lix/tests/functional/lang/eval-fail-duplicate-traces.nix
Rebecca Turner 7434caca05
Fix segfault on infinite recursion in some cases
This fixes a segfault on infinite function call recursion (rather than
infinite thunk recursion) by tracking the function call depth in
`EvalState`.

Additionally, to avoid printing extremely long stack traces, stack
frames are now deduplicated, with a `(19997 duplicate traces omitted)`
message. This should only really be triggered in infinite recursion
scenarios.

Before:

    $ nix-instantiate --eval --expr '(x: x x) (x: x x)'
    Segmentation fault: 11

After:

    $ nix-instantiate --eval --expr '(x: x x) (x: x x)'
    error: stack overflow

           at «string»:1:14:
                1| (x: x x) (x: x x)
                 |              ^

    $ nix-instantiate --eval --expr '(x: x x) (x: x x)' --show-trace
    error:
           … from call site
             at «string»:1:1:
                1| (x: x x) (x: x x)
                 | ^

           … while calling anonymous lambda
             at «string»:1:2:
                1| (x: x x) (x: x x)
                 |  ^

           … from call site
             at «string»:1:5:
                1| (x: x x) (x: x x)
                 |     ^

           … while calling anonymous lambda
             at «string»:1:11:
                1| (x: x x) (x: x x)
                 |           ^

           … from call site
             at «string»:1:14:
                1| (x: x x) (x: x x)
                 |              ^

           (19997 duplicate traces omitted)

           error: stack overflow
           at «string»:1:14:
                1| (x: x x) (x: x x)
                 |              ^
2023-12-29 22:16:44 -08:00

10 lines
257 B
Nix

# Check that we only omit duplicate stack traces when there's a bunch of them.
# Here, there's only a couple duplicate entries, so we output them all.
let
throwAfter = n:
if n > 0
then throwAfter (n - 1)
else throw "Uh oh!";
in
throwAfter 2