Pass the shell arguments directly to bash

This allows us to run the "run" script using "set -eo pipefail" by default.

The previous wrapper executed the arguments as a bash command string, which
allowed the user to run any command, but didn't give us a chance to special case
if the argument was a script passed from the GHA "run" command.

This is a breaking change.

Porting guide:

* Instead of `msys2 mybinary` you now have to run `msys2 -c 'mybinary'`
* To revert the bash error settings you can use `set +e` and `set +o pipefail`
  in your run script

.github/workflows/action.yml

@@ -199,7 +199,7 @@ jobs:
         rm -rf node_modules
     - name: run action
       uses: ./
-    - run: msys2 go env
+    - run: msys2 -c "go env"
       env:
         MSYS2_PATH_TYPE: inherit
 
@@ -219,7 +219,7 @@ jobs:
       uses: ./
       with:
         path-type: inherit
-    - run: msys2 go env
+    - run: msys2 -c "go env"
 
   install:
     needs: [path-type]
@@ -292,3 +292,41 @@ jobs:
         update: true
         install: base-devel git
     - run: git describe --dirty --tags
+
+  errorhandling:
+    needs: [defaultdirty]
+    runs-on: windows-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: build action
+      shell: bash
+      run: |
+        npm ci
+        npm run pkg
+        rm -rf node_modules
+    - name: run action
+      uses: ./
+    - shell: msys2 {0}
+      run: |
+        (! false | true) || exit 1; # make sure "-o pipefail" is active  by default
+        [[ "$-" =~ 'e' ]] || exit 1; # make sure "set -e" is active by default
+
+  workingdir:
+    needs: [errorhandling]
+    runs-on: windows-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: build action
+      shell: bash
+      run: |
+        npm ci
+        npm run pkg
+        rm -rf node_modules
+    - name: run action
+      uses: ./
+    - shell: msys2 {0}
+      run: |
+        # make sure we are in checkout directory
+        dir="$(pwd)"
+        cd "$GITHUB_WORKSPACE"
+        [[ "$dir" == "$(pwd)" ]]

README.md

@@ -33,7 +33,7 @@ Then, for multi-line scripts:
 Or, for single line commands:
 
 ```yaml
-  - run: msys2 uname -a
+  - run: msys2 -c 'uname -a'
 ```
 
 ### Default shell
@@ -90,7 +90,7 @@ Furthermore, the environment variable can be overridden. This is useful when mul
       pacman --noconfirm -U mingw-w64-*-any.pkg.tar.xz
   - run: |
       set MSYSTEM=MINGW64
-      msys2 <command to test the package>
+      msys2 -c '<command to test the package>'
 ```
 
 #### path-type

main.js

@@ -38,12 +38,12 @@ async function run() {
     const p_install = core.getInput('install');
     const p_cache = core.getInput('cache');
 
-    let drive = 'C:';
+    let base = 'C:';
 
     if (p_release) {
       // Use upstream package instead of the default installation in the virtual environment.
       core.startGroup('Downloading MSYS2...');
-      drive = '%~dp0';
+      base = '%~dp0';
       let inst_dest = path.join(tmp_dir, 'base.exe');
       await tc.downloadTool(inst_url, inst_dest);
 
@@ -60,18 +60,11 @@ async function run() {
     }
 
     let wrap = [
-      `setlocal`,
       `@echo off`,
+      `setlocal`,
       `IF NOT DEFINED MSYS2_PATH_TYPE set MSYS2_PATH_TYPE=` + p_pathtype,
-      `set "args=%*"`,
-      `set "args=%args:\\=/%"`,
-      /* TODO:
-        See https://www.msys2.org/wiki/Launchers/#the-idea
-        Ideally, there would be some better solution than 'cd $OLDPWD', such as using 'CHERE_INVOKING=1'.
-        However, since an intermediate file is used, it would probably make CHERE_INVOKING use the location of
-        'msys2.cmd' or the temporal file created by GitHub's runner.
-      */
-      drive + `\\msys64\\usr\\bin\\env.exe /usr/bin/bash --norc -ilceo pipefail "cd $OLDPWD && %args%"`
+      `set CHERE_INVOKING=1`,
+      base + `\\msys64\\usr\\bin\\bash.exe -leo pipefail %*`
     ].join('\r\n');
 
     let cmd = path.join(dest, 'msys2.cmd');
@@ -89,7 +82,7 @@ async function run() {
     }
 
     async function run(args, opts) {
-      await exec.exec('cmd', ['/D', '/S', '/C', cmd].concat(args), opts);
+      await exec.exec('cmd', ['/D', '/S', '/C', cmd].concat(['-c', args.join(' ')]), opts);
     }
 
     async function pacman(args, opts) {