linking failure in run subcommand: x86_64-pc-windows-msvc instead of x86_64-pc-windows-gnu

I use 64 bit Mingw-w64 with the latest gcc, 64 bit, and Rust 1.35 on Windows 10 64 bit. I changed the toolchain to x86_64-pc-windows-gnu when installing Rust.

After hacking together a toolchain that can compile pyoxidizer, pyoxidizer init is successful and pyoxidizer run fails because x86_64-pc-windows-msvc is used instead of x86_64-pc-windows-gnu.

error occurred: Failed to find tool. Is `cl.exe` installed? (see https://github.com/alexcrichton/cc-rs#compile-time-requirements for help)

The gcc toolchain appears to be utterly unsupported (projectmgmt,rs):

/// Attempt to resolve the default Rust target for a build.
pub fn default_target() -> Result {
// TODO derive these more intelligently.
if cfg!(target_os = "linux") {
Ok("x86_64-unknown-linux-gnu".to_string())
} else if cfg!(target_os = "windows") {
Ok("x86_64-pc-windows-msvc".to_string())
} else if cfg!(target_os = "macos") {
Ok("x86_64-apple-darwin".to_string())
} else {
Err("unable to resolve target".to_string())
}
}

Start in projectmgmt.rs at default_target(), then reproduce the difference between pyoxidizer init and pyoxidizer run on a Windows x86_64-pc-windows-gnu toolchain. Trace where the run build target is selected and verify that the GNU target is retained instead of x86_64-pc-windows-msvc; done means the run subcommand no longer requires cl.exe for this toolchain.

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