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macros: ty matcher doesn't accept trait object types with + (type sums) #39080

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petrochenkov opened this issue Jan 15, 2017 · 2 comments · Fixed by #40043
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macros: ty matcher doesn't accept trait object types with + (type sums) #39080

petrochenkov opened this issue Jan 15, 2017 · 2 comments · Fixed by #40043
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@petrochenkov
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A-macros Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..)

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@petrochenkov
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Code:

macro_rules! m {
    ($t: ty) => ()
}

fn main() {
    m!(Write + Send);
}

Expected result: code compiles.

Actual result:

rustc 1.16.0-nightly (1a2ed98d3 2017-01-13)
error: no rules expected the token `+`
 --> <anon>:6:14
  |
6 |     m!(Write + Send);
  |              ^
@petrochenkov
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Workaround:

m!((Write + Send));

@petrochenkov petrochenkov mentioned this issue Jan 16, 2017
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bors added a commit that referenced this issue Jan 17, 2017
@bors
Auto merge of #39110 - petrochenkov:sum, r=eddyb
a167c04 
Merge ObjectSum and PolyTraitRef in AST/HIR + some other refactoring

`ObjectSum` and `PolyTraitRef` are the same thing (list of bounds), they exist separately only due to parser quirks. The second commit merges them.

The first commit replaces `Path` with `Ty` in (not yet supported) equality predicates. They are parsed as types anyway and arbitrary types can always be disguised as paths using aliases, so this doesn't add any new functionality.

The third commit uses `Vec` instead of `P<[T]>` in AST. AST is not immutable like HIR and `Vec`s are more convenient for it, unnecessary conversions are also avoided.

The last commit renames `parse_ty_sum` (which is used for parsing types in general) into `parse_ty`, and renames `parse_ty` (which is used restricted contexts where `+` is not permitted due to operator priorities or other reasons) into `parse_ty_no_plus`.

This is the first part of #39085 (comment) and #39080 focused on data changes and mechanical renaming, I'll submit a PR with parser changes a bit later.

r? @eddyb
@brson
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brson commented Jan 19, 2017

cc @pnkfelix @nrc

@brson brson added A-macros Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..) I-wrong labels Jan 19, 2017
@petrochenkov petrochenkov self-assigned this Feb 19, 2017
@petrochenkov petrochenkov mentioned this issue Feb 23, 2017
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bors added a commit that referenced this issue Mar 22, 2017
@bors
Auto merge of #40043 - petrochenkov:objpars, r=nikomatsakis
8c4f2c6 
Refactor parsing of trait object types

Bugs are fixed and code is cleaned up.

User visible changes:
- `ty` matcher in macros accepts trait object types like `Write + Send` (#39080)
- Buggy priority of `+` in trait object types starting with `for` is fixed (#39317). `&for<'a> Trait<'a> + Send` is now parsed as `(&for<'a> Trait<'a>) + Send` and requires parens `&(for<'a> Trait<'a> + Send)`. For comparison, `&Send + for<'a> Trait<'a>` was parsed like this since [Nov 27, 2014](#19298).
- Trailing `+`s are supported in trait objects, like in other bounds.
- Better error reporting for trait objects starting with `?Sized`.

Fixes #39080
Fixes #39317 [breaking-change]
Closes #39298
cc #39085 (fixed, then reverted #40043 (comment))
cc #39318 (fixed, then reverted #40043 (comment))

r? @nikomatsakis
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Refactor parsing of trait object types petrochenkov/rust
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@brson @petrochenkov