Remove incorrect Vulkan-only restriction on SubpassData dimension

The C++ validator does not restrict SubpassData to Vulkan environments.
Only the Arrayed==0 constraint is Vulkan-specific. Remove the blanket
environment check and make the Arrayed check Vulkan-only to match.

Author: LegNeato

rust/spirv-tools-core/src/validation/error.rs

@@ -4159,16 +4159,8 @@ pub enum ValidationError {
         /// Actual operand count.
         actual: usize,
     },
-    /// OpTypeImage with SubpassData dimension requires Vulkan environment.
-    #[error("OpTypeImage {type_id:?} with SubpassData dimension is only allowed in Vulkan, current environment is {env:?}")]
-    ImageTypeSubpassDataRequiresVulkan {
-        /// The image type ID.
-        type_id: Option<TypeId>,
-        /// The current target environment.
-        env: crate::target_env::TargetEnv,
-    },
-    /// OpTypeImage with SubpassData dimension must not be arrayed.
-    #[error("OpTypeImage {type_id:?} with SubpassData dimension must not be arrayed")]
+    /// OpTypeImage with SubpassData dimension must not be arrayed (Vulkan).
+    #[error("OpTypeImage {type_id:?} with SubpassData dimension must not be arrayed in Vulkan")]
     ImageTypeSubpassDataMustNotBeArrayed {
         /// The image type ID.
         type_id: Option<TypeId>,

rust/spirv-tools-core/src/validation/rules/image.rs

@@ -293,18 +293,10 @@ impl ValidationRule for ImageTypeRule {
                 );
             }
 
-            // SubpassData requires Vulkan environment
-            if dim == Dim::DimSubpassData && !ctx.env.is_vulkan() {
-                return Err(ValidationError::ImageTypeSubpassDataRequiresVulkan {
-                    type_id,
-                    env: ctx.env,
-                }
-                .into());
-            }
-
             // SubpassData constraints
             if dim == Dim::DimSubpassData {
-                if arrayed != 0 {
+                // Arrayed must be 0 in Vulkan (VUID-StandaloneSpirv-SubpassData-06214)
+                if ctx.env.is_vulkan() && arrayed != 0 {
                     return Err(
                         ValidationError::ImageTypeSubpassDataMustNotBeArrayed { type_id }.into(),
                     );

rust/spirv-tools-core/src/validation/tests/misc.rs

@@ -7272,7 +7272,7 @@ OpFunctionEnd
 }
 
 // ============================================================================
-// SubpassData Vulkan-only restriction
+// SubpassData validation
 // ============================================================================
 
 #[test]
@@ -7297,7 +7297,7 @@ OpFunctionEnd
 }
 
 #[test]
-fn subpass_data_rejected_in_non_vulkan() {
+fn subpass_data_accepted_in_universal() {
     let text = r#"
 OpCapability Shader
 OpCapability InputAttachment
@@ -7313,13 +7313,57 @@ OpExecutionMode %main OriginUpperLeft
 OpReturn
 OpFunctionEnd
 "#;
-    let err = assemble_and_validate_with_env(text, TargetEnv::Universal1_6)
-        .expect_err("SubpassData should be rejected in non-Vulkan");
+    assemble_and_validate_with_env(text, TargetEnv::Universal1_3)
+        .expect("SubpassData should be accepted in Universal environment");
+}
+
+#[test]
+fn subpass_data_arrayed_rejected_in_vulkan() {
+    // In Vulkan, SubpassData Arrayed must be 0 (VUID-StandaloneSpirv-SubpassData-06214)
+    let text = r#"
+OpCapability Shader
+OpCapability InputAttachment
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %main "main"
+OpExecutionMode %main OriginUpperLeft
+%void = OpTypeVoid
+%fn = OpTypeFunction %void
+%f32 = OpTypeFloat 32
+%img = OpTypeImage %f32 SubpassData 0 1 0 2 Unknown
+%main = OpFunction %void None %fn
+%entry = OpLabel
+OpReturn
+OpFunctionEnd
+"#;
+    let err = assemble_and_validate_with_env(text, TargetEnv::Vulkan1_2)
+        .expect_err("SubpassData with Arrayed=1 should be rejected in Vulkan");
     assert!(
         matches!(
             err,
-            ValidationError::ImageTypeSubpassDataRequiresVulkan { .. }
+            ValidationError::ImageTypeSubpassDataMustNotBeArrayed { .. }
         ),
-        "expected ImageTypeSubpassDataRequiresVulkan, got {err:?}"
+        "expected ImageTypeSubpassDataMustNotBeArrayed, got {err:?}"
     );
 }
+
+#[test]
+fn subpass_data_arrayed_accepted_in_universal() {
+    // Outside Vulkan, arrayed SubpassData is not restricted
+    let text = r#"
+OpCapability Shader
+OpCapability InputAttachment
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %main "main"
+OpExecutionMode %main OriginUpperLeft
+%void = OpTypeVoid
+%fn = OpTypeFunction %void
+%f32 = OpTypeFloat 32
+%img = OpTypeImage %f32 SubpassData 0 1 0 2 Unknown
+%main = OpFunction %void None %fn
+%entry = OpLabel
+OpReturn
+OpFunctionEnd
+"#;
+    assemble_and_validate_with_env(text, TargetEnv::Universal1_3)
+        .expect("SubpassData with Arrayed=1 should be accepted in Universal");
+}