[vala/staging] codegen: Make every co-routine state its own CodeBlock and bump state early

[Rico Tzschichholz <ricotz src gnome org>]

commit 6020ae80e54c6a5cbc5d6db9bf8449b6443afa85
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Oct 21 11:08:08 2017 +0200

    codegen: Make every co-routine state its own CodeBlock and bump state early
    
    https://bugzilla.gnome.org/show_bug.cgi?id=789249

 ccode/valaccodefunction.vala           |   13 +++++++++++++
 codegen/valaccodebasemodule.vala       |    4 +++-
 codegen/valaccodemethodcallmodule.vala |    4 +++-
 codegen/valaccodemethodmodule.vala     |    1 +
 codegen/valagasyncmodule.vala          |    5 ++++-
 codegen/valagdbusclientmodule.vala     |    2 ++
 tests/Makefile.am                      |    1 +
 tests/asynchronous/bug789249.vala      |   17 +++++++++++++++++
 8 files changed, 44 insertions(+), 3 deletions(-)
---
diff --git a/ccode/valaccodefunction.vala b/ccode/valaccodefunction.vala
index 91addcd..7c9883d 100644
--- a/ccode/valaccodefunction.vala
+++ b/ccode/valaccodefunction.vala
@@ -314,6 +314,19 @@ public class Vala.CCodeFunction : CCodeNode {
                add_statement (stmt);
        }
 
+       public void prepend_statement (CCodeNode stmt) {
+               stmt.line = current_line;
+               current_block.prepend_statement (stmt);
+       }
+
+       public void prepend_expression (CCodeExpression expression) {
+               prepend_statement (new CCodeExpressionStatement (expression));
+       }
+
+       public void prepend_assignment (CCodeExpression left, CCodeExpression right) {
+               prepend_expression (new CCodeAssignment (left, right));
+       }
+
        public void close () {
                do {
                        var top = statement_stack.remove_at (statement_stack.size - 1);
diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index cd5ae3d..ad04755 100644
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -4797,10 +4797,12 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
                                // set state before calling async function to support immediate callbacks
                                int state = emit_context.next_coroutine_state++;
 
-                               ccode.add_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier 
("_data_"), "_state_"), new CCodeConstant (state.to_string ()));
+                               ccode.prepend_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier 
("_data_"), "_state_"), new CCodeConstant (state.to_string ()));
                                ccode.add_expression (async_call);
                                ccode.add_return (new CCodeConstant ("FALSE"));
+
                                ccode.add_label ("_state_%d".printf (state));
+                               ccode.open_block ();
                        }
 
                        creation_expr = creation_call;
diff --git a/codegen/valaccodemethodcallmodule.vala b/codegen/valaccodemethodcallmodule.vala
index c911b91..10bf763 100644
--- a/codegen/valaccodemethodcallmodule.vala
+++ b/codegen/valaccodemethodcallmodule.vala
@@ -708,10 +708,12 @@ public class Vala.CCodeMethodCallModule : CCodeAssignmentModule {
                        // set state before calling async function to support immediate callbacks
                        int state = emit_context.next_coroutine_state++;
 
-                       ccode.add_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier ("_data_"), 
"_state_"), new CCodeConstant (state.to_string ()));
+                       ccode.prepend_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier 
("_data_"), "_state_"), new CCodeConstant (state.to_string ()));
                        ccode.add_expression (async_call);
                        ccode.add_return (new CCodeConstant ("FALSE"));
+
                        ccode.add_label ("_state_%d".printf (state));
+                       ccode.open_block ();
                }
 
                if (expr.is_assert) {
diff --git a/codegen/valaccodemethodmodule.vala b/codegen/valaccodemethodmodule.vala
index 4efd04b..27f8012 100644
--- a/codegen/valaccodemethodmodule.vala
+++ b/codegen/valaccodemethodmodule.vala
@@ -485,6 +485,7 @@ public abstract class Vala.CCodeMethodModule : CCodeStructModule {
 
                                        // coroutine body
                                        ccode.add_label ("_state_0");
+                                       ccode.open_block ();
                                }
 
                                if (m.closure) {
diff --git a/codegen/valagasyncmodule.vala b/codegen/valagasyncmodule.vala
index dd8e916..40157fc 100644
--- a/codegen/valagasyncmodule.vala
+++ b/codegen/valagasyncmodule.vala
@@ -775,11 +775,14 @@ public class Vala.GAsyncModule : GtkModule {
                }
 
                if (stmt.yield_expression == null) {
+                       // set state early to support immediate callbacks
                        int state = emit_context.next_coroutine_state++;
 
-                       ccode.add_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier ("_data_"), 
"_state_"), new CCodeConstant (state.to_string ()));
+                       ccode.prepend_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier 
("_data_"), "_state_"), new CCodeConstant (state.to_string ()));
                        ccode.add_return (new CCodeConstant ("FALSE"));
+
                        ccode.add_label ("_state_%d".printf (state));
+                       ccode.open_block ();
                        ccode.add_statement (new CCodeEmptyStatement ());
 
                        return;
diff --git a/codegen/valagdbusclientmodule.vala b/codegen/valagdbusclientmodule.vala
index 4d9caa1..ef58337 100644
--- a/codegen/valagdbusclientmodule.vala
+++ b/codegen/valagdbusclientmodule.vala
@@ -412,7 +412,9 @@ public class Vala.GDBusClientModule : GDBusModule {
                                ccode.add_assignment (new CCodeMemberAccess.pointer (new CCodeIdentifier 
("_data_"), "_state_"), new CCodeConstant (state.to_string ()));
                                ccode.add_expression (ccall);
                                ccode.add_return (new CCodeConstant ("FALSE"));
+
                                ccode.add_label ("_state_%d".printf (state));
+                               ccode.open_block ();
 
                                ccall = new CCodeFunctionCall (new CCodeIdentifier 
("g_async_initable_new_finish"));
                                ccall.add_argument (new CCodeMemberAccess.pointer (new CCodeIdentifier 
("_data_"), "_source_object_"));
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 6f18747..311eeda 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -279,6 +279,7 @@ TESTS = \
        asynchronous/bug762819.vala \
        asynchronous/bug777242.vala \
        asynchronous/bug783543.vala \
+       asynchronous/bug789249.vala \
        asynchronous/closures.vala \
        asynchronous/generator.vala \
        asynchronous/yield.vala \
diff --git a/tests/asynchronous/bug789249.vala b/tests/asynchronous/bug789249.vala
new file mode 100644
index 0000000..0b4bb12
--- /dev/null
+++ b/tests/asynchronous/bug789249.vala
@@ -0,0 +1,17 @@
+static int counter = 0;
+
+static async void foo () {
+       counter++;
+       assert (counter <= 1);
+
+       // This is the simplest way to trigger the issue,
+       // it may happen due to GTask/ThreadPool/threads
+       // getting to call the callback before yield, too.
+       foo.callback ();
+       yield;
+}
+
+void main () {
+       foo.begin ();
+       yield;
+}