Auto merge of #128611 - ChrisDenton:cygpath, r=<try>

run-make: Only use cygpath if the path looks unixy

`cygpath -w` can mangle paths that are already Windows paths. Therefore only use it if the path looks like a Unix path. Additionally fallback to using the path as given if `cygpath` fails on the assumption that the path is already good or else will be an error when it's actually used.

Tbh, I'm not entirely convinced that `cygpath` is necessary but if it is used then it shouldn't get in the way of using Windows paths.

try-job: x86_64-msvc
try-job: i686-msvc
try-job: i686-mingw
try-job: x86_64-mingw

Author: bors

src/tools/run-make-support/src/external_deps/cygpath.rs

@@ -1,8 +1,6 @@
-use std::panic;
 use std::path::Path;
 
 use crate::command::Command;
-use crate::util::handle_failed_output;
 
 /// Use `cygpath -w` on a path to get a Windows path string back. This assumes that `cygpath` is
 /// available on the platform!
@@ -22,14 +20,19 @@ use crate::util::handle_failed_output;
 #[track_caller]
 #[must_use]
 pub fn get_windows_path<P: AsRef<Path>>(path: P) -> String {
-    let caller = panic::Location::caller();
-    let mut cygpath = Command::new("cygpath");
-    cygpath.arg("-w");
-    cygpath.arg(path.as_ref());
-    let output = cygpath.run();
-    if !output.status().success() {
-        handle_failed_output(&cygpath, output, caller.line());
+    // If the path looks unixy then use cygpath otherwise return it unchanged.
+    // If cygpath fails then fallback to just using the path as given.
+    if path.as_ref().starts_with("/") {
+        let mut cygpath = Command::new("cygpath");
+        cygpath.arg("-w");
+        cygpath.arg(path.as_ref());
+        let output = cygpath.run();
+        if !output.status().success() {
+            return path.as_ref().to_str().unwrap().into();
+        }
+        // cygpath -w can attach a newline
+        output.stdout_utf8().trim().to_string()
+    } else {
+        path.as_ref().to_str().unwrap().into()
     }
-    // cygpath -w can attach a newline
-    output.stdout_utf8().trim().to_string()
 }