Never resolve extensionless scripts on Windows

Toolchains like groovy and kotlin ship an extensionless unix launcher
next to the .bat; find_in_dir preferred the exact name, handing
CreateProcess a shell script (error 193). On Windows only .exe/.cmd/
.bat/.com count, extension search order otherwise. Also restores a
quote my earlier edit dropped in the Alpine groovy smoke line.

Co-Authored-By: Claude Fable 5 <[email protected]>

Author: BoxingOctopus

.github/workflows/ci.yml

@@ -95,7 +95,7 @@ jobs:
               linguo jvm run -- java -version
               linguo groovy install
               linguo groovy use 5
-              linguo groovy run -- groovy -e "println \"groovy on musl ok\"
+              linguo groovy run -- groovy -e "println \"groovy on musl ok\""
 
               # node and go have no official musl builds: expect honest errors
               linguo node install 2>/dev/null && exit 1 || echo "node bails as expected"

src/exec.rs

@@ -14,22 +14,26 @@ pub fn exe(name: &str) -> String {
     }
 }
 
-/// Locate an executable named `name` in `dir`, trying Windows executable
-/// extensions when `name` has none.
+/// Locate an executable named `name` in `dir`. On Windows only files with
+/// executable extensions count: toolchains often ship an extensionless unix
+/// script alongside a .bat (groovy, kotlin), and handing the script to
+/// CreateProcess fails with "not a valid Win32 application".
 pub fn find_in_dir(dir: &Path, name: &str) -> Option<PathBuf> {
-    let direct = dir.join(name);
-    if is_executable(&direct) {
-        return Some(direct);
-    }
-    if cfg!(windows) && Path::new(name).extension().is_none() {
-        for ext in ["exe", "cmd", "bat"] {
+    if cfg!(windows) {
+        if Path::new(name).extension().is_some() {
+            let direct = dir.join(name);
+            return direct.is_file().then_some(direct);
+        }
+        for ext in ["exe", "cmd", "bat", "com"] {
             let candidate = dir.join(format!("{name}.{ext}"));
             if candidate.is_file() {
                 return Some(candidate);
             }
         }
+        return None;
     }
-    None
+    let direct = dir.join(name);
+    is_executable(&direct).then_some(direct)
 }
 
 /// A Command for `program`, resolved against linguo-managed dirs first with