[vala/wip/bug567269: 2/7] Warn when using 'this' before chain up

[Rico Tzschichholz <ricotz src gnome org>]

commit f0ebbdee0b2fd2bd808699e303d4cd8ac02e02ca
Author: Simon Werbeck <simon werbeck gmail com>
Date:   Wed Nov 26 12:24:31 2014 +0100

    Warn when using 'this' before chain up
    
    Do flow analysis on 'this' parameter in creation methods. Report a
    warning if it is used before a chain up call.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=567269

 vala/valaflowanalyzer.vala             |   12 ++++++++++--
 vala/valamemberaccess.vala             |    2 +-
 vala/valamethodcall.vala               |   19 +++++++++++++++++--
 vala/valaobjectcreationexpression.vala |   13 +++++++++++++
 4 files changed, 41 insertions(+), 5 deletions(-)
---
diff --git a/vala/valaflowanalyzer.vala b/vala/valaflowanalyzer.vala
index 9f94a42..56a399d 100644
--- a/vala/valaflowanalyzer.vala
+++ b/vala/valaflowanalyzer.vala
@@ -416,7 +416,11 @@ public class Vala.FlowAnalyzer : CodeVisitor {
                                                        Report.error (used_var.source_reference, "use of 
possibly unassigned local variable `%s'".printf (used_var.name));
                                                } else {
                                                        // parameter
-                                                       Report.warning (used_var.source_reference, "use of 
possibly unassigned parameter `%s'".printf (used_var.name));
+                                                       if (used_var.name == "this") {
+                                                               Report.warning (used_var.source_reference, 
"possible reference to `this' before chaining up");
+                                                       } else {
+                                                               Report.warning (used_var.source_reference, 
"use of possibly unassigned parameter `%s'".printf (used_var.name));
+                                                       }
                                                }
                                                continue;
                                        }
@@ -448,7 +452,11 @@ public class Vala.FlowAnalyzer : CodeVisitor {
                                                Report.error (node.source_reference, "use of possibly 
unassigned local variable `%s'".printf (var_symbol.name));
                                        } else {
                                                // parameter
-                                               Report.warning (node.source_reference, "use of possibly 
unassigned parameter `%s'".printf (var_symbol.name));
+                                               if (var_symbol.name == "this") {
+                                                       Report.warning (node.source_reference, "possible 
reference to `this' before chaining up");
+                                               } else {
+                                                       Report.warning (node.source_reference, "use of 
possibly unassigned parameter `%s'".printf (var_symbol.name));
+                                               }
                                        }
                                        continue;
                                }
diff --git a/vala/valamemberaccess.vala b/vala/valamemberaccess.vala
index 6911bef..4a660a9 100644
--- a/vala/valamemberaccess.vala
+++ b/vala/valamemberaccess.vala
@@ -934,7 +934,7 @@ public class Vala.MemberAccess : Expression {
                var param = symbol_reference as Parameter;
                if (local != null) {
                        collection.add (local);
-               } else if (param != null && param.direction == ParameterDirection.OUT) {
+               } else if (param != null && (param.direction == ParameterDirection.OUT || param.name == 
"this" && param.parent_symbol is CreationMethod && ((CreationMethod)param.parent_symbol).chain_up)) {
                        collection.add (param);
                }
        }
diff --git a/vala/valamethodcall.vala b/vala/valamethodcall.vala
index f620316..f8208b7 100644
--- a/vala/valamethodcall.vala
+++ b/vala/valamethodcall.vala
@@ -291,6 +291,7 @@ public class Vala.MethodCall : Expression {
 
                        var struct_creation_expression = new ObjectCreationExpression ((MemberAccess) call, 
source_reference);
                        struct_creation_expression.struct_creation = true;
+                       struct_creation_expression.struct_chainup = is_chainup;
                        foreach (Expression arg in get_argument_list ()) {
                                struct_creation_expression.add_argument (arg);
                        }
@@ -669,7 +670,19 @@ public class Vala.MethodCall : Expression {
        }
 
        public override void get_defined_variables (Collection<Variable> collection) {
-               call.get_defined_variables (collection);
+               if (is_chainup) {
+                       var this_parameter = call.symbol_reference as Parameter;
+                       if (this_parameter == null) {
+                               Symbol sym = (Block)parent_statement.parent_node;
+                               do {
+                                       sym = sym.parent_symbol;
+                               } while (sym is Block);
+                               this_parameter = ((Method)sym).this_parameter;
+                       }
+                       collection.add (this_parameter);
+               } else {
+                       call.get_defined_variables (collection);
+               }
 
                foreach (Expression arg in argument_list) {
                        arg.get_defined_variables (collection);
@@ -677,7 +690,9 @@ public class Vala.MethodCall : Expression {
        }
 
        public override void get_used_variables (Collection<Variable> collection) {
-               call.get_used_variables (collection);
+               if (!is_chainup) {
+                       call.get_used_variables (collection);
+               }
 
                foreach (Expression arg in argument_list) {
                        arg.get_used_variables (collection);
diff --git a/vala/valaobjectcreationexpression.vala b/vala/valaobjectcreationexpression.vala
index c4b119a..cd5f299 100644
--- a/vala/valaobjectcreationexpression.vala
+++ b/vala/valaobjectcreationexpression.vala
@@ -46,6 +46,7 @@ public class Vala.ObjectCreationExpression : Expression {
        public bool is_yield_expression { get; set; }
 
        public bool struct_creation { get; set; }
+       public bool struct_chainup { get; set; }
 
        private List<Expression> argument_list = new ArrayList<Expression> ();
 
@@ -530,6 +531,18 @@ public class Vala.ObjectCreationExpression : Expression {
        }
 
        public override void get_defined_variables (Collection<Variable> collection) {
+               if (struct_chainup) {
+                       var this_parameter = member_name.inner.symbol_reference as Parameter;
+                       if (this_parameter == null) {
+                               Symbol sym = (Block)parent_statement.parent_node;
+                               do {
+                                       sym = sym.parent_symbol;
+                               } while (sym is Block);
+                               this_parameter = ((Method)sym).this_parameter;
+                       }
+                       collection.add (this_parameter);
+               }
+
                foreach (Expression arg in argument_list) {
                        arg.get_defined_variables (collection);
                }