Add abstract c_inc{} and cxx_inc{} target types

These abstract base target types are meant for deriving additional target
types (for example, Qt moc{}) that can be #include'd in C and C++ translation
units, respectively. In particular, only such targets will be considered to
reverse-lookup extensions to target types (see dyndep_rule::map_extension()
for background).

3 files changed, 36 insertions, 3 deletions

diff --git a/libbuild2/cxx/init.cxx b/libbuild2/cxx/init.cxx
index 3cf330f..d5476a6 100644
--- a/libbuild2/cxx/init.cxx
+++ b/libbuild2/cxx/init.cxx
@@ -806,8 +806,8 @@ namespace build2
     };
 
     // Note that we don't include S{} here because none of the files we
-    // compile can plausibly want to include .S. (Maybe in inline assember
-    // instrcutions?)
+    // compile can plausibly want to include .S. (Maybe in inline assembler
+    // instructions?)
     //
     static const target_type* const inc[] =
     {
@@ -820,6 +820,8 @@ namespace build2
       &c::static_type,
       &mm::static_type,
       &m::static_type,
+      &cxx_inc::static_type,
+      &cc::c_inc::static_type,
       nullptr
     };
 
diff --git a/libbuild2/cxx/target.cxx b/libbuild2/cxx/target.cxx
index 5ead620..37096c3 100644
--- a/libbuild2/cxx/target.cxx
+++ b/libbuild2/cxx/target.cxx
@@ -90,5 +90,18 @@ namespace build2
       &file_search,
       target_type::flag::none
     };
+
+    const target_type cxx_inc::static_type
+    {
+      "cxx_inc",
+      &cc::static_type,
+      nullptr,
+      nullptr,
+      nullptr,
+      nullptr,
+      nullptr,
+      &target_search,
+      target_type::flag::none
+    };
   }
 }
diff --git a/libbuild2/cxx/target.hxx b/libbuild2/cxx/target.hxx
index fc85f75..06e8a67 100644
--- a/libbuild2/cxx/target.hxx
+++ b/libbuild2/cxx/target.hxx
@@ -7,7 +7,6 @@
 #include <libbuild2/types.hxx>
 #include <libbuild2/utility.hxx>
 
-#include <libbuild2/target.hxx>
 #include <libbuild2/cc/target.hxx>
 
 #include <libbuild2/cxx/export.hxx>
@@ -104,6 +103,25 @@ namespace build2
     public:
       static const target_type static_type;
     };
+
+    // This is an abstract base target for deriving additional targets (for
+    // example, Qt moc{}) that can be #include'd in C++ translation units. In
+    // particular, only such targets will be considered to reverse-lookup
+    // extensions to target types (see dyndep_rule::map_extension() for
+    // background).
+    //
+    class LIBBUILD2_CXX_SYMEXPORT cxx_inc: public cc::cc
+    {
+    public:
+      cxx_inc (context& c, dir_path d, dir_path o, string n)
+        : cc (c, move (d), move (o), move (n))
+      {
+        dynamic_type = &static_type;
+      }
+
+    public:
+      static const target_type static_type;
+    };
   }
 }