[vala/staging] codegen: Add "error_pos" CCode attribute and use it as needed

[Rico Tzschichholz <ricotz src gnome org>]

commit b2fd797bdfc8ee825c64b80b70d1c526472758ac
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Thu Jan 10 09:55:11 2019 +0100

    codegen: Add "error_pos" CCode attribute and use it as needed
    
    This makes it possible to use non-standard error parameter positions
    within the vala source.
    
    Fixes https://gitlab.gnome.org/GNOME/vala/issues/728

 codegen/valaccode.vala                 |  4 +++
 codegen/valaccodedelegatemodule.vala   |  6 ++---
 codegen/valaccodemethodcallmodule.vala |  4 +--
 codegen/valaccodemethodmodule.vala     |  4 +--
 tests/Makefile.am                      |  1 +
 tests/delegates/error-pos.vala         | 47 ++++++++++++++++++++++++++++++++++
 vala/valausedattr.vala                 |  2 +-
 7 files changed, 60 insertions(+), 8 deletions(-)
---
diff --git a/codegen/valaccode.vala b/codegen/valaccode.vala
index 2954b3e37..8e6b6b4a3 100644
--- a/codegen/valaccode.vala
+++ b/codegen/valaccode.vala
@@ -276,6 +276,10 @@ namespace Vala {
                }
        }
 
+       public static double get_ccode_error_pos (Callable c) {
+               return c.get_attribute_double ("CCode", "error_pos", -1);
+       }
+
        public static bool get_ccode_array_length (CodeNode node) {
                return get_ccode_attribute(node).array_length;
        }
diff --git a/codegen/valaccodedelegatemodule.vala b/codegen/valaccodedelegatemodule.vala
index e71d87a5c..a0620f8b9 100644
--- a/codegen/valaccodedelegatemodule.vala
+++ b/codegen/valaccodedelegatemodule.vala
@@ -94,7 +94,7 @@ public class Vala.CCodeDelegateModule : CCodeArrayModule {
                }
                if (d.tree_can_fail) {
                        var cparam = new CCodeParameter ("error", "GError**");
-                       cparam_map.set (get_param_pos (-1), cparam);
+                       cparam_map.set (get_param_pos (get_ccode_error_pos (d)), cparam);
                }
 
                // append C parameters in the right order
@@ -258,7 +258,7 @@ public class Vala.CCodeDelegateModule : CCodeArrayModule {
 
                if (m.tree_can_fail) {
                        var cparam = new CCodeParameter ("error", "GError**");
-                       cparam_map.set (get_param_pos (-1), cparam);
+                       cparam_map.set (get_param_pos (get_ccode_error_pos (d)), cparam);
                }
 
                // append C parameters in the right order
@@ -381,7 +381,7 @@ public class Vala.CCodeDelegateModule : CCodeArrayModule {
                }
 
                if (m.tree_can_fail) {
-                       carg_map.set (get_param_pos (-1), new CCodeIdentifier ("error"));
+                       carg_map.set (get_param_pos (get_ccode_error_pos (m)), new CCodeIdentifier ("error"));
                }
 
                var ccall = new CCodeFunctionCall (new CCodeIdentifier (get_ccode_name (m)));
diff --git a/codegen/valaccodemethodcallmodule.vala b/codegen/valaccodemethodcallmodule.vala
index 9086268e8..ade38ab83 100644
--- a/codegen/valaccodemethodcallmodule.vala
+++ b/codegen/valaccodemethodcallmodule.vala
@@ -631,10 +631,10 @@ public class Vala.CCodeMethodCallModule : CCodeAssignmentModule {
                        // method can fail
                        current_method_inner_error = true;
                        // add &inner_error before the ellipsis arguments
-                       out_arg_map.set (get_param_pos (-1), new CCodeUnaryExpression 
(CCodeUnaryOperator.ADDRESS_OF, get_variable_cexpression ("_inner_error_")));
+                       out_arg_map.set (get_param_pos (get_ccode_error_pos ((Callable) m ?? deleg)), new 
CCodeUnaryExpression (CCodeUnaryOperator.ADDRESS_OF, get_variable_cexpression ("_inner_error_")));
                } else if (m != null && m.has_error_type_parameter () && async_call != ccall) {
                        // inferred error argument from base method
-                       out_arg_map.set (get_param_pos (-1), new CCodeConstant ("NULL"));
+                       out_arg_map.set (get_param_pos (get_ccode_error_pos (m)), new CCodeConstant ("NULL"));
                }
 
