Diagnose on using uninitialized `out` param. (#2803)

* Diagnose on using uninitialized `out` param.

* Hack to allow `out Vertices<T>`.

* Fix.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/tests/diagnostics/uninitialized-out.slang b/tests/diagnostics/uninitialized-out.slang
new file mode 100644
index 000000000..c285970da
--- /dev/null
+++ b/tests/diagnostics/uninitialized-out.slang
@@ -0,0 +1,7 @@
+//DIAGNOSTIC_TEST:SIMPLE:
+
+float foo(out float3 v)
+{
+    float r = v.x + 1.0;
+    return r;
+}
diff --git a/tests/diagnostics/uninitialized-out.slang.expected b/tests/diagnostics/uninitialized-out.slang.expected
new file mode 100644
index 000000000..feb8c494a
--- /dev/null
+++ b/tests/diagnostics/uninitialized-out.slang.expected
@@ -0,0 +1,8 @@
+result code = -1
+standard error = {
+tests/diagnostics/uninitialized-out.slang(5): error 41015: use of uninitialized value.
+    float r = v.x + 1.0;
+                ^
+}
+standard output = {
+}