Implement test.target variable

The plan is to use it for the portable path conversions.

4 files changed, 42 insertions, 19 deletions

diff --git a/build/root.build b/build/root.build
index 57f70ac..78e3abd 100644
--- a/build/root.build
+++ b/build/root.build
@@ -31,3 +31,7 @@ if! $cli.configured
 #
 tests/exe{*}:      test = true
 unit-tests/exe{*}: test = true
+
+# Specify the test target for cross-testing.
+#
+test.target = $cxx.target
diff --git a/build2/test/init.cxx b/build2/test/init.cxx
index af83aea..f592568 100644
--- a/build2/test/init.cxx
+++ b/build2/test/init.cxx
@@ -37,25 +37,38 @@ namespace build2
       // Enter module variables. Do it during boot in case they get assigned
       // in bootstrap.build.
       //
+      auto& vp (var_pool);
+
+      // Note: none are overridable.
+      //
+      // The test variable is a name which can be a path (with the
+      // true/false special values) or a target name.
+      //
+      vp.insert<name>    ("test",           variable_visibility::target);
+      vp.insert<name>    ("test.input",     variable_visibility::project);
+      vp.insert<name>    ("test.output",    variable_visibility::project);
+      vp.insert<name>    ("test.roundtrip", variable_visibility::project);
+      vp.insert<strings> ("test.options",   variable_visibility::project);
+      vp.insert<strings> ("test.arguments", variable_visibility::project);
+
+      // These are only used in testscript.
+      //
+      vp.insert<strings> ("test.redirects", variable_visibility::project);
+      vp.insert<strings> ("test.cleanups",  variable_visibility::project);
+
+      // Test target platform.
+      //
+      // Unless already set, default test.target to build.host. Note that it
+      // can still be overriden by the user, e.g., in root.build.
+      //
       {
-        auto& v (var_pool);
+        value& v (
+          rs.assign (
+            vp.insert<target_triplet> (
+              "test.target", variable_visibility::project)));
 
-        // Note: none are overridable.
-        //
-        // The test variable is a name which can be a path (with the
-        // true/false special values) or a target name.
-        //
-        v.insert<name>    ("test",           variable_visibility::target);
-        v.insert<name>    ("test.input",     variable_visibility::project);
-        v.insert<name>    ("test.output",    variable_visibility::project);
-        v.insert<name>    ("test.roundtrip", variable_visibility::project);
-        v.insert<strings> ("test.options",   variable_visibility::project);
-        v.insert<strings> ("test.arguments", variable_visibility::project);
-
-        // These are only used in testscript.
-        //
-        v.insert<strings> ("test.redirects", variable_visibility::project);
-        v.insert<strings> ("test.cleanups", variable_visibility::project);
+        if (!v || v.empty ())
+          v = cast<target_triplet> ((*global_scope)["build.host"]);
       }
     }
 
diff --git a/build2/test/rule.cxx b/build2/test/rule.cxx
index 5851e2f..ccbf932 100644
--- a/build2/test/rule.cxx
+++ b/build2/test/rule.cxx
@@ -419,7 +419,10 @@ namespace build2
       auto run = [&t, &wd] (testscript& ts)
       {
         if (verb)
-          text << "test " << t << " with " << ts;
+        {
+          const auto& tt (cast<target_triplet> (t["test.target"]));
+          text << "test " << t << " with " << ts << " on " << tt;
+        }
 
         script::parser p;
         script::script s (t, ts, wd);
diff --git a/tests/build/root.build b/tests/build/root.build
index 2792187..1903c41 100644
--- a/tests/build/root.build
+++ b/tests/build/root.build
@@ -13,5 +13,8 @@ cxx{*}: extension = cxx
 # as our $build.path).
 #
 import b = build2%exe{b}
-
 dir{*}: test = $b
+
+# Specify the test target for cross-testing.
+#
+test.target = $cxx.target