remove support for typeof #148256
remove support for typeof #148256
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rustbot added S-waiting-on-author rustbot added S-waiting-on-review 
lcnr changed the title typeof lcnr added the S-waiting-on-MCP 
traviscross added the I-lang-radar 
| !ident_token.is_reserved_ident() | ||
| || ident_token.is_path_segment_keyword() | ||
| || [kw::Underscore, kw::For, kw::Impl, kw::Fn, kw::Unsafe, kw::Extern, kw::Typeof, kw::Dyn] | ||
| || [kw::Underscore, kw::For, kw::Impl, kw::Fn, kw::Unsafe, kw::Extern, kw::Dyn] |
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q: is there a chance this affects macros?
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Yes, the following artificial snippet will go from pass→fail:
macro_rules! ck { ($ty:ty) => {}; } ck!(typeof(0));After this PR it'll fail with no rules expected keyword `typeof` (and hypothetically if typeof were to be demoted to a normal identifier, it would start failing with expected type, found `0`).
However, it's very unlikely anybody is relying on it. So it's not really a concern. MBE is notoriously forward incompatible.
| | ty::CoroutineWitness(..) | ||
| | ty::Alias(ty::Free, _) | ||
| | ty::Bound(..) | ||
| | ty::Placeholder(_) | ||
| | ty::Infer(_) => { |
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q: How is this related to this PR?
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With the removal of typeof inference, it should now be impossible to sneak these unnameable types into an impl (even with TAIT you can't do that IINM)
Yes, there's currently no way to get unnameable types into impl headers or encounter them in coherence, and it's nice to be able to reason about that
| // Reference | ||
| self.expect_and()?; | ||
| self.parse_borrowed_pointee()? | ||
| } else if self.eat_keyword_noexpect(kw::Typeof) { |
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It may be nice to keep a precise error message here and recover into an error type
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see rust-lang/compiler-team#940
r? types