Fixes #29362.

Refactor `TyStruct`/`TyEnum`/`TyUnion` into `TyAdt`

r? @EddyB

save-analysis bits and pieces

Fix argument to FIONBIO ioctl

The FIONBIO ioctl takes as argument a pointer to an integer, which
should be either 0 or 1 to indicate whether nonblocking mode is to
be switched off or on.  The type of the pointed-to variable is "int".

However, the set_nonblocking routine in libstd/sys/unix/net.rs passes
a pointer to a libc::c_ulong variable.  This doesn't matter on all
32-bit platforms and on all litte-endian platforms, but it will
break on big-endian 64-bit platforms.

Found while porting Rust to s390x (a big-endian 64-bit platform).
Signed-off-by: NUlrich Weigand <ulrich.weigand@de.ibm.com>

Follow target ABI sign-/zero-extension rules for enum types

While attempting to port Rust to s390x, I ran into an ABI violation
(that caused rust_eh_personality to be miscompiled, breaking unwinding).
The problem is that this function returns an enum type, which is
supposed to be sign-extended according to the s390x ABI.  However,
common code would ignore target sign-/zero-extension rules for any
types that do not satisfy is_integral(), which includes enums.

For the general case of Rust enum types, which map to structure types
with a discriminant, that seems correct.  However, in the special case
of simple enums that map directly to C enum types (i.e. LLVM integers),
this is incorrect; we must follow the target extension rules for those.
Signed-off-by: NUlrich Weigand <ulrich.weigand@de.ibm.com>

Issue deprecation warnings for safe accesses to extern statics

Fixes https://github.com/rust-lang/rust/issues/35112
cc https://github.com/rust-lang/rust/issues/36247

Fix soundness bug described in #29859

This is an attempt at fixing the problems described in #29859 based on an IRC conversation between @nikomatsakis and I today. I'm waiting on a full build to come back, otherwise both tests trigger the correct error.

Clean code a bit

Avoid instaiblity errors in code generated by `syntax_ext::deriving::call_intrinsic()`

r? @EddyB

Removing the extraneous not_equal implementation for slices

Happened to stumble upon this one awhile back. Seemed a bit silly to have both the equals and not equals implementation when they're so similar.

macros: stackless expansion

After this PR, macro expansion cannot overflow the stack unless the expanded crate is too deep to fold.
Everything but the stackless placeholder expansion commit is also groundwork for macro modularization.

r? @nrc or @EddyB

rustbuild: per target musl-root

config.toml now accepts a target.$TARGET.musl-root key that lets you
override the "build" musl-root value, which is set via the --musl-root
flag or via the build.musl-root key.

With this change, it's now possible to compile std for several musl
targets at once. Here's are the sample commands to do such thing:

```
$ configure \
    --enable-rustbuild \
    --target=x86_64-unknown-linux-musl,arm-unknown-linux-musleabi \
    --musl-root=/musl/x86_64-unknown-linux-musl/

$ edit config.toml && tail config.toml
[target.arm-unknown-linux-musleabi]
musl-root = "/x-tools/arm-unknown-linux-musleabi/arm-unknown-linux-musleabi/sysroot/usr"

$ make
```

r? @alexcrichton
With this we should be able to start producing releases of std for arm musl targets

rustdoc: Filter more incorrect methods inherited through Deref

Old code filtered out only static methods. This code also excludes &mut self methods if there is no DerefMut implementation.

Fixes #35169

re-add accidentally removed line in wfcheck

Fixes #36299, introduced in #36119.

r? @EddyB

The FIONBIO ioctl takes as argument a pointer to an integer, which
should be either 0 or 1 to indicate whether nonblocking mode is to
be switched off or on.  The type of the pointed-to variable is "int".

However, the set_nonblocking routine in libstd/sys/unix/net.rs passes
a pointer to a libc::c_ulong variable.  This doesn't matter on all
32-bit platforms and on all litte-endian platforms, but it will
break on big-endian 64-bit platforms.

Found while porting Rust to s390x (a big-endian 64-bit platform).
Signed-off-by: NUlrich Weigand <ulrich.weigand@de.ibm.com>

While attempting to port Rust to s390x, I ran into an ABI violation
(that caused rust_eh_personality to be miscompiled, breaking unwinding).
The problem is that this function returns an enum type, which is
supposed to be sign-extended according to the s390x ABI.  However,
common code would ignore target sign-/zero-extension rules for any
types that do not satisfy is_integral(), which includes enums.

For the general case of Rust enum types, which map to structure types
with a discriminant, that seems correct.  However, in the special case
of simple enums that map directly to C enum types (i.e. LLVM integers),
this is incorrect; we must follow the target extension rules for those.
Signed-off-by: NUlrich Weigand <ulrich.weigand@de.ibm.com>

resolve: Suggest `use self` when import resolves

Improves errors messages by replacing "Maybe a missing `extern crate`" messages
with "Did you mean `self::...`" when the `self` import would succeed.

Fixes #34191.

Thank you for the help @jseyfried!

Count and report time taken by MIR passes

There’s some desire for deeper introspectability into what MIR passes cost us.

