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Matthias Krüger 504a78e2f2
Rollup merge of - Nadrieril:false-edges2, r=matthewjasper
match lowering: make false edges more precise

When lowering match expressions, we add false edges to hide details of the lowering from borrowck. Morally we pretend we're testing the patterns (and guards) one after the other in order. See the tests for examples. Problem is, the way we implement this today is too coarse for deref patterns.

In deref patterns, a pattern like `deref [1, x]` matches on a `Vec` by creating a temporary to store the output of the call to `deref()` and then uses that to continue matching. Here the pattern has a binding, which we set up after the pre-binding block. Problem is, currently the false edges tell borrowck that the pre-binding block can be reached from a previous arm as well, so the `deref()` temporary may not be initialized. This triggers an error when we try to use the binding `x`.

We could call `deref()` a second time, but this opens the door to soundness issues if the deref impl is weird. Instead in this PR I rework false edges a little bit.

What we need from false edges is a (fake) path from each candidate to the next, specifically from candidate C's pre-binding block to next candidate D's pre-binding block. Today, we link the pre-binding blocks directly. In this PR, I link them indirectly by choosing an earlier node on D's success path. Specifically, I choose the earliest block on D's success path that doesn't make a loop (if I chose e.g. the start block of the whole match (which is on the success path of all candidates), that would make a loop). This turns out to be rather straightforward to implement.

r? `@matthewjasper` if you have the bandwidth, otherwise let me know
2024-04-04 14:51:16 +02:00
.github Revert cargo update changes 2024-03-26 15:36:12 +00:00
.reuse std: move Once implementations to sys 2024-03-12 15:41:06 +01:00
compiler Rollup merge of - Nadrieril:false-edges2, r=matthewjasper 2024-04-04 14:51:16 +02:00
library Rollup merge of - devnexen:dfbsd_build_fix, r=jhpratt 2024-04-03 20:17:04 -04:00
LICENSES Add missing CC-BY-SA-4.0. 2023-11-27 11:03:53 +00:00
src Rollup merge of - high-cloud:move-hir-tree, r=oli-obk 2024-04-04 14:51:15 +02:00
tests Rollup merge of - Nadrieril:false-edges2, r=matthewjasper 2024-04-04 14:51:16 +02:00
.editorconfig Only use max_line_length = 100 for *.rs 2023-07-10 15:18:36 -07:00
.git-blame-ignore-revs Ignore compiletest test directive migration commits 2024-02-22 18:55:02 +00:00
.gitattributes Rename config.toml.example to config.example.toml 2023-03-11 14:10:00 -08:00
.gitignore don't globally ignore rustc-ice files 2023-09-16 09:44:44 +02:00
.gitmodules Update to LLVM 18 2024-02-13 10:33:40 +01:00
.mailmap Add my former address to .mailmap 2024-03-25 18:48:54 -07:00
Cargo.lock Rollup merge of - ferrocene:hoverbear/bump-sysinfo-to-0.30.8, r=Nilstrieb 2024-04-02 21:22:04 +02:00
Cargo.toml Add a test 2024-03-20 23:36:05 -04:00
CODE_OF_CONDUCT.md Remove the code of conduct; instead link https://www.rust-lang.org/conduct.html 2019-10-05 22:55:19 +02:00
config.example.toml use more accurate terminology 2024-03-19 20:32:55 +02:00
configure Ensure ./configure works when configure.py path contains spaces 2024-02-16 18:57:22 +00:00
CONTRIBUTING.md fix: Update CONTRIBUTING.md recommend -> recommended 2023-11-16 23:57:09 +05:30
COPYRIGHT Update COPYRIGHT file 2022-10-30 10:23:14 -04:00
INSTALL.md chore: fix some comments 2024-03-27 22:32:53 +08:00
LICENSE-APACHE Remove appendix from LICENCE-APACHE 2019-12-30 14:25:53 +00:00
LICENSE-MIT LICENSE-MIT: Remove inaccurate (misattributed) copyright notice 2017-07-26 16:51:58 -07:00
README.md Use SVG logos in the README.md. 2024-04-03 19:48:20 +02:00
RELEASES.md Forward port 1.77.1 release notes 2024-03-29 10:44:19 +03:00
rust-bors.toml Increase timeout for new bors bot 2024-03-13 08:31:07 +01:00
rustfmt.toml Remove exception for deleted file from rustfmt.toml 2024-03-08 20:46:33 +00:00
triagebot.toml beep boop 2024-03-31 20:18:37 +01:00
x Make x capable of resolving symlinks 2023-10-14 17:53:33 +03:00
x.ps1 use & instead of start-process in x.ps1 2023-12-09 09:46:16 -05:00
x.py Fix recent python linting errors 2023-08-02 04:40:28 -04:00

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