Support arithmetics on generic arguments (#3968)

Resovles an issue #3935

Slang had to fold the generic arguments after specialization.

1 files changed, 35 insertions, 0 deletions

diff --git a/tests/bugs/gh-3935.slang b/tests/bugs/gh-3935.slang
new file mode 100644
index 000000000..9c8e9f19c
--- /dev/null
+++ b/tests/bugs/gh-3935.slang
@@ -0,0 +1,35 @@
+// Test if generic arguments using arithmetics are folded properly.
+
+//TEST:SIMPLE(filecheck=HLSL): -stage compute -entry computeMain -target hlsl
+
+RWStructuredBuffer<float> outputBuffer;
+
+__generic<let ArraySize:int>
+struct MyStruct
+{
+  int elems[ArraySize];
+};
+
+__generic<let ArraySize:int>
+MyStruct<ArraySize / 2> Reduce(MyStruct<ArraySize> o)
+{
+  MyStruct<ArraySize / 2> result;
+  //HLSL:[[ReturnType:MyStruct_[0-9]*]] Reduce
+  //HLSL:[[ReturnType]] result
+
+  result.elems[0] = o.elems[0];
+
+  // Error happened here as the return type differs
+  // from the type of "result".
+  return result;
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
+{
+  MyStruct<4> a;
+  a.elems[0] = 2;
+
+  let result = Reduce(a);
+  outputBuffer[0] = result.elems[0];
+}