Felix S. Klock II ae67b74ec8 Make configure respect (and save) values for CC, CXX, CFLAGS, etc.
I mostly tried to remain backwards compatible with old invocations of
the `configure` script; if you do not want to use `CC` et al., you
should not have to; you can keep using `--enable-clang` and/or
`--enable-ccache`.

The overall intention is to capture the following precedences for
guessing the C compiler:

 1. Value of `CC` at make invocation time.
 2. Value of `CC` at configure invocation time.
 3. Compiler inferred at configure invocation time (`gcc` or `clang`).

The strategy is to check (at `configure` time) if each of the
environment variables is set, and if so, save its value in a
corresponding `CFG_` variable (e.g. `CFG_CC`).

Then, in the makefiles, if `CC` is not set but `CFG_CC` is, then we
use the `CFG_CC` setting as `CC`.

Also, I fold the potential user-provided `CFLAGS` and `CXXFLAGS`
values into all of the per-platform `CFLAGS` and `CXXFLAGS` settings.
(This was opposed to adding `$(CFLAGS)` in an ad-hoc manner to various
parts of the mk files.)

Fix #13805.

----

Note that if you try to set the compiler to clang via the `CC` and
`CXX` environment variables, you will probably need to also set
`CXXFLAGS` to `--enable-libcpp` so that LLVM will be configured
properly.

----

Introduce CFG_USING_CLANG, which is distinguished from
CFG_ENABLE_CLANG because the former represents "we think we're using
clang, choose appropriate warning-control options" while the latter
represents "we asked configure (or the host required) that we attempt
to use clang, so check that we have an appropriate version of clang."

The main reason I added this is that I wanted to allow the user to
choose clang via setting the `CC` environment variable, but I did not
want that method of selection to get confused with the user passing
the `--enable-clang` option.

----

A digression: The `configure` script does not infer the compiler
setting if `CC` is set; but if `--enable-clang` was passed, then it
*does* still attempt to validate that the clang version is compatible.

Supporting this required revising `CLANG_VERSION` check to be robust
in face of user-provided `CC` value.

In particular, on Travis, the `CC` is set to `gcc` and so the natural
thing to do is to attempt to use `gcc` as the compiler, but Travis is
also passing `--enable-clang` to configure.  So, what is the right
answer in the face of these contradictory requests?

One approach would be to have `--enable-clang` supersede the setting
for `CC` (and instead just call whatever we inferred for `CFG_CLANG`).
That sounds maximally inflexible to me (pnkfelix): a developer
requesting a `CC` value probably wants it respected, and should be
able to set it to something else; it is harder for that developer to
hack our configure script to change its inferred path to clang.

A second approach would be to blindly use the `CC` value but keep
going through the clang version check when `--enable-clang` is turned
on.  But on Travis (a Linux host), the `gcc` invocation won't print a
clang version, so we would not get past the CLANG_VERSION check in
that context.

A third approach would be to never run the CLANG_VERSION check if `CC`
is explicitly set.  That is not a terrible idea; but if the user uses
`CC` to pass in a path to some other version of clang that they want
to test, probably should still send that through the `CLANG_VERSION`
check.

So in the end I (pnkfelix) took a fourth approach: do the
CLANG_VERSION check if `CC` is unset *or* if `CC` is set to a string
ending with `clang`.  This way setting `CC` to things like
`path/to/clang` or `ccache clang` will still go through the
CLANG_VERSION check, while setting `CC` to `gcc` or some unknown
compiler will skip the CLANG_VERSION check (regardless of whether the
user passed --enable-clang to `configure`).

----

Drive-by fixes:

* The call that sets `CFG_CLANG_VERSION` was quoting `"$CFG_CC"` in
  its invocation, but that does not play nicely with someone who sets
  `$CFG_CC` to e.g. `ccache clang`, since you do not want to intepret
  that whole string as a command.

  (On the other hand, a path with spaces might need the quoted
  invocation.  Not sure which one of these corner use-cases is more
  important to support.)

* Fix chk_cc error message to point user at `gcc` not `cc`.
2014-05-20 21:37:08 +02:00

The Rust Programming Language

This is a compiler for Rust, including standard libraries, tools and documentation.

Quick Start

  1. Download a binary installer for your platform.
  2. Read the tutorial.
  3. Enjoy!

Note: Windows users can read the detailed getting started notes on the wiki.

Building from Source

  1. Make sure you have installed the dependencies:

    • g++ 4.7 or clang++ 3.x
    • python 2.6 or later (but not 3.x)
    • perl 5.0 or later
    • GNU make 3.81 or later
    • curl
    • git
  2. Download and build Rust:

    You can either download a tarball or build directly from the repo.

    To build from the tarball do:

     $ curl -O http://static.rust-lang.org/dist/rust-nightly.tar.gz
     $ tar -xzf rust-nightly.tar.gz
     $ cd rust-nightly
    

    Or to build from the repo do:

     $ git clone https://github.com/mozilla/rust.git
     $ cd rust
    

    Now that you have Rust's source code, you can configure and build it:

     $ ./configure
     $ make && make install
    

    Note: You may need to use sudo make install if you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a --prefix argument to configure. Various other options are also supported, pass --help for more information on them.

    When complete, make install will place several programs into /usr/local/bin: rustc, the Rust compiler, and rustdoc, the API-documentation tool. system.

  3. Read the tutorial.

  4. Enjoy!

Notes

Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.

Snapshot binaries are currently built and tested on several platforms:

  • Windows (7, 8, Server 2008 R2), x86 only
  • Linux (2.6.18 or later, various distributions), x86 and x86-64
  • OSX 10.7 (Lion) or greater, x86 and x86-64

You may find that other platforms work, but these are our officially supported build environments that are most likely to work.

Rust currently needs about 1.5 GiB of RAM to build without swapping; if it hits swap, it will take a very long time to build.

There is a lot more documentation in the wiki.

License

Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.

See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.

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