Preserve the ability to call BuildDir() multiple times with the same source and target dirs. (Charles Crain)

2 files changed, 17 insertions, 0 deletions

diff --git a/src/engine/SCons/Node/FS.py b/src/engine/SCons/Node/FS.py
index 9a4fb97..45809f9 100644
--- a/src/engine/SCons/Node/FS.py
+++ b/src/engine/SCons/Node/FS.py
@@ -793,6 +793,8 @@ class FS:
         if src_dir.is_under(build_dir):
             raise SCons.Errors.UserError, "Source directory cannot be under build directory."
         if build_dir.srcdir:
+            if build_dir.srcdir == src_dir:
+                return # We already did this.
             raise SCons.Errors.UserError, "'%s' already has a source directory: '%s'."%(build_dir, build_dir.srcdir)
         build_dir.link(src_dir, duplicate)
 
diff --git a/src/engine/SCons/Node/FSTests.py b/src/engine/SCons/Node/FSTests.py
index cbda758..fcd605b 100644
--- a/src/engine/SCons/Node/FSTests.py
+++ b/src/engine/SCons/Node/FSTests.py
@@ -384,6 +384,21 @@ class BuildDirTestCase(unittest.TestCase):
             test.unlink( "src/foo" )
             test.unlink( "build/foo" )
 
+        fs = SCons.Node.FS.FS()
+        fs.BuildDir('build', 'src1')
+
+        # Calling the same BuildDir twice should work fine.
+        fs.BuildDir('build', 'src1')
+
+        # Trying to move a build dir to a second source dir
+        # should blow up
+        try:
+            fs.BuildDir('build', 'src2')
+        except SCons.Errors.UserError:
+            pass
+        else:
+            assert 0, "Should have caught a UserError."
+
         # Test against a former bug.  Make sure we can get a repository
         # path for the build directory itself!
         fs=SCons.Node.FS.FS(test.workpath('work'))