Add support for changing location that ODB views as class definition

This is useful for making third-party/system types into ODB composite
value types. New pragma: definition. New test: common/definition.

4 files changed, 45 insertions, 14 deletions

diff --git a/odb/common.cxx b/odb/common.cxx
index 0edcb0d..81a416b 100644
--- a/odb/common.cxx
+++ b/odb/common.cxx
@@ -593,7 +593,7 @@ check (semantics::typedefs& t)
   if (hint != &t)
     return false;
 
-  // And the pragma may have to be in the file we are compiling.
+  // And the definition may have to be in the file we are compiling.
   //
   if (!included_)
   {
diff --git a/odb/context.cxx b/odb/context.cxx
index 693ada4..8335ec4 100644
--- a/odb/context.cxx
+++ b/odb/context.cxx
@@ -501,9 +501,18 @@ class_fq_name (semantics::class_& c)
 semantics::path context::
 class_file (semantics::class_& c)
 {
-  return c.is_a<semantics::class_instantiation> ()
-    ? semantics::path (LOCATION_FILE (c.get<location_t> ("location")))
-    : c.file ();
+  // If we have an explicit definition location, use that.
+  //
+  if (c.count ("definition"))
+    return semantics::path (LOCATION_FILE (c.get<location_t> ("definition")));
+  //
+  // Otherwise, if it is a template instantiation, use the location
+  // of the qualifier.
+  //
+  else if (c.is_a<semantics::class_instantiation> ())
+    return semantics::path (LOCATION_FILE (c.get<location_t> ("location")));
+  else
+    return c.file ();
 }
 
 string context::
diff --git a/odb/include.cxx b/odb/include.cxx
index ca7e2aa..3d17b9a 100644
--- a/odb/include.cxx
+++ b/odb/include.cxx
@@ -84,7 +84,8 @@ namespace
 
       // Not interested in classes that we are generating.
       //
-      // If this is a class template instantiation, then get the file
+      // If we have an explicit definition location, use that. Otherwise,
+      // if this is a class template instantiation, then get the file
       // corresponding to the pragma, not the instantiation itself,
       // since that's where we are generation the code for this class.
       // While at it, also get the location.
@@ -94,7 +95,12 @@ namespace
       path f;
       location_t l;
 
-      if (c.is_a<semantics::class_instantiation> ())
+      if (c.count ("definition"))
+      {
+        l = c.get<location_t> ("definition");
+        f = path (LOCATION_FILE (l));
+      }
+      else if (c.is_a<semantics::class_instantiation> ())
       {
         l = c.get<location_t> ("location");
         f = path (LOCATION_FILE (l));
@@ -104,18 +110,21 @@ namespace
         f = c.file ();
         tree decl (TYPE_NAME (c.tree_node ()));
         l = DECL_SOURCE_LOCATION (decl);
-      }
 
-      if (f == unit.file ())
-      {
         // Any include directives that follow are trailing (specified at
         // the end of the main file). Note that we ignore views in this
         // test so if a file defines only views, then all includes will
         // be treated as leading. This is ok since views cannot have
-        // circular dependencies.
+        // circular dependencies. We also ignore overridden locations for
+        // the purpose of this test since they are not really in the file
+        // being compiled. We assume that any includes that come after
+        // such classes are still leading.
         //
-        trailing_ = true;
-        return;
+        if (f == unit.file ())
+        {
+          trailing_ = true;
+          return;
+        }
       }
 
       // This is a persistent object or composite value type declared in
@@ -129,7 +138,6 @@ namespace
         {
           lm = INCLUDED_FROM (line_table, lm);
 
-          path f (c.file ());
           f.complete ();
           f.normalize ();
 
diff --git a/odb/pragma.cxx b/odb/pragma.cxx
index abb6692..ffe711f 100644
--- a/odb/pragma.cxx
+++ b/odb/pragma.cxx
@@ -404,7 +404,8 @@ check_spec_decl_type (tree d,
            p == "query" ||
            p == "object" ||
            p == "optimistic" ||
-           p == "polymorphic")
+           p == "polymorphic" ||
+           p == "definition")
   {
     if (tc != RECORD_TYPE)
     {
@@ -1162,6 +1163,19 @@ handle_pragma (cxx_lexer& l,
 
     tt = l.next (tl, &tn);
   }
+  else if (p == "definition")
+  {
+    // definition
+    //
+
+    // Make sure we've got the correct declaration type.
+    //
+    if (decl != 0 && !check_spec_decl_type (decl, decl_name, p, loc))
+      return;
+
+    val = l.location ();
+    tt = l.next (tl, &tn);
+  }
   else if (p == "callback")
   {
     // callback (name)