Files
lix/tests/functional/repl_characterization/data/stacktrace_relative.test
T
blokyk daadfed9ae libcmd/repl: allow :st argument to be relative to current stack index
See [lix-project/lix#1156], but basically currently the `:st <n>`
debugger command doesn't allow any negative indices, and putting a plus
sign in front of the arg doesn't change anything; thus, we can exploit
that "design space" to allow users to move between different stack
frames easily, by simply prepending their arg with a +/- sign.

The actual behavior is little more nuanced when you account for errors:
as suggested by @pennae (thanks! :), when the user inputs an offset that
would result in an invalid frame index, the debugger instead clamps it
to the closest bound (i.e. 0 for negative offsets, $maxFrame for
positive ones) and just prints a warning.

Fixes #1156

[lix-project/lix#1156]: https://git.lix.systems/lix-project/lix/issues/1156

Change-Id: I02a0cdb6aaebbdb0515308880a3bf9c0d2fcd25e
2026-03-20 18:22:24 +01:00

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@args --debugger
nix-repl> let f = _: throw "x_x"; x = f 5; in x
error: x_x
absolute indices still work:
nix-repl> :st 1
1: while calling a function
«string»:1:12
1| let f = _: throw "x_x"; x = f 5; in x
| ^
Env level 0
static: _
Env level 1
static: f x
Env level 2
static:
Env level 3
abort baseNameOf break builtins derivation derivationStrict dirOf false fetchGit fetchMercurial fetchTarball fetchTree fromTOML import isNull map null placeholder removeAttrs scopedImport throw toString true
index with + goes up the stack relative to current (1 in this case):
nix-repl> :st +3
4: while evaluating a 'let' expression
«string»:1:1
1| let f = _: throw "x_x"; x = f 5; in x
| ^
Env level 0
static: f x
Env level 1
static:
Env level 2
abort baseNameOf break builtins derivation derivationStrict dirOf false fetchGit fetchMercurial fetchTarball fetchTree fromTOML import isNull map null placeholder removeAttrs scopedImport throw toString true
index with - goes down and is also relative to current (4):
nix-repl> :st -1
3: while calling a function
«string»:1:29
1| let f = _: throw "x_x"; x = f 5; in x
| ^
Env level 0
static: f x
Env level 1
static:
Env level 2
abort baseNameOf break builtins derivation derivationStrict dirOf false fetchGit fetchMercurial fetchTarball fetchTree fromTOML import isNull map null placeholder removeAttrs scopedImport throw toString true
quit
nix-repl> :quit
error: x_x