Fix bug with overload resolution under nested generics (#3107)

* Add test for generic param inference bug for nested generics

* Change description & simplify test

* Add expected file

* Check parent decl before unifying type parameters

2 files changed, 42 insertions, 0 deletions

diff --git a/tests/compute/generics-overload-2.slang b/tests/compute/generics-overload-2.slang
new file mode 100644
index 000000000..8ca55ce7d
--- /dev/null
+++ b/tests/compute/generics-overload-2.slang
@@ -0,0 +1,38 @@
+//TEST(smoke,compute):COMPARE_COMPUTE: -shaderobj
+//TEST(smoke,compute):COMPARE_COMPUTE:-cpu -shaderobj
+
+// Test overload resolution for nested generic definitions
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+
+__generic<T : __BuiltinFloatingPointType>
+struct Foo
+{
+	T test(uint index, T x)
+    {
+        return __realCast<T, float>(1.f);
+	}
+
+	__generic<let N: int>
+	T test(vector<uint, N> index, T x)
+    {
+        return __realCast<T, float>(2.f);
+	}
+};
+
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+	uint tid = dispatchThreadID.x + 2;
+	
+	Foo<float> obj;
+
+	float outVal = obj.test(tid, 0.f);
+	outputBuffer[0] = outVal; // Expect: 1
+
+	float outVal2 = obj.test(uint2(tid, tid), 0.f);
+	outputBuffer[1] = outVal2; // Expect: 2
+}
\ No newline at end of file
diff --git a/tests/compute/generics-overload-2.slang.expected.txt b/tests/compute/generics-overload-2.slang.expected.txt
new file mode 100644
index 000000000..b7ad1e4a8
--- /dev/null
+++ b/tests/compute/generics-overload-2.slang.expected.txt
@@ -0,0 +1,4 @@
+3F800000
+40000000
+0
+0