5b4bd154de
proc_macro/bridge: use the cross-thread executor for nested proc-macros While working on some other changes in the bridge, I noticed that when running a nested proc-macro (which is currently only possible using the unstable `TokenStream::expand_expr`), any symbols held by the proc-macro client would be invalidated, as the same thread would be used for the nested macro by default, and the interner doesn't handle nested use. After discussing with `@eddyb,` we decided the best approach might be to force the use of the cross-thread executor for nested invocations, as it will never re-use thread-local storage, avoiding the issue. This shouldn't impact performance, as expand_expr is still unstable, and infrequently used. This was chosen rather than making the client symbol interner handle nested invocations, as that would require replacing the internal interner `Vec` with a `BTreeMap` (as valid symbol id ranges could now be disjoint), and the symbol interner is known to be fairly perf-sensitive. This patch adds checks to the execution strategy to use the cross-thread executor when doing nested invocations. An alternative implementation strategy could be to track this information in the `ExtCtxt`, however a thread-local in the `proc_macro` crate was chosen to add an assertion so that `rust-analyzer` is aware of the issue if it implements `expand_expr` in the future. r? `@eddyb` |
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| .. | ||
| bootstrap | ||
| ci | ||
| doc | ||
| etc | ||
| librustdoc | ||
| llvm-project@670e5f673a | ||
| rustdoc-json-types | ||
| test | ||
| tools | ||
| README.md | ||
| stage0.json | ||
| version | ||
This directory contains the source code of the rust project, including:
- The test suite
- The bootstrapping build system
- Various submodules for tools, like cargo, miri, etc.
For more information on how various parts of the compiler work, see the rustc dev guide.