From 08252967a8c2ab15f3fb8bdfb848f007d4032d50 Mon Sep 17 00:00:00 2001 From: eldritch horrors Date: Fri, 8 Mar 2024 07:09:48 +0100 Subject: libexpr: Support structured error classes While preparing PRs like #9753, I've had to change error messages in dozens of code paths. It would be nice if instead of EvalError("expected 'boolean' but found '%1%'", showType(v)) we could write TypeError(v, "boolean") or similar. Then, changing the error message could be a mechanical refactor with the compiler pointing out places the constructor needs to be changed, rather than the error-prone process of grepping through the codebase. Structured errors would also help prevent the "same" error from having multiple slightly different messages, and could be a first step towards error codes / an error index. This PR reworks the exception infrastructure in `libexpr` to support exception types with different constructor signatures than `BaseError`. Actually refactoring the exceptions to use structured data will come in a future PR (this one is big enough already, as it has to touch every exception in `libexpr`). The core design is in `eval-error.hh`. Generally, errors like this: state.error("'%s' is not a string", getAttrPathStr()) .debugThrow() are transformed like this: state.error("'%s' is not a string", getAttrPathStr()) .debugThrow() The type annotation has moved from `ErrorBuilder::debugThrow` to `EvalState::error`. (cherry picked from commit c6a89c1a1659b31694c0fbcd21d78a6dd521c732) Change-Id: Iced91ba4e00ca9e801518071fb43798936cbd05a --- src/libexpr/primops/fromTOML.cc | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'src/libexpr/primops/fromTOML.cc') diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc index 2f4d4022e..94be7960a 100644 --- a/src/libexpr/primops/fromTOML.cc +++ b/src/libexpr/primops/fromTOML.cc @@ -83,10 +83,7 @@ static void prim_fromTOML(EvalState & state, const PosIdx pos, Value * * args, V try { visit(val, toml::parse(tomlStream, "fromTOML" /* the "filename" */)); } catch (std::exception & e) { // TODO: toml::syntax_error - throw EvalError({ - .msg = hintfmt("while parsing a TOML string: %s", e.what()), - .errPos = state.positions[pos] - }); + state.error("while parsing TOML: %s", e.what()).atPos(pos).debugThrow(); } } -- cgit v1.2.3