Allow lifetimes in macros #46895

ricochet1k · 2017-12-20T22:26:29Z

This is a resurrection of PR #41927 which was a resurrection of #33135, which is intended to fix #34303.

In short, this allows macros_rules! to use :lifetime as a matcher to match 'lifetimes.

Still to do:

Feature gate

rust-highfive · 2017-12-20T22:26:34Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @arielb1 (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

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arielb1 · 2017-12-20T23:13:43Z

r? @jseyfried

bjorn3 · 2017-12-21T07:28:45Z

src/libsyntax/parse/parser.rs

+            token::Interpolated(ref nt) => match nt.0 {
+                token::NtLifetime(lifetime) => 
+                    lifetime,
+                    //Lifetime { ident: lifetime.ident, span: lifetime.span, id: ast::DUMMY_NODE_ID },


ricochet1k · 2017-12-21T20:37:00Z

I think this is ready for review now.

bors · 2017-12-24T10:08:31Z

☔ The latest upstream changes (presumably #46888) made this pull request unmergeable. Please resolve the merge conflicts.

jseyfried

Looks great! r=me

jseyfried · 2017-12-27T19:14:05Z

src/libsyntax/ext/tt/macro_rules.rs

@@ -887,6 +888,18 @@ fn is_legal_fragment_specifier(sess: &ParseSess,
    match frag_name {
        "item" | "block" | "stmt" | "expr" | "pat" |
        "path" | "ty" | "ident" | "meta" | "tt" | "" => true,
+        "lifetime" => {
+            if     !features.borrow().macro_lifetime_matcher
+                && !attr::contains_name(attrs, "allow_internal_unstable") {


formatting nit -- this is more idiomatic:

if condition1 && condition2 { // ... }

jseyfried · 2017-12-27T19:14:34Z

src/libsyntax/feature_gate.rs

@@ -514,7 +517,7 @@ declare_features! (
    (accepted, loop_break_value, "1.19.0", Some(37339)),
    // Permits numeric fields in struct expressions and patterns.
    (accepted, relaxed_adts, "1.19.0", Some(35626)),
-    // Coerces non capturing closures to function pointers
+   // Coerces non capturing closures to function pointers


stray whitespace change

jseyfried · 2017-12-27T19:18:22Z

src/libsyntax/parse/parser.rs

+            token::Interpolated(ref nt) => match nt.0 {
+                token::NtLifetime(lifetime) =>
+                    lifetime,
+                _ => self.span_bug(self.span, "not a lifetime")


Optional improvement -- to avoid duplicating these matches, I'd refactor out token.lifetime() such that token.is_lifetime() is token.lifetime().is_some(); see token.ident().

That sounds nice but it isn't that straightforward, since token::Lifetime has an ident and token::NtLifetime has a lifetime.

I see. I think it would work if token.lifetime() took an argument token.lifetime(span) so that the token::Lifetime case would return Lifetime { ident, span, id: ast::DUMMY_NODE_ID }.

@sgrif

Started rebasing @sgrif's PR rust-lang#33135 off of current master. (Well, actually merging it into a new branch based off current master.) The following files still need to be fixed or at least reviewed: - `src/libsyntax/ext/tt/macro_parser.rs`: calls `Parser::parse_lifetime`, which doesn't exist anymore - `src/libsyntax/parse/parser.rs`: @sgrif added an error message to `Parser::parse_lifetime`. Code has since been refactored, so I just took it out for now. - `src/libsyntax/ext/tt/transcribe.rs`: This code has been refactored bigtime. Not sure whether @sgrif's changes here are still necessary. Took it out for this commit.

made `parser::Parser::expect_lifetime` public, so it can be called from `macro_parser::parse_nt`

ricochet1k · 2017-12-31T03:05:09Z

@jseyfried Refactoring done.

jseyfried · 2018-01-01T04:21:54Z

Nice! @bors r+

bors · 2018-01-01T04:21:56Z

📌 Commit 8b4bdc2 has been approved by jseyfried

Allow lifetimes in macros This is a resurrection of PR #41927 which was a resurrection of #33135, which is intended to fix #34303. In short, this allows macros_rules! to use :lifetime as a matcher to match 'lifetimes. Still to do: - [x] Feature gate

bors · 2018-01-01T07:21:34Z

⌛ Testing commit 8b4bdc2 with merge 1bcc6dc...

bors · 2018-01-01T10:02:40Z

☀️ Test successful - status-appveyor, status-travis
Approved by: jseyfried
Pushing 1bcc6dc to master...

ivanovaleksey · 2018-03-07T09:30:12Z

Hello, how could I know in which Rust version I could use this feature?

ricochet1k · 2018-03-07T15:43:06Z

Nightlies from 1.23.0 and onward should include it.

durka · 2018-05-02T00:28:15Z

Tracking issues should point an open issue (that is closed when the feature is stabilized or deprecated), not to the implementing PR.

rust-highfive assigned arielb1 Dec 20, 2017

rust-highfive assigned jseyfried and unassigned arielb1 Dec 20, 2017

bjorn3 requested changes Dec 21, 2017

View reviewed changes

kennytm added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 21, 2017

ricochet1k force-pushed the macro-lifetimes branch 2 times, most recently from a83bb7b to 000e3f5 Compare December 21, 2017 16:30

kennytm added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Dec 27, 2017

jseyfried approved these changes Dec 27, 2017

View reviewed changes

mikeyhew and others added 8 commits December 28, 2017 11:32

replace parse_lifetime with expect_lifetime

e12b870

made `parser::Parser::expect_lifetime` public, so it can be called from `macro_parser::parse_nt`

Fix build and add a macro lifetime labels test

0e53360

Fix tests

ce76b1a

Cleanup

e838cfc

Add feature gate macro_lifetime_matcher

b284419

Add an entry in the unstable book

0f9c9b6

Cleanup

f552425

ricochet1k force-pushed the macro-lifetimes branch from c5d7264 to f552425 Compare December 28, 2017 22:51

refactor lifetime out of is_lifetime

8b4bdc2

bors merged commit 8b4bdc2 into rust-lang:master Jan 1, 2018

ivanovaleksey mentioned this pull request Mar 7, 2018

Macros with lifetimes paritytech/jsonrpc#241

Closed

ricochet1k deleted the macro-lifetimes branch March 7, 2018 15:43

durka mentioned this pull request May 2, 2018

Tracking issue for macro :lifetime matcher #50380

Closed

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Allow lifetimes in macros #46895

Allow lifetimes in macros #46895

ricochet1k commented Dec 20, 2017 •

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durka commented May 2, 2018

Allow lifetimes in macros #46895

Allow lifetimes in macros #46895

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