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@nodakai nodakai commented Dec 1, 2014

(This PR depends on my another PR rust-lang#19439 )

After the library successfully called fork(2), the child does several
setup works such as setting UID, GID and current directory before it
calls exec(2). When those setup works failed, the child exits but the
parent didn't call waitpid(2) and left it as a zombie.

This patch also add several sanity checks. They shouldn't make any
noticeable impact to runtime performance.

The new test case in libstd/io/process.rs calls the ps command to check
if the new code can really reap a zombie.
The output of ps -A -o pid,sid,command should look like this:

  PID   SID COMMAND
    1     1 /sbin/init
    2     0 [kthreadd]
    3     0 [ksoftirqd/0]
...
12562  9237 ./spawn-failure
12563  9237 [spawn-failure] <defunct>
12564  9237 [spawn-failure] <defunct>
...
12592  9237 [spawn-failure] <defunct>
12593  9237 ps -A -o pid,sid,command
12884 12884 /bin/zsh
12922 12922 /bin/zsh
...

where ./spawn-failure is my test program which intentionally leaves many
zombies. Filtering the output with the "SID" (session ID) column is
a quick way to tell if a process (zombie) was spawned by my own test
program. Then the number of "defunct" lines is the number of zombie
children.

…xec(2).

After the library successfully called fork(2), the child does several
setup works such as setting UID, GID and current directory before it
calls exec(2).  When those setup works failed, the child exits but the
parent didn't call waitpid(2) and left it as a zombie.

This patch also add several sanity checks.  They shouldn't make any
noticeable impact to runtime performance.

The new test case in libstd/io/process.rs calls the ps command to check
if the new code can really reap a zombie.
The output of "ps -A -o pid,sid,command" should look like this:

  PID   SID COMMAND
    1     1 /sbin/init
    2     0 [kthreadd]
    3     0 [ksoftirqd/0]
...
12562  9237 ./spawn-failure
12563  9237 [spawn-failure] <defunct>
12564  9237 [spawn-failure] <defunct>
...
12592  9237 [spawn-failure] <defunct>
12593  9237 ps -A -o pid,sid,command
12884 12884 /bin/zsh
12922 12922 /bin/zsh
...

where ./spawn-failure is my test program which intentionally leaves many
zombies.  Filtering the output with the "SID" (session ID) column is
a quick way to tell if a process (zombie) was spawned by my own test
program.  Then the number of "defunct" lines is the number of zombie
children.

Signed-off-by: NODA, Kai <[email protected]>
@nodakai nodakai closed this Dec 1, 2014
@nodakai nodakai deleted the libstd-reap-failed-child branch December 1, 2014 21:21
nodakai pushed a commit that referenced this pull request Jan 1, 2015
Fixes rust-lang#19707.

In terms of output, it currently uses the form `argument #1`, `argument #2`, etc. If anyone has any better suggestions I would be glad to consider them.
nodakai pushed a commit that referenced this pull request Dec 18, 2015
…hange

Change verbiage in Stack & Heap page
nodakai pushed a commit that referenced this pull request Feb 2, 2016
update tests emitter.rs
nodakai pushed a commit that referenced this pull request Mar 6, 2016
Change import a trait suggestion from:

   help: candidate #1: use `std::io::Write`

to

   help: candidate #1: `use std::io::Write`

so that the code can be copied directly.
nodakai pushed a commit that referenced this pull request Mar 6, 2016
suggest: Put the `use` in suggested code inside the quotes

Change import a trait suggestion from:

       help: candidate #1: use `std::io::Write`

to

       help: candidate #1: `use std::io::Write`

so that the code can be copied directly.

Fixes rust-lang#31864
nodakai pushed a commit that referenced this pull request May 28, 2016
nodakai pushed a commit that referenced this pull request Aug 23, 2016
rustc_trans: don't Assert(Overflow(Neg)) when overflow checks are off.

Generic functions using `Neg` on primitive types would panic even in release mode, with MIR trans.
The solution is a bit hacky, as I'm checking the message, since there's no dedicated `CheckedUnOp`.

