Implement non-capturing closure to fn coercion#40025

est31 · 2017-02-22T02:20:43Z

Implements non capturing closure coercion (RFC 1558).

cc tracking issue #39817

rust-highfive · 2017-02-22T02:20:54Z

r? @pnkfelix

(rust_highfive has picked a reviewer for you, use r? to override)

est31 · 2017-02-22T02:20:55Z

r? @eddyb

est31 · 2017-02-23T21:32:23Z

@eddyb Its ready for review!

eddyb · 2017-02-23T22:26:07Z

src/librustc_trans/mir/constant.rs

+                                    .unwrap().def_id;
+                                // Now create its substs [Closure, Tuple]
+                                let input = tcx.closure_type(def_id, substs).sig.input(0);
+                                let substs = Substs::for_item(tcx,


You can just make Substs by doing tcx.mk_substs([operand.ty, input.skip_binder()].iter().cloned()) IIRC.

eddyb · 2017-02-23T22:26:34Z

src/librustc_trans/mir/rvalue.rs

+                                    .unwrap().def_id;
+                                // Now create its substs [Closure, Tuple]
+                                let input = bcx.tcx().closure_type(def_id, substs).sig.input(0);
+                                let substs = Substs::for_item(bcx.tcx(),


eddyb · 2017-02-23T22:27:22Z

src/librustc_typeck/check/coercion.rs

+
+        let b = self.shallow_resolve(b);
+
+        let node_id_a :NodeId = self.tcx.hir.as_local_node_id(def_id_a).unwrap();


Type annotations shouldn't be needed.

eddyb · 2017-02-23T22:27:33Z

src/librustc_typeck/check/coercion.rs

+                let sig = self.closure_type(def_id_a, substs_a).sig;
+                let converted_sig = sig.input(0).map_bound(|v| {
+                    let params_iter = match v.sty {
+                        TypeVariants::TyTuple(params, _) => {


ty::TyTuple

eddyb · 2017-02-23T22:28:07Z

src/librustc_typeck/check/coercion.rs

+                // to
+                //     `fn(arg0,arg1,...) -> _`
+                let sig = self.closure_type(def_id_a, substs_a).sig;
+                let converted_sig = sig.input(0).map_bound(|v| {


I meant sig.map_bound. Because that lets you avoid skip_binder on output too.

eddyb · 2017-02-23T22:30:12Z

src/test/compile-fail/closure-no-fn.rs

+
+fn main() {
+    let mut a = 0u8;
+    let foo :fn(u8) -> u8 = |v: u8| { a += v; a };


let x :T is unidiomatic, should be let x: T.

eddyb · 2017-02-23T22:30:52Z

src/test/run-pass/closure-to-fn-coercion.rs

+    assert_eq!({BAR[1](&mut a); a }, 1);
+    assert_eq!({BAR[2](&mut a); a }, 3);
+    assert_eq!({BAR[3](&mut a); a }, 6);
+    assert_eq!({BAR[4](&mut a); a }, 10);


{ should be followed by a space just like } should be preceded by one.

* use more convenient mk_substs function * remove type annotations * use map_bound one level farther outside * style improvements

eddyb · 2017-02-24T00:08:08Z

@bors r+

bors · 2017-02-24T00:08:09Z

📌 Commit 77f131d has been approved by eddyb

Implement non-capturing closure to fn coercion Implements non capturing closure coercion ([RFC 1558](https://github.com/rust-lang/rfcs/blob/master/text/1558-closure-to-fn-coercion.md)). cc tracking issue rust-lang#39817

Rollup of 28 pull requests - Successful merges: #39859, #39864, #39888, #39903, #39905, #39914, #39945, #39950, #39953, #39961, #39980, #39988, #39993, #39995, #40019, #40020, #40022, #40024, #40025, #40026, #40027, #40031, #40035, #40037, #40038, #40064, #40069, #40086 - Failed merges: #39927, #40008, #40047

rust-highfive assigned pnkfelix Feb 22, 2017

rust-highfive assigned eddyb and unassigned pnkfelix Feb 22, 2017

est31 force-pushed the master branch 3 times, most recently from f0d612f to 03b534c Compare February 23, 2017 21:31

Implement non-capturing closure to fn coercion

1b9b322

Feature gate

f753a6e

est31 force-pushed the master branch from 03b534c to 21c3898 Compare February 23, 2017 21:33

Two more tests

21c3898

est31 mentioned this pull request Feb 23, 2017

Only subset of errors printed #40067

Closed

eddyb suggested changes Feb 23, 2017

View reviewed changes

Review changes

77f131d

* use more convenient mk_substs function * remove type annotations * use map_bound one level farther outside * style improvements

eddyb approved these changes Feb 25, 2017

View reviewed changes

eddyb mentioned this pull request Feb 25, 2017

Rollup of 29 pull requests #40089

Closed

eddyb mentioned this pull request Feb 25, 2017

Rollup of 28 pull requests #40091

Merged

bors merged commit 77f131d into rust-lang:master Feb 25, 2017

archshift mentioned this pull request Mar 2, 2017

ICE when coercing certain closures (with discarded arguments) to fn #40204

Closed

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Implement non-capturing closure to fn coercion#40025