compile_flags.append('-I' + include_path)
+            for _ in include_path:
+                compile_flags.append('-I' + _)
 
         lib_path = _get_flag_value_from_var('-L', 'LDFLAGS')
         if lib_path:
-            link_flags.append('-L' + lib_path)
-            link_flags.append('-Wl,-rpath,' + lib_path)
+            for _ in include_path:
+                link_flags.append('-L' + _)
+                link_flags.append('-Wl,-rpath,' + _)
 
         if not check_apple_clang():
             compile_flags.append('-fopenmp')
diff --git a/extension_helpers/tests/test_openmp_helpers.py b/extension_helpers/tests/test_openmp_helpers.py
index 6a704b3..0baecd6 100644
--- a/extension_helpers/tests/test_openmp_helpers.py
+++ b/extension_helpers/tests/test_openmp_helpers.py
@@ -8,7 +8,7 @@
 import pytest
 from setuptools import Extension
 
-from .._openmp_helpers import add_openmp_flags_if_available, generate_openmp_enabled_py
+from .._openmp_helpers import _get_flag_value_from_var, add_openmp_flags_if_available, generate_openmp_enabled_py
 
 
 @pytest.fixture
@@ -51,3 +51,18 @@ def test_generate_openmp_enabled_py(openmp_expected):
 
     if openmp_expected is not None:
         assert openmp_expected is is_openmp_enabled
+
+
+def test_get_flag_value_from_var():
+    # define input
+    var = 'EXTTESTFLAGS'
+    flag = '-I'
+    # non existing var (at least should not)
+    assert _get_flag_value_from_var(flag, var) is None
+    # setup env varN
+    os.environ[var] = '-I/path/to/file1 -I/path/to/file2 -custom_option1 -custom_option2'
+    # non existing flag
+    assert _get_flag_value_from_var('-L', var) is None
+    # existing flag
+    assert _get_flag_value_from_var(flag, var) == ['/path/to/file1', '/path/to/file2']
+

From e93d69581da4f7f5c67a92c30da1696f2e490b2f Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Mon, 11 Apr 2022 14:51:19 +0200
Subject: [PATCH 12/15] fix typo regarding lib path parsing

---
 extension_helpers/_openmp_helpers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 9d3d2b4..792d149 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -149,7 +149,7 @@ def get_openmp_flags():
 
         lib_path = _get_flag_value_from_var('-L', 'LDFLAGS')
         if lib_path:
-            for _ in include_path:
+            for _ in lib_path:
                 link_flags.append('-L' + _)
                 link_flags.append('-Wl,-rpath,' + _)
 

From cc7aafd5eb1a38f767c957a15be52bb56725cda5 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Tue, 12 Apr 2022 15:25:51 +0200
Subject: [PATCH 13/15] check for the OS (i.e. MacOS) before testing for Apple
 Clang compiler

---
 extension_helpers/_setup_helpers.py | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/extension_helpers/_setup_helpers.py b/extension_helpers/_setup_helpers.py
index ee1b53a..782c0ac 100644
--- a/extension_helpers/_setup_helpers.py
+++ b/extension_helpers/_setup_helpers.py
@@ -9,6 +9,7 @@
 import shutil
 import logging
 import subprocess
+import sys
 from collections import defaultdict
 
 from setuptools import Extension, find_packages
@@ -42,24 +43,26 @@ def check_apple_clang():
     'Apple Clang' (which requires a specific management of OpenMP compilation
     and linking flags).
     
-    In addition, it may require that you install `libomp` (e.g. with
-    `brew install libomp`).
+    Note: it first checks that the OS is indeed MacOS.
 
     Returns
     -------
     apple_clang : bool
         Indicator whether current compiler is 'Apple Clang'.
     """
-    try:
-        ccompiler = new_compiler()
-        customize_compiler(ccompiler)
-        compiler_version = subprocess.run(
-            [ccompiler.compiler[0], "--version"], capture_output=True
-        )
-        apple_clang = "Apple clang" in str(compiler_version.stdout)
-    except Exception:
-        apple_clang = False
-    return apple_clang
+    if sys.platform != "darwin":
+        return False
+    else:
+        try:
+            ccompiler = new_compiler()
+            customize_compiler(ccompiler)
+            compiler_version = subprocess.run(
+                [ccompiler.compiler[0], "--version"], capture_output=True
+            )
+            apple_clang = "Apple clang" in str(compiler_version.stdout)
+        except Exception:
+            apple_clang = False
+        return apple_clang
 
 
 def get_extensions(srcdir='.'):

From b1a10a52fff1658cdb988f2ce303da5761a04444 Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Tue, 12 Apr 2022 15:31:30 +0200
Subject: [PATCH 14/15] improve libomp search on MacOS

---
 extension_helpers/_openmp_helpers.py | 52 ++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 14 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 792d149..26f2296 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -65,7 +65,7 @@ def _get_flag_value_from_var(flag, var, delim=' '):
     Returns
     -------
     extracted_flags : None|list
-        List of flags starting with flag extracted from var  environment
+        List of flags starting with flag extracted from var environment
         variable.
 
