Fix generation of wgsl case arms (#7374)

* Fix generation of wgsl case arms

* Added test case to test generation of switch case

---------

Co-authored-by: Harsh Aggarwal (NVIDIA) <haaggarwal@nvidia.com>

2 files changed, 100 insertions, 6 deletions

diff --git a/source/slang/slang-emit-wgsl.cpp b/source/slang/slang-emit-wgsl.cpp
index d8a243b32..61f34d408 100644
--- a/source/slang/slang-emit-wgsl.cpp
+++ b/source/slang/slang-emit-wgsl.cpp
@@ -66,16 +66,24 @@ void WGSLSourceEmitter::emitSwitchCaseSelectorsImpl(
     // "case 2, 3, 4: ...;" instead of the C-like syntax
     // "case 2: case 3: case 4: ...;".
 
-    m_writer->emit("case ");
-    for (auto caseVal : currentCase->values)
+    if (!isDefault)
     {
-        emitOperand(caseVal, getInfo(EmitOp::General));
-        m_writer->emit(", ");
+        m_writer->emit("case ");
+        auto& values = currentCase->values;
+        for (Index i = 0; i < values.getCount(); ++i)
+        {
+            emitOperand(values[i], getInfo(EmitOp::General));
+            if (i < values.getCount() - 1)
+            {
+                m_writer->emit(", ");
+            }
+        }
     }
-    if (isDefault)
+    else
     {
-        m_writer->emit("default, ");
+        m_writer->emit("default ");
     }
+
     m_writer->emit(":\n");
 }
 
diff --git a/tests/wgsl/switch-case.slang b/tests/wgsl/switch-case.slang
new file mode 100644
index 000000000..c4ff0996e
--- /dev/null
+++ b/tests/wgsl/switch-case.slang
@@ -0,0 +1,86 @@
+//TEST:SIMPLE(filecheck=WGSL): -target wgsl -conformance "Circle:IShape=0" -conformance "Rectangle:IShape=1"
+
+[anyValueSize(16)]
+interface IShape
+{
+    float getArea();
+}
+
+struct Circle : IShape
+{
+    float radius;
+    
+    float getArea() { return 3.14159 * radius * radius; }
+}
+
+struct Rectangle : IShape
+{
+    float width;
+    float height;
+    
+    float getArea() { return width * height; }
+}
+
+struct ShapeDataBlob { uint type; uint payload[16]; }
+
+struct ShapeBuffer
+{
+    StructuredBuffer<ShapeDataBlob> shapes;
+    IShape getShape(uint index)
+    {
+      uint type = shapes[index].type;
+      return createDynamicObject<IShape, ShapeDataBlob>(type, shapes[index]);
+    }
+}
+
+struct VertexInput
+{
+    float2 position;
+    float3 color;
+}
+
+struct VertexOutput
+{
+    float4 position : SV_POSITION;
+    float3 color : TEXCOORD0;
+    float area : TEXCOORD1;
+}
+
+
+[shader("vertex")]
+func vs_main( input: VertexInput, shapes: ShapeBuffer)->VertexOutput
+{
+    VertexOutput output;
+    output.position = float4(input.position, 0.0, 1.0);
+    output.color = input.color;
+    output.area = shapes.getShape(0).getArea(); 
+    return output;
+}
+
+struct FragmentOutput
+{
+    float4 color : SV_TARGET;
+}
+
+[shader("fragment")]
+func fs_main(VertexOutput input)->FragmentOutput
+{
+    FragmentOutput output;
+    output.color = float4(input.color * input.area, 1.0);
+    return output;
+}
+
+//WGSL: fn _S9( _S10 : Tuple_0) -> f32
+//WGSL-NEXT: {
+//WGSL-NEXT:     switch(_S10.value1_0.x)
+//WGSL-NEXT:     {
+//WGSL-NEXT:     case u32(0):
+//WGSL-NEXT:         {
+//WGSL-NEXT:             return Circle_getArea_0(unpackAnyValue16_0(_S10.value2_0));
+//WGSL-NEXT:         }
+//WGSL-NEXT:     default :
+//WGSL-NEXT:         {
+//WGSL-NEXT:             return Rectangle_getArea_0(unpackAnyValue16_1(_S10.value2_0));
+//WGSL-NEXT:         }
+//WGSL-NEXT:     }
+//WGSL-NEXT: }