blokyk
daadfed9ae
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
113 lines
4.0 KiB
Plaintext
113 lines
4.0 KiB
Plaintext
@args --debugger
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:c at the root repl is not allowed since no debugger is running yet
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nix-repl> :c
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error: command 'c' can only be used when the debugger is active
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:c and other commands become available once a debugger starts
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nix-repl> with {}; a
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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nix-repl> :?
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The following commands are available:
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<expr> Evaluate and print expression
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<x> = <expr> Bind expression to variable
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:?, :help Print help about all commands (this content)
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:a, :add <expr> Add attributes from resulting set to scope
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:b, :build <expr> Build a derivation
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:bl, :build-with-gc-roots <expr> Build a derivation, creating GC roots in the working directory
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:doc <expr> Show documentation for the provided function (experimental lambda support)
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:e, :edit <expr> Open package or function in $EDITOR
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:env Show environment stack
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:i, :build-and-install <expr> Build derivation, then install result into current profile
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:l, :load <path> Load Nix expression and add it to scope
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:log <expr | .drv path> Show logs for a derivation
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:p, :print <expr> Evaluate and print expression recursively
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Strings are printed directly, without escaping.
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:q, :quit Exit the REPL
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:r, :reload Reload all files successfully loaded
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:sh, :shell <expr> Build dependencies of derivation, then start nix-shell
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:t, :type <expr> Describe result of evaluation
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:te, :trace-enable [bool] Enable, disable, or toggle showing traces for errors
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:u, :use <expr> Build derivation, then start nix-shell
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Debug mode commands
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:bt, :backtrace Show trace stack
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:c, :continue Go until end of program, exception or builtins.break
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:s, :step Go one step
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:st, :show-trace [integer index] Show current trace. If an integer is provided, this switches to that stack beforehand. If the integer has an explicit + or - sign, it is treated as relative to the current stack index.
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Flakes commands
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:lf, :load-flake <flakeref> Load Nix flake and add it to the scope
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we can now inspect state
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nix-repl> :bt
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0: error: undefined variable 'a'
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«string»:1:10
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1| with {}; a
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| ^
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1: error: Fake frame for debugging purposes
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«string»:1:10
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1| with {}; a
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| ^
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and resume execution
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nix-repl> :c
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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the debugger is once again disabled
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nix-repl> :c
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error: command 'c' can only be used when the debugger is active
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leaving the debugger from a toplevel error and entering it again doesn't leave old frames visible
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nix-repl> with {}; a
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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nix-repl> :s
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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nix-repl> with {}; b
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error: undefined variable 'b'
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at «string»:1:10:
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1| with {}; b
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| ^
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nix-repl> :bt
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0: error: undefined variable 'b'
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«string»:1:10
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1| with {}; b
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| ^
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1: error: Fake frame for debugging purposes
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«string»:1:10
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1| with {}; b
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| ^
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exiting from here prints the error
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nix-repl> :q
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error: undefined variable 'b'
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at «string»:1:10:
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1| with {}; b
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| ^
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