25 lines
1.1 KiB
Rust
25 lines
1.1 KiB
Rust
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// revisions: rpass1 rpass2
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// aux-build:respan.rs
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// aux-build:invalid-span-helper-lib.rs
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// This issue has several different parts. The high level idea is:
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// 1. We create an 'invalid' span with the help of the `respan` proc-macro,
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// The compiler attempts to prevent the creation of invalid spans by
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// refusing to join spans with different `SyntaxContext`s. We work around
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// this by applying the same `SyntaxContext` to the span of every token,
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// using `Span::resolved_at`
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// 2. We using this invalid span in the body of a function, causing it to get
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// encoded into the `optimized_mir`
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// 3. We call the function from a different crate - since the function is generic,
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// monomorphization runs, causing `optimized_mir` to get called.
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// 4. We re-run compilation using our populated incremental cache, but without
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// making any changes. When we recompile the crate containing our generic function
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// (`invalid_span_helper_lib`), we load the span from the incremental cache, and
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// write it into the crate metadata.
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extern crate invalid_span_helper_lib;
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fn main() {
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invalid_span_helper_lib::foo::<u8>();
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}
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