unsafeGetAttrPos

builtins.unsafeGetAttrPos

Primop

Docs pulled from | This Revision | about 19 hours ago

Nix manual

Takes 2 arguments

s, set

unsafeGetAttrPos returns the position of the attribute named s from set. This is used by Nixpkgs to provide location information in error messages.

Noogle detected

Aliases

lib.unsafeGetAttrPos
lib.debug.unsafeGetAttrPos

Implementation

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

src/libexpr/primops.cc:3131

static void prim_unsafeGetAttrPos(EvalState & state, const PosIdx pos, Value ** args, Value & v)
{
    auto attr = state.forceStringNoCtx(
        *args[0], pos, "while evaluating the first argument passed to builtins.unsafeGetAttrPos");
    state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.unsafeGetAttrPos");
    auto i = args[1]->attrs()->get(state.symbols.create(attr));
    if (!i)
        v.mkNull();
    else
        state.mkPos(v, i->pos);
}