Blocks Servo rustup ([failure #1](http://build.servo.org/builders/linux-rel/builds/2477/steps/test_3/logs/stdio), [failure #2](http://build.servo.org/builders/mac-rel-css/builds/2364/steps/test/logs/stdio)) - this should be the last hurdle, it affects only one test.
nodakai pushed a commit that referenced this pull request Feb 16, 2017
For a given file

```rust
trait A { fn foo(&self) {} }
trait B : A { fn foo(&self) {} }

fn bar<T: B>(a: &T) {
  a.foo()
}
```

provide the following output

```
error[E0034]: multiple applicable items in scope
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^ multiple `foo` found
  |
note: candidate #1 is defined in the trait `A`
 --> file.rs:2:11
  |
2 | trait A { fn foo(&self, a: usize) {} }
  |           ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to use it here write `A::foo(&a, 1)` instead
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^
note: candidate #2 is defined in the trait `B`
 --> file.rs:3:15
  |
3 | trait B : A { fn foo(&self, a: usize) {} }
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to use it here write `B::foo(&a, 1)` instead
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^
```
nodakai pushed a commit that referenced this pull request Feb 16, 2017
E0034: provide disambiguated syntax for candidates

For a given file

```rust
trait A { fn foo(&self) {} }
trait B : A { fn foo(&self) {} }

fn bar<T: B>(a: &T) {
  a.foo()
}
```

provide the following output

```
error[E0034]: multiple applicable items in scope
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^ multiple `foo` found
  |
note: candidate #1 is defined in the trait `A`
 --> file.rs:2:11
  |
2 | trait A { fn foo(&self, a: usize) {} }
  |           ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to use it here write `A::foo(&a, 1)` instead
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^
note: candidate #2 is defined in the trait `B`
 --> file.rs:3:15
  |
3 | trait B : A { fn foo(&self, a: usize) {} }
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to use it here write `B::foo(&a, 1)` instead
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^
```

