Support dependent generic constraints. (#4870)

* Support dependent generic constraints.

* Fix warning.

* Update comment.

* Fix.

* Add a test case to verify fix of #3804.

* Address review.

3 files changed, 131 insertions, 0 deletions

diff --git a/tests/language-feature/generics/dependent-generic-2.slang b/tests/language-feature/generics/dependent-generic-2.slang
new file mode 100644
index 000000000..909669827
--- /dev/null
+++ b/tests/language-feature/generics/dependent-generic-2.slang
@@ -0,0 +1,49 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -shaderobj -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -vk -shaderobj -output-using-type
+
+// Test that we can infer a generic type parameter from the base type of a dependent generic argument.
+
+interface IFoo : IDefaultInitializable
+{
+    int get();
+}
+
+struct Foo : IFoo
+{
+    int get()
+    {
+        return 1;
+    }
+}
+
+interface IBar<T : IFoo>
+{
+    int getVal();
+}
+
+struct Bar<T : IFoo> : IBar<T>
+{
+    int getVal()
+    {
+        T t = T();
+        return t.get();
+    }
+}
+
+int test<T:IFoo, B : IBar<T>>(B b)
+{
+    return b.getVal();
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
+{
+    Bar<Foo> obj2;
+    let result = test(obj2);
+
+    // CHECK: 1
+    outputBuffer[0] = result;
+}
diff --git a/tests/language-feature/generics/dependent-generic-3.slang b/tests/language-feature/generics/dependent-generic-3.slang
new file mode 100644
index 000000000..024d09285
--- /dev/null
+++ b/tests/language-feature/generics/dependent-generic-3.slang
@@ -0,0 +1,32 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -shaderobj -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -vk -shaderobj -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+interface IOperation<T : __BuiltinFloatingPointType>
+{
+  static T apply(T lhs, T rhs);
+};
+ 
+T applyOp<T:__BuiltinFloatingPointType, TOp:IOperation<T>>(T lhs, T rhs)
+{
+  return TOp::apply(lhs, rhs);
+}
+
+struct AddOp<T : __BuiltinFloatingPointType> : IOperation<T>
+{
+    static T apply(T lhs, T rhs)
+    {
+        return lhs + rhs;
+    }
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
+{
+    let result = applyOp<float, AddOp<float>>(1.0, 2.0);
+
+    // CHECK: 3
+    outputBuffer[0] = (int)result;
+}
diff --git a/tests/language-feature/generics/dependent-generic.slang b/tests/language-feature/generics/dependent-generic.slang
new file mode 100644
index 000000000..16f063c65
--- /dev/null
+++ b/tests/language-feature/generics/dependent-generic.slang
@@ -0,0 +1,50 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -shaderobj -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -vk -shaderobj -output-using-type
+
+// Test that we can define a generic where one of the type parameter conforms to an generic interface parameterized on another
+// type parameter.
+
+interface IFoo
+{
+    int get();
+}
+
+struct Foo : IFoo
+{
+    int get()
+    {
+        return 1;
+    }
+}
+
+interface IBar<T : IFoo>
+{
+    int getVal(T t);
+}
+
+struct Bar<T : IFoo> : IBar<T>
+{
+    int getVal(T t)
+    {
+        return t.get();
+    }
+}
+
+int test<T:IFoo, B : IBar<T>>(B b, T t)
+{
+    return b.getVal(t);
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
+{
+    Foo obj1;
+    Bar<Foo> obj2;
+    let result = test(obj2, obj1);
+
+    // CHECK: 1
+    outputBuffer[0] = result;
+}