From 0e528c37b75a4875c71e93c82542518956ddabc1 Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@scylladb.com>
Date: Wed, 24 Jan 2024 11:33:42 +0200
Subject: [PATCH] Update supported C++ standards to C++23 and C++20 (dropping
 C++17)

C++23 has passed all the ballots [1]. We can therefore support it now
formally. This means that C++17 is no longer supported, and C++20 is
supported until C++26 is released.

The primary benefit of C++23 support is that we can now use coroutines
in core Seastar code, as all supported C++ versions have them.

[1] https://lists.isocpp.org/std-proposals/2024/01/8880.php
---
 .circleci/config.yml | 6 +++---
 CMakeLists.txt       | 2 +-
 configure.py         | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index ae88af07418..dacc635abbb 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -71,7 +71,7 @@ workflows:
           matrix:
             parameters:
               compiler: ["clang++-17", "g++-13"]
-              standard: ["20", "17"]
+              standard: ["23", "20"]
               mode: ["dev", "debug", "release"]
       # only build this combination with dpdk enabled, so we don't double
       # the size of the test matrix, and can at least test the build with
@@ -80,7 +80,7 @@ workflows:
           matrix:
             parameters:
               compiler: ["clang++-17"]
-              standard: ["20"]
+              standard: ["23"]
               mode: ["release"]
               with_dpdk: [ "enable-dpdk" ]
       # only build this combination with C++20 moduels enabled, so we don't double
@@ -90,6 +90,6 @@ workflows:
           matrix:
             parameters:
               compiler: ["clang++-17"]
-              standard: ["20"]
+              standard: ["23"]
               mode: ["debug"]
               with_modules: [ "enable-modules" ]
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 785c3a6ff3d..0cec62ccba9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -141,7 +141,7 @@ set (CMAKE_CXX_FLAGS_SANITIZE
   FORCE)
 
 set (CMAKE_CXX_STANDARD
-  "20"
+  "23"
   CACHE
   STRING
   "C++ standard to build with.")
diff --git a/configure.py b/configure.py
index 85eed5f663a..3e67bcb7232 100755
--- a/configure.py
+++ b/configure.py
@@ -159,7 +159,7 @@ def identify_best_standard(cpp_standards, compiler):
 
 
 if args.cpp_standard == '':
-    cpp_standards = ['23', '20', '17']
+    cpp_standards = ['23', '20']
     args.cpp_standard = identify_best_standard(cpp_standards, compiler=args.cxx)