[vala/0.40] vala: Report error for async creation expression without yield

[Rico Tzschichholz <ricotz src gnome org>]

commit 2d57c8ddc910217f34c95d4d92063afb052d3277
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Thu Nov 14 14:53:04 2019 +0100

    vala: Report error for async creation expression without yield

 tests/Makefile.am                              |  1 +
 tests/asynchronous/creation-missing-yield.test | 10 ++++++++++
 vala/valaobjectcreationexpression.vala         |  5 +++++
 3 files changed, 16 insertions(+)
---
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 935aac999..2dca4e3e6 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -434,6 +434,7 @@ TESTS = \
        asynchronous/bug792942.vala \
        asynchronous/bug793158.vala \
        asynchronous/catch-in-finally.vala \
+       asynchronous/creation-missing-yield.test \
        asynchronous/closures.vala \
        asynchronous/generator.vala \
        asynchronous/result-pos.vala \
diff --git a/tests/asynchronous/creation-missing-yield.test b/tests/asynchronous/creation-missing-yield.test
new file mode 100644
index 000000000..0fe234a6e
--- /dev/null
+++ b/tests/asynchronous/creation-missing-yield.test
@@ -0,0 +1,10 @@
+Invalid Code
+
+class Foo {
+       public async Foo () {
+       }
+}
+
+void main () {
+       var foo = new Foo ();
+}
diff --git a/vala/valaobjectcreationexpression.vala b/vala/valaobjectcreationexpression.vala
index aa387fc37..a54291925 100644
--- a/vala/valaobjectcreationexpression.vala
+++ b/vala/valaobjectcreationexpression.vala
@@ -367,6 +367,11 @@ public class Vala.ObjectCreationExpression : Expression {
                                        error = true;
                                        Report.error (source_reference, "yield expression not available 
outside async method");
                                }
+                       } else if (m is CreationMethod) {
+                               if (m.coroutine) {
+                                       error = true;
+                                       Report.error (source_reference, "missing `yield' before async 
creation expression");
+                               }
                        }
 
                        // FIXME partial code duplication of MethodCall.check