%template scope enforcement and class definition fixes

The scoping rules around %template have been specified and enforced.
The %template directive for a class template is the equivalent to an
explicit instantiation of a C++ class template. The scope for a valid
%template instantiation is now the same as the scope required for a
valid explicit instantiation of a C++ template. A definition of the
template for the explicit instantiation must be in scope where the
instantiation is declared and must not be enclosed within a different
namespace.

For example, a few %template and explicit instantiations of std::vector
are shown below:

  // valid
  namespace std {
    %template(vin) vector<int>;
    template class vector<int>;
  }

  // valid
  using namespace std;
  %template(vin) vector<int>;
  template class vector<int>;

  // valid
  using std::vector;
  %template(vin) vector<int>;
  template class vector<int>;

  // ill-formed
  namespace unrelated {
    using std::vector;
    %template(vin) vector<int>;
    template class vector<int>;
  }

  // ill-formed
  namespace unrelated {
    using namespace std;
    %template(vin) vector<int>;
    template class vector<int>;
  }

  // ill-formed
  namespace unrelated {
    namespace std {
      %template(vin) vector<int>;
      template class vector<int>;
    }
  }

  // ill-formed
  namespace unrelated {
    %template(vin) std::vector<int>;
    template class std::vector<int>;
  }

When the scope is incorrect, an error now occurs such as:

cpp_template_scope.i:34: Error: 'vector' resolves to 'std::vector' and
was incorrectly instantiated in scope 'unrelated' instead of within scope 'std'.

Previously SWIG accepted the ill-formed examples above but this led to
numerous subtle template scope problems especially in the presence of
using declarations and using directives as well as with %feature and %typemap.

Actually, a valid instantiation is one which conforms to the C++03
standard as C++11 made a change to disallow using declarations and
using directives to find a template.

  // valid C++03, ill-formed C++11
  using std::vector;
  template class vector<int>;

Similar fixes for defining classes using forward class references have
also been put in place. For example:

namespace Space1 {
  struct A;
}
namespace Space2 {
  struct Space1::A {
    void x();
  }
}

will now error out with:

cpp_class_definition.i:5: Error: 'Space1::A' resolves to 'Space1::A' and
was incorrectly instantiated in scope 'Space2' instead of within scope 'Space1'.

Examples/test-suite/errors/cpp_class_definition.i

@@ -0,0 +1,26 @@
+%module xxx
+
+// This should error but doesn't
+#if 0
+namespace OtherSpace {
+  struct L;
+}
+namespace Space11 {
+  namespace SubSpace11 {
+    using OtherSpace::L;
+    struct L {
+      void ll();
+    };
+  }
+}
+#endif
+
+namespace Space1 {
+  struct A;
+}
+namespace Space2 {
+  struct Space1::A {
+    void x();
+  };
+}
+

Examples/test-suite/errors/cpp_class_definition.stderr

@@ -0,0 +1 @@
+cpp_class_definition.i:22: Error: 'Space1::A' resolves to 'Space1::A' and was incorrectly instantiated in scope 'Space2' instead of within scope 'Space1'.

Examples/test-suite/errors/cpp_namespace_template_bad.i

@@ -0,0 +1,40 @@
+%module namespace_template
+
+namespace test {
+  template<typename T> T max(T a, T b) { return (a > b) ? a : b; }
+  template<typename T> class vector { 
+  public:
+    vector() { }
+    ~vector() { }
+  }; 
+}
+
+namespace test2 {
+  using namespace test;
+  %template(maxshort) max<short>;
+  %template(vectorshort) vector<short>;
+}
+
+namespace test3 {
+  using test::max;
+  using test::vector;
+  %template(maxlong) max<long>;
+  %template(vectorlong) vector<long>;
+}
+
+namespace test4 {
+  using namespace test;
+  typedef int Integer;
+}
+
+namespace test4 {
+  %template(maxInteger) max<Integer>;
+  %template(vectorInteger) vector<Integer>;
+}
+
+using namespace test;
+namespace test5 {
+  %template(maxdouble) max<double>;
+  %template(vectordouble) vector<double>;
+}
+

