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`#[cfg]`s are frequently used to gate crate content behind cargo features. This can lead to very confusing errors when features are missing. For example, `serde` doesn't have the `derive` feature by default. Therefore, `serde::Serialize` fails to resolve with a generic error, even though the macro is present in the docs. This commit adds a list of all stripped item names to metadata. This is filled during macro expansion and then, through a fed query, persisted in metadata. The downstream resolver can then access the metadata to look at possible candidates for mentioning in the errors. This slightly increases metadata (800k->809k for the feature-heavy windows crate), but not enough to really matter.
32 lines
1.3 KiB
Rust
32 lines
1.3 KiB
Rust
// aux-build:cfged_out.rs
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extern crate cfged_out;
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fn main() {
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// There is no uwu at this path - no diagnostic.
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cfged_out::uwu(); //~ ERROR cannot find function
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//~^ NOTE not found in `cfged_out`
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// It does exist here - diagnostic.
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cfged_out::inner::uwu(); //~ ERROR cannot find function
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//~^ NOTE found an item that was configured out
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//~| NOTE not found in `cfged_out::inner`
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// The module isn't found - we would like to get a diagnostic, but currently don't due to
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// the awkward way the resolver diagnostics are currently implemented.
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// FIXME(Nilstrieb): Also add a note to the cfg diagnostic here
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cfged_out::inner::doesnt_exist::hello(); //~ ERROR failed to resolve
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//~^ NOTE could not find `doesnt_exist` in `inner`
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// It should find the one in the right module, not the wrong one.
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cfged_out::inner::right::meow(); //~ ERROR cannot find function
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//~^ NOTE found an item that was configured out
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//~| NOTE not found in `cfged_out::inner::right
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//~| NOTE the item is gated behind the `what-a-cool-feature` feature
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// Exists in the crate root - diagnostic.
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cfged_out::vanished(); //~ ERROR cannot find function
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//~^ NOTE found an item that was configured out
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//~| NOTE not found in `cfged_out`
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}
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