[vala/staging] vala: Don't carry floating reference into unknown target type expression

[Rico Tzschichholz <ricotz src gnome org>]

commit eb797855ec320dfcfe50cfa3bf056dc999ee3782
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Fri Jun 26 15:27:11 2020 +0200

    vala: Don't carry floating reference into unknown target type expression
    
    A floating reference result of a method, which may throw an error, needs
    to be sinked when passed as argument for ellipsis parameter.
    
    Fixes https://gitlab.gnome.org/GNOME/vala/issues/1018

 tests/Makefile.am                            |  1 +
 tests/semantic/floating-reference-error.vala | 22 ++++++++++++++++++++++
 tests/semantic/floating-reference.vala       | 17 +++++++++++++++++
 vala/valamethodcall.vala                     |  5 +++++
 4 files changed, 45 insertions(+)
---
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 02af2fd59..35b610d2a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -821,6 +821,7 @@ TESTS = \
        semantic/field-valist.test \
        semantic/field-void.test \
        semantic/floating-reference.vala \
+       semantic/floating-reference-error.vala \
        semantic/foreach-iterator-args.test \
        semantic/foreach-iterator-element-owned.test \
        semantic/foreach-iterator-void.test \
diff --git a/tests/semantic/floating-reference-error.vala b/tests/semantic/floating-reference-error.vala
new file mode 100644
index 000000000..37839d683
--- /dev/null
+++ b/tests/semantic/floating-reference-error.vala
@@ -0,0 +1,22 @@
+[CCode (returns_floating_reference = true)]
+Variant? get_floating_variant_with_error () throws Error {
+       return new Variant.string ("bar");
+}
+
+void variant_args (int first, ...) {
+       var va = va_list ();
+       assert (!va.arg<Variant> ().is_floating ());
+}
+
+void main () {
+       {
+               variant_args (23, get_floating_variant_with_error ());
+       }
+       {
+               try {
+                       variant_args (42, get_floating_variant_with_error ());
+               } catch {
+                       assert_not_reached ();
+               }
+       }
+}
diff --git a/tests/semantic/floating-reference.vala b/tests/semantic/floating-reference.vala
index f690d690d..3cba74865 100644
--- a/tests/semantic/floating-reference.vala
+++ b/tests/semantic/floating-reference.vala
@@ -3,6 +3,11 @@ Variant get_floating_variant () {
        return new Variant.string ("foo");
 }
 
+[CCode (returns_floating_reference = true)]
+Variant? get_floating_variant_with_error () throws Error {
+       return new Variant.string ("bar");
+}
+
 void test_variant () {
        {
                string? @value = "bar";
@@ -45,6 +50,18 @@ void test_variant () {
                Variant? variant = get_floating_variant ();
                assert (!variant.is_floating ());
        }
+       {
+               Variant? variant = get_floating_variant_with_error ();
+               assert (!variant.is_floating ());
+       }
+       {
+               try {
+                       Variant? variant = get_floating_variant_with_error ();
+                       assert (!variant.is_floating ());
+               } catch {
+                       assert_not_reached ();
+               }
+       }
 }
 
 void test_variant_builder () {
diff --git a/vala/valamethodcall.vala b/vala/valamethodcall.vala
index 3573113c4..baf704f45 100644
--- a/vala/valamethodcall.vala
+++ b/vala/valamethodcall.vala
@@ -664,6 +664,11 @@ public class Vala.MethodCall : Expression {
                                var local = new LocalVariable (value_type.copy (), get_temp_name (), null, 
source_reference);
                                var decl = new DeclarationStatement (local, source_reference);
 
+                               // don't carry floating reference any further if the target-type is unknown
+                               if (target_type == null) {
+                                       local.variable_type.floating_reference = false;
+                               }
+
                                insert_statement (context.analyzer.insert_block, decl);
 
                                var temp_access = SemanticAnalyzer.create_temp_access (local, target_type);