new option: abort-on-warn

Co-authored-by: Emilia Bopp <contact@ebopp.de> Change-Id: I3c3347e51d8543fbeb2b4e6ed12b0f556a6a6964
2025-11-22 16:48:53 +01:00
parent 2d85d4c7b6
commit b3e24cb3e5
7 changed files with 34 additions and 1 deletions
@@ -10,4 +10,6 @@ Like `builtins.trace`, it takes two arguments: the message to emit, and the expr
 _Unlike_ `builtins.trace`, `builtins.warn` requires the first argument — the message — to be a string.
 In the future we may extend `builtins.warn` to accept a more structured API.

-To go along with this, we also have a new config setting [`debugger-on-warn`](@docroot@/command-ref/conf-file.md#conf-debugger-on-warn), which, when used with `--debugger`, makes `builtins.warn` also function like [`builtins.break`](@docroot@/language/builtins.md#builtins-break).
+To go along with this, we also have two new config settings:
+- [`debugger-on-warn`](@docroot@/command-ref/conf-file.md#conf-debugger-on-warn), which, when used with `--debugger`, makes `builtins.warn` also function like [`builtins.break`](@docroot@/language/builtins.md#builtins-break).
+- [`abort-on-warn`](@docroot@/command-ref/conf-file.md#conf-abort-on-warn), which aborts evaluation entirely after the warning is emitted.
@@ -15,6 +15,7 @@ subdir('flake')

 libexpr_setting_definitions = files(
  # keep-sorted start
+  'settings/abort-on-warn.md',
  'settings/allow-import-from-derivation.md',
  'settings/allow-unsafe-native-code-during-evaluation.md',
  'settings/allowed-uris.md',
@@ -779,6 +779,11 @@ static void prim_warn(EvalState & state, Value ** args, Value & v)

    printTaggedWarning("%s", Uncolored(msg));

+    if (evalSettings.abortOnWarn) {
+        state.ctx.errors.make<Abort>("evaluation aborted (abort-on-warn)")
+            .debugThrow();
+    }
+
    if (evalSettings.debuggerOnWarn) {
        if (auto const trace = state.ctx.nextDebugTrace()) {
            auto const error = EvalError(ErrorInfo{
@@ -0,0 +1,10 @@
+---
+name: abort-on-warn
+internalName: abortOnWarn
+type: bool
+default: false
+---
+If set to true, [`builtins.warn`](@docroot@/language/builtins.md#builtins-warn) will throw an error when logging a warning.
+This will give you a stack trace that leads to the location of the warning.
+This is useful for finding information about warnings in third-party Nix code when you can not start the interactive debugger, such as when Nix is called from a non-interactive script. See [`debugger-on-warn`](#conf-debugger-on-warn).
+Currently, a stack trace can only be produced when the debugger is enabled, or when evaluation is aborted.
@@ -0,0 +1,9 @@
+warning: meow
+error:
+       … while calling the 'warn' builtin
+         at /pwd/in.nix:1:1:
+            1| builtins.warn "meow" (throw "must abort before this")
+             | ^
+            2|
+
+       error: evaluation aborted (abort-on-warn)
@@ -0,0 +1 @@
+builtins.warn "meow" (throw "must abort before this")
@@ -4,3 +4,8 @@ runner = "eval-okay"
 [[test]]
 runner = "eval-fail"
 in = "in-reject-non-string.nix"
+
+[[test]]
+runner = "eval-fail"
+flags = ["--option", "abort-on-warn", "true"]
+in = "in-abort.nix"
				`@@ -0,0 +1 @@`
				`builtins.warn "meow" (throw "must abort before this")`