Warn when the user tries to set TARGET[S] or SOURCE[S] in an Environment.

4 files changed, 46 insertions, 7 deletions

diff --git a/src/engine/SCons/Environment.py b/src/engine/SCons/Environment.py
index 54c91bb..6857109 100644
--- a/src/engine/SCons/Environment.py
+++ b/src/engine/SCons/Environment.py
@@ -315,7 +315,13 @@ class Environment:
 	return dlist
 
     def __setitem__(self, key, value):
-        if key == 'BUILDERS':
+        if key == 'TARGET' or \
+           key == 'TARGETS' or \
+           key == 'SOURCE' or \
+           key == 'SOURCES':
+            SCons.Warnings.warn(SCons.Warnings.ReservedVariableWarning,
+                                "Ignoring attempt to set reserved variable `%s'" % key)
+        elif key == 'BUILDERS':
             try:
                 bd = self._dict[key]
                 for k in bd.keys():
diff --git a/src/engine/SCons/EnvironmentTests.py b/src/engine/SCons/EnvironmentTests.py
index e313939..1163545 100644
--- a/src/engine/SCons/EnvironmentTests.py
+++ b/src/engine/SCons/EnvironmentTests.py
@@ -332,6 +332,26 @@ class EnvironmentTestCase(unittest.TestCase):
         for tnode in tgt:
             assert tnode.builder == InstallBuilder
 
+    def test_ReservedVariables(self):
+        """Test generation of warnings when reserved variable names
+        are set in an environment."""
+
+        SCons.Warnings.enableWarningClass(SCons.Warnings.ReservedVariableWarning)
+        old = SCons.Warnings.warningAsException(1)
+
+        try:
+            env4 = Environment()
+            for kw in ['TARGET', 'TARGETS', 'SOURCE', 'SOURCES']:
+                exc_caught = None
+                try:
+                    env4[kw] = 'xyzzy'
+                except SCons.Warnings.ReservedVariableWarning:
+                    exc_caught = 1
+                assert exc_caught, "Did not catch ReservedVariableWarning for `%s'" % kw
+                assert not env4.has_key(kw), "`%s' variable was incorrectly set" % kw
+        finally:
+            SCons.Warnings.warningAsException(old)
+
     def test_Replace(self):
         """Test replacing construction variables in an Environment
 
diff --git a/src/engine/SCons/Warnings.py b/src/engine/SCons/Warnings.py
index 30f1b00..6d75c06 100644
--- a/src/engine/SCons/Warnings.py
+++ b/src/engine/SCons/Warnings.py
@@ -43,6 +43,9 @@ class DependencyWarning(Warning):
 class CorruptSConsignWarning(Warning):
     pass
 
+class ReservedVariableWarning(Warning):
+    pass
+
 _warningAsException = 0
 
 # The below is a list of 2-tuples.  The first element is a class object.
@@ -62,8 +65,11 @@ def enableWarningClass(clazz):
     _enabled.insert(0, (clazz, 1))
 
 def warningAsException(flag=1):
+    """Turn warnings into exceptions.  Returns the old value of the flag."""
     global _warningAsException
+    old = _warningAsException
     _warningAsException = flag
+    return old
 
 def warn(clazz, *args):
     global _enabled, _warningAsException, _warningOut
diff --git a/src/engine/SCons/WarningsTests.py b/src/engine/SCons/WarningsTests.py
index e04ffc3..1016fdb 100644
--- a/src/engine/SCons/WarningsTests.py
+++ b/src/engine/SCons/WarningsTests.py
@@ -57,16 +57,23 @@ class WarningsTestCase(unittest.TestCase):
         SCons.Warnings._warningAsException = 0
 
         SCons.Warnings.enableWarningClass(SCons.Warnings.Warning)
-        SCons.Warnings.warningAsException()
+        old = SCons.Warnings.warningAsException()
+        assert old == 0, old
+        exc_caught = 0
         try:
             SCons.Warnings.warn(SCons.Warnings.Warning, "Foo")
         except:
-            pass
-        else:
-            assert 0
+            exc_caught = 1
+        assert exc_caught == 1
 
-        SCons.Warnings.warningAsException(0)
-        SCons.Warnings.warn(SCons.Warnings.Warning, "Foo")
+        old = SCons.Warnings.warningAsException(old)
+        assert old == 1, old
+        exc_caught = 0
+        try:
+            SCons.Warnings.warn(SCons.Warnings.Warning, "Foo")
+        except:
+            exc_caught = 1
+        assert exc_caught == 0
 
     def test_Disable(self):
         """Test disabling/enabling warnings."""