     Examples
@@ -74,7 +74,7 @@ def _get_flag_value_from_var(flag, var, delim=' '):
     function will then return the following:
 
         >>> _get_flag_value_from_var('-L', 'LDFLAGS')
-        '/usr/local/include'
+        ['/usr/local/include']
 
     Notes
     -----
@@ -128,6 +128,9 @@ def get_openmp_flags():
     -----
     The flags returned are not tested for validity, use
     `check_openmp_support(openmp_flags=get_openmp_flags())` to do so.
+
+    On MacOS, it may require that you install `libomp` (e.g. with
+    `brew install libomp`).
     """
 
     compile_flags = []
@@ -166,13 +169,14 @@ def get_openmp_flags():
                    for instance by running `brew install libomp`.
                 2. OpenMP source and library should be findable by the compiler.
 
-                By default, OpenMP source and library will be looked in
-                `/usr/local/opt/libomp/include` and `/usr/local/opt/libomp/lib`
-                respectively.
+                By default, `brew` will be use to find OpenMP source and
+                library. If not available, they will be looked for in
+                standard system directories.
 
-                To use specific OpenMP source and library paths, you can setup
-                the following environment variables `CFLAGS` (or `CXXFLAGS`)
-                and `LDFLAGS` before any compilation/installation, e.g.
+                To override this behavior and use specific OpenMP source and
+                library paths, you can setup the following environment
+                variables `CFLAGS` (or `CXXFLAGS`) and `LDFLAGS` before any
+                compilation/installation, e.g.
                 ```
                 export CFLAGS="-I/usr/local/opt/libomp/include"
                 export LDFLAGS="-L/usr/local/opt/libomp/lib"
@@ -180,14 +184,34 @@ def get_openmp_flags():
                 """
             )
             log.warn(msg)
+            # try to find path to libomp
+            try:
+                brew_check = subprocess.run(
+                    ["brew", "--prefix", "libomp"], capture_output=True
+                )
+                libomp = str(brew_check.stdout)
+            except Exception:
+                if os.path.isdir('/usr/local/opt/libomp'):
+                    libomp = '/usr/local/opt/libomp'
+                elif os.path.isfile('/opt/homebrew/include/omp.h') \
+                    and os.path.isfile('/opt/homebrew/lib/libomp.a'):
+                    libomp = '/opt/homebrew'
+                else:
+                    libomp = None
+            # compile flags
             compile_flags.append('-Xpreprocessor -fopenmp')
-            if not 'CFLAGS' in os.environ and not 'CXXFLAGS' in os.environ and \
-                os.path.isdir('/usr/local/opt/libomp/include'):
-                compile_flags.append('-I/usr/local/opt/libomp/include')
+            # additional include flag
+            if not 'CFLAGS' in os.environ and not 'CXXFLAGS' in os.environ \
+                and libomp is not None \
+                and os.path.isdir(os.path.join(libomp, 'include')):
+                    compile_flags.append('-I' + os.path.join(libomp, 'include'))
+            # link flag
             link_flags.append('-lomp')
-            if not 'LDFLAGS' in os.environ and \
-                os.path.isdir('/usr/local/opt/libomp/lib'):
-                link_flags.append('-L/usr/local/opt/libomp/lib')
+            # additional link flag
+            if not 'LDFLAGS' in os.environ \
+                and libomp is not None \
+                and os.path.isdir(os.path.join(libomp, 'lib')):
+                link_flags.append('-L' + os.path.join(libomp, 'lib'))
 
     return {'compiler_flags': compile_flags, 'linker_flags': link_flags}
 

From f88cdbb3f523f9fbd0ae0c86b783ee25afa5f54e Mon Sep 17 00:00:00 2001
From: GD <gd.dev@libertymail.net>
Date: Tue, 12 Apr 2022 17:54:07 +0200
Subject: [PATCH 15/15] improve extraction of command output

---
 extension_helpers/_openmp_helpers.py | 2 +-
 extension_helpers/_setup_helpers.py  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/extension_helpers/_openmp_helpers.py b/extension_helpers/_openmp_helpers.py
index 26f2296..6a1033e 100644
--- a/extension_helpers/_openmp_helpers.py
+++ b/extension_helpers/_openmp_helpers.py
@@ -189,7 +189,7 @@ def get_openmp_flags():
                 brew_check = subprocess.run(
                     ["brew", "--prefix", "libomp"], capture_output=True
                 )
-                libomp = str(brew_check.stdout)
+                libomp = brew_check.stdout.decode('utf-8').strip()
             except Exception:
                 if os.path.isdir('/usr/local/opt/libomp'):
                     libomp = '/usr/local/opt/libomp'
diff --git a/extension_helpers/_setup_helpers.py b/extension_helpers/_setup_helpers.py
index 782c0ac..85b5714 100644
--- a/extension_helpers/_setup_helpers.py
+++ b/extension_helpers/_setup_helpers.py
@@ -59,7 +59,7 @@ def check_apple_clang():
             compiler_version = subprocess.run(
                 [ccompiler.compiler[0], "--version"], capture_output=True
             )
-            apple_clang = "Apple clang" in str(compiler_version.stdout)
+            apple_clang = "Apple clang" in compiler_version.stdout.decode('utf-8')
         except Exception:
             apple_clang = False
         return apple_clang