Fix rust-lang#37767.
nodakai pushed a commit that referenced this pull request Feb 16, 2017
LeakSanitizer, ThreadSanitizer, AddressSanitizer and MemorySanitizer support

```
$ cargo new --bin leak && cd $_

$ edit Cargo.toml && tail -n3 $_
```

``` toml
[profile.dev]
opt-level = 1
```

```
$ edit src/main.rs && cat $_
```

``` rust
use std::mem;

fn main() {
    let xs = vec![0, 1, 2, 3];
    mem::forget(xs);
}
```

```
$ RUSTFLAGS="-Z sanitizer=leak" cargo run --target x86_64-unknown-linux-gnu; echo $?
    Finished dev [optimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/leak`

=================================================================
==10848==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x557c3488db1f in __interceptor_malloc /shared/rust/checkouts/lsan/src/compiler-rt/lib/lsan/lsan_interceptors.cc:55
    #1 0x557c34888aaa in alloc::heap::exchange_malloc::h68f3f8b376a0da42 /shared/rust/checkouts/lsan/src/liballoc/heap.rs:138
    #2 0x557c34888afc in leak::main::hc56ab767de6d653a $PWD/src/main.rs:4
    #3 0x557c348c0806 in __rust_maybe_catch_panic ($PWD/target/debug/leak+0x3d806)

SUMMARY: LeakSanitizer: 16 byte(s) leaked in 1 allocation(s).
23
```

```
$ cargo new --bin racy && cd $_

$ edit src/main.rs && cat $_
```

``` rust
use std::thread;

static mut ANSWER: i32 = 0;

fn main() {
    let t1 = thread::spawn(|| unsafe { ANSWER = 42 });
    unsafe {
        ANSWER = 24;
    }
    t1.join().ok();
}
```

```
$ RUSTFLAGS="-Z sanitizer=thread" cargo run --target x86_64-unknown-linux-gnu; echo $?
==================
WARNING: ThreadSanitizer: data race (pid=12019)
  Write of size 4 at 0x562105989bb4 by thread T1:
    #0 racy::main::_$u7b$$u7b$closure$u7d$$u7d$::hbe13ea9e8ac73f7e $PWD/src/main.rs:6 (racy+0x000000010e3f)
    #1 _$LT$std..panic..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..FnOnce$LT$$LP$$RP$$GT$$GT$::call_once::h2e466a92accacc78 /shared/rust/checkouts/lsan/src/libstd/panic.rs:296 (racy+0x000000010cc5)
    #2 std::panicking::try::do_call::h7f4d2b38069e4042 /shared/rust/checkouts/lsan/src/libstd/panicking.rs:460 (racy+0x00000000c8f2)
    #3 __rust_maybe_catch_panic <null> (racy+0x0000000b4e56)
    #4 std::panic::catch_unwind::h31ca45621ad66d5a /shared/rust/checkouts/lsan/src/libstd/panic.rs:361 (racy+0x00000000b517)
    #5 std::thread::Builder::spawn::_$u7b$$u7b$closure$u7d$$u7d$::hccfc37175dea0b01 /shared/rust/checkouts/lsan/src/libstd/thread/mod.rs:357 (racy+0x00000000c226)
    #6 _$LT$F$u20$as$u20$alloc..boxed..FnBox$LT$A$GT$$GT$::call_box::hd880bbf91561e033 /shared/rust/checkouts/lsan/src/liballoc/boxed.rs:605 (racy+0x00000000f27e)
    #7 std::sys::imp::thread::Thread::new::thread_start::hebdfc4b3d17afc85 <null> (racy+0x0000000abd40)

  Previous write of size 4 at 0x562105989bb4 by main thread:
    #0 racy::main::h23e6e5ca46d085c3 $PWD/src/main.rs:8 (racy+0x000000010d7c)
    #1 __rust_maybe_catch_panic <null> (racy+0x0000000b4e56)
    #2 __libc_start_main <null> (libc.so.6+0x000000020290)

  Location is global 'racy::ANSWER::h543d2b139f819b19' of size 4 at 0x562105989bb4 (racy+0x0000002f8bb4)

  Thread T1 (tid=12028, running) created by main thread at:
    #0 pthread_create /shared/rust/checkouts/lsan/src/compiler-rt/lib/tsan/rtl/tsan_interceptors.cc:902 (racy+0x00000001aedb)
    #1 std::sys::imp::thread::Thread::new::hce44187bf4a36222 <null> (racy+0x0000000ab9ae)
    #2 std::thread::spawn::he382608373eb667e /shared/rust/checkouts/lsan/src/libstd/thread/mod.rs:412 (racy+0x00000000b5aa)
    #3 racy::main::h23e6e5ca46d085c3 $PWD/src/main.rs:6 (racy+0x000000010d5c)
    #4 __rust_maybe_catch_panic <null> (racy+0x0000000b4e56)
    #5 __libc_start_main <null> (libc.so.6+0x000000020290)

SUMMARY: ThreadSanitizer: data race $PWD/src/main.rs:6 in racy::main::_$u7b$$u7b$closure$u7d$$u7d$::hbe13ea9e8ac73f7e
==================
ThreadSanitizer: reported 1 warnings
66
```

```
$ cargo new --bin oob && cd $_

$ edit src/main.rs && cat $_
```

``` rust
fn main() {
    let xs = [0, 1, 2, 3];
    let y = unsafe { *xs.as_ptr().offset(4) };
}
```

```
$ RUSTFLAGS="-Z sanitizer=address" cargo run --target x86_64-unknown-linux-gnu; echo $?
=================================================================
==13328==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fff29f3ecd0 at pc 0x55802dc6bf7e bp 0x7fff29f3ec90 sp 0x7fff29f3ec88
READ of size 4 at 0x7fff29f3ecd0 thread T0
    #0 0x55802dc6bf7d in oob::main::h0adc7b67e5feb2e7 $PWD/src/main.rs:3
    #1 0x55802dd60426 in __rust_maybe_catch_panic ($PWD/target/debug/oob+0xfe426)
    #2 0x55802dd58dd9 in std::rt::lang_start::hb2951fc8a59d62a7 ($PWD/target/debug/oob+0xf6dd9)
    #3 0x55802dc6c002 in main ($PWD/target/debug/oob+0xa002)
    #4 0x7fad8c3b3290 in __libc_start_main (/usr/lib/libc.so.6+0x20290)
    #5 0x55802dc6b719 in _start ($PWD/target/debug/oob+0x9719)

Address 0x7fff29f3ecd0 is located in stack of thread T0 at offset 48 in frame
    #0 0x55802dc6bd5f in oob::main::h0adc7b67e5feb2e7 $PWD/src/main.rs:1

  This frame has 1 object(s):
    [32, 48) 'xs' <== Memory access at offset 48 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow $PWD/src/main.rs:3 in oob::main::h0adc7b67e5feb2e7
Shadow bytes around the buggy address:
  0x1000653dfd40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfd50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfd60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfd70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x1000653dfd90: 00 00 00 00 f1 f1 f1 f1 00 00[f3]f3 00 00 00 00
  0x1000653dfda0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfdb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfdc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfdd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000653dfde0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==13328==ABORTING
1
```

```
$ cargo new --bin uninit && cd $_

$ edit src/main.rs && cat $_
```

``` rust
use std::mem;

fn main() {
    let xs: [u8; 4] = unsafe { mem::uninitialized() };
    let y = xs[0] + xs[1];
}
```

```
$ RUSTFLAGS="-Z sanitizer=memory" cargo run; echo $?
==30198==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x563f4b6867da in uninit::main::hc2731cd4f2ed48f8 $PWD/src/main.rs:5
    #1 0x563f4b7033b6 in __rust_maybe_catch_panic ($PWD/target/debug/uninit+0x873b6)
    #2 0x563f4b6fbd69 in std::rt::lang_start::hb2951fc8a59d62a7 ($PWD/target/debug/uninit+0x7fd69)
    #3 0x563f4b6868a9 in main ($PWD/target/debug/uninit+0xa8a9)
    #4 0x7fe844354290 in __libc_start_main (/usr/lib/libc.so.6+0x20290)
    #5 0x563f4b6864f9 in _start ($PWD/target/debug/uninit+0xa4f9)

SUMMARY: MemorySanitizer: use-of-uninitialized-value $PWD/src/main.rs:5 in uninit::main::hc2731cd4f2ed48f8
Exiting
77
```
nodakai pushed a commit that referenced this pull request Mar 7, 2017
nodakai pushed a commit that referenced this pull request Mar 14, 2017
Group "missing variable bind" spans in `or` matches and clarify wording
for the two possible cases: when a variable from the first pattern is
not in any of the subsequent patterns, and when a variable in any of the
other patterns is not in the first one.

