fix(sdk): keep the drive letter of a JDK home on a mapped drive

A JDK on a mapped network drive was canonicalized to \\?\UNC\server\share\…
too, so Maven ran with that JAVA_HOME and mvn.cmd failed with "The system
cannot find the path specified" even with a local Maven home. JDK homes
(configured, JAVA_HOME, the java on PATH) now keep their drive letter like
Maven homes do.

crates/ide-sdk/src/discover.rs

@@ -545,7 +545,7 @@ fn jdk() -> Vec<Sdk> {
 
 /// A JDK as the SDK pickers list it (`Eclipse Adoptium 25.0.1`).
 pub fn jdk_sdk(j: &crate::java::Jdk) -> Sdk {
-    let java_home = std::env::var_os("JAVA_HOME").and_then(|h| dunce::canonicalize(h).ok());
+    let java_home = std::env::var_os("JAVA_HOME").and_then(|h| crate::launch_path(Path::new(&h)).ok());
     let release = std::fs::read_to_string(j.home.join("release")).unwrap_or_default();
     let version = release_value(&release, "JAVA_VERSION").unwrap_or_else(|| j.major.to_string());
     let name = match release_value(&release, "IMPLEMENTOR") {
@@ -579,31 +579,6 @@ fn maven_version(home: &Path) -> Option<String> {
     })
 }
 
-/// `path` with symlinks resolved (Homebrew's `bin/mvn` → its Cellar), except that a Windows
-/// drive letter is kept: on a mapped network drive or a `subst` drive canonicalizing gives
-/// `\\?\UNC\server\share\…` or another drive, and cmd.exe can't start `mvn.cmd` from a
-/// `\\?\` path (nor is it the path the user knows).
-fn launch_path(path: &Path) -> std::io::Result<PathBuf> {
-    let real = dunce::canonicalize(path)?;
-    #[cfg(windows)]
-    {
-        use std::path::{Component, Prefix};
-        let drive = |p: &Path| match p.components().next() {
-            Some(Component::Prefix(x)) => match x.kind() {
-                Prefix::Disk(d) | Prefix::VerbatimDisk(d) => Some(d.to_ascii_uppercase()),
-                _ => None,
-            },
-            _ => None,
-        };
-        if let Some(d) = drive(path)
-            && drive(&real) != Some(d)
-        {
-            return std::path::absolute(path);
-        }
-    }
-    Ok(real)
-}
-
 /// A Maven home (`bin/mvn` and `lib/`); Homebrew's formula keeps it in `libexec`.
 fn maven_home(dir: &Path) -> Option<PathBuf> {
     let mvn = if cfg!(windows) { "mvn.cmd" } else { "mvn" };
@@ -620,7 +595,7 @@ fn maven() -> Vec<Sdk> {
     } else {
         which("mvn")
     };
-    if let Some(mvn) = on_path.and_then(|p| launch_path(&p).ok())
+    if let Some(mvn) = on_path.and_then(|p| crate::launch_path(&p).ok())
         && let Some(home) = mvn.parent().and_then(Path::parent)
     {
         found.push((home.to_path_buf(), "path"));
@@ -654,7 +629,7 @@ fn maven() -> Vec<Sdk> {
     let mut out = Vec::new();
     for (dir, source) in found {
         let Some(home) = maven_home(&dir) else { continue };
-        let home = launch_path(&home).unwrap_or(home);
+        let home = crate::launch_path(&home).unwrap_or(home);
         if !seen.insert(home.clone()) {
             continue;
         }

crates/ide-sdk/src/java.rs

@@ -38,10 +38,7 @@ pub fn jdk_at(home: &Path) -> Option<Jdk> {
     if !home.join("bin").join(crate::exe("java")).is_file() {
         return None;
     }
-    Some(Jdk {
-        major: parse_release(&release)?,
-        home: dunce::canonicalize(home).unwrap_or_else(|_| home.to_path_buf()),
-    })
+    Some(Jdk { major: parse_release(&release)?, home: crate::launch_path(home).unwrap_or_else(|_| home.to_path_buf()) })
 }
 
 fn children(dir: &Path) -> Vec<PathBuf> {
@@ -90,7 +87,7 @@ fn scan() -> Vec<Jdk> {
     let path = std::env::var_os("PATH").unwrap_or_default();
     if let Some(java) = std::env::split_paths(&path).map(|d| d.join(crate::exe("java"))).find(|j| j.is_file()) {
         // Through symlinks (`/usr/bin/java`, Homebrew, SDKMAN `current`) to `<home>/bin/java`.
-        if let Some(home) = dunce::canonicalize(java).ok().and_then(|j| j.parent()?.parent().map(Path::to_path_buf)) {
+        if let Some(home) = crate::launch_path(&java).ok().and_then(|j| j.parent()?.parent().map(Path::to_path_buf)) {
             homes.push(home);
         }
     }

crates/ide-sdk/src/lib.rs

@@ -82,6 +82,31 @@ pub(crate) fn exe(name: &str) -> String {
     if cfg!(windows) { format!("{name}.exe") } else { name.to_owned() }
 }
 
+/// `path` with symlinks resolved (Homebrew's `bin/mvn` → its Cellar), except that a Windows
+/// drive letter is kept: on a mapped network drive or a `subst` drive canonicalizing gives
+/// `\\?\UNC\server\share\…` or another drive, and cmd.exe can't start a script from a
+/// `\\?\` path (`mvn.cmd`, or `mvn.cmd` with such a `JAVA_HOME`), nor is it the path the user knows.
+pub(crate) fn launch_path(path: &Path) -> std::io::Result<PathBuf> {
+    let real = dunce::canonicalize(path)?;
+    #[cfg(windows)]
+    {
+        use std::path::{Component, Prefix};
+        let drive = |p: &Path| match p.components().next() {
+            Some(Component::Prefix(x)) => match x.kind() {
+                Prefix::Disk(d) | Prefix::VerbatimDisk(d) => Some(d.to_ascii_uppercase()),
+                _ => None,
+            },
+            _ => None,
+        };
+        if let Some(d) = drive(path)
+            && drive(&real) != Some(d)
+        {
+            return std::path::absolute(path);
+        }
+    }
+    Ok(real)
+}
+
 pub(crate) fn home_dir() -> Option<PathBuf> {
     std::env::var_os("HOME").or_else(|| std::env::var_os("USERPROFILE")).map(PathBuf::from)
 }