The invocation of vcvars is only needed for versions of Visual Studio that
rustbuild or cmake doesn't understand, but if older versions are installed then
there's no need to call vcvars.
Closes#34576
The ./configure command in README.md's Building Documentation section was
missing the $ prefix. Add the prefix to be consistent with other commands in the
document.
The LLVM build system is somewhat picky about which Python is used to build it
as it's known to be incompatible with the default `python2` package that ships
with MinGW. This was previously detected for MSVC builds but the logic was left
out for MinGW by accident (now that we've switched to cmake builds for LLVM
everywhere).
This corrects the `./configure` check and also updates the `README.md`
accordingly. Additionally, a number of instructions were updated to work with
the most recent copy of MSYS2.
Closes#34489
http://mingw-w64.org/doku.php/download/mingw-builds now provides GCC 5.x as a default version, but avoiding 5.x is exactly the reason why Mingw-builds is recommended instead of MSYS2's own mingw toolchain. One of the 4.9.x versions has to manually chosen during installation.
In other words, enforce what was documented in #30626 (and also stop blaming it on LLVM, we have at least one Python script of our own).
Also, there is no Python later than 2.7 and there never will be.
Running `/usr/bin/time -v make` to build rust (using local llvm) shows the maximum memory usage at 715 megabytes on 32-bit x86 (on arm linux it's even less @ 580M).
Reworded according to @brson's input.
This PR adds a note to the end of the Windows build instructions to reflect the issues detailed in #28260, as well as a work around using older versions of gcc. I've avoided going into detail as I did not wish to bloat the README, and so that the changes are easy to yank once the issue is resolved.
Remove leading newlines; replace lines containing only whitespace with empty lines; replace multiple trailing newlines with a single newline; remove trailing whitespace in lines
Encountered an issue going through the guide for installing the `mingw` toolchain on Windows with msys2, after some googling I found the [solution](https://github.com/Alexpux/MSYS2-packages/issues/163#issuecomment-73555971) and thought it would be good to update the README so people don't get frustrated. :)
- Various grammatical changes.
- Use triple-backtick syntax and sh highlighting for code blocks.
- Fix indentation of code block in step 2 of "Building on Windows".
- Use title case for "Getting Help" subheading.
