VS: Compute project GUIDs deterministically

Compute deterministic GUIDs that are unique to the build tree by
hashing the path to the build tree with the GUID logical name.
Avoid storing them in the cache, but honor any found there.
This will allow project GUIDs to be reproduced in a fresh build
tree so long as its path is the same as the original, which may
be useful for incremental builds.

1 files changed, 18 insertions, 34 deletions

diff --git a/Source/cmGlobalVisualStudio7Generator.cxx b/Source/cmGlobalVisualStudio7Generator.cxx
index 4dd54d0..a242046 100644
--- a/Source/cmGlobalVisualStudio7Generator.cxx
+++ b/Source/cmGlobalVisualStudio7Generator.cxx
@@ -513,8 +513,6 @@ void cmGlobalVisualStudio7Generator::WriteTargetsToSolution(
 
             cumulativePath = cumulativePath + "/" + *iter;
             }
-
-          this->CreateGUID(cumulativePath.c_str());
           }
 
         if (!cumulativePath.empty())
@@ -899,7 +897,6 @@ cmGlobalVisualStudio7Generator::WriteUtilityDepend(cmTarget const* target)
   fname += ".vcproj";
   cmGeneratedFileStream fout(fname.c_str());
   fout.SetCopyIfDifferent(true);
-  this->CreateGUID(pname.c_str());
   std::string guid = this->GetGUID(pname.c_str());
 
   fout <<
@@ -943,41 +940,28 @@ cmGlobalVisualStudio7Generator::WriteUtilityDepend(cmTarget const* target)
   return pname;
 }
 
-std::string cmGlobalVisualStudio7Generator::GetGUID(const std::string& name)
+//----------------------------------------------------------------------------
+std::string cmGlobalVisualStudio7Generator::GetGUID(std::string const& name)
 {
-  std::string guidStoreName = name;
-  guidStoreName += "_GUID_CMAKE";
-  const char* storedGUID =
-    this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str());
-  if(storedGUID)
+  std::string const& guidStoreName = name + "_GUID_CMAKE";
+  if (const char* storedGUID =
+      this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str()))
     {
     return std::string(storedGUID);
     }
-  cmSystemTools::Error("Unknown Target referenced : ",
-                       name.c_str());
-  return "";
-}
-
-
-void cmGlobalVisualStudio7Generator::CreateGUID(const std::string& name)
-{
-  std::string guidStoreName = name;
-  guidStoreName += "_GUID_CMAKE";
-  if(this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str()))
-    {
-    return;
-    }
-  std::string ret;
-  UUID uid;
-  unsigned short *uidstr;
-  UuidCreate(&uid);
-  UuidToStringW(&uid,&uidstr);
-  ret = cmsys::Encoding::ToNarrow(reinterpret_cast<wchar_t*>(uidstr));
-  RpcStringFreeW(&uidstr);
-  ret = cmSystemTools::UpperCase(ret);
-  this->CMakeInstance->AddCacheEntry(guidStoreName.c_str(),
-                                     ret.c_str(), "Stored GUID",
-                                     cmState::INTERNAL);
+  // Compute a GUID that is deterministic but unique to the build tree.
+  std::string input = this->CMakeInstance->GetState()->GetBinaryDirectory();
+  input += "|";
+  input += name;
+  std::string md5 = cmSystemTools::ComputeStringMD5(input);
+  assert(md5.length() == 32);
+  std::string const& guid =
+    (md5.substr( 0,8)+"-"+
+     md5.substr( 8,4)+"-"+
+     md5.substr(12,4)+"-"+
+     md5.substr(16,4)+"-"+
+     md5.substr(20,12));
+  return cmSystemTools::UpperCase(guid);
 }
 
 //----------------------------------------------------------------------------