LLDB's output may be None instead of '', and that will cause type
mismatch when normalize_whitespace() expects a string instead of
None. This commit simply ensures we do pass '' even if the output
is None.

As per rust-lang#29370

Also remove trailing whitespace to pass tidy checks.

…ted since Python 2.5

Add pretty printer files into test execution time-stamping

Move find_rust_src_path() as a method for Config

Move find_rust_src_path() as a method for Config

Call find_rust_src_path() from Config

Move find_rust_src_path() from common.rs to header.rs

Add pretty printer files as relevant files to get up_to_date information

Remove dead code

Add two pretty printer files to keep a close watch on

Move find_rust_src_path() as a method for Config

Move find_rust_src_path() as a method for Config

Call find_rust_src_path() from Config

Move find_rust_src_path() from common.rs to header.rs

Remove dead code

Add two pretty printer files to keep a close watch on

…eklabnik

Don't encourage people to ignore threading errors in the docs

Debugger pretty printer files are take into account in test execution time-stamping

This PR is proposed to solve the issue rust-lang#45022.

debuginfo-test: Fix rust-lang#45086.

Fixes rust-lang#45086, where all debuginfo-lldb fails when using LLDB from Xcode 9.

Add links and examples for std::process::Stdio

As per rust-lang#29370

…chton

Fix raising a bare str as an exception in configure.py

Raising a bare `str` has been [deprecated since Python 2.5](https://docs.python.org/2/whatsnew/2.5.html#pep-352-exceptions-as-new-style-classes).

On Python 2.7 it produces the following error:

```
TypeError: exceptions must be old-style classes or derived from BaseException, not str
```

For maximum compatibility with Python 2.7 and 3.x, we wrap the error message in `RuntimeError` which derives from `Exception`.

…alexcrichton

Fix variable name reference

As best I can tell, this was a typo due to how similar it looks to the function above it. PyCharm found this as a unbound local variable.

…ackler

Use identity operator `is` when comparing to None

This is very minor, but idiomatic Python code uses `is` for comparisons to `None`. This is because semantically we want to compare to the "identity" of `None`, not its value.

See [PEP8 for details](https://www.python.org/dev/peps/pep-0008/#programming-recommendations).

Update grammar to parse current rust syntax

Mainly addressing rust-lang#32723. This PR updates the bison grammar so that it can parse the current rust syntax, except for feature-gated syntax additions. It has been tested with all the tests in run-pass.

The grammar in this repo doesn't have build logic anymore, but you can test it out in https://github.com/bleibig/rust-grammar, which has all of what's in this PR. If you are interested in having build logic and grammar tests again, I can look into implementing that as well.

I'm aware that things are somewhat undecided as to what an official rust grammar should be from the discussion in rust-lang#30942. With this PR we can go back to having an up-to-date flex/bison based grammar, but the rustypop grammar looks interesting as well.

Clarify RAM usage during build in README

The sentence wasn't immediately clear if it meant RAM or disk space before reading the next sentence.

I think this helps clarify it.