From 4bc5ad4c37483fc250e936189b90fc6682df1b35 Mon Sep 17 00:00:00 2001
From: Igor Kudrin <ikudrin.dev@gmail.com>
Date: Thu, 19 Nov 2015 19:08:45 +0000
Subject: [PATCH] [ELF] Prevent SEGFAULT in case of conflict with an internally
 defined symbol.

Differential Revision: http://reviews.llvm.org/D14832

llvm-svn: 253588
---
 lld/ELF/SymbolTable.cpp           |  3 ++-
 lld/test/ELF/duplicate-internal.s | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 lld/test/ELF/duplicate-internal.s

diff --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index f47035be9ccb..6e4f55ac8325 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -139,7 +139,8 @@ void SymbolTable<ELFT>::reportConflict(const Twine &Message,
   }
 
   std::string Msg = (Message + ": " + Old.getName() + " in " +
-                     OldFile->getName() + " and " + NewFile->getName())
+                     (OldFile ? OldFile->getName() : "(internal)") + " and " +
+                     (NewFile ? NewFile->getName() : "(internal)"))
                         .str();
   if (Warning)
     warning(Msg);
diff --git a/lld/test/ELF/duplicate-internal.s b/lld/test/ELF/duplicate-internal.s
new file mode 100644
index 000000000000..2395a6cae0db
--- /dev/null
+++ b/lld/test/ELF/duplicate-internal.s
@@ -0,0 +1,11 @@
+# Should print an expected message in case of conflict with an internally generated symbol.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
+# RUN: not ld.lld -shared %t.o -o %t.so 2>&1 | FileCheck %s
+
+# CHECK: duplicate symbol: _gp in (internal) and {{.*}}
+
+# REQUIRES: mips
+
+  .globl  _gp
+_gp = 0