Reconstruct span information lost by compiler #87
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error[E0425]: cannot find value `_0` in this scope
--> tests/test_display.rs:208:29
|
208 | #[derive(Debug, Error)]
| ^^^^^ not found in this scope
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Fixes #86.
This is a workaround for rust-lang/rust#43081. The tokens were coming in with all spans erased (
#0 bytes(0..0)) due to the compiler bug, and so the call_site spans that we used in the generatedmatchexpression in the Display impl were not resolving the same as identifiers generated from the macro input. The workaround is to grab a fairly arbitrary span from the macro input (I chose the span of the format string) and use that for all new bindings inmatch. This way, ordinarily that span is going to have the same hygiene context as call_site, but if rust-lang/rust#43081 is happening then it will be #0 hygiene the same as the input tokens.