1 files changed, 65 insertions, 1 deletions

diff --git a/libbuild2/config/functions.cxx b/libbuild2/config/functions.cxx
index aaf74ec..b1a61a2 100644
--- a/libbuild2/config/functions.cxx
+++ b/libbuild2/config/functions.cxx
@@ -7,6 +7,7 @@
 #include <libbuild2/function.hxx>
 #include <libbuild2/variable.hxx>
 
+#include <libbuild2/config/module.hxx>
 #include <libbuild2/config/operation.hxx>
 
 using namespace std;
@@ -20,6 +21,58 @@ namespace build2
     {
       function_family f (m, "config");
 
+      // $config.origin()
+      //
+      // Return the origin of the value of the specified configuration
+      // variable. Possible result values and their semantics are as follows:
+      //
+      // undefined
+      //    The variable is undefined.
+      //
+      // default
+      //    The variable has the default value from the config directive (or
+      //    as specified by a module).
+      //
+      // buildfile
+      //    The variable has the value from a buildfile, normally config.build
+      //    but could also be from file(s) specified with config.config.load.
+      //
+      // override
+      //    The variable has the command line override value. Note that if
+      //    the override happens to be append/prepend, then the value could
+      //    incorporate the original value.
+      //
+      // Note that the variable must be specified as a name and not as an
+      // expansion (i.e., without $).
+      //
+      // Note that this function is not pure.
+      //
+      f.insert (".origin", false) += [] (const scope* s, names name)
+      {
+        if (s == nullptr)
+          fail << "config.origin() called out of scope" << endf;
+
+        // Only look in the root scope since that's the only config.*
+        // variables we generally consider.
+        //
+        s = s->root_scope ();
+
+        if (s == nullptr)
+          fail << "config.origin() called out of project" << endf;
+
+        switch (origin (*s, convert<string> (move (name))).first)
+        {
+        case variable_origin::undefined: return "undefined";
+        case variable_origin::default_:  return "default";
+        case variable_origin::buildfile: return "buildfile";
+        case variable_origin::override_: return "override";
+        }
+
+        return ""; // Should not reach.
+      };
+
+      // $config.save()
+      //
       // Return the configuration file contents as a string, similar to the
       // config.config.save variable functionality.
       //
@@ -27,7 +80,9 @@ namespace build2
       // config module creation was requested for other meta-operations with
       // config.config.module=true in bootstrap.build.
       //
-      f[".save"] = [] (const scope* s)
+      // Note that this function is not pure.
+      //
+      f.insert (".save", false) += [] (const scope* s)
       {
         if (s == nullptr)
           fail << "config.save() called out of scope" << endf;
@@ -37,6 +92,14 @@ namespace build2
         if (s == nullptr)
           fail << "config.save() called out of project" << endf;
 
+        // See save_config() for details.
+        //
+        assert (s->ctx.phase == run_phase::load);
+        const module* mod (s->find_module<module> (module::name));
+
+        if (mod == nullptr)
+          fail << "config.save() called without config module";
+
         ostringstream os;
 
         // Empty project set should is ok as long as inherit is false.
@@ -45,6 +108,7 @@ namespace build2
         save_config (*s,
                      os, path_name ("config.save()"),
                      false /* inherit */,
+                     *mod,
                      ps);
 
         return os.str ();