SPIRV `Block` decoration fixes. (#4303)

* SPIRV `Block` decoration fixes.

- SPIRV does not allow duplicate `Block` decorations. So we shouldn't be generating them.

- Also fixes duplication of OpName.

- SPIRV and HLSL do not allow ConstantBuffer with trailing unsized arrays. Added a check in the front-end against such code.

* Convert failing cross-compile tests to filecheck.

---------

Co-authored-by: Jay Kwak <82421531+jkwak-work@users.noreply.github.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/tests/diagnostics/constant-buffer-unsized.slang b/tests/diagnostics/constant-buffer-unsized.slang
new file mode 100644
index 000000000..25644e803
--- /dev/null
+++ b/tests/diagnostics/constant-buffer-unsized.slang
@@ -0,0 +1,21 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv
+
+struct T2 {
+    float4 _m0;
+};
+
+[[vk::binding(0)]]
+cbuffer ubo : register(b0)
+{
+    int in_val;
+    // CHECK: ([[# @LINE+1]]): error 31215
+    T2 _z0[]; // error 31215: cannot use unsized type 'T2[]' in a constant buffer.
+}
+
+[shader("fragment")]
+float4 main() : SV_TARGET
+{
+    uint x = in_val;
+    float4 data = _z0[x]._m0;
+    return data;
+}
\ No newline at end of file