From b49acb11ca78e12ff8470ddc1c2db0e990b016b6 Mon Sep 17 00:00:00 2001
From: Hans-Kristian Arntzen <post@arntzen-software.no>
Date: Fri, 23 Aug 2024 10:53:01 +0200
Subject: [PATCH] Handle SpecConstantOp used as switch case.

---
 .../frag/switch-spec-constant-op.frag         | 32 +++++++++++++++++++
 .../frag/switch-spec-constant-op.frag         | 23 +++++++++++++
 spirv_cross.cpp                               |  5 +++
 3 files changed, 60 insertions(+)
 create mode 100644 reference/shaders-no-opt/frag/switch-spec-constant-op.frag
 create mode 100644 shaders-no-opt/frag/switch-spec-constant-op.frag

diff --git a/reference/shaders-no-opt/frag/switch-spec-constant-op.frag b/reference/shaders-no-opt/frag/switch-spec-constant-op.frag
new file mode 100644
index 000000000..7dc375418
--- /dev/null
+++ b/reference/shaders-no-opt/frag/switch-spec-constant-op.frag
@@ -0,0 +1,32 @@
+#version 450
+
+#ifndef SPIRV_CROSS_CONSTANT_ID_0
+#define SPIRV_CROSS_CONSTANT_ID_0 4
+#endif
+const int FOO = SPIRV_CROSS_CONSTANT_ID_0;
+const int _9 = (FOO + 4);
+
+layout(location = 0) out vec4 FragColor;
+
+void main()
+{
+    switch (_9)
+    {
+        case 4:
+        {
+            FragColor = vec4(10.0);
+            break;
+        }
+        case 6:
+        {
+            FragColor = vec4(20.0);
+            break;
+        }
+        default:
+        {
+            FragColor = vec4(0.0);
+            break;
+        }
+    }
+}
+
diff --git a/shaders-no-opt/frag/switch-spec-constant-op.frag b/shaders-no-opt/frag/switch-spec-constant-op.frag
new file mode 100644
index 000000000..1098618e1
--- /dev/null
+++ b/shaders-no-opt/frag/switch-spec-constant-op.frag
@@ -0,0 +1,23 @@
+#version 450
+
+layout(location = 0) out vec4 FragColor;
+layout(location = 0) in vec4 Attr;
+layout(constant_id = 0) const int FOO = 4;
+
+void main()
+{
+	switch (FOO + 4)
+	{
+		case 4:
+			FragColor = vec4(10.0);
+			break;
+
+		case 6:
+			FragColor = vec4(20.0);
+			break;
+
+		default:
+			FragColor = vec4(0.0);
+			break;
+	}
+}
diff --git a/spirv_cross.cpp b/spirv_cross.cpp
index 8c3e7d381..5471b3515 100644
--- a/spirv_cross.cpp
+++ b/spirv_cross.cpp
@@ -1850,6 +1850,11 @@ const SmallVector<SPIRBlock::Case> &Compiler::get_case_list(const SPIRBlock &blo
 		const auto &type = get<SPIRType>(constant->constant_type);
 		width = type.width;
 	}
+	else if (const auto *op = maybe_get<SPIRConstantOp>(block.condition))
+	{
+		const auto &type = get<SPIRType>(op->basetype);
+		width = type.width;
+	}
 	else if (const auto *var = maybe_get<SPIRVariable>(block.condition))
 	{
 		const auto &type = get<SPIRType>(var->basetype);