forbid dyn Trait in patterns
#71038
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forbid dyn Trait in patterns
#71038
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IMO this PR's title/description should focus on pattern-matching. r? @pnkfelix |
eddyb
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Apr 11, 2020
eddyb
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eddyb
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| if !ty_is_partial_eq { | ||
| // span_fatal avoids ICE from resolution of non-existent method (rare case). | ||
| self.tcx().sess.span_fatal(self.span, &make_msg()); | ||
| self.tcx().sess.span_fatal(self.span, &msg); |
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Doesn't this stop your ICE as well?
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nope. ty_is_partial_eq is true for &dyn PartialEq<u32>. It is fixed for all other traits though.
This fails correctly
const F: &'static dyn Send = &7u32;
fn main() {
let a: &dyn Send = &7u32;
match a {
F => panic!(),
//~^ ERROR trait object cannot be used in patterns
_ => {}
}
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I changed the test to dyn Send and rebased.
Don't know how to test for an ICE, we could just open an issue for dyn PartialEq after this is merged (which is then added to glacier).
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@pnkfelix this is ready for review |
pnkfelix
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Apr 28, 2020
| impl A for B {} | ||
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| fn test<const T: &'static dyn A>() { | ||
| //~^ ERROR the types of const generic parameters must derive `PartialEq` and `Eq` |
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The PR seems fine and I'm planning to r+ it, but I wanted to ask about this part:
Do you see the error here as being the absence of PartialEq and Eq, as indicated by the diagnostic? Or is it that any use of dyn A will be broken here?
I personally suspect that, unless we expose a StructuralMatch marker trait (at which point maybe one would be able to do trait A: StructuralMatch {}), the user error here is in the use of dyn A, and therefore the diagnostic message in this case is misleading.
But I'm willing to deal with that in a followup patch.
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Not sure tbh, I think that we should allow something like trait A: StructuralMatch {} in the future.
cc @eddyb i guess
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@bors r+ rollup |
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📌 Commit 4549ef5 has been approved by |
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…pnkfelix forbid `dyn Trait` in patterns Do not allow `&dyn Trait` as a generic const parameters. This also changes dyn trait in pattern from ICE to error. closes rust-lang#63322 closes rust-lang#70972 r? @eddyb
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failed in rollup @bors r- |
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fixed |
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☔ The latest upstream changes (presumably #67343) made this pull request unmergeable. Please resolve the merge conflicts. |
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@pnkfelix This should be ready for merge afaict. |
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@bors r+ |
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📌 Commit 2f5c0f5 has been approved by |
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Rollup of 5 pull requests Successful merges: - rust-lang#71038 (forbid `dyn Trait` in patterns) - rust-lang#71697 (Added MIR constant propagation of Scalars into function call arguments) - rust-lang#71773 (doc: misc rustdoc things) - rust-lang#71810 (Do not try to find binop method on RHS `TyErr`) - rust-lang#71877 (Use f64 in f64 examples) Failed merges: r? @ghost
RalfJung
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May 5, 2020
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Do not allow
&dyn Traitas a generic const parameters.This also changes dyn trait in pattern from ICE to error.
closes #63322
closes #70972
r? @eddyb