-Z time-passes after this PR:

```
   Compiling test_shim v0.1.0 (file:///home/nagisa/Documents/rust/rust/src/rustc/test_shim)
time: 0.000; rss: 29MB	parsing
time: 0.000; rss: 29MB	configuration
time: 0.000; rss: 29MB	recursion limit
time: 0.000; rss: 29MB	crate injection
time: 0.000; rss: 29MB	plugin loading
time: 0.000; rss: 29MB	plugin registration
time: 0.032; rss: 54MB	expansion
time: 0.000; rss: 54MB	maybe building test harness
time: 0.000; rss: 54MB	assigning node ids
time: 0.000; rss: 54MB	checking for inline asm in case the target doesn't support it
time: 0.000; rss: 54MB	complete gated feature checking
time: 0.000; rss: 54MB	collecting defs
time: 0.004; rss: 54MB	external crate/lib resolution
time: 0.000; rss: 54MB	early lint checks
time: 0.000; rss: 54MB	AST validation
time: 0.001; rss: 54MB	name resolution
time: 0.000; rss: 54MB	lowering ast -> hir
time: 0.000; rss: 56MB	indexing hir
time: 0.000; rss: 56MB	attribute checking
time: 0.000; rss: 56MB	language item collection
time: 0.000; rss: 56MB	lifetime resolution
time: 0.000; rss: 56MB	looking for entry point
time: 0.000; rss: 56MB	looking for plugin registrar
time: 0.000; rss: 56MB	region resolution
time: 0.000; rss: 56MB	loop checking
time: 0.000; rss: 56MB	static item recursion checking
time: 0.000; rss: 56MB	compute_incremental_hashes_map
time: 0.000; rss: 56MB	load_dep_graph
time: 0.000; rss: 56MB	type collecting
time: 0.000; rss: 56MB	variance inference
time: 0.011; rss: 59MB	coherence checking
time: 0.000; rss: 59MB	wf checking
time: 0.000; rss: 59MB	item-types checking
time: 0.000; rss: 59MB	item-bodies checking
time: 0.000; rss: 59MB	drop-impl checking
time: 0.000; rss: 59MB	const checking
time: 0.000; rss: 59MB	privacy checking
time: 0.000; rss: 59MB	stability index
time: 0.000; rss: 59MB	intrinsic checking
time: 0.000; rss: 59MB	effect checking
time: 0.000; rss: 59MB	match checking
time: 0.000; rss: 59MB	liveness checking
time: 0.000; rss: 59MB	rvalue checking
time: 0.000; rss: 59MB	MIR dump
  time: 0.000; rss: 59MB	SimplifyCfg
  time: 0.000; rss: 59MB	QualifyAndPromoteConstants
  time: 0.000; rss: 59MB	TypeckMir
  time: 0.000; rss: 59MB	SimplifyBranches
  time: 0.000; rss: 59MB	SimplifyCfg
time: 0.000; rss: 59MB	MIR passes
time: 0.000; rss: 59MB	borrow checking
time: 0.000; rss: 59MB	reachability checking
time: 0.000; rss: 59MB	death checking
time: 0.000; rss: 59MB	stability checking
time: 0.000; rss: 59MB	unused lib feature checking
time: 0.000; rss: 59MB	lint checking
time: 0.000; rss: 59MB	resolving dependency formats
  time: 0.000; rss: 59MB	NoLandingPads
  time: 0.000; rss: 59MB	SimplifyCfg
  time: 0.000; rss: 59MB	EraseRegions
  time: 0.000; rss: 59MB	AddCallGuards
  time: 0.000; rss: 59MB	ElaborateDrops
  time: 0.000; rss: 59MB	NoLandingPads
  time: 0.000; rss: 59MB	SimplifyCfg
  time: 0.000; rss: 59MB	Deaggregator
  time: 0.000; rss: 59MB	AddCallGuards
  time: 0.000; rss: 59MB	PreTrans
time: 0.000; rss: 59MB	Prepare MIR codegen passes
  time: 0.000; rss: 59MB	write metadata
  time: 0.000; rss: 61MB	translation item collection
  time: 0.000; rss: 61MB	codegen unit partitioning
  time: 0.000; rss: 61MB	internalize symbols
time: 0.007; rss: 61MB	translation
time: 0.000; rss: 61MB	assert dep graph
time: 0.000; rss: 61MB	serialize dep graph
time: 0.000; rss: 61MB	llvm function passes [2]
time: 0.000; rss: 61MB	llvm function passes [3]
time: 0.000; rss: 61MB	llvm function passes [1]
time: 0.000; rss: 61MB	llvm function passes [0]
time: 0.000; rss: 61MB	llvm module passes [2]
time: 0.000; rss: 61MB	llvm module passes [1]
time: 0.000; rss: 61MB	llvm module passes [0]
time: 0.000; rss: 61MB	llvm module passes [3]
time: 0.001; rss: 62MB	codegen passes [1]
time: 0.001; rss: 62MB	codegen passes [2]
time: 0.001; rss: 62MB	codegen passes [0]
time: 0.001; rss: 62MB	codegen passes [3]
time: 0.001; rss: 63MB	codegen passes [1]
time: 0.005; rss: 63MB	LLVM passes
time: 0.000; rss: 63MB	serialize work products
time: 0.001; rss: 63MB	linking
```

r? @EddyB or @nikomatsakis

cc @nrc, @Mark-Simulacrum

Fix "field is never used" warning to take unions into account

When compiling code containing a union with an unused field, rustc says
"struct field is never used".

Rather than saying "struct or union", or adding logic to determine the
type of the item, just change the message to "field is never used",
dropping the "struct".

Update tests accordingly.

Rollup of 8 pull requests

- Successful merges: #36121, #36128, #36241, #36243, #36263, #36267, #36273, #36298
- Failed merges:

incr. comp.: Take spans into account for ICH

This PR makes the ICH (incr. comp. hash) take spans into account when debuginfo is enabled.

A side-effect of this is that the SVH (which is based on the ICHs of all items in the crate) becomes sensitive to the tiniest change in a code base if debuginfo is enabled. Since we are not trying to model ABI compatibility via the SVH anymore (this is done via the crate disambiguator now), this should be not be a problem.

Fixes #33888.
Fixes #32753.