From: Eli Bendersky <eliben@google.com>
Date: Fri, 12 Jun 2015 23:26:42 +0000 (+0000)
Subject: Fix returning error message in LLVMLinkModules
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=21a987d1ac00aa7100a7abd48896c944475775c7;p=oota-llvm.git

Fix returning error message in LLVMLinkModules

On error, the temporary output stream wouldn't be flushed and therefore the
caller would see an empty error message.

Patch by Antoine Pitrou

Differential Revision: http://reviews.llvm.org/D10241


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239646 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index 1b7a33168f1..b47d2685d42 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -1802,7 +1802,9 @@ LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
   LLVMBool Result = Linker::LinkModules(
       D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
 
-  if (OutMessages && Result)
+  if (OutMessages && Result) {
+    Stream.flush();
     *OutMessages = strdup(Message.c_str());
+  }
   return Result;
 }
diff --git a/unittests/Linker/LinkModulesTest.cpp b/unittests/Linker/LinkModulesTest.cpp
index b4689cba560..58a3e72f63e 100644
--- a/unittests/Linker/LinkModulesTest.cpp
+++ b/unittests/Linker/LinkModulesTest.cpp
@@ -15,6 +15,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/Linker/Linker.h"
 #include "llvm/Support/SourceMgr.h"
+#include "llvm-c/Linker.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
@@ -125,6 +126,22 @@ TEST_F(LinkModuleTest, BlockAddress) {
   delete LinkedModule;
 }
 
+static Module *getExternal(LLVMContext &Ctx, StringRef FuncName) {
+  // Create a module with an empty externally-linked function
+  Module *M = new Module("ExternalModule", Ctx);
+  FunctionType *FTy = FunctionType::get(
+      Type::getVoidTy(Ctx), Type::getInt8PtrTy(Ctx), false /*=isVarArgs*/);
+
+  Function *F =
+      Function::Create(FTy, Function::ExternalLinkage, FuncName, M);
+  F->setCallingConv(CallingConv::C);
+
+  BasicBlock *BB = BasicBlock::Create(Ctx, "", F);
+  IRBuilder<> Builder(BB);
+  Builder.CreateRetVoid();
+  return M;
+}
+
 static Module *getInternal(LLVMContext &Ctx) {
   Module *InternalM = new Module("InternalModule", Ctx);
   FunctionType *FTy = FunctionType::get(
@@ -178,4 +195,27 @@ TEST_F(LinkModuleTest, TypeMerge) {
             M1->getNamedGlobal("t2")->getType());
 }
 
+TEST_F(LinkModuleTest, CAPISuccess) {
+  std::unique_ptr<Module> DestM(getExternal(Ctx, "foo"));
+  std::unique_ptr<Module> SourceM(getExternal(Ctx, "bar"));
+  char *errout = nullptr;
+  LLVMBool result = LLVMLinkModules(wrap(DestM.get()), wrap(SourceM.get()),
+                                    LLVMLinkerDestroySource, &errout);
+  EXPECT_EQ(0, result);
+  EXPECT_EQ(nullptr, errout);
+  // "bar" is present in destination module
+  EXPECT_NE(nullptr, DestM->getFunction("bar"));
+}
+
+TEST_F(LinkModuleTest, CAPIFailure) {
+  // Symbol clash between two modules
+  std::unique_ptr<Module> DestM(getExternal(Ctx, "foo"));
+  std::unique_ptr<Module> SourceM(getExternal(Ctx, "foo"));
+  char *errout = nullptr;
+  LLVMBool result = LLVMLinkModules(wrap(DestM.get()), wrap(SourceM.get()),
+                                    LLVMLinkerDestroySource, &errout);
+  EXPECT_EQ(1, result);
+  EXPECT_STREQ("Linking globals named 'foo': symbol multiply defined!", errout);
+}
+
 } // end anonymous namespace