Interpolate the null string for illegal list subscripts.

3 files changed, 19 insertions, 2 deletions

diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index 7717ce6..d441604 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -77,6 +77,9 @@ RELEASE 0.14 - XXX
 
   - Add internal SCons.Node.FS.{Dir,File}.Entry() methods.
 
+  - Interpolate the null string if an out-of-range subscript is used
+    for a construction variable.
+
   From Damyan Pepper:
 
   - Quote the "Entering directory" message like Make.
diff --git a/src/engine/SCons/Util.py b/src/engine/SCons/Util.py
index 8d81437..3b97907 100644
--- a/src/engine/SCons/Util.py
+++ b/src/engine/SCons/Util.py
@@ -456,7 +456,7 @@ def scons_subst_list(strSubst, env, mode=SUBST_RAW, target=None, source=None):
             key = key[1:-1]
         try:
             e = eval(key, global_vars, local_vars)
-        except NameError:
+        except (IndexError, NameError, TypeError):
             return '\0\5'
         if callable(e):
             # We wait to evaluate callables until the end of everything
@@ -524,7 +524,7 @@ def scons_subst(strSubst, env, mode=SUBST_RAW, target=None, source=None):
             key = key[1:-1]
         try:
             e = eval(key, global_vars, local_vars)
-        except NameError:
+        except (IndexError, NameError, TypeError):
             return '\0\5'
         if callable(e):
             e = e(target=target, source=source, env=env,
diff --git a/src/engine/SCons/UtilTests.py b/src/engine/SCons/UtilTests.py
index a48b302..84655a9 100644
--- a/src/engine/SCons/UtilTests.py
+++ b/src/engine/SCons/UtilTests.py
@@ -227,6 +227,20 @@ class UtilTestCase(unittest.TestCase):
         newcom = scons_subst("$FOO $BAZ $BAR", DummyEnv(glob))
         assert newcom == "BAR $FOO BAR", newcom
 
+        # Test that we don't blow up even if they subscript something
+        # in ways they "can't."
+        glob = { "FOO" : "BAR",
+                 "NOTHING" : "" ,
+                 "NONE" : None }
+        newcom = scons_subst("${FOO[0]}", DummyEnv(glob))
+        assert newcom == "B", newcom
+        newcom = scons_subst("${FOO[7]}", DummyEnv(glob))
+        assert newcom == "", newcom
+        newcom = scons_subst("${NOTHING[1]}", DummyEnv(glob))
+        assert newcom == "", newcom
+        newcom = scons_subst("${NONE[2]}", DummyEnv(glob))
+        assert newcom == "", newcom
+
     def test_splitext(self):
         assert splitext('foo') == ('foo','')
         assert splitext('foo.bar') == ('foo','.bar')