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https://github.com/NixOS/nix
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7434caca05
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)
| ^
37 lines
1 KiB
Nix
37 lines
1 KiB
Nix
# Check that stack frame deduplication only affects consecutive intervals, and
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# that they are reported independently of any preceding sections, even if
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# they're indistinguishable.
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#
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# In terms of the current implementation, we check that we clear the set of
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# "seen frames" after eliding a group of frames.
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#
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# Suppose we have:
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# - 10 frames in a function A
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# - 10 frames in a function B
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# - 10 frames in a function A
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#
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# We want to output:
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# - a few frames of A (skip the rest)
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# - a few frames of B (skip the rest)
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# - a few frames of A (skip the rest)
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#
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# If we implemented this in the naive manner, we'd instead get:
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# - a few frames of A (skip the rest)
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# - a few frames of B (skip the rest, _and_ skip the remaining frames of A)
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let
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throwAfterB = recurse: n:
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if n > 0
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then throwAfterB recurse (n - 1)
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else if recurse
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then throwAfterA false 10
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else throw "Uh oh!";
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throwAfterA = recurse: n:
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if n > 0
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then throwAfterA recurse (n - 1)
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else if recurse
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then throwAfterB true 10
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else throw "Uh oh!";
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in
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throwAfterA true 10
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