Improve clang executable search (#171)

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## [1.8.2] - UNRELEASED
 
+### Changed
+- Improved `Clang::find` to first check directories related to the runtime-loaded `libclang` instance (if any)
+
 ### Fixed
 - Fixed linking to `libclang` on Windows with MSYS2
 - Fixed `Clang::find` to support both the `-target` and `--target` arguments

src/link.rs

@@ -100,8 +100,8 @@ macro_rules! link {
         /// A dynamically loaded instance of the `libclang` library.
         #[derive(Debug)]
         pub struct SharedLibrary {
-            library: libloading::Library,
-            path: PathBuf,
+            pub(crate) library: libloading::Library,
+            pub(crate) path: PathBuf,
             pub functions: Functions,
         }
 

src/support.rs

@@ -44,11 +44,13 @@ impl Clang {
     /// Returns a `clang` executable if one can be found.
     ///
     /// If the `CLANG_PATH` environment variable is set, that is the instance of
-    /// `clang` used. Otherwise, a series of directories are searched. First, if
-    /// a path is supplied, that is the first directory searched. Then, the
-    /// directory returned by `llvm-config --bindir` is searched. On macOS
-    /// systems, `xcodebuild -find clang` will next be queried. Last, the
-    /// directories in the system's `PATH` are searched.
+    /// `clang` used. Otherwise, these directories are searched in order:
+    ///
+    ///   1. The supplied path (if provided)
+    ///   2. Sibling directories for the runtime-loaded `libclang` instance (if any)
+    ///   3. The directory returned by `llvm-config --bindir`
+    ///   4. The directory returned by `xcodebuild -find clang` (on macOS)
+    ///   5. The directories in the system's `PATH` environment variable
     ///
     /// ## Cross-compilation
     ///
@@ -83,6 +85,16 @@ impl Clang {
             paths.push(path.into());
         }
 
+        #[cfg(feature = "runtime")]
+        if let Some(library) = crate::get_library() {
+            if let Some(directory) = library.path().parent() {
+                paths.push(directory.into());
+                if let Some(parent) = directory.parent() {
+                    paths.push(parent.join("bin"));
+                }
+            }
+        }
+
         if let Ok(path) = run_llvm_config(&["--bindir"]) {
             if let Some(line) = path.lines().next() {
                 paths.push(line.into());

tests/lib.rs

@@ -50,3 +50,14 @@ fn test_support_target() {
     let clang = support::Clang::find(None, args).unwrap();
     println!("{:?}", clang);
 }
+
+#[cfg(feature = "runtime")]
+#[test]
+fn test_support_runtime() {
+    load().unwrap();
+    let library = get_library().unwrap();
+    let clang = support::Clang::find(None, &[]).unwrap();
+    println!("Library path: {}", library.path().display());
+    println!("Clang path:   {}", clang.path.display());
+    unload().unwrap();
+}