'Explicit specialization' experiments with extensions (#2099)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Explicit specialization with multiple parameters.

* Fix tabs.

* Small improvements in test comments.

1 files changed, 56 insertions, 0 deletions

diff --git a/tests/experiments/generic/explicit-specialization-3.slang b/tests/experiments/generic/explicit-specialization-3.slang
new file mode 100644
index 000000000..e53f97158
--- /dev/null
+++ b/tests/experiments/generic/explicit-specialization-3.slang
@@ -0,0 +1,56 @@
+//DISABLE_TEST:SIMPLE:-target hlsl -entry computeMain -profile cs_6_2
+
+/* 
+In C++ we are able to explicitly specialize over more than one type/value. Here we try to use a 'dummy' generic 
+type such that an extension can be applied to it.
+
+I can't just specialize a function also complicating things. 
+
+If I try explicit function specialization in C++. In g++11.1 it will complain if there isn't a specialition visible. 
+Visual studio it seems to assume it is available for import and doesn't complain.
+*/
+
+RWStructuredBuffer<float> outputBuffer;
+
+interface IDoThing
+{
+    static float doThing(float v);
+};
+
+struct Combination<T, let V : int> {};
+
+extension Combination<int, 10> : IDoThing
+{
+    static float doThing(float v)
+    {
+        return int(v) + 10;
+    }
+};
+
+extension Combination<float, 20> : IDoThing
+{
+    static float doThing(float v)
+    {
+        return float(v) + 20;
+    }
+};
+
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    uint tid = dispatchThreadID.x;
+
+    let v = Combination<float, 20>::doThing(tid) + 
+        Combination<int, 10>::doThing(tid);
+    
+    // Produces an error - although the error message of typeof(Combination)
+    // is probably not great.
+    // 
+    // slang(35): error 30027: 'doThing' is not a member of 'typeof(Combination)'.
+    //
+    //let y = Combination<int, 20>::doThing(tid);
+    
+    outputBuffer[tid] = v;
+}
+