[vala/staging] vala: Improve check of expression passed to yield

[Rico Tzschichholz <ricotz src gnome org>]

commit 29e6a79ef827c0dba5d3efd35c84b5f1b5410ab3
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Mon Jul 20 10:37:53 2020 +0200

    vala: Improve check of expression passed to yield
    
    Report a proper error and fix codegen cricical when a signal is given:
    
      vala_ccode_function_add_expression: assertion 'expression != NULL' failed
    
    See https://gitlab.gnome.org/GNOME/vala/issues/1039

 tests/Makefile.am                                  |  1 +
 .../yield-call-requires-async-method-2.test        | 12 ++++++++++++
 vala/valamethodcall.vala                           | 22 +++++++++++-----------
 3 files changed, 24 insertions(+), 11 deletions(-)
---
diff --git a/tests/Makefile.am b/tests/Makefile.am
index d80ef2ed0..c3fb9cfdc 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -981,6 +981,7 @@ TESTS = \
        semantic/with-value.vala \
        semantic/yield-call-requires-async-context.test \
        semantic/yield-call-requires-async-method.test \
+       semantic/yield-call-requires-async-method-2.test \
        semantic/yield-creation-requires-async-context.test \
        semantic/yield-creation-requires-async-method.test \
        semantic/yield-statement-requires-async-context.test \
diff --git a/tests/semantic/yield-call-requires-async-method-2.test 
b/tests/semantic/yield-call-requires-async-method-2.test
new file mode 100644
index 000000000..f3d1fe67d
--- /dev/null
+++ b/tests/semantic/yield-call-requires-async-method-2.test
@@ -0,0 +1,12 @@
+Invalid Code
+
+class Foo {
+       signal void bar ();
+
+       void run () {
+               yield bar ();
+       }
+}
+
+void main () {
+}
diff --git a/vala/valamethodcall.vala b/vala/valamethodcall.vala
index aeacb958a..d7b58ac85 100644
--- a/vala/valamethodcall.vala
+++ b/vala/valamethodcall.vala
@@ -510,19 +510,19 @@ public class Vala.MethodCall : Expression {
                formal_value_type = ret_type.copy ();
                value_type = formal_value_type.get_actual_type (target_object_type, method_type_args, this);
 
-               if (mtype is MethodType) {
-                       unowned Method m = ((MethodType) mtype).method_symbol;
-                       if (is_yield_expression) {
-                               if (!m.coroutine) {
-                                       error = true;
-                                       Report.error (source_reference, "yield expression requires async 
method");
-                               }
-                               if (context.analyzer.current_method == null || 
!context.analyzer.current_method.coroutine) {
-                                       error = true;
-                                       Report.error (source_reference, "yield expression not available 
outside async method");
-                               }
+               if (is_yield_expression) {
+                       if (!(mtype is MethodType) || !((MethodType) mtype).method_symbol.coroutine) {
+                               error = true;
+                               Report.error (source_reference, "yield expression requires async method");
+                       }
+                       if (context.analyzer.current_method == null || 
!context.analyzer.current_method.coroutine) {
+                               error = true;
+                               Report.error (source_reference, "yield expression not available outside async 
method");
                        }
+               }
 
+               if (mtype is MethodType) {
+                       unowned Method m = ((MethodType) mtype).method_symbol;
                        if (m.returns_floating_reference) {
                                value_type.floating_reference = true;
                        }