Fix compilation with C++17 and later

[prj-]

No description provided.

[prj-]

@andreasnoack, very trivial PR, would you mind reviewing/integrating it? Thanks in advance.

[balay]

https://github.com/elemental/Elemental/actions/runs/38260879078/job/114897739085

@prj-

I'm rerunning the failed job. But the following is the likely CI fix:

--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,6 +33,7 @@
       CC: ${{ matrix.cc }}
       CXX: ${{ matrix.cxx }}
       FC: ${{ matrix.f77 }}
+      UCX_TLS: tcp,self,sm

     steps:
       - uses: actions/checkout@v4

Also claude suggests:

--- a/include/El/core/environment/decl.hpp
+++ b/include/El/core/environment/decl.hpp
@@ -37,8 +37,7 @@
 using std::exception;
 inline bool has_uncaught_exception() noexcept
 {
-#if __cplusplus >= 201703L || \
-    (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
+#ifdef __cpp_lib_uncaught_exceptions
     return std::uncaught_exceptions() > 0;
 #else
     return std::uncaught_exception();

[balay]

I'm rerunning the failed job

so that worked!

[prj-]

I didn't know you had write access here. That simplifies everything.

[balay]

create a PR with some additional CI changes at #282

[prj-]

Will apply your suggestions after the other PR is merged.

[prj-]

I've applied your suggestion for include/El/core/environment/decl.hpp, and left the one for .github/workflows/ci.yml since it should leave in your other PR.

[balay]

calude is suggesting one more fix, I think good to apply:

include/El/core/environment/decl.hpp:40 tests __cpp_lib_uncaught_exceptions, but <exception> (and <version>) is never included — core.hpp:16-32 has <stdexcept> and friends, not <exception>.

  It works today only because libstdc++ pulls <exception> in transitively 

diff --git a/include/El/core.hpp b/include/El/core.hpp
index 0f89acaed..fde84a01e 100644
--- a/include/El/core.hpp
+++ b/include/El/core.hpp
@@ -20,6 +20,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <ctime>
+#include <exception>
 #include <fstream>
 #include <functional>
 #include <iostream>

[balay]

Since this is simpler MR (than #282) - I'll go ahead and merge this in (after the above fix, and a successful CI run).

[balay]

Hm - opencode is suggesting:

noexcept → EL_NO_EXCEPT — matches the convention already used elsewhere in the same file

diff --git a/include/El/core/environment/decl.hpp b/include/El/core/environment/decl.hpp
index c236307e0..e87c46441 100644
--- a/include/El/core/environment/decl.hpp
+++ b/include/El/core/environment/decl.hpp
@@ -9,6 +9,8 @@
 #ifndef EL_ENVIRONMENT_DECL_HPP
 #define EL_ENVIRONMENT_DECL_HPP
 
+#include <exception>
+
 namespace El {
 
 using std::size_t;
@@ -35,7 +37,7 @@ using std::ostream;
 using std::ostringstream;
 
 using std::exception;
-inline bool has_uncaught_exception() noexcept
+inline bool has_uncaught_exception() EL_NO_EXCEPT
 {
 #ifdef __cpp_lib_uncaught_exceptions
     return std::uncaught_exceptions() > 0;

[prj-]

I don't get why we should #include <exception>, there is not a single #include in this file.

[prj-]

Applied Claude suggestion and the OpenCode second suggestion.