ENH: Enforce unique binary directories

The second argument of add_subdirectory must name a unique binary
directory or the build files will clobber each other.  This enforces
uniqueness with an error message.

1 files changed, 15 insertions, 0 deletions

diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 3a8ab2a..d22cebd 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -1536,6 +1536,21 @@ void cmMakefile::AddSubDirectory(const char* srcPath, const char *binPath,
       }
     }
 
+  // Make sure the binary directory is unique.
+  cmGlobalGenerator* gg = this->LocalGenerator->GetGlobalGenerator();
+  if(!gg->BinaryDirectoryIsNew(binPath))
+    {
+    cmOStringStream e;
+    e << "The binary directory\n"
+      << "  " << binPath << "\n"
+      << "is already used to build another source directory, so it cannot "
+      << "be used to build source directory\n"
+      << "  " << srcPath << "\n"
+      << "Specify a unique binary directory name.";
+    this->IssueMessage(cmake::FATAL_ERROR, e.str());
+    return;
+    }
+
   // create a new local generator and set its parent
   cmLocalGenerator *lg2 =
     this->LocalGenerator->GetGlobalGenerator()->CreateLocalGenerator();