Fix enum array indexing by adding implicit conversion support (#7815)

* Initial plan

* Fix enum array indexing by adding implicit conversion support

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Update enum array indexing test to support GPU backends

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/tests/language-feature/enums/enum-array-indexing.slang b/tests/language-feature/enums/enum-array-indexing.slang
new file mode 100644
index 000000000..c9294ad0c
--- /dev/null
+++ b/tests/language-feature/enums/enum-array-indexing.slang
@@ -0,0 +1,36 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -shaderobj -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK):-cpu -shaderobj -output-using-type
+//TEST(compute, vulkan):COMPARE_COMPUTE(filecheck-buffer=CHECK):-vk -shaderobj -output-using-type
+
+// Test that enums can be used as array indices without explicit casting
+
+enum Fruit { Apple, Orange, Banana };
+
+//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0 0 0], stride=4)
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(1,1,1)]
+void computeMain()
+{
+    int fruits[10];
+    
+    // Initialize arrays with some values
+    for (int i = 0; i < 10; i++)
+    {
+        fruits[i] = i * 10;
+    }
+    
+    // Test basic enum indexing - this should work with our fix
+    int appleCost = fruits[Fruit::Apple];     // Should access fruits[0] = 0
+    int orangeCost = fruits[Fruit::Orange];   // Should access fruits[1] = 10
+    int bananaCost = fruits[Fruit::Banana];   // Should access fruits[2] = 20
+    
+    // CHECK: 0
+    outputBuffer[0] = appleCost;
+    // CHECK: 10
+    outputBuffer[1] = orangeCost;
+    // CHECK: 20
+    outputBuffer[2] = bananaCost;
+    // CHECK: 42
+    outputBuffer[3] = 42; // Just a test value
+}
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