diff --git a/new/targets.jam b/new/targets.jam
index 6ddd77c67..5270772cb 100644
--- a/new/targets.jam
+++ b/new/targets.jam
@@ -569,7 +569,9 @@ rule basic-target ( name : project
                 local source-targets = [ generate-sources $(rproperties) ] ;                
                 
                 self.generated.$(property-set) = 
-                  [ construct $(source-targets) : $(rproperties) ] ;                             
+                  [ construct $(source-targets) : $(rproperties) ] ;
+                check-for-unused-sources 
+                  $(self.generated.$(property-set)) : $(source-targets) ;
                 
                 # Apply use requirement of this target to all generated
                 # virtual targets.
@@ -591,6 +593,27 @@ rule basic-target ( name : project
         }                
         return $(self.generated.$(property-set)) ;
     }
+    
+    # Check that 'result' makes use of all the 'sources'. If not,
+    # issues a warning.
+    local rule check-for-unused-sources ( result + : sources * )
+    {
+        local used-sources ;
+        for local r in $(result)
+        {
+            used-sources += [ virtual-target.traverse $(r) : include-roots : 1 ] ; #: includes-sources ] ;
+        }
+               
+        for local s in $(sources)
+        {
+            if ! $(s) in $(used-sources)
+            {
+                errors.warning "Unused source target" [ $(s).str ] 
+                  : "Main target is " [ full-name ] ;
+            }
+        }        
+    }
+    
         
     # Constructs the virtual targets for this abstract targets and
     # the dependecy graph. Returns the list of virtual targets.
diff --git a/new/virtual-target.jam b/new/virtual-target.jam
index c896acde0..78fa8511b 100644
--- a/new/virtual-target.jam
+++ b/new/virtual-target.jam
@@ -729,8 +729,10 @@ rule register ( target )
 }
 
 # Traverses the dependency graph of 'target' and return all targets that will
-# be created before this one is created.
-rule traverse ( target )
+# be created before this one is created. If root of some dependency graph is
+# found during traversal, it's either included or not, dependencing of the
+# value of 'include-roots'. In either case, sources of root are not traversed.
+rule traverse ( target : include-roots ? : include-sources ? )
 {
     local result ;
     if [ $(target).action ]
@@ -743,10 +745,18 @@ rule traverse ( target )
         {
             if ! [ $(t).root ]
             {
-                result += [ traverse $(t) ] ;
+                result += [ traverse $(t) : $(include-roots) : $(include-sources) ] ;
             }
+            else if $(include-roots)
+            {
+                result += $(t) ;
+            }            
         }
     }
+    else if $(include-sources)
+    {
+        result = $(target) ;
+    }    
     return $(result) ;
 }
 
diff --git a/test/test_all.py b/test/test_all.py
index d8a67a605..834662f7d 100644
--- a/test/test_all.py
+++ b/test/test_all.py
@@ -83,6 +83,7 @@ tests = [ "project_test1",
           "make_rule",
           "alias",
           "alternatives",
+          "unused",
 	  ]
 
 if os.name == 'posix':
diff --git a/test/unused.py b/test/unused.py
new file mode 100644
index 000000000..59199ffca
--- /dev/null
+++ b/test/unused.py
@@ -0,0 +1,30 @@
+#!/usr/bin/python
+
+# Test that unused sources are at least reported.
+
+from BoostBuild import Tester
+from string import find
+t = Tester()
+
+t.write("a.h", """ 
+""")
+
+t.write("a.cpp", """ 
+int main()
+{
+    return 0;
+} 
+""")
+
+t.write("Jamfile", """ 
+exe a : a.cpp a.h ; 
+""")
+
+t.write("project-root.jam", """ 
+""")
+
+t.run_build_system()
+t.fail_test(find(t.stdout(), "warning: Unused source target { a.H }") == -1)
+
+t.cleanup()
+
diff --git a/v2/build/targets.jam b/v2/build/targets.jam
index 6ddd77c67..5270772cb 100644
--- a/v2/build/targets.jam
+++ b/v2/build/targets.jam
@@ -569,7 +569,9 @@ rule basic-target ( name : project
                 local source-targets = [ generate-sources $(rproperties) ] ;                
                 
                 self.generated.$(property-set) = 
-                  [ construct $(source-targets) : $(rproperties) ] ;                             
+                  [ construct $(source-targets) : $(rproperties) ] ;
+                check-for-unused-sources 
+                  $(self.generated.$(property-set)) : $(source-targets) ;
                 
