From 2cb623776807e1e401ac82e2b6b09e1db6b66b3f Mon Sep 17 00:00:00 2001
From: stevenknight <stevenknight@fdb21ef1-2011-0410-befe-b5e4ea1792b1>
Date: Sat, 6 Dec 2003 14:22:09 +0000
Subject: [PATCH] Preserve the ability to call BuildDir() multiple times with
 the same source and target dirs.  (Charles Crain)

git-svn-id: http://scons.tigris.org/svn/scons/trunk@857 fdb21ef1-2011-0410-befe-b5e4ea1792b1
---
 src/CHANGES.txt                  |  3 +++
 src/engine/SCons/Node/FS.py      |  2 ++
 src/engine/SCons/Node/FSTests.py | 15 +++++++++++++++
 3 files changed, 20 insertions(+)

diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index b95cfc03..9baeba33 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -46,6 +46,9 @@ RELEASE 0.95 - XXX
   - Make sure side-effect nodes are prepare()d before building their
     corresponding target.
 
+  - Preserve the ability to call BuildDir() multiple times with the
+    same target and source directory arguments.
+
   From Scott Lystig Fritchie:
 
   - Fix the ability to use a custom _concat() function in the
diff --git a/src/engine/SCons/Node/FS.py b/src/engine/SCons/Node/FS.py
index 9a4fb976..45809f90 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 cbda7583..fcd605b4 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'))
-- 
2.26.2