e645e51d97
This... is a weird test. It has two impls: - `impl<T> From<Foo<T>> for Box<T>` (commented out, more on that later), and - `impl<T> Into<Vec<T>> for Foo<T>` The idea of that test is to show that the first impl doesn't compile, but the second does, thus `TryFrom` should be using `Into` and not `From` (because `Into` is more general, since the `From` impl doesn't compile). However: 1. The types are different -- `Box` vs `Vec`, which is significant b/c `Box` is fundamental 2. The commented out impl actually compiles! (which wasn't detected b/c it's commented out :\ ) Here is a table for compilation of the impls: | | `Vec` | `Box` | |--------|--------------|----------------| | `From` | since 1.41.0 | never | | `Into` | always | not since 1.28 | [godbolt used to test this](https://godbolt.org/z/T38E3jGKa) Order of events: 1. in `1.28` the `incoherent_fundamental_impls` lint becomes deny by default (this is *not* mentioned in the changelog yay) 2. `1.32` changed absolutely nothing, even though this version is credited in the test 3. the test was added (I'm not exactly sure when) (see https://github.com/rust-lang/rust/pull/56796) 4. in `1.41` coherence was relaxed to allow `From`+`Vec` to compile To conclude: since `1.41` this test does nothing (and before that it was written in a way which did not detect this change). It looks to me like today (since `1.41`) we *could* bound `TryFrom` impl with `From` (but now it'd be a useless breaking change of course). Am I missing anything? Is there a useful version of this test that could be written? |
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| assembly-llvm | ||
| auxiliary | ||
| codegen-llvm | ||
| codegen-units | ||
| coverage | ||
| coverage-run-rustdoc | ||
| crashes | ||
| debuginfo | ||
| incremental | ||
| mir-opt | ||
| pretty | ||
| run-make | ||
| run-make-cargo | ||
| rustdoc | ||
| rustdoc-gui | ||
| rustdoc-js | ||
| rustdoc-js-std | ||
| rustdoc-json | ||
| rustdoc-ui | ||
| ui | ||
| ui-fulldeps | ||
| COMPILER_TESTS.md | ||