Before:

```
error[E0408]: variable `a` from pattern #1 is not bound in pattern #2
  --> file.rs:10:23
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                       ^^^^^^^^^^^ pattern doesn't bind `a`

error[E0408]: variable `b` from pattern #2 is not bound in pattern #1
  --> file.rs:10:32
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                ^ pattern doesn't bind `b`

error[E0408]: variable `a` from pattern #1 is not bound in pattern #3
  --> file.rs:10:37
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                     ^^^^^^^^ pattern doesn't bind `a`

error[E0408]: variable `d` from pattern #1 is not bound in pattern #3
  --> file.rs:10:37
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                     ^^^^^^^^ pattern doesn't bind `d`

error[E0408]: variable `c` from pattern #3 is not bound in pattern #1
  --> file.rs:10:43
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                           ^ pattern doesn't bind `c`

error[E0408]: variable `d` from pattern #1 is not bound in pattern #4
  --> file.rs:10:48
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                                ^^^^^^^^ pattern doesn't bind `d`

error: aborting due to 6 previous errors
```

After:

```
error[E0408]: variable `a` is not bound in all patterns
  --> file.rs:20:37
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
   |               -       ^^^^^^^^^^^   ^^^^^^^^         - variable
t in all patterns
   |               |       |             |
   |               |       |             pattern doesn't bind `a`
   |               |       pattern doesn't bind `a`
   |               variable not in all patterns

error[E0408]: variable `d` is not bound in all patterns
  --> file.rs:20:37
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
   |                  -          -       ^^^^^^^^   ^^^^^^^^ pattern
esn't bind `d`
   |                  |          |       |
   |                  |          |       pattern doesn't bind `d`
   |                  |          variable not in all patterns
   |                  variable not in all patterns

error[E0408]: variable `b` is not bound in all patterns
  --> file.rs:20:37
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
   |         ^^^^^^^^^^^            -    ^^^^^^^^   ^^^^^^^^ pattern
esn't bind `b`
   |         |                      |    |
   |         |                      |    pattern doesn't bind `b`
   |         |                      variable not in all patterns
   |         pattern doesn't bind `b`

error[E0408]: variable `c` is not bound in all patterns
  --> file.rs:20:48
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => {
intln!("{:?}", a); }
   |         ^^^^^^^^^^^   ^^^^^^^^^^^         -    ^^^^^^^^ pattern
esn't bind `c`
   |         |             |                   |
   |         |             |                   variable not in all
tterns
   |         |             pattern doesn't bind `c`
   |         pattern doesn't bind `c`

error: aborting due to 4 previous errors
```

* Have only one presentation for binding consistency errors
* Point to same binding in multiple patterns when possible
* Check inconsistent bindings in all arms
* Simplify wording of diagnostic message
* Sort emition and spans of binding errors for deterministic output
nodakai pushed a commit that referenced this pull request Mar 14, 2017
Clean up "pattern doesn't bind x" messages

Group "missing variable bind" spans in `or` matches and clarify wording
for the two possible cases: when a variable from the first pattern is
not in any of the subsequent patterns, and when a variable in any of the
other patterns is not in the first one.

