Using system Rust to install cross.

As the cross requires recent enough Rust and cwd might be overriden to use old one toolchain, switching cwd temporary to install cross.

src/main.ts

@@ -1,3 +1,6 @@
+const os = require('os');
+const process = require('process');
+
 import * as core from '@actions/core';
 import * as exec from '@actions/exec';
 import * as io from '@actions/io';
@@ -13,6 +16,19 @@ async function getCross(): Promise<string> {
         core.debug('Unable to find cross, installing it now');
     }
 
+    // Somewhat new Rust is required to compile `cross`
+    // (TODO: Not sure what version exactly, should clarify)
+    // but if some action will set an override toolchain before this action called
+    // (ex. `@actions-rs/toolchain` with `toolchain: 1.31.0`)
+    // `cross` compilation will fail.
+    //
+    // In order to skip this problem and install `cross` globally
+    // using the pre-installed system Rust,
+    // we are going to jump to the tmpdir (skipping directory override that way)
+    // install `cross` from there and then jump back.
+
+    const cwd = process.cwd();
+    process.chdir(os.tmpdir());
     try {
         core.startGroup('Install cross');
         core.warning('Git version of cross will be installed, \
@@ -28,6 +44,8 @@ see https://github.com/actions-rs/cargo/issues/1');
         core.setFailed(error.message);
         throw new Error(error);
     } finally {
+        // It is important to chdir back!
+        process.chdir(cwd);
         core.endGroup();
     }
 
@@ -56,6 +74,7 @@ async function run() {
         await exec.exec(program, args);
     } catch (error) {
         core.setFailed(error.message);
+        throw error;
     }
 }