From 81eea9e4312253afb655c051d0bf0661744ab56e Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Fri, 21 Jul 2017 09:41:20 -0700
Subject: [PATCH] Thread through the original error when opening archives

This updates the management of opening archives to thread through the original
piece of error information from LLVM over to the end consumer, trans.
---
 src/librustc_llvm/archive_ro.rs    |  6 +++---
 src/librustc_trans/back/archive.rs |  7 +++----
 src/librustc_trans/metadata.rs     | 16 ++++++++--------
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/librustc_llvm/archive_ro.rs b/src/librustc_llvm/archive_ro.rs
index b3f5f8e536052..0b24e55541b07 100644
--- a/src/librustc_llvm/archive_ro.rs
+++ b/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 })
             }
         };
 
diff --git a/src/librustc_trans/back/archive.rs b/src/librustc_trans/back/archive.rs
index 902065c8688d0..6ec40bd689c23 100644
--- a/src/librustc_trans/back/archive.rs
+++ b/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,
diff --git a/src/librustc_trans/metadata.rs b/src/librustc_trans/metadata.rs
index 2c0148dfbb371..883808c59091a 100644
--- a/src/librustc_trans/metadata.rs
+++ b/src/librustc_trans/metadata.rs
@@ -31,10 +31,10 @@ 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()
@@ -42,10 +42,10 @@ impl MetadataLoader for LlvmMetadataLoader {
                     .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())
     }