From 5c111ebef679c994047df95bbdf90181ccb2d067 Mon Sep 17 00:00:00 2001
From: jarcherNV <jarcher@nvidia.com>
Date: Wed, 2 Apr 2025 01:46:52 -0700
Subject: Use correct syntax for WGSL array transpiling (#6693)

Fixes issue #6533

This patch updates handling of Array and ConstantBuffer types for WGSL
transpiling, giving correct syntax for arrays of buffers in WGSL.
---
 source/slang/slang-emit-wgsl.cpp | 12 ++++++++++++
 tests/wgsl/buffer-array.slang    | 24 ++++++++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 tests/wgsl/buffer-array.slang

diff --git a/source/slang/slang-emit-wgsl.cpp b/source/slang/slang-emit-wgsl.cpp
index 227c6cf75..8a3a3cc01 100644
--- a/source/slang/slang-emit-wgsl.cpp
+++ b/source/slang/slang-emit-wgsl.cpp
@@ -656,6 +656,11 @@ void WGSLSourceEmitter::emitSimpleTypeImpl(IRType* type)
             m_writer->emit(">");
             return;
         }
+    case kIROp_ConstantBufferType:
+        {
+            emitType((IRType*)type->getOperand(0));
+            return;
+        }
     default:
         break;
     }
@@ -771,6 +776,13 @@ void WGSLSourceEmitter::emitVarKeywordImpl(IRType* type, IRInst* varDecl)
     {
         m_writer->emit("<workgroup>");
     }
+    else if (
+        type->getOp() == kIROp_ArrayType &&
+        type->getOperand(0)->getOp() == kIROp_ConstantBufferType)
+    {
+        // Arrays of constant buffers should use the uniform keyword.
+        m_writer->emit("<uniform>");
+    }
     else if (
         type->getOp() == kIROp_HLSLRWStructuredBufferType ||
         type->getOp() == kIROp_HLSLRasterizerOrderedStructuredBufferType ||
diff --git a/tests/wgsl/buffer-array.slang b/tests/wgsl/buffer-array.slang
new file mode 100644
index 000000000..3ab27eaac
--- /dev/null
+++ b/tests/wgsl/buffer-array.slang
@@ -0,0 +1,24 @@
+//TEST:SIMPLE(filecheck=WGSL): -stage vertex -entry main -target wgsl
+
+static const int cubeCount = 3;
+
+struct PerInstanceUniforms
+{
+    float4x4 model;
+    float4x4 normalModel;
+};
+
+// WGSL: @binding(0) @group(0) var<uniform> perInstance_0 : array<PerInstanceUniforms_std140_0, i32(3)>;
+[[vk::binding(0, 0)]] ConstantBuffer<PerInstanceUniforms> perInstance[cubeCount] : register(b0, space0);
+
+struct VertexInput
+{
+    float4 position : POSITION0;
+};
+
+float4 main(VertexInput input)
+{
+    // Only here to ensure that perInstance is not ignored.
+    float4 pos = mul(input.position, perInstance[0].model);
+    return pos;
+}
-- 
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