'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, 35 insertions, 7 deletions

diff --git a/tests/experiments/generic/type-to-value-4.slang b/tests/experiments/generic/type-to-value-4.slang
index 986fffaf7..741b30791 100644
--- a/tests/experiments/generic/type-to-value-4.slang
+++ b/tests/experiments/generic/type-to-value-4.slang
@@ -2,12 +2,40 @@
 
 /* Test here is to try and associate a value with a type
 
-This doesn't work - it produces dynamic dispatch code, that is uncompilable because cases 
-are missing.
+This doesn't work without 'public' on struct B. This is necessary such that
+those implementations of `IGetE` are visible for dynamic dispatch.
 
-.slang(24): error :  control reaches end of non-void function [-Wreturn-type]
-dxc: note : }
-dxc: note : ^
+Otherwise the error 
+
+> tests/experiments/generic/type-to-value-4.slang(21): error 50100: No type conformances are found for interface 'IGetE'. Code generation for current target requires at least one implementation type present in the linkage.
+> interface IGetE
+          ^~~~~
+
+This is somewhat 'surprising' because the code *explicitly* instanciates B, so why is it necessary to make it 
+public?
+
+If we make both struct A and struct B public, the following code uses dynamic dispatch in order to implement e.getE(). When it does this it introduces
+
+```HLSL
+struct Tuple_0
+{
+    uint2 value0_0;
+    uint2 value1_0;
+    AnyValue16 value2_0;
+};
+
+Tuple_0 _S1;
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID_0 : SV_DISPATCHTHREADID)
+{
+    int _S7 = U_S3tu05IGetE4getEp0p3tu04Enum_0(_S1.value1_0);
+
+    // ...
+}
+```
+
+But _S1 is never intialized (in HLSL it becomes a Global in a constant buffer). Why does creating a local variable produce something in a constant buffer?
 
 */
 
@@ -24,12 +52,12 @@ interface IGetE
 	static Enum getE();    
 };
 
-struct A : IGetE
+public struct A : IGetE
 {
     static Enum getE() { return Enum::A; }
 };
 
-struct B : IGetE
+public struct B : IGetE
 {
     static Enum getE() { return Enum::B; }
 };