Previously the existence of bodies inside a foreign function block would
cause a panic in the hir `NodeCollector` during its collection of crate
bodies to compute a crate hash:

https://github.com/rust-lang/rust/blob/e59b08e62ea691916d2f063cac5aab4634128022/src/librustc_middle/hir/map/collector.rs#L154-L158

The collector walks the hir tree and creates a map of hir nodes, then
attaching bodies in the crate to their owner in the map. For a code like

```rust
extern "C" {
    fn f() {
        fn g() {}
    }
}
```

The crate bodies include the body of the function `g`. But foreign
functions cannot have bodies, and while the parser AST permits a foreign
function to have a body, the hir doesn't. This means that the body of
`f` is not present in the hir, and so neither is `g`. So when the
`NodeCollector` finishes the walking the hir, it has no record of `g`,
cannot find an owner for the body of `g` it sees in the crate bodies,
and blows up.

Why do the crate bodies include the body of `g`? The AST walker has a
need a for walking function bodies, and FFIs share the same AST node as
functions in other contexts.

There are at least two options to fix this:

- Don't unwrap the map entry for an hir node in the `NodeCollector`
- Modifier the ast->hir lowering visitor to ignore foreign function
  blocks

I don't think the first is preferrable, since we want to know when we
can't find a body for an hir node that we thought had one (dropping this
information may lead to an invalid hash). So this commit implements the
second option.

Closes rust-lang#74120

…o hir

This forwards the caller span to `Handler::delay_span_bug`

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

Release Notes:

```
v1.38.47: 10/02/2019
--------------------
 - Add support for FETCH API in WASM backend. This doesn't support FETCH in the
   main thread (`USE_FETCH_WORKER=0` is enforced). rust-lang#9490
 - Redefine errno values to be consistent with wasi. This will let us avoid
   needing to convert the values back and forth as we use more wasi APIs.
   This is an ABI change, which should not be noticeable from user code
   unless you use errno defines (like EAGAIN) *and* keep around binaries
   compiled with an older version that you link against. In that case, you
   should rebuild them. See rust-lang#9545.
 - Removed build option `-s ONLY_MY_CODE` as we now have much better solutions
   for that, like building to a wasm object file or using `STANDALONE_WASM`
   etc. (see
   https://github.com/emscripten-core/emscripten/wiki/WebAssembly-Standalone).
 - Emscripten now supports the config file (.emscripten) being placed in the
   emscripten directory rather that the current user's home directory.
   See rust-lang#9543
```

This commit adds support for lang items (`#[lang = "..."]` attributes)
on enum variants.

Signed-off-by: David Wood <david@davidtw.co>

This commit adds a test for rust-lang#61019 where a extern crate is imported as
`std` which results in name resolution to fail due to the uses of `std`
types introduced from lowering.

Signed-off-by: David Wood <david@davidtw.co>

This commit adds new lang items which will be used in AST lowering once
`QPath::LangItem` is introduced.

Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>
Signed-off-by: David Wood <david@davidtw.co>

This commit introduces `QPath::LangItem` to the HIR and uses it in AST
lowering instead of constructing a `hir::Path` from a slice of symbols.

This might be better for performance, but is also much cleaner as the
previous approach is fragile. In addition, it resolves a bug (rust-lang#61019)
where an extern crate imported as "std" would result in the paths
created during AST lowering being resolved incorrectly (or not at all).

Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>
Signed-off-by: David Wood <david@davidtw.co>

This commit implements support for `QPath::LangItem` and
`GenericBound::LangItemTrait` in save analysis.

Signed-off-by: David Wood <david@davidtw.co>

This commit simplifies `is_range_literal` by checking for
`QPath::LangItem` containing range-related lang items, rather than using
a heuristic.

Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>
Signed-off-by: David Wood <david@davidtw.co>

This commit modifies name resolution to ensure that new scopes are
introduced from lang-item generic bounds.

Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>
Signed-off-by: David Wood <david@davidtw.co>

This commit adds support for cleaning `QPath::LangItem` and
`hir::GenericBound::LangItemTrait` in rustdoc. `QPath::LangItem`
does not require lowering, and `hir::GenericBound::LangItemTrait`
is lowered to a `GenericBound::TraitBound`.

Signed-off-by: David Wood <david@davidtw.co>

This commit updates clippy with the introduction of `QPath::LangItem` so
that it still compiles.

Signed-off-by: David Wood <david@davidtw.co>

Don't visit foreign function bodies when lowering ast to hir

Previously the existence of bodies inside a foreign function block would
cause a panic in the hir `NodeCollector` during its collection of crate
bodies to compute a crate hash:

https://github.com/rust-lang/rust/blob/e59b08e62ea691916d2f063cac5aab4634128022/src/librustc_middle/hir/map/collector.rs#L154-L158

The collector walks the hir tree and creates a map of hir nodes, then
attaching bodies in the crate to their owner in the map. For a code like

```rust
extern "C" {
    fn f() {
        fn g() {}
    }
}
```

The crate bodies include the body of the function `g`. But foreign
functions cannot have bodies, and while the parser AST permits a foreign
function to have a body, the hir doesn't. This means that the body of
`f` is not present in the hir, and so neither is `g`. So when the
`NodeCollector` finishes the walking the hir, it has no record of `g`,
cannot find an owner for the body of `g` it sees in the crate bodies,
and blows up.

