builtins.derivationStrict

This function is implemented in c++ and is part of the native nix runtime.

src/libexpr/primops.cc:1414

static void prim_derivationStrict(EvalState & state, const PosIdx pos, Value ** args, Value & v)
{
    state.forceAttrs(*args[0], pos, "while evaluating the argument passed to builtins.derivationStrict");

    auto attrs = args[0]->attrs();

    /* Figure out the name first (for stack backtraces). */
    auto nameAttr =
        state.getAttr(state.s.name, attrs, "in the attrset passed as argument to builtins.derivationStrict");

    std::string_view drvName;
    try {
        drvName = state.forceStringNoCtx(
            *nameAttr->value, pos, "while evaluating the `name` attribute passed to builtins.derivationStrict");
    } catch (Error & e) {
        e.addTrace(state.positions[nameAttr->pos], "while evaluating the derivation attribute 'name'");
        throw;
    }

    try {
        derivationStrictInternal(state, drvName, attrs, v);
    } catch (Error & e) {
        Pos pos = state.positions[nameAttr->pos];
        /*
         * Here we make two abuses of the error system
         *
         * 1. We print the location as a string to avoid a code snippet being
         * printed. While the location of the name attribute is a good hint, the
         * exact code there is irrelevant.
         *
         * 2. We mark this trace as a frame trace, meaning that we stop printing
         * less important traces from now on. In particular, this prevents the
         * display of the automatic "while calling builtins.derivationStrict"
         * trace, which is of little use for the public we target here.
         *
         * Please keep in mind that error reporting is done on a best-effort
         * basis in nix. There is no accurate location for a derivation, as it
         * often results from the composition of several functions
         * (derivationStrict, derivation, mkDerivation, mkPythonModule, etc.)
         */
        e.addTrace(
            nullptr,
            HintFmt(
                "while evaluating derivation '%s'\n"
                "  whose name attribute is located at %s",
                drvName,
                pos));
        throw;
    }
}