Examples/test-suite/errors/cpp_namespace_template_bad.stderr

@@ -0,0 +1,9 @@
+cpp_namespace_template_bad.i:14: Error: 'max' resolves to 'test::max' and was incorrectly instantiated in scope 'test2' instead of within scope 'test'.
+cpp_namespace_template_bad.i:15: Error: 'vector' resolves to 'test::vector' and was incorrectly instantiated in scope 'test2' instead of within scope 'test'.
+cpp_namespace_template_bad.i:21: Error: 'max' resolves to 'test::max' and was incorrectly instantiated in scope 'test3' instead of within scope 'test'.
+cpp_namespace_template_bad.i:22: Error: 'vector' resolves to 'test::vector' and was incorrectly instantiated in scope 'test3' instead of within scope 'test'.
+cpp_namespace_template_bad.i:31: Error: 'max' resolves to 'test::max' and was incorrectly instantiated in scope 'test4' instead of within scope 'test'.
+cpp_namespace_template_bad.i:32: Error: 'vector' resolves to 'test::vector' and was incorrectly instantiated in scope 'test4' instead of within scope 'test'.
+cpp_namespace_template_bad.i:37: Error: 'max' resolves to 'test::max' and was incorrectly instantiated in scope 'test5' instead of within scope 'test'.
+cpp_namespace_template_bad.i:37: Error: Template 'max' undefined.
+cpp_namespace_template_bad.i:38: Error: 'vector' resolves to 'test::vector' and was incorrectly instantiated in scope 'test5' instead of within scope 'test'.

Examples/test-suite/errors/cpp_nested_template.stderr

@@ -1,2 +1,4 @@
+cpp_nested_template.i:9: Error: 'Temply' resolves to '::Temply' and was incorrectly instantiated in scope 'A' instead of within scope ''.
 cpp_nested_template.i:9: Warning 324: Named nested template instantiations not supported. Processing as if no name was given to %template().
+cpp_nested_template.i:18: Error: 'Temply' resolves to '::Temply' and was incorrectly instantiated in scope 'B' instead of within scope ''.
 cpp_nested_template.i:18: Warning 324: Named nested template instantiations not supported. Processing as if no name was given to %template().

Examples/test-suite/errors/cpp_template_scope.i

@@ -0,0 +1,57 @@
+%module xxx
+
+namespace std {
+  template<typename T> class vector {};
+}
+
+struct S1 {};
+struct S2 {};
+struct S3 {};
+struct S4 {};
+struct S5 {};
+struct S6 {};
+struct S7 {};
+
+// valid
+namespace std {
+  %template(vi1) vector<S1>;
+  template class vector<S1>;
+}
+
+// valid
+using namespace std;
+%template(vi2) vector<S2>;
+template class vector<S2>;
+
+// valid
+using std::vector;
+%template(vi3) vector<S3>;
+template class vector<S3>;
+
+// ill-formed
+namespace unrelated {
+  using std::vector;
+  %template(vi4) vector<S4>;
+  template class vector<S4>;
+}
+
+// ill-formed
+namespace unrelated {
+  using namespace std;
+  %template(vi5) vector<S5>;
+  template class vector<S5>;
+}
+
+// ill-formed
+namespace unrelated {
+  namespace std {
+    %template(vi6) vector<S6>;
+    template class vector<S6>;
+  }
+}
+
+// ill-formed
+namespace unrelated {
+  %template(vi7) std::vector<S7>;
+  template class std::vector<S7>;
+}

Examples/test-suite/errors/cpp_template_scope.stderr

@@ -0,0 +1,11 @@
+cpp_template_scope.i:18: Warning 320: Explicit template instantiation ignored.
+cpp_template_scope.i:24: Warning 320: Explicit template instantiation ignored.
+cpp_template_scope.i:29: Warning 320: Explicit template instantiation ignored.
+cpp_template_scope.i:34: Error: 'vector' resolves to 'std::vector' and was incorrectly instantiated in scope 'unrelated' instead of within scope 'std'.
+cpp_template_scope.i:35: Warning 320: Explicit template instantiation ignored.
+cpp_template_scope.i:41: Error: 'vector' resolves to 'std::vector' and was incorrectly instantiated in scope 'unrelated' instead of within scope 'std'.
+cpp_template_scope.i:42: Warning 320: Explicit template instantiation ignored.
+cpp_template_scope.i:48: Error: 'vector' resolves to 'std::vector' and was incorrectly instantiated in scope 'unrelated::std' instead of within scope 'std'.
+cpp_template_scope.i:49: Warning 320: Explicit template instantiation ignored.
+cpp_template_scope.i:55: Error: 'std::vector' resolves to 'std::vector' and was incorrectly instantiated in scope 'unrelated' instead of within scope 'std'.
+cpp_template_scope.i:56: Warning 320: Explicit template instantiation ignored.