Fix pointers and C-like layout in varying parameters (#8425)

Closes #8409, but ended up being more about fixing another bug. While
the issue itself seems to only be a simple typo fix (see second commit
in this PR), I found out during writing a test that pointers never got
correct locations regardless of layout. Their locations were always
assigned to zero due to lacking a resource usage entry in `TypeLayout`.
They were also missing the `Flat` decoration, so I went ahead and added
that too.

I can split this up into two separate PRs if that's preferred; both
aspects just share a test right now and fix a similar-looking issue in
the resulting SPIR-V.

1 files changed, 46 insertions, 0 deletions

diff --git a/tests/spirv/c-layout-buffer-3.slang b/tests/spirv/c-layout-buffer-3.slang
new file mode 100644
index 000000000..55647f51b
--- /dev/null
+++ b/tests/spirv/c-layout-buffer-3.slang
@@ -0,0 +1,46 @@
+//TEST:SIMPLE(filecheck=SPIRV): -stage fragment -entry fragmentMain -target spirv -fvk-use-c-layout
+struct A {
+    int64_t i;
+    float f;
+};
+
+struct B {
+    A a;
+    float b;
+};
+
+struct FIn
+{
+    Ptr<B> i0;
+    Ptr<B> i1;
+    float c;
+    float d;
+}
+
+struct FOut
+{
+	float4 outputColor : SV_Target0;
+}
+
+StructuredBuffer<Ptr<B>, Std430DataLayout> testBuffer;
+
+[shader("fragment")]
+FOut fragmentMain(FIn input)
+{
+
+	FOut output;
+	output.outputColor = float4(input.i0.a.f, input.i0.b, input.i1.a.f, input.i1.b)+input.c-input.d;
+    output.outputColor += testBuffer[0].b;
+	return output;
+}
+
+// SPIRV: OpDecorate %input_i0 Location 0
+// SPIRV: OpDecorate %input_i0 Flat
+// SPIRV: OpDecorate %input_i1 Location 1
+// SPIRV: OpDecorate %input_i1 Flat
+// SPIRV: OpDecorate %input_c Location 2
+// SPIRV: OpDecorate %input_d Location 3
+// SPIRV: OpMemberDecorate %A_c 0 Offset 0
+// SPIRV: OpMemberDecorate %A_c 1 Offset 8
+// SPIRV: OpMemberDecorate %B_c 0 Offset 0
+// SPIRV: OpMemberDecorate %B_c 1 Offset 16