Why do the crate bodies include the body of `g`? The AST walker has a
need a for walking function bodies, and FFIs share the same AST node as
functions in other contexts.

There are at least two options to fix this:

- Don't unwrap the map entry for an hir node in the `NodeCollector`
- Modifier the ast->hir lowering visitor to ignore foreign function
  blocks

I don't think the first is preferrable, since we want to know when we
can't find a body for an hir node that we thought had one (dropping this
information may lead to an invalid hash). So this commit implements the
second option.

Closes rust-lang#74120

…matsakis

rustc_typeck: construct {Closure,Generator}Substs more directly.

We've previously not had a way to create `{Closure,Generator}Substs` other than instantiating all generics as inference variables and unifying the inference types (extracted using the regular `{Closure,Generator}Substs` accessors), with the actual types.

With this PR, those hacks, and assumptions about the order of closure/generator-specific components, are replaced with a simple API where the base `Substs` are combined with the additional information into a `{Closure,Generator}Substs`.
This might also be faster than relying inference, although probably not by much.

r? @nikomatsakis cc rust-lang#53488 @blitzerr

Use LocalDefId instead of HirId for reachable_set elements.

The only `HirId`s being tracked there that don't have matching `DefId`s are local variables, and that's an accident from rust-lang#44316 (where I preserved the old behavior, even if nothing relied on reachability tracking local variables).

Move DelaySpanBugEmitted to ty::context

This makes it even hard to abuse.

r? @eddyb

cc @LeSeulArtichaut as this will probably conflict with your PR :/

…efid-for-lang-items, r=petrochenkov

Preallocate `DefId`s for lang items

Fixes rust-lang#60607 and fixes rust-lang#61019.

This PR introduces `QPath::LangItem` to the HIR and uses it in AST lowering instead of constructing a `hir::Path` from a slice of symbols:

- Credit for much of this work goes to @matthewjasper, I basically just [rebased their earlier work](matthewjasper@a227c70#diff-c0f791ead38d2d02916faaad0f56f41d).
- Changes to Clippy might not be correct, they compile but attempting to run tests through `./x.py` produced failures which appeared spurious, so I didn't run any clippy tests.
- Changes to save analysis might not be correct - tests pass but I don't have a lot of confidence in those changes being correct.
- I've used `GenericBounds::LangItemTrait` rather than changing `PolyTraitRef`, as suggested by @matthewjasper [in this comment](matthewjasper@a227c70#r40107992) but I'd prefer that be left for a follow-up.
- I've split things into smaller commits fairly arbitrarily to make the diff easier to review, each commit should compile but might not pass tests until the final commit.

r? @oli-obk
cc @matthewjasper

Add regression test for issue-66768

Fixes rust-lang#66768

This is fixed by rust-lang#70452 (in particular, https://github.com/rust-lang/rust/pull/70452/files#diff-53aef089a36a8e2ed07627fc8915fe63R1763) and I'm not sure it's worth to add this test (i.e. the tests in rust-lang#70452 are enough), so r? @eddyb to confirm it.

…ler, r=eddyb

Add #[track_caller] to `Session::delay_span_bug`

This forwards the caller span to `Handler::delay_span_bug`

…int, r=dtolnay

Move to intra-doc links for /library/core/src/hint.rs

Helps with rust-lang#75080.

@rustbot modify labels: T-doc, A-intra-doc-links, T-rustdoc

Bump minor version of emsdk to 1.38.47

Release Notes:

```
v1.38.47: 10/02/2019
--------------------
 - Add support for FETCH API in WASM backend. This doesn't support FETCH in the
   main thread (`USE_FETCH_WORKER=0` is enforced). rust-lang#9490
 - Redefine errno values to be consistent with wasi. This will let us avoid
   needing to convert the values back and forth as we use more wasi APIs.
   This is an ABI change, which should not be noticeable from user code
   unless you use errno defines (like EAGAIN) *and* keep around binaries
   compiled with an older version that you link against. In that case, you
   should rebuild them. See rust-lang#9545.
 - Removed build option `-s ONLY_MY_CODE` as we now have much better solutions
   for that, like building to a wasm object file or using `STANDALONE_WASM`
   etc. (see
   https://github.com/emscripten-core/emscripten/wiki/WebAssembly-Standalone).
 - Emscripten now supports the config file (.emscripten) being placed in the
   emscripten directory rather that the current user's home directory.
   See rust-lang#9543
```

Motivated by changes to errno values which are currently out of sync with those
in libc crate which uses wasi values already. Helps with rust-lang#72808 and rust-lang#75532.

Switch to intra-doc links in /sys/windows/ext/{ffi,fs,process}.rs

Partial fix for rust-lang#75080

@rustbot modify labels: T-doc, A-intra-doc-links, T-rustdoc

r? @jyn514