d: Fix ICE in assign_temp, at function.c:984 (PR94777)

Named arguments were being passed around by invisible reference, just
not variadic arguments.  There is a need to de-duplicate the routines
that handle declaration/parameter promotion and reference checking.
However for now, the parameter helper functions have just been renamed
to parameter_reference_p and parameter_type, to make it more clear that
it is the Parameter equivalent to declaration_reference_p and
declaration_type.

On writing the tests, a forward-reference bug was discovered on x86_64
during va_list type semantic.  This was due to fields not having their
parent set-up correctly.

gcc/d/ChangeLog:

	PR d/94777
	* d-builtins.cc (build_frontend_type): Set parent for generated
	fields of built-in types.
	* d-codegen.cc (argument_reference_p): Rename to ...
	(parameter_reference_p): ... this.
	(type_passed_as): Rename to ...
	(parameter_type): ... this.  Make TREE_ADDRESSABLE types restrict.
	(d_build_call): Move handling of non-POD types here from ...
	* d-convert.cc (convert_for_argument): ... here.
	* d-tree.h (argument_reference_p): Rename declaration to ...
	(parameter_reference_p): ... this.
	(type_passed_as): Rename declaration to ...
	(parameter_type): ... this.
	* types.cc (TypeVisitor::visit (TypeFunction *)): Update caller.

gcc/testsuite/ChangeLog:

	PR d/94777
	* gdc.dg/pr94777a.d: New test.
	* gdc.dg/pr94777b.d: New test.

3 files changed, 202 insertions, 0 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 07fe8a6..1f412a0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-27  Iain Buclaw  <ibuclaw@gdcproject.org>
+
+	PR d/94777
+	* gdc.dg/pr94777a.d: New test.
+	* gdc.dg/pr94777b.d: New test.
+
 2020-04-26  Iain Sandoe  <iain@sandoe.co.uk>
 
 	PR c++/94752
diff --git a/gcc/testsuite/gdc.dg/pr94777a.d b/gcc/testsuite/gdc.dg/pr94777a.d
new file mode 100644
index 0000000..a58fa55
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr94777a.d
@@ -0,0 +1,15 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94777
+// { dg-do compile }
+
+extern void variadic(...);
+
+void f94777()
+{
+    struct S94777
+    {
+        int fld;
+        this(this) { }
+    }
+    auto var = S94777(0);
+    variadic(var, S94777(1));
+}
diff --git a/gcc/testsuite/gdc.dg/pr94777b.d b/gcc/testsuite/gdc.dg/pr94777b.d
new file mode 100644
index 0000000..a230adb
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr94777b.d
@@ -0,0 +1,181 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94777
+// { dg-additional-options "-fmain -funittest" }
+// { dg-do run { target hw } }
+// { dg-skip-if "needs gcc/config.d" { ! d_runtime } }
+
+void testVariadic(T)(int nargs, ...)
+{
+    import core.stdc.stdarg;
+    foreach(i; 0 .. nargs)
+    {
+        auto arg = va_arg!T(_argptr);
+        static if (__traits(compiles, arg.value))
+        {
+            assert(arg.value == i);
+        }
+        else static if (__traits(compiles, arg[0]))
+        {
+            foreach (value; arg)
+                assert(value == i);
+        }
+        else
+        {
+            assert(arg == T.init);
+        }
+    }
+}
+
+/******************************************/
+
+struct Constructor
+{
+    static int count;
+    int value;
+    this(int v) { count++; this.value = v; }
+}
+
+unittest
+{
+    auto a0 = Constructor(0);
+    auto a1 = Constructor(1);
+    auto a2 = Constructor(2);
+    testVariadic!Constructor(3, a0, a1, a2);
+    assert(Constructor.count == 3);
+}
+
+/******************************************/
+
+struct Postblit
+{
+    static int count = 0;
+    int value;
+    this(this) { count++; }
+}
+
+unittest
+{
+    auto a0 = Postblit(0);
+    auto a1 = Postblit(1);
+    auto a2 = Postblit(2);
+    testVariadic!Postblit(3, a0, a1, a2);
+    assert(Postblit.count == 3);
+}
+
+/******************************************/
+
+struct Destructor
+{
+    static int count = 0;
+    int value;
+    ~this() { count++; }
+}
+
+unittest
+{
+    {
+        auto a0 = Destructor(0);
+        auto a1 = Destructor(1);
+        auto a2 = Destructor(2);
+        static assert(!__traits(compiles, testVariadic!Destructor(3, a0, a1, a2)));
+    }
+    assert(Destructor.count == 3);
+}
+
+/******************************************/
+
+struct CopyConstructor 
+{
+    static int count = 0;
+    int value;
+    this(int v) { this.value = v; }
+    this(ref typeof(this) other) { count++; this.value = other.value; }
+}
+
+unittest
+{
+    auto a0 = CopyConstructor(0);
+    auto a1 = CopyConstructor(1);
+    auto a2 = CopyConstructor(2);
+    testVariadic!CopyConstructor(3, a0, a1, a2);
+    // NOTE: Cpctors are not implemented yet.
+    assert(CopyConstructor.count == 0 || CopyConstructor.count == 3);
+}
+
+/******************************************/
+
+unittest
+{
+    struct Nested
+    {
+        int value;
+    }
+
+    auto a0 = Nested(0);
+    auto a1 = Nested(1);
+    auto a2 = Nested(2);
+    testVariadic!Nested(3, a0, a1, a2);
+}
+
+/******************************************/
+
+unittest
+{
+    struct Nested2
+    {
+        int value;
+    }
+
+    void testVariadic2(int nargs, ...)
+    {
+        import core.stdc.stdarg;
+        foreach(i; 0 .. nargs)
+        {
+            auto arg = va_arg!Nested2(_argptr);
+            assert(arg.value == i);
+        }
+    }
+
+    auto a0 = Nested2(0);
+    auto a1 = Nested2(1);
+    auto a2 = Nested2(2);
+    testVariadic2(3, a0, a1, a2);
+}
+
+/******************************************/
+
+struct EmptyStruct
+{
+}
+
+unittest
+{
+    auto a0 = EmptyStruct();
+    auto a1 = EmptyStruct();
+    auto a2 = EmptyStruct();
+    testVariadic!EmptyStruct(3, a0, a1, a2);
+}
+
+/******************************************/
+
+alias StaticArray = int[4];
+
+unittest
+{
+    StaticArray a0 = 0;
+    StaticArray a1 = 1;
+    StaticArray a2 = 2;
+    // XBUG: Front-end rewrites static arrays as dynamic arrays.
+    //testVariadic!StaticArray(3, a0, a1, a2);
+}
+
+/******************************************/
+
+alias EmptyArray = void[0];
+
+unittest
+{
+    auto a0 = EmptyArray.init;
+    auto a1 = EmptyArray.init;
+    auto a2 = EmptyArray.init;
+    testVariadic!EmptyArray(3, a0, a1, a2);
+}