Auto merge of #38165 - Yamakaky:better-backtrace, r=petrochenkov

Improve backtrace formating while panicking.

Fixes #37783.

Done:

- Fix alignment of file paths for better readability
- `RUST_BACKTRACE=full` prints all the informations (current behaviour)
- `RUST_BACKTRACE=(short|yes)` is the default and does:
  - Skip irrelevant frames at the beginning and the end
  - Remove function address
  - Remove the current directory from the absolute paths
  - Remove `::hfabe6541873` at the end of the symbols
- `RUST_BACKTRACE=(0|no)` disables the backtrace.
- `RUST_BACKTRACE=<everything else>` is equivalent to `short` for
  backward compatibility.
- doc
- More uniform printing across platforms.

Removed, TODO in a new PR:

- Remove path prefix for libraries and libstd

Example of short backtrace:
```rust
fn fail() {
    panic!();
}

fn main() {
    let closure = || fail();
    closure();
}
```
Short:
```
thread 'main' panicked at 'explicit panic', t.rs:2
Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: t::fail
            at ./t.rs:2
   1: t::main::{{closure}}
            at ./t.rs:6
   2: t::main
            at ./t.rs:7
```
Full:
```
thread 'main' panicked at 'This function never returns!', t.rs:2
stack backtrace:
   0:     0x558ddf666478 - std::sys::imp::backtrace::tracing::imp::unwind_backtrace::hec84c9dd8389cc5d
                               at /home/yamakaky/dev/rust/rust/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1:     0x558ddf65d90e - std::sys_common::backtrace::_print::hfa25f8b31f4b4353
                               at /home/yamakaky/dev/rust/rust/src/libstd/sys_common/backtrace.rs:71
   2:     0x558ddf65cb5e - std::sys_common::backtrace::print::h9b711e11ac3ba805
                               at /home/yamakaky/dev/rust/rust/src/libstd/sys_common/backtrace.rs:60
   3:     0x558ddf66796e - std::panicking::default_hook::{{closure}}::h736d216e74748044
                               at /home/yamakaky/dev/rust/rust/src/libstd/panicking.rs:355
   4:     0x558ddf66743c - std::panicking::default_hook::h16baff397e46ea10
                               at /home/yamakaky/dev/rust/rust/src/libstd/panicking.rs:371
   5:     0x558ddf6682bc - std::panicking::rust_panic_with_hook::h6d5a9bb4eca42c80
                               at /home/yamakaky/dev/rust/rust/src/libstd/panicking.rs:559
   6:     0x558ddf64ea93 - std::panicking::begin_panic::h17dc549df2f10b99
                               at /home/yamakaky/dev/rust/rust/src/libstd/panicking.rs:521
   7:     0x558ddf64ec42 - t::diverges::he6bc43fc925905f5
                               at /tmp/p/t.rs:2
   8:     0x558ddf64ec5a - t::main::h0ffc20356b8a69c0
                               at /tmp/p/t.rs:6
   9:     0x558ddf6687f5 - core::ops::FnOnce::call_once::hce41f19c0db56f93
  10:     0x558ddf667cde - std::panicking::try::do_call::hd4c8c97efb4291df
                               at /home/yamakaky/dev/rust/rust/src/libstd/panicking.rs:464
  11:     0x558ddf698d77 - __rust_try
  12:     0x558ddf698c57 - __rust_maybe_catch_panic
                               at /home/yamakaky/dev/rust/rust/src/libpanic_unwind/lib.rs:98
  13:     0x558ddf667adb - std::panicking::try::h2c56ed2a59ec1d12
                               at /home/yamakaky/dev/rust/rust/src/libstd/panicking.rs:440
  14:     0x558ddf66cc9a - std::panic::catch_unwind::h390834e0251cc9af
                               at /home/yamakaky/dev/rust/rust/src/libstd/panic.rs:361
  15:     0x558ddf6809ee - std::rt::lang_start::hb73087428e233982
                               at /home/yamakaky/dev/rust/rust/src/libstd/rt.rs:57
  16:     0x558ddf64ec92 - main
  17:     0x7fecb869e290 - __libc_start_main
  18:     0x558ddf64e8b9 - _start
  19:                0x0 - <unknown>
```

1 files changed, 62 insertions, 0 deletions

diff --git a/src/libstd/sys/windows/backtrace/backtrace_gnu.rs b/src/libstd/sys/windows/backtrace/backtrace_gnu.rs
new file mode 100644
index 00000000000..f0d29dd4178
--- /dev/null
+++ b/src/libstd/sys/windows/backtrace/backtrace_gnu.rs
@@ -0,0 +1,62 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use io;
+use sys::c;
+use libc::c_char;
+use path::PathBuf;
+use fs::{OpenOptions, File};
+use sys::ext::fs::OpenOptionsExt;
+use sys::handle::Handle;
+use super::super::{fill_utf16_buf, os2path, to_u16s, wide_char_to_multi_byte};
+
+fn query_full_process_image_name() -> io::Result<PathBuf> {
+    unsafe {
+        let process_handle = Handle::new(c::OpenProcess(c::PROCESS_QUERY_INFORMATION,
+                                                        c::FALSE,
+                                                        c::GetCurrentProcessId()));
+        fill_utf16_buf(|buf, mut sz| {
+            if c::QueryFullProcessImageNameW(process_handle.raw(), 0, buf, &mut sz) == 0 {
+                0
+            } else {
+                sz
+            }
+        }, os2path)
+    }
+}
+
+fn lock_and_get_executable_filename() -> io::Result<(PathBuf, File)> {
+    // We query the current image name, open the file without FILE_SHARE_DELETE so it
+    // can't be moved and then get the current image name again. If the names are the
+    // same than we have successfully locked the file
+    let image_name1 = query_full_process_image_name()?;
+    let file = OpenOptions::new()
+                .read(true)
+                .share_mode(c::FILE_SHARE_READ | c::FILE_SHARE_WRITE)
+                .open(&image_name1)?;
+    let image_name2 = query_full_process_image_name()?;
+
+    if image_name1 != image_name2 {
+        return Err(io::Error::new(io::ErrorKind::Other,
+                                  "executable moved while trying to lock it"));
+    }
+
+    Ok((image_name1, file))
+}
+
+// Get the executable filename for libbacktrace
+// This returns the path in the ANSI code page and a File which should remain open
+// for as long as the path should remain valid
+pub fn get_executable_filename() -> io::Result<(Vec<c_char>, File)> {
+    let (executable, file) = lock_and_get_executable_filename()?;
+    let u16_executable = to_u16s(executable.into_os_string())?;
+    Ok((wide_char_to_multi_byte(c::CP_ACP, c::WC_NO_BEST_FIT_CHARS,
+                                &u16_executable, true)?, file))
+}