From 069c52fa111e592f65605c54f5e9b77be0676595 Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek@google.com>
Date: Mon, 1 Jul 2019 17:28:10 -0700
Subject: [PATCH] Check if the archive has already been added to avoid
 duplicates

This avoids adding archives multiple times, which results in duplicate
objects in the resulting rlib, leading to symbol collision and link
failures. This could happen when crate contains multiple link attributes
that all reference the same archive.
---
 src/librustc_codegen_llvm/back/archive.rs | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/librustc_codegen_llvm/back/archive.rs b/src/librustc_codegen_llvm/back/archive.rs
index e0e26e9af2537..90c0cf748d1e0 100644
--- a/src/librustc_codegen_llvm/back/archive.rs
+++ b/src/librustc_codegen_llvm/back/archive.rs
@@ -36,11 +36,20 @@ enum Addition {
         name_in_archive: String,
     },
     Archive {
+        path: PathBuf,
         archive: ArchiveRO,
         skip: Box<dyn FnMut(&str) -> bool>,
     },
 }
 
+impl Addition {
+    fn path(&self) -> &Path {
+        match self {
+            Addition::File { path, .. } | Addition::Archive { path, .. } => path,
+        }
+    }
+}
+
 fn is_relevant_child(c: &Child<'_>) -> bool {
     match c.name() {
         Some(name) => !name.contains("SYMDEF"),
@@ -188,12 +197,16 @@ impl<'a> LlvmArchiveBuilder<'a> {
                       -> io::Result<()>
         where F: FnMut(&str) -> bool + 'static
     {
-        let archive = match ArchiveRO::open(archive) {
+        let archive_ro = match ArchiveRO::open(archive) {
             Ok(ar) => ar,
             Err(e) => return Err(io::Error::new(io::ErrorKind::Other, e)),
         };
+        if self.additions.iter().any(|ar| ar.path() == archive) {
+            return Ok(())
+        }
         self.additions.push(Addition::Archive {
-            archive,
+            path: archive.to_path_buf(),
+            archive: archive_ro,
             skip: Box::new(skip),
         });
         Ok(())
@@ -243,7 +256,7 @@ impl<'a> LlvmArchiveBuilder<'a> {
                         strings.push(path);
                         strings.push(name);
                     }
-                    Addition::Archive { archive, skip } => {
+                    Addition::Archive { archive, skip, .. } => {
                         for child in archive.iter() {
                             let child = child.map_err(string_to_io_error)?;
                             if !is_relevant_child(&child) {