                 # Apply use requirement of this target to all generated
                 # virtual targets.
@@ -591,6 +593,27 @@ rule basic-target ( name : project
         }                
         return $(self.generated.$(property-set)) ;
     }
+    
+    # Check that 'result' makes use of all the 'sources'. If not,
+    # issues a warning.
+    local rule check-for-unused-sources ( result + : sources * )
+    {
+        local used-sources ;
+        for local r in $(result)
+        {
+            used-sources += [ virtual-target.traverse $(r) : include-roots : 1 ] ; #: includes-sources ] ;
+        }
+               
+        for local s in $(sources)
+        {
+            if ! $(s) in $(used-sources)
+            {
+                errors.warning "Unused source target" [ $(s).str ] 
+                  : "Main target is " [ full-name ] ;
+            }
+        }        
+    }
+    
         
     # Constructs the virtual targets for this abstract targets and
     # the dependecy graph. Returns the list of virtual targets.
diff --git a/v2/build/virtual-target.jam b/v2/build/virtual-target.jam
index c896acde0..78fa8511b 100644
--- a/v2/build/virtual-target.jam
+++ b/v2/build/virtual-target.jam
@@ -729,8 +729,10 @@ rule register ( target )
 }
 
 # Traverses the dependency graph of 'target' and return all targets that will
-# be created before this one is created.
-rule traverse ( target )
+# be created before this one is created. If root of some dependency graph is
+# found during traversal, it's either included or not, dependencing of the
+# value of 'include-roots'. In either case, sources of root are not traversed.
+rule traverse ( target : include-roots ? : include-sources ? )
 {
     local result ;
     if [ $(target).action ]
@@ -743,10 +745,18 @@ rule traverse ( target )
         {
             if ! [ $(t).root ]
             {
-                result += [ traverse $(t) ] ;
+                result += [ traverse $(t) : $(include-roots) : $(include-sources) ] ;
             }
+            else if $(include-roots)
+            {
+                result += $(t) ;
+            }            
         }
     }
+    else if $(include-sources)
+    {
+        result = $(target) ;
+    }    
     return $(result) ;
 }
 
diff --git a/v2/test/test_all.py b/v2/test/test_all.py
index d8a67a605..834662f7d 100644
--- a/v2/test/test_all.py
+++ b/v2/test/test_all.py
@@ -83,6 +83,7 @@ tests = [ "project_test1",
           "make_rule",
           "alias",
           "alternatives",
+          "unused",
 	  ]
 
 if os.name == 'posix':
diff --git a/v2/test/unused.py b/v2/test/unused.py
new file mode 100644
index 000000000..59199ffca
--- /dev/null
+++ b/v2/test/unused.py
@@ -0,0 +1,30 @@
+#!/usr/bin/python
+
+# Test that unused sources are at least reported.
+
+from BoostBuild import Tester
+from string import find
+t = Tester()
+
+t.write("a.h", """ 
+""")
+
+t.write("a.cpp", """ 
+int main()
+{
+    return 0;
+} 
+""")
+
+t.write("Jamfile", """ 
+exe a : a.cpp a.h ; 
+""")
+
+t.write("project-root.jam", """ 
+""")
+
+t.run_build_system()
+t.fail_test(find(t.stdout(), "warning: Unused source target { a.H }") == -1)
+
+t.cleanup()
+