                if (ellipsis) {
diff --git a/codegen/valaccodemethodmodule.vala b/codegen/valaccodemethodmodule.vala
index fef66ef32..4faf055c1 100644
--- a/codegen/valaccodemethodmodule.vala
+++ b/codegen/valaccodemethodmodule.vala
@@ -116,9 +116,9 @@ public abstract class Vala.CCodeMethodModule : CCodeStructModule {
                        }
 
                        var cparam = new CCodeParameter ("error", "GError**");
-                       cparam_map.set (get_param_pos (-1), cparam);
+                       cparam_map.set (get_param_pos (get_ccode_error_pos (m)), cparam);
                        if (carg_map != null) {
-                               carg_map.set (get_param_pos (-1), new CCodeIdentifier (cparam.name));
+                               carg_map.set (get_param_pos (get_ccode_error_pos (m)), new CCodeIdentifier 
(cparam.name));
                        }
                }
        }
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 87afd9070..3144f9c4b 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -234,6 +234,7 @@ TESTS = \
        delegates/delegate_only.vala \
        delegates/delegates.vala \
        delegates/delegates-error.test \
+       delegates/error-pos.vala \
        delegates/fields.vala \
        delegates/fields-no-target.vala \
        delegates/instance-method-to-no-target.test \
diff --git a/tests/delegates/error-pos.vala b/tests/delegates/error-pos.vala
new file mode 100644
index 000000000..2e9301a68
--- /dev/null
+++ b/tests/delegates/error-pos.vala
@@ -0,0 +1,47 @@
+errordomain FooError {
+       BAR;
+}
+
+[CCode (error_pos = 1.8, instance_pos = 1.9)]
+delegate string FooFunc (int i) throws FooError;
+
+class Bar {
+       [CCode (error_pos = 0.8)]
+       public string foo (int i) throws FooError {
+               assert (this is Bar);
+               return "%i".printf (i);
+       }
+
+       [CCode (error_pos = 0.8)]
+       public string faz (int i) throws FooError {
+               assert (this is Bar);
+               throw new FooError.BAR ("%i".printf (i));
+       }
+}
+
+void foo (FooFunc f) {
+       try {
+               assert (f (23) == "23");
+       } catch {
+               assert_not_reached ();
+       }
+}
+
+void main () {
+       try {
+               var bar = new Bar ();
+               assert (bar.foo (42) == "42");
+               foo (bar.foo);
+       } catch {
+               assert_not_reached ();
+       }
+
+       try {
+               var bar = new Bar ();
+               bar.faz (42);
+       } catch (FooError.BAR e) {
+               assert (e.message == "42");
+       } catch {
+               assert_not_reached ();
+       }
+}
diff --git a/vala/valausedattr.vala b/vala/valausedattr.vala
index 97e9e9da9..cb003d2e9 100644
--- a/vala/valausedattr.vala
+++ b/vala/valausedattr.vala
@@ -40,7 +40,7 @@ public class Vala.UsedAttr : CodeVisitor {
                "array_length_type", "array_length", "array_length_cname", "array_length_cexpr", 
"array_null_terminated",
                "vfunc_name", "finish_vfunc_name", "finish_name", "free_function_address_of", "pos", 
"delegate_target", "delegate_target_cname",
                "array_length_pos", "delegate_target_pos", "destroy_notify_pos", "ctype", "has_new_function", 
"notify", "finish_instance",
-               "use_inplace", "feature_test_macro", "default_value_on_error", "async_result_pos", "",
+               "use_inplace", "feature_test_macro", "default_value_on_error", "async_result_pos", 
"error_pos", "",
 
                "Immutable", "",
                "SingleInstance", "",