From b684b395812872184cbf10e0e0513e2a18546047 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Mon, 7 Jan 2013 11:31:52 -0500
Subject: [PATCH] VS11: Simplify external object file handling (#13831)

Since commit 9a6ff950 (Fix for bug where VS2010 did not use .obj files as
part of the build, 2011-04-01) and commit b291d9e7 (VS10: Fix external
objects generated outside target, 2012-03-19) we try to detect whether an
external object file is also a custom command output in the same target.
This is because VS10 includes .obj custom command outputs on the link line
by default.

VS 11 supports a "<LinkObjects ...>false</LinkObjects>" setting in custom
command rules to tell VS not to link the outputs.  From the VS help:

 Specify whether the Inputs and output files with specific extensions (.obj,
 .lib, .res, .rsc) are passed to the linker.

Treat all external object files the same and add "<Object>" settings for them.
---
 Source/cmVisualStudio10TargetGenerator.cxx | 25 +++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/Source/cmVisualStudio10TargetGenerator.cxx b/Source/cmVisualStudio10TargetGenerator.cxx
index ec9c125a9..2596d7340 100644
--- a/Source/cmVisualStudio10TargetGenerator.cxx
+++ b/Source/cmVisualStudio10TargetGenerator.cxx
@@ -572,6 +572,12 @@ cmVisualStudio10TargetGenerator::WriteCustomRule(cmSourceFile* source,
       sep = ";";
       }
     (*this->BuildFileStream ) << "</Outputs>\n";
+    if(this->LocalGenerator->GetVersion() > cmLocalVisualStudioGenerator::VS10)
+      {
+      // VS >= 11 let us turn off linking of custom command outputs.
+      this->WritePlatformConfigTag("LinkObjects", i->c_str(), 3);
+      (*this->BuildFileStream ) << "false</LinkObjects>\n";
+      }
     }
   this->WriteString("</CustomBuild>\n", 2);
 }
@@ -879,14 +885,23 @@ void cmVisualStudio10TargetGenerator::WriteAllSources()
       }
     }
 
-  for(std::vector<cmSourceFile*>::const_iterator
-        si = this->GeneratorTarget->ExternalObjects.begin();
-      si != this->GeneratorTarget->ExternalObjects.end(); ++si)
+  if(this->LocalGenerator->GetVersion() > cmLocalVisualStudioGenerator::VS10)
+    {
+    // For VS >= 11 we use LinkObjects to avoid linking custom command
+    // outputs.  Use Object for all external objects, generated or not.
+    this->WriteSources("Object", this->GeneratorTarget->ExternalObjects);
+    }
+  else
     {
     // If an object file is generated in this target, then vs10 will use
     // it in the build, and we have to list it as None instead of Object.
-    std::vector<cmSourceFile*> const* d = this->Target->GetSourceDepends(*si);
-    this->WriteSource((d && !d->empty())? "None":"Object", *si);
+    for(std::vector<cmSourceFile*>::const_iterator
+          si = this->GeneratorTarget->ExternalObjects.begin();
+        si != this->GeneratorTarget->ExternalObjects.end(); ++si)
+      {
+      std::vector<cmSourceFile*> const* d=this->Target->GetSourceDepends(*si);
+      this->WriteSource((d && !d->empty())? "None":"Object", *si);
+      }
     }
 
   this->WriteSources("None", this->GeneratorTarget->ExtraSources);