The way we deal with unreachable expressions in trans is pretty ad hoc,
but this at least doesn't make it worse, and eliminates the LLVM
assertion failure reported in #5741.
Fixes https://github.com/mozilla/rust/issues/6578 by merging the 3 different ways to build an AST into a single `AstBuilder` trait, creating a more uniform and briefer interface.
Also, converts the `ext_ctxt` trait-object to be a plain struct, as well as renaming it to `ExtCtxt`.
Seems to make expansion slightly faster for the normal case (e.g. `libcore` and `libstd`), but slower for `librustc` (slightly) and `libsyntax` (0.3s -> 0.8s! I'm investigating this, but I'd prefer this patch to land relatively quickly.).
`git blame` suggests maybe @graydon or @erickt are familiar with this area of the code. r?
This adds a lint mode for detecting unnecessary allocations on the heap. This isn't super fancy, currently it only has two rules
1. For a function's arguments, if you allocate a `[~|@]str` literal, when the type of the argument is a `&str`, emit a warning.
2. For the same case, emit warnings for boxed vectors when slices are required.
After adding the lint, I rampaged through the libraries and removed all the unnecessary allocations I could find.
Currently, trait_info is a hashmap that allows a quick lookup of all
methods contained in a given trait, but we actually only use it to
lookup traits that contain a given method. Adjusting the map to support
the lookup we actually need gives a nice speed boost, reducing the time
required for the resolution step for librustc from ~2.6s to ~1.0s on my
box.
With this, the build is almost 100% warning free.
One more can be fixed after the next snapshot, and there's one other that I filed an issue about already.
It uses the private field of TCB head to store stack limit. I tested on my Raspberry PI. A simple hello world program ran without any problem. However, for a more complex program, it segfaulted as #6231.
Closes#2647
This way it's much easier to add lints throughout compilation correctly, and
functions on impls can alter the way lints are emitted. This involved pretty much rewriting how lints are emitted. Beforehand, only items could alter the lint settings, so whenever a lint was added it had to be associated with whatever item id it was coming from. I removed this (possibly questionably) in favor of just specifying a span and a message when adding a lint. When lint checking comes around, it looks at all the lints and sees which node with attributes best encloses it and uses that level of linting. This means that all consumer code doesn't have to deal with what item things came from (especially because functions on impls aren't items). More details of this can be found in the code (and comments).
As a bonus, I managed to greatly simplify emission of lints in resolve.rs about unused imports. Now instead of it manually tracking what the lint level is, it's all moved over into the lint module (as is to be expected).
r? @nikomatsakis Impls can implement either zero or one traits; this has been true
more or less since we removed classes. So I got rid of the comments
saying "we should support multiple traits" and changed the code to
make it clear that we don't. This is just cleanup, and doesn't break
any existing tests.
Impls can implement either zero or one traits; this has been true
more or less since we removed classes. So I got rid of the comments
saying "we should support multiple traits" and changed the code to
make it clear that we don't. This is just cleanup, and doesn't break
any existing tests.
