From 61577402ba331451a10051b11cf77bdc80f83fa8 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Thu, 11 Jul 2024 11:35:58 +0200
Subject: [PATCH] Add EvalErrorBuilder::panic()

An nicer alternative to printError + abort, or assert(false /* foo */)
---
 src/libexpr/eval-error.cc | 8 ++++++++
 src/libexpr/eval-error.hh | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/src/libexpr/eval-error.cc b/src/libexpr/eval-error.cc
index bd84e0428a3..cdb0b477242 100644
--- a/src/libexpr/eval-error.cc
+++ b/src/libexpr/eval-error.cc
@@ -92,6 +92,14 @@ void EvalErrorBuilder<T>::debugThrow()
     throw error;
 }
 
+template<class T>
+void EvalErrorBuilder<T>::panic()
+{
+    logError(error.info());
+    printError("This is a bug! An unexpected condition occurred, causing the Nix evaluator to have to stop. If you could share a reproducible example or a core dump, please open an issue at https://github.com/NixOS/nix/issues");
+    abort();
+}
+
 template class EvalErrorBuilder<EvalBaseError>;
 template class EvalErrorBuilder<EvalError>;
 template class EvalErrorBuilder<AssertionError>;
diff --git a/src/libexpr/eval-error.hh b/src/libexpr/eval-error.hh
index fe48e054bf2..6409dc68a28 100644
--- a/src/libexpr/eval-error.hh
+++ b/src/libexpr/eval-error.hh
@@ -112,6 +112,12 @@ public:
      * Delete the `EvalErrorBuilder` and throw the underlying exception.
      */
     [[gnu::noinline, gnu::noreturn]] void debugThrow();
+
+    /**
+     * A programming error or fatal condition occurred. Abort the process for core dump and debugging.
+     * This does not print a proper backtrace, because unwinding the stack is destructive.
+     */
+    [[gnu::noinline, gnu::noreturn]] void panic();
 };
 
 }