Merge pull request #9914 from 9999years/debugger-on-trace

Enter debugger on `builtins.trace` with an option
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Théophane Hufschmitt 2024-02-21 18:32:56 +01:00 committed by GitHub
commit 774e7ca584
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3 changed files with 29 additions and 0 deletions

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@ -0,0 +1,9 @@
---
synopsis: Enter the `--debugger` when `builtins.trace` is called if `debugger-on-trace` is set
prs: 9914
---
If the `debugger-on-trace` option is set and `--debugger` is given,
`builtins.trace` calls will behave similarly to `builtins.break` and will enter
the debug REPL. This is useful for determining where warnings are being emitted
from.

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@ -127,6 +127,16 @@ struct EvalSettings : Config
Setting<unsigned int> maxCallDepth{this, 10000, "max-call-depth",
"The maximum function call depth to allow before erroring."};
Setting<bool> builtinsTraceDebugger{this, false, "debugger-on-trace",
R"(
If set to true and the `--debugger` flag is given,
[`builtins.trace`](@docroot@/language/builtins.md#builtins-trace) will
enter the debugger like
[`builtins.break`](@docroot@/language/builtins.md#builtins-break).
This is useful for debugging warnings in third-party Nix code.
)"};
};
extern EvalSettings evalSettings;

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@ -986,6 +986,10 @@ static void prim_trace(EvalState & state, const PosIdx pos, Value * * args, Valu
printError("trace: %1%", args[0]->string_view());
else
printError("trace: %1%", ValuePrinter(state, *args[0]));
if (evalSettings.builtinsTraceDebugger && state.debugRepl && !state.debugTraces.empty()) {
const DebugTrace & last = state.debugTraces.front();
state.runDebugRepl(nullptr, last.env, last.expr);
}
state.forceValue(*args[1], pos);
v = *args[1];
}
@ -997,6 +1001,12 @@ static RegisterPrimOp primop_trace({
Evaluate *e1* and print its abstract syntax representation on
standard error. Then return *e2*. This function is useful for
debugging.
If the
[`debugger-on-trace`](@docroot@/command-ref/conf-file.md#conf-debugger-on-trace)
option is set to `true` and the `--debugger` flag is given, the
interactive debugger will be started when `trace` is called (like
[`break`](@docroot@/language/builtins.md#builtins-break)).
)",
.fun = prim_trace,
});