-std=c++11 breaks clang builds

[jobovy]

The fix from #75 breaks the build process on Macs with clang (the default compiler), because clang doesn't allow the -std=c++11 flag when compiling C code. So ideally, you'd only want to have this flag on for the *.cpp files, but not for the *.c files. However, this seems quite difficult to do, as distutils tries hard to use the same flags for all files. The easiest solution might just be to make this an optional flag that can be turned off or detecting that this flag doesn't work and turning it off automatically. Note that the current way of checking the compiler flags doesn't detect this issue, because it compiles a C++ file and for that the flag is fine. You could do the check with a C file, but I'm not sure that that doesn't lead to other issues.

[beckermr]

See this diff for a potential fix:

--- setup.py.orig	2023-01-08 06:55:28
+++ setup.py	2023-01-08 06:55:49
@@ -123,7 +123,8 @@
     cflags = extra_compile_args
     lflags = extra_link_args
 
-    cflags += ["-std=c++11"]
+    if platform.system() != "Darwin":
+        cflags += ["-std=c++11"]
 
     if platform.system() == "Darwin":
         # Usually Macs need this, but they might not, so try it, and only add

[jobovy]

I don’t think this will work, because you need the -std=c++11 flag with clang too, just only for the C compiler.

[jobovy]

Or maybe you don't need the flag currently, although eventually you might need it. It's been a while since I opened this issue and haven't checked recently.

[beckermr]

The builds on conda-forge worked just fine.

[beckermr]

the default in clang is past c++11 now

[jobovy]

the default in clang is past c++11 now

Yes, it does seem to work to just not set the -std flag with clang, I can't really figure out why, because as you say, the default standard in clang is beyond c+11 now.

Checking if platform.system() != "Darwin": might not be the best way, because if somebody is using gcc 11 on a Mac, they would probably need the -std=c++11 flag? A better option might be to check whether the compiler supports the flag and if not, drop it (using similar code as is in the setup.py file already).

[MacDaddy1660B]

Confirmed: commenting line #cflags += ["-std=c++11"] on Darwin systems results in a successful build.

[esheldon]

I'm happy to take a PR on this

[esheldon]

where are we on this?

[jobovy]

I can take a look and see whether I can fix this quickly. Still having the issue locally...