1 files changed, 17 insertions, 2 deletions
diff --git a/build2/cc/target b/build2/cc/target
index 2d8125b..465ea61 100644
--- a/build2/cc/target
+++ b/build2/cc/target
@@ -14,6 +14,21 @@ namespace build2
 {
   namespace cc
   {
+    // This is an abstract base target for all c-common source files. We use
+    // this arrangement in rule matching to detect "unknown" (to this rule)
+    // source files that it cannot handle but should not ignore either. For
+    // example, a C link rule that sees a C++ source file.
+    //
+    class cc: public file
+    {
+    public:
+      using file::file;
+
+    public:
+      static const target_type static_type;
+      virtual const target_type& dynamic_type () const = 0;
+    };
+
     // There is hardly a c-family compilation without a C header inclusion.
     // As a result, this target type is registered for any c-family module.
     //
@@ -33,10 +48,10 @@ namespace build2
     // also without relaxing things too much (i.e., the user still won't be
     // able to refer to c{} without loading the c module).
     //
-    class c: public file
+    class c: public cc
     {
     public:
-      using file::file;
+      using cc::cc;
 
     public:
       static const target_type static_type;