Before:

```rust
error[E0408]: variable `a` from pattern #1 is not bound in pattern #2
  --> file.rs:10:23
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                       ^^^^^^^^^^^ pattern doesn't bind `a`

error[E0408]: variable `b` from pattern #2 is not bound in pattern #1
  --> file.rs:10:32
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                ^ pattern doesn't bind `b`

error[E0408]: variable `a` from pattern #1 is not bound in pattern #3
  --> file.rs:10:37
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                     ^^^^^^^^ pattern doesn't bind `a`

error[E0408]: variable `d` from pattern #1 is not bound in pattern #3
  --> file.rs:10:37
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                     ^^^^^^^^ pattern doesn't bind `d`

error[E0408]: variable `c` from pattern #3 is not bound in pattern #1
  --> file.rs:10:43
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                           ^ pattern doesn't bind `c`

error[E0408]: variable `d` from pattern #1 is not bound in pattern #4
  --> file.rs:10:48
   |
10 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                                                ^^^^^^^^ pattern doesn't bind `d`

error: aborting due to 6 previous errors
```

After:

```rust
error[E0408]: variable `d` is not bound in all patterns
  --> $DIR/issue-39698.rs:20:37
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |                  -          -       ^^^^^^^^   ^^^^^^^^ pattern doesn't bind `d`
   |                  |          |       |
   |                  |          |       pattern doesn't bind `d`
   |                  |          variable not in all patterns
   |                  variable not in all patterns

error[E0408]: variable `c` is not bound in all patterns
  --> $DIR/issue-39698.rs:20:48
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |         ^^^^^^^^^^^   ^^^^^^^^^^^         -    ^^^^^^^^ pattern doesn't bind `c`
   |         |             |                   |
   |         |             |                   variable not in all patterns
   |         |             pattern doesn't bind `c`
   |         pattern doesn't bind `c`

error[E0408]: variable `a` is not bound in all patterns
  --> $DIR/issue-39698.rs:20:37
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |               -       ^^^^^^^^^^^   ^^^^^^^^         - variable not in all patterns
   |               |       |             |
   |               |       |             pattern doesn't bind `a`
   |               |       pattern doesn't bind `a`
   |               variable not in all patterns

error[E0408]: variable `b` is not bound in all patterns
  --> $DIR/issue-39698.rs:20:37
   |
20 |         T::T1(a, d) | T::T2(d, b) | T::T3(c) | T::T4(a) => { println!("{:?}", a); }
   |         ^^^^^^^^^^^            -    ^^^^^^^^   ^^^^^^^^ pattern doesn't bind `b`
   |         |                      |    |
   |         |                      |    pattern doesn't bind `b`
   |         |                      variable not in all patterns
   |         pattern doesn't bind `b`

error: aborting due to 4 previous errors
```

Fixes rust-lang#39698.
nodakai pushed a commit that referenced this pull request Jun 26, 2018
When encountering an unexisting method for a given trait where an
associated function has the same name, suggest using the appropriate
syntax, instead of using `help` text.

When only one candidate is found, do not call it "candidate #1", just
call it "the candidate".
nodakai pushed a commit that referenced this pull request Jun 26, 2018
Tweak output on E0599 for assoc fn used as method

 - Use suggestion instead of `help` when possible
 - Add primary span label
 - Remove incorrect `help` suggestion using incorrect syntax
 - Do not refer to only one possible candidate as `candidate #1`, refer to it as `the candidate`
nodakai pushed a commit that referenced this pull request Jul 8, 2018
Suggestion for 'static impl Trait return

When encountering a named or anonymous sup requirement (for example,
`&'a self`) and a `'static` impl Trait return type, suggest adding the
`'_` lifetime constraing to the return type.

Fix rust-lang#43719, rust-lang#51282.

```
error: cannot infer an appropriate lifetime
  --> $DIR/static-return-lifetime-infered.rs:17:16
   |
LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
   |                                   ----------------------- this return type evaluates to the `'static` lifetime...
LL |         self.x.iter().map(|a| a.0)
   |         ------ ^^^^
   |         |
   |         ...but this borrow...
   |
note: ...can't outlive the anonymous lifetime #1 defined on the method body at 16:5
  --> $DIR/static-return-lifetime-infered.rs:16:5
   |
LL | /     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
LL | |         self.x.iter().map(|a| a.0)
LL | |     }
   | |_____^
help: you can add a constraint to the return type to make it last less than `'static` and match the anonymous lifetime #1 defined on the method body at 16:5
   |
LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
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