Dan Gohman (Mar 25 2020 at 13:36): Dan Gohman (Mar 25 2020 at 13:36):@Jakub Konka Do you know if there's a way to figure out where errors inside of proc macros are coming from?
Dan Gohman (Mar 25 2020 at 13:36):I'm experimenting with some changes, and I have an error like this:
Dan Gohman (Mar 25 2020 at 13:36):error[E0308]: mismatched types --> crates/wasi-common/src/wasi.rs:6:1 | 6 | / wiggle::from_witx!({ 7 | | witx: ["wig/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx"], 8 | | ctx: WasiCtx, 9 | | }); | | ^ | | | | |___expected `usize`, found `i32` | in this macro invocation | help: you can convert an `i32` to `usize` and panic if the converted value wouldn't fit | 6 | wiggle::from_witx!({ 7 | witx: ["wig/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx"], 8 | ctx: WasiCtx, 9 | });.try_into().unwrap()
Dan Gohman (Mar 25 2020 at 13:38):I can use cargo expand, but then I get the whole from_witx expansion and no indication of where the error is
Dan Gohman (Mar 25 2020 at 13:38):And rustc's help message isn't so helpful here :o}
Jakub Konka (Mar 25 2020 at 13:41):Yeah, currently tracking errors is pretty hard and messages don't tell anything meaningful at all. I'm not an expert in this but I guess in the future we should probably invest into some error tracking like in wasm-bindgen (if at all possible).
Jakub Konka (Mar 25 2020 at 13:41):All I can recommend right now is to use cargo expand
Jakub Konka (Mar 25 2020 at 13:41):which is less than ideal
Pat Hickey (Mar 25 2020 at 17:38):debugging proc macros is unfortunately very difficult :(
Pat Hickey (Mar 25 2020 at 17:39):there are a lot of smaller test cases in the crates/wiggle/tests directory, i would try to reproduce your error there
Pat Hickey (Mar 25 2020 at 17:39):so that the expansion is a little smaller
Last updated: Nov 22 2024 at 16:03 UTC