Add optional runtime fallback directory (#8610)

1 files changed, 10 insertions, 1 deletions

diff --git a/helix-loader/src/lib.rs b/helix-loader/src/lib.rs
index 82ed2ede..5337d602 100644
--- a/helix-loader/src/lib.rs
+++ b/helix-loader/src/lib.rs
@@ -60,7 +60,8 @@ pub fn initialize_log_file(specified_file: Option<PathBuf>) {
 /// 1. sibling directory to `CARGO_MANIFEST_DIR` (if environment variable is set)
 /// 2. subdirectory of user config directory (always included)
 /// 3. `HELIX_RUNTIME` (if environment variable is set)
-/// 4. subdirectory of path to helix executable (always included)
+/// 4. `HELIX_DEFAULT_RUNTIME` (if environment variable is set *at build time*)
+/// 5. subdirectory of path to helix executable (always included)
 ///
 /// Postcondition: returns at least two paths (they might not exist).
 fn prioritize_runtime_dirs() -> Vec<PathBuf> {
@@ -81,6 +82,14 @@ fn prioritize_runtime_dirs() -> Vec<PathBuf> {
         rt_dirs.push(dir.into());
     }
 
+    // If this variable is set during build time, it will always be included
+    // in the lookup list. This allows downstream packagers to set a fallback
+    // directory to a location that is conventional on their distro so that they
+    // need not resort to a wrapper script or a global environment variable.
+    if let Some(dir) = std::option_env!("HELIX_DEFAULT_RUNTIME") {
+        rt_dirs.push(dir.into());
+    }
+
     // fallback to location of the executable being run
     // canonicalize the path in case the executable is symlinked
     let exe_rt_dir = std::env::current_exe()