From ffc960ae3c04df03ea98deb263b03195acb3006e Mon Sep 17 00:00:00 2001
From: Rodrigo Reichert <rodrigo.reichert@swift-nav.com>
Date: Wed, 7 May 2025 14:22:41 +1000
Subject: [PATCH] Global C++ version

---
 cc/BUILD.bazel                             | 28 ++++++++++++++++++++++
 cc/toolchains/llvm/cc_toolchain_config.bzl | 10 ++++----
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/cc/BUILD.bazel b/cc/BUILD.bazel
index dfbbbbf..53bc98e 100644
--- a/cc/BUILD.bazel
+++ b/cc/BUILD.bazel
@@ -122,6 +122,34 @@ config_setting(
     visibility = ["//visibility:public"],
 )
 
+# Globally sets the default C++ version, even for third-party libraries
+string_flag(
+    name = "global_cxx_standard",
+    build_setting_default = "",  #inactive by default
+    visibility = ["//visibility:public"],
+)
+
+# Enable with --@rules_swiftnav//:global_cxx_standard=17
+config_setting(
+    name = "global_cxx17",
+    flag_values = {":global_cxx_standard": "17"},
+    visibility = ["//visibility:public"],
+)
+
+# Enable with --@rules_swiftnav//:global_cxx_standard=20
+config_setting(
+    name = "global_cxx20",
+    flag_values = {":global_cxx_standard": "20"},
+    visibility = ["//visibility:public"],
+)
+
+# Enable with --@rules_swiftnav//:global_cxx_standard=23
+config_setting(
+    name = "global_cxx23",
+    flag_values = {":global_cxx_standard": "23"},
+    visibility = ["//visibility:public"],
+)
+
 bool_flag(
     name = "enable_symbolizer",
     build_setting_default = False,
diff --git a/cc/toolchains/llvm/cc_toolchain_config.bzl b/cc/toolchains/llvm/cc_toolchain_config.bzl
index 8e5c937..9407103 100644
--- a/cc/toolchains/llvm/cc_toolchain_config.bzl
+++ b/cc/toolchains/llvm/cc_toolchain_config.bzl
@@ -77,10 +77,12 @@ def cc_toolchain_config(
         "-fdata-sections",
     ]
 
-    cxx_flags = [
-        # The whole codebase should build with c++14
-        "-std=c++14",
-    ]
+    cxx_flags = select({
+        "//cc:global_cxx17": ["-std=c++17"],
+        "//cc:global_cxx20": ["-std=c++20"],
+        "//cc:global_cxx23": ["-std=c++23"],
+        "//conditions:default": ["-std=c++14"],
+    })
 
     link_flags = [
         "--target=" + target_system_name,