From 1efbd30551a64c83dce27dfe61c2c9453f63d1d6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 May 2026 23:12:24 +0200
Subject: [PATCH] Send assertion messages to sentry

---
 .../common/assert-fail/wrap-assert-fail.cc               | 4 +++-
 src/libutil/include/nix/util/meson.build                 | 1 +
 src/libutil/include/nix/util/sentry.hh                   | 9 +++++++++
 src/libutil/util.cc                                      | 2 ++
 src/nix/main.cc                                          | 9 ++++-----
 5 files changed, 19 insertions(+), 6 deletions(-)
 create mode 100644 src/libutil/include/nix/util/sentry.hh

diff --git a/nix-meson-build-support/common/assert-fail/wrap-assert-fail.cc b/nix-meson-build-support/common/assert-fail/wrap-assert-fail.cc
index d9e34168bc97..292c57e7e4c7 100644
--- a/nix-meson-build-support/common/assert-fail/wrap-assert-fail.cc
+++ b/nix-meson-build-support/common/assert-fail/wrap-assert-fail.cc
@@ -1,4 +1,5 @@
 #include "nix/util/error.hh"
+#include "nix/util/sentry.hh"
 
 #include <cstdio>
 #include <cstdlib>
@@ -13,5 +14,6 @@ __wrap___assert_fail(const char * assertion, const char * file, unsigned int lin
         snprintf(buf, sizeof(buf), "Assertion '%s' failed in %s at %s:%" PRIuLEAST32, assertion, function, file, line);
     if (n < 0)
         nix::panic("Assertion failed and could not format error message");
-    nix::panic(std::string_view(buf, std::min(static_cast<int>(sizeof(buf)), n)));
+    nix::setSentryTag("assertion", buf);
+    nix::panic(buf);
 }
diff --git a/src/libutil/include/nix/util/meson.build b/src/libutil/include/nix/util/meson.build
index 6061c57c2851..381c1e6e4295 100644
--- a/src/libutil/include/nix/util/meson.build
+++ b/src/libutil/include/nix/util/meson.build
@@ -77,6 +77,7 @@ headers = [ config_pub_h ] + files(
   'ref.hh',
   'regex-combinators.hh',
   'repair-flag.hh',
+  'sentry.hh',
   'serialise.hh',
   'signals.hh',
   'signature/local-keys.hh',
diff --git a/src/libutil/include/nix/util/sentry.hh b/src/libutil/include/nix/util/sentry.hh
new file mode 100644
index 000000000000..8da0fe867517
--- /dev/null
+++ b/src/libutil/include/nix/util/sentry.hh
@@ -0,0 +1,9 @@
+#pragma once
+
+#include "nix/util/fun.hh"
+
+namespace nix {
+
+extern fun<void(const char *, const char *)> setSentryTag;
+
+}
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 6e84f448edfd..14cdec31801b 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -307,4 +307,6 @@ std::pair<std::string_view, std::string_view> getLine(std::string_view s)
     }
 }
 
+fun<void(const char *, const char *)> setSentryTag = [](const char *, const char *) {};
+
 } // namespace nix
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 2356bc4a487c..4758ca1082fc 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -23,6 +23,7 @@
 #include "nix/flake/flake.hh"
 #include "nix/flake/settings.hh"
 #include "nix/util/json-utils.hh"
+#include "nix/util/sentry.hh"
 
 #include "self-exe.hh"
 #include "crash-handler.hh"
@@ -420,7 +421,8 @@ void mainWrapped(int argc, char ** argv)
         sentry_options_set_auto_session_tracking(options, false);
         sentry_options_set_handler_path(options, CRASHPAD_HANDLER_PATH);
         sentry_init(options);
-        sentry_set_tag("nix_command", argc > 0 ? std::string(baseNameOf(argv[0])).c_str() : "");
+        setSentryTag = [](const char * key, const char * value) { sentry_set_tag(key, value); };
+        setSentryTag("nix_command", argc > 0 ? std::string(baseNameOf(argv[0])).c_str() : "");
         sentryEnabled = true;
     }
 
@@ -629,10 +631,7 @@ void mainWrapped(int argc, char ** argv)
         evalSettings.pureEval = false;
     }
 
-#if HAVE_SENTRY
-    if (sentryEnabled)
-        sentry_set_tag("nix_subcommand", concatStringsSep(" ", subcommand).c_str());
-#endif
+    setSentryTag("nix_subcommand", concatStringsSep(" ", subcommand).c_str());
 
     try {
         args.command->second->run();