don't clone types that are copy, round two.

[matthiaskrgr]

Apparently fixing some of these issues makes clippy find even more so I did a couple of rounds now.

r? @eddyb

[bors]

☔ The latest upstream changes (presumably #68474) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-highfive]

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.

2020-01-23T08:47:00.5903346Z Prepare build directory.
2020-01-23T08:47:00.6352040Z Set build variables.
2020-01-23T08:47:00.6396913Z Download all required tasks.
2020-01-23T08:47:00.6573295Z Downloading task: Bash (3.159.3)
2020-01-23T08:48:46.4530074Z ##[warning]Failed to download task 'Bash'. Error The read operation failed, see inner exception.
2020-01-23T08:48:46.4541788Z ##[warning]Inner Exception: {ex.InnerException.Message}
2020-01-23T08:48:46.4546690Z ##[warning]Back off 29.917 seconds before retry.
2020-01-23T08:51:17.7949505Z ##[warning]Failed to download task 'Bash'. Error The read operation failed, see inner exception.
2020-01-23T08:51:17.7949814Z ##[warning]Inner Exception: {ex.InnerException.Message}
2020-01-23T08:51:17.7950491Z ##[warning]Back off 29.818 seconds before retry.
2020-01-23T08:53:14.2163279Z ##[error]The read operation failed, see inner exception.
2020-01-23T08:53:14.2271856Z ##[section]Finishing: Linux mingw-check

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)

[eddyb]

You might want to leave it for another PR but level should probably be Level, not &Level.
@petrochenkov and/or @estebank might know more about what's happening in this code though.

[estebank]

I think at some point Level wasn't Copy, this is probably just a leftover from that.

[eddyb]

cc @matthewjasper Why is there a reference to a Local here - is it a mutable reference perhaps?

[eddyb]

@oli-obk @spastorino Maybe we need to consider passing Place by value more often?
(it's a pair of an integer and a pointer, so it should be really compact)

[oli-obk]

That doesn't work if there are subslices of the projection involved. We do have a PlaceRef type for exactly that use case though

[spastorino]

Yeah, except in the cases @oli-obk mentions I'd change most of the uses to take Place by value. I need to do a bunch of cleanups still :).

[eddyb]

This entire .map(|elem| ...) feels like .copied().
So really, projs is just self.projs.clone().

Or better, self.projs.fold_with(folder) (and derive/impl TypeFoldable on ProjectionElem if it doesn't already have that - it should, though).

[eddyb]

Actually, the way this is structured is probably a bad idea and should be exhaustive, hmpf.

[matthiaskrgr]

--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -2466,7 +2466,13 @@ impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection {
                 Deref => Deref,
                 Field(f, ()) => Field(*f, ()),
                 Index(()) => Index(()),
-                elem => *elem,
+                Downcast(symbol, variantidx) => Downcast(*symbol, *variantidx),
+                ConstantIndex { offset, min_length, from_end } => {
+                    ConstantIndex { offset: *offset, min_length: *min_length, from_end: *from_end }
+                }
+                Subslice { from, to, from_end } => {
+                    Subslice { from: *from, to: *to, from_end: *from_end }
+                }
             })
             .collect();

[eddyb]

@bors r+ Thanks!

[bors]

📌 Commit 6a722acfa9700993dabea1ae4f766cc208cbf94c has been approved by eddyb

[bors]

☔ The latest upstream changes (presumably #68407) made this pull request unmergeable. Please resolve the merge conflicts.

[eddyb]

@bors r+

[bors]

📌 Commit f7dcdcc has been approved by eddyb

[bors]

⌛ Testing commit f7dcdcc with merge fa4004a3d536df6cda05dd0a48c9d65eb5b40172...

[pietroalbini]

@bors retry

Yielding priority to the stable release.