Refactor with {ast, hir, hair::pattern}::Binding

[Centril]

Instead of having the binding information directly inside PatKind::Binding(...), we move everything to the left of @ into a struct Binding (for each IR).

Also, we rename ast::PatKind::Ident to ast::PatKind::Binding.

r? @oli-obk

[rust-highfive]

The job x86_64-gnu-llvm-7 of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-12-25T21:15:46.8754141Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-12-25T21:15:46.8936197Z ##[command]git config gc.auto 0
2019-12-25T21:15:46.9003804Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-12-25T21:15:46.9052170Z ##[command]git config --get-all http.proxy
2019-12-25T21:15:46.9186160Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/67620/merge:refs/remotes/pull/67620/merge
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2019-12-25T22:21:22.4242135Z Uplifting stage1 rustc (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
2019-12-25T22:21:22.4242719Z Copying stage2 rustc from stage1 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
---
2019-12-25T22:33:21.2907959Z 
2019-12-25T22:33:21.2908891Z    Doc-tests core
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2019-12-25T22:39:31.1738771Z test result: ok. 983 passed; 0 failed; 20 ignored; 0 measured; 0 filtered out
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2019-12-25T22:39:31.1844942Z  finished in 163.917
2019-12-25T22:39:31.1858020Z Testing term stage1 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
---
2019-12-25T22:42:55.4248845Z    Compiling syntax_expand v0.0.0 (/checkout/src/libsyntax_expand)
2019-12-25T22:42:55.6790207Z error[E0532]: expected tuple struct or tuple variant, found struct `ast::Binding`
2019-12-25T22:42:55.6791124Z    --> src/libsyntax_expand/parse/tests.rs:169:37
2019-12-25T22:42:55.6791504Z     |
2019-12-25T22:42:55.6791945Z 169 |         fn visit_binding(&mut self, ast::Binding(_, ast::Ident { span, .. }): &'a ast::Binding) {
2019-12-25T22:42:55.6792383Z     |                                     ^^^^^^^^^^^^ did you mean `ast::Binding { /* fields */ }`?
2019-12-25T22:42:55.6793071Z help: possible better candidate is found in another module, you can import it into scope
2019-12-25T22:42:55.6793361Z     |
2019-12-25T22:42:55.6793722Z 1   | use syntax::ast::PatKind::Binding;
2019-12-25T22:42:55.6794016Z     |
2019-12-25T22:42:55.6794016Z     |
2019-12-25T22:42:55.6794152Z 
2019-12-25T22:42:55.7202275Z error: unused import: `PatKind`
2019-12-25T22:42:55.7203235Z  --> src/libsyntax_expand/parse/tests.rs:5:31
2019-12-25T22:42:55.7203641Z   |
2019-12-25T22:42:55.7204230Z 5 | use syntax::ast::{self, Name, PatKind};
2019-12-25T22:42:55.7204976Z   |
2019-12-25T22:42:55.7205858Z   = note: `-D unused-imports` implied by `-D warnings`
2019-12-25T22:42:55.7206034Z 
2019-12-25T22:42:56.6526960Z error: aborting due to 2 previous errors
2019-12-25T22:42:56.6526960Z error: aborting due to 2 previous errors
2019-12-25T22:42:56.6527953Z 
2019-12-25T22:42:56.6528641Z For more information about this error, try `rustc --explain E0532`.
2019-12-25T22:42:56.6660979Z error: could not compile `syntax_expand`.
2019-12-25T22:42:57.3481743Z 
2019-12-25T22:42:57.3483368Z To learn more, run the command again with --verbose.
2019-12-25T22:42:57.3483705Z 
2019-12-25T22:42:57.3483888Z 
2019-12-25T22:42:57.3484881Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "test" "-Zconfig-profile" "--target" "x86_64-unknown-linux-gnu" "-Zbinary-dep-depinfo" "-j" "2" "--release" "--locked" "--color" "always" "--features" " llvm" "--manifest-path" "/checkout/src/rustc/Cargo.toml" "-p" "syntax_expand" "--" "--quiet"
2019-12-25T22:42:57.3485205Z 
2019-12-25T22:42:57.3485311Z 
2019-12-25T22:42:57.3485454Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
2019-12-25T22:42:57.3485737Z Build completed unsuccessfully in 1:20:45
2019-12-25T22:42:57.3485737Z Build completed unsuccessfully in 1:20:45
2019-12-25T22:42:57.3486036Z == clock drift check ==
2019-12-25T22:42:57.3486170Z   local time: Wed Dec 25 22:42:56 UTC 2019
2019-12-25T22:42:57.3486297Z   network time: Wed, 25 Dec 2019 22:42:57 GMT
2019-12-25T22:42:57.3486419Z == end clock drift check ==
2019-12-25T22:42:57.8237820Z 
2019-12-25T22:42:57.8355318Z ##[error]Bash exited with code '1'.
2019-12-25T22:42:57.8387255Z ##[section]Starting: Checkout
2019-12-25T22:42:57.8388998Z ==============================================================================
2019-12-25T22:42:57.8389041Z Task         : Get sources
2019-12-25T22:42:57.8389096Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[bors]

☔ The latest upstream changes (presumably #66936) made this pull request unmergeable. Please resolve the merge conflicts.

[petrochenkov]

The story behind ast::PatKind::Ident is that it's not necessarily a binding, it may be a const or unit struct pattern as well, but we don't know it until resolve.
So it has a "syntactic" name (Ident) rather than semantic (Binding).

However, given that multiple syntactic things that are not necessarily identifiers (like ref ident or ident @ PAT) are merged into ast::PatKind::Ident, it's not a perfect name either.
So it should be ok to "lie in the other direction" and rename it to Binding even if it's not necessarily binding.

[petrochenkov]

Not sure what is the motivation behind the introduction of the Binding struct, it's not clear from this PR. Looks like some code re-hashing, but not an improvement.

[joelpalmer]

Triaged

[Dylan-DPC-zz]

Closing this