Instructions on how to build Rust with rustbuild

[retep998]

This is a much simpler option for those on Windows who use msvc.

[rust-highfive]

r? @aturon

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[steveklabnik]

LGTM. Would you mind wrapping to 80 columns though?

[alexcrichton]

In theory we only need python 2 (not 3) and there shouldn't be a need for the vcvars bit. Does it not work without either of these though? May be worth opening bugs on these two to ensure they get fixed at some point if so.

[hanna-kruppe]

Having both Python 2 and Python 3 in PATH is nonsense, only one will get picked up (at least when you type python bootstrap.py — with the py launcher you could pull multi-version tricks but I sure hope the build system isn't that crazy).

[retep998]

I'm running a build now to figure out whether python 3 and vcvars are strictly necessary.

[retep998]

C:\msys64\home\Peter\rust [please-be-robust-already ≡]> python.exe .\src\bootstrap\bootstrap.py
thread '<main>' panicked at 'couldn't determine visual studio generator', C:\Users\Peter\.cargo\registry\src\github.com-1ecc6299db9ec823\cmake-0.1.17\src\lib.rs:382
stack backtrace:
   0:     0x7ff6f805c482 - std::rt::lang_start::h77a570d0150f3bb2
   1:     0x7ff6f805ba6d - std::rt::lang_start::h77a570d0150f3bb2
   2:     0x7ff6f8041775 - std::panicking::rust_panic_with_hook::h86decb25b2d9b2e0
   3:     0x7ff6f7fde944 - begin_panic<&str>
                        at C:\msys64\home\Peter\src\libstd\panicking.rs:328
   4:     0x7ff6f7fe15f9 - visual_studio_generator
                        at C:\msys64\home\Peter\rust\<std macros>:3
   5:     0x7ff6f7fd30cf - build
                        at C:\Users\Peter\.cargo\registry\src\github.com-1ecc6299db9ec823\cmake-0.1.17\src\lib.rs:276
   6:     0x7ff6f7efc997 - llvm
                        at C:\msys64\home\Peter\rust\src\bootstrap\build\native.rs:113
   7:     0x7ff6f7ee978b - build
                        at C:\msys64\home\Peter\rust\src\bootstrap\build\mod.rs:230
   8:     0x7ff6f7ee12ba - main
                        at C:\msys64\home\Peter\rust\src\bootstrap\main.rs:48
   9:     0x7ff6f805b46c - std::rt::lang_start::h77a570d0150f3bb2
  10:     0x7ff6f80616c1 - _rust_maybe_catch_panic
  11:     0x7ff6f805b1a4 - std::rt::lang_start::h77a570d0150f3bb2
  12:     0x7ff6f7eee9f9 - main
  13:     0x7ff6f8068bef - __scrt_common_main_seh
                        at f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:255
  14:     0x7ffe8ad78101 - BaseThreadInitThunk

Guess vcvars is strictly necessary.

[retep998]

Updated PR with python 3 removed and adjusted things to fit in 80 columns.

[bors]

☔ The latest upstream changes (presumably #34515) made this pull request unmergeable. Please resolve the merge conflicts.

[retep998]

Rebased.

[alexcrichton]

@bors: r+ be43c65

[arielb1]

@bors rollup

[bors]

⌛ Testing commit be43c65 with merge 20183f4...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-cargotest, auto-linux-64-cross-freebsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-mir, auto-linux-64-opt-rustbuild, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-cargotest, auto-win-msvc-64-opt, auto-win-msvc-64-opt-mir, auto-win-msvc-64-opt-rustbuild