Fix `getInheritanceInfo` for `ExtractExistentialType`. (#5971)

1 files changed, 40 insertions, 0 deletions

diff --git a/tests/language-feature/interfaces/gh-5900.slang b/tests/language-feature/interfaces/gh-5900.slang
new file mode 100644
index 000000000..996347b41
--- /dev/null
+++ b/tests/language-feature/interfaces/gh-5900.slang
@@ -0,0 +1,40 @@
+//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK): -output-using-type
+
+interface IFoo
+{
+    float get();
+}
+
+extension<FooType : IFoo> FooType {
+    float load()
+    {
+        return get();
+    }
+}
+
+struct Foo : IFoo
+{
+    RWStructuredBuffer<float> buffer;
+    int dummy;
+
+    float get() { return buffer[0]; }
+}
+
+float bugTest(IFoo t)
+{
+    return t.load();
+}
+
+//TEST_INPUT: set input = new Foo { ubuffer(data=[1.0 0 0 0], stride=4), 0 }
+ConstantBuffer<Foo> input;
+
+//TEST_INPUT: set output = out ubuffer(data=[0], stride=4)
+uniform RWStructuredBuffer<float> output;
+
+[shader("compute")]
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+    // CHECK: 1.0
+    output[0] = bugTest(input);
+}
\ No newline at end of file