Support for building executables

[jansegre]

I can create a pull request for this, but I wanted to discuss it first.

In some situations I find myself writing small C programs to generate Rust files with const's taken from header defines. For such it would practical to reuse gcc-rs abstractions over a C compiler.

Therefore, I propose a compile_exectuable function and to change Config::compile behavior to detect whether to build an executable or a lib based on the simple pattern, lib.so* for a library, and "not . and not lib*" for executable.

[alexcrichton]

Unfortunately this doesn't quite play well with this crate's cross compilation story. If you want to get the value of a #define for the target, you need to compile an executable for the target but you may not be able to run it.

[jansegre]

Hmm, I hadn't thought of that. I can see it getting messy if the executable
target is always native, specially because defines are usually dependant on
the target.

Maybe the most universal way for automatic defines extraction is closer to
bindgen.

Anyway I still consider the option to fork gcc-rs to provide only
executable generation without cross compilation support. Though that may
not be a good practice overall seems better than hard invoking cc and
compiled commands, in a way that will definitely not work on Windows.

On Sun, Jun 21, 2015, 15:20 Alex Crichton notifications@github.com wrote:

Unfortunately this doesn't quite play well with this crate's cross
compilation story. If you want to get the value of a #define for the
target, you need to compile an executable for the target but you may not be
able to run it.

—
Reply to this email directly or view it on GitHub
#46 (comment).

[alexcrichton]

This crate could certainly provide the ability to build executables, but I think I'd prefer to not do so as it's not something that should be relied upon. That being said, if this crate could facilitate you in emitting a binary, feel free to open an issue!

[oli-obk]

on a side-note for anyone reaching this issue: You can use this crate to create executables quite easily:

let mut gcc = gcc::Config::new();
gcc.cpp(true);
gcc.include(".");
let mut cmd = gcc.get_compiler().to_command();
cmd.arg("main.cpp");
assert!(cmd.status().unwrap().success());

[teythoon]

I'd appreciate proper support for creating executables as well. Our use case is that we have a crate with a C API that we want to compile tests for. We wouldn't mind building for the target and not for the build host if we are cross-compiling.

Currently, we invoke make and rely on the compiler understanding -lsomething and friends, which obviously does not fly with VS.