Thread through the original error when opening archives

src/librustc_llvm/archive_ro.rs

@@ -39,14 +39,14 @@ impl ArchiveRO {
     ///
     /// If this archive is used with a mutable method, then an error will be
     /// raised.
-    pub fn open(dst: &Path) -> Option<ArchiveRO> {
+    pub fn open(dst: &Path) -> Result<ArchiveRO, String> {
         return unsafe {
             let s = path2cstr(dst);
             let ar = ::LLVMRustOpenArchive(s.as_ptr());
             if ar.is_null() {
-                None
+                Err(::last_error().unwrap_or("failed to open archive".to_string()))
             } else {
-                Some(ArchiveRO { ptr: ar })
+                Ok(ArchiveRO { ptr: ar })
             }
         };
 

src/librustc_trans/back/archive.rs

@@ -126,7 +126,7 @@ impl<'a> ArchiveBuilder<'a> {
             Some(ref src) => src,
             None => return None,
         };
-        self.src_archive = Some(ArchiveRO::open(src));
+        self.src_archive = Some(ArchiveRO::open(src).ok());
         self.src_archive.as_ref().unwrap().as_ref()
     }
 
@@ -186,9 +186,8 @@ impl<'a> ArchiveBuilder<'a> {
         where F: FnMut(&str) -> bool + 'static
     {
         let archive = match ArchiveRO::open(archive) {
-            Some(ar) => ar,
-            None => return Err(io::Error::new(io::ErrorKind::Other,
-                                              "failed to open archive")),
+            Ok(ar) => ar,
+            Err(e) => return Err(io::Error::new(io::ErrorKind::Other, e)),
         };
         self.additions.push(Addition::Archive {
             archive: archive,

src/librustc_trans/metadata.rs

@@ -31,21 +31,21 @@ impl MetadataLoader for LlvmMetadataLoader {
         // just keeping the archive along while the metadata is in use.
         let archive = ArchiveRO::open(filename)
             .map(|ar| OwningRef::new(box ar))
-            .ok_or_else(|| {
-                            debug!("llvm didn't like `{}`", filename.display());
-                            format!("failed to read rlib metadata: '{}'", filename.display())
-                        })?;
+            .map_err(|e| {
+                debug!("llvm didn't like `{}`: {}", filename.display(), e);
+                format!("failed to read rlib metadata in '{}': {}", filename.display(), e)
+            })?;
         let buf: OwningRef<_, [u8]> = archive
             .try_map(|ar| {
                 ar.iter()
                     .filter_map(|s| s.ok())
                     .find(|sect| sect.name() == Some(METADATA_FILENAME))
                     .map(|s| s.data())
                     .ok_or_else(|| {
-                                    debug!("didn't find '{}' in the archive", METADATA_FILENAME);
-                                    format!("failed to read rlib metadata: '{}'",
-                                            filename.display())
-                                })
+                        debug!("didn't find '{}' in the archive", METADATA_FILENAME);
+                        format!("failed to read rlib metadata: '{}'",
+                                filename.display())
+                    })
             })?;
         Ok(buf.erase_owner())
     }