IR fuzz target with Arbitrary implementations

Cargo.toml

@@ -14,10 +14,12 @@ resolver = "2"
 [package.metadata.docs.rs]
 all-features = true
 
-[dependencies]
 # MSRV warnings:
 # - bitflags 1.3 requires Rust-1.46
 # - indexmap 1.7 requires Rust-1.49
+
+[dependencies]
+arbitrary = { version = "1", features = ["derive"], optional = true }
 bitflags = "1"
 bit-set = "0.5"
 codespan-reporting = { version = "0.11.0", optional = true }

fuzz/Cargo.toml

@@ -14,7 +14,7 @@ libfuzzer-sys = "0.4"
 
 [dependencies.naga]
 path = ".."
-features = ["spv-in", "wgsl-in", "glsl-in"]
+features = ["arbitrary", "spv-in", "wgsl-in", "glsl-in", "validate"]
 
 # Prevent this from interfering with workspaces
 [workspace]
@@ -37,3 +37,9 @@ name = "glsl_parser"
 path = "fuzz_targets/glsl_parser.rs"
 test = false
 doc = false
+
+[[bin]]
+name = "ir"
+path = "fuzz_targets/ir.rs"
+test = false
+doc = false

fuzz/fuzz_targets/ir.rs

@@ -0,0 +1,10 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|module: naga::Module| {
+    use naga::valid as v;
+    // Check if the module validates without errors.
+    //TODO: may also fuzz the flags and capabilities
+    let mut validator = v::Validator::new(v::ValidationFlags::all(), v::Capabilities::empty());
+    let _result = validator.validate(&module);
+});

fuzz/fuzz_targets/spv_parser.rs

@@ -1,6 +1,6 @@
 #![no_main]
 use libfuzzer_sys::fuzz_target;
-use naga::front::spv::{Parser, Options};
+use naga::front::spv::{Options, Parser};
 
 fuzz_target!(|data: Vec<u32>| {
     // Ensure the parser can handle potentially malformed data without crashing.

src/arena.rs

@@ -17,6 +17,7 @@ use indexmap::set::IndexSet;
     any(feature = "serialize", feature = "deserialize"),
     serde(transparent)
 )]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Handle<T> {
     index: Index,
     #[cfg_attr(any(feature = "serialize", feature = "deserialize"), serde(skip))]
@@ -110,6 +111,7 @@ impl<T> Handle<T> {
     any(feature = "serialize", feature = "deserialize"),
     serde(transparent)
 )]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Range<T> {
     inner: ops::Range<u32>,
     #[cfg_attr(any(feature = "serialize", feature = "deserialize"), serde(skip))]
@@ -154,6 +156,7 @@ impl<T> Iterator for Range<T> {
 /// a reference to the stored item.
 #[cfg_attr(feature = "serialize", derive(serde::Serialize))]
 #[cfg_attr(feature = "serialize", serde(transparent))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct Arena<T> {
     /// Values of this arena.
@@ -543,8 +546,7 @@ impl<T> ops::Index<Handle<T>> for UniqueArena<T> {
 #[cfg(feature = "serialize")]
 impl<T> serde::Serialize for UniqueArena<T>
 where
-    T: Eq + hash::Hash,
-    T: serde::Serialize,
+    T: Eq + hash::Hash + serde::Serialize,
 {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -557,8 +559,7 @@ where
 #[cfg(feature = "deserialize")]
 impl<'de, T> serde::Deserialize<'de> for UniqueArena<T>
 where
-    T: Eq + hash::Hash,
-    T: serde::Deserialize<'de>,
+    T: Eq + hash::Hash + serde::Deserialize<'de>,
 {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -575,3 +576,36 @@ where
         })
     }
 }
+
+//Note: largely borrowed from `HashSet` implementation
+#[cfg(feature = "arbitrary")]
+impl<'a, T> arbitrary::Arbitrary<'a> for UniqueArena<T>
+where
+    T: Eq + hash::Hash + arbitrary::Arbitrary<'a>,
+{
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        let mut arena = Self::default();
+        for elem in u.arbitrary_iter()? {
+            arena.set.insert(elem?);
+            #[cfg(feature = "span")]
+            arena.span_info.push(Span::UNDEFINED);
+        }
+        Ok(arena)
+    }
+
+    fn arbitrary_take_rest(u: arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        let mut arena = Self::default();
+        for elem in u.arbitrary_take_rest_iter()? {
+            arena.set.insert(elem?);
+            #[cfg(feature = "span")]
+            arena.span_info.push(Span::UNDEFINED);
+        }
+        Ok(arena)
+    }
+
+    #[inline]
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        let depth_hint = <usize as arbitrary::Arbitrary>::size_hint(depth);
+        arbitrary::size_hint::and(depth_hint, (0, None))
+    }
+}

src/block.rs

@@ -5,6 +5,7 @@ use std::ops::{Deref, DerefMut, RangeBounds};
 #[derive(Debug, Clone, Default)]
 #[cfg_attr(feature = "serialize", derive(serde::Serialize))]
 #[cfg_attr(feature = "serialize", serde(transparent))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Block {
     body: Vec<Statement>,
     #[cfg(feature = "span")]

src/lib.rs

@@ -217,6 +217,8 @@ pub mod valid;
 pub use crate::arena::{Arena, Handle, Range, UniqueArena};
 
 pub use crate::span::{Span, SpanContext, WithSpan};
+#[cfg(feature = "arbitrary")]
+use arbitrary::Arbitrary;
 #[cfg(feature = "deserialize")]
 use serde::Deserialize;
 #[cfg(feature = "serialize")]
@@ -248,6 +250,7 @@ pub(crate) type NamedExpressions = FastHashMap<Handle<Expression>, String>;
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct EarlyDepthTest {
     conservative: Option<ConservativeDepth>,
 }
@@ -264,6 +267,7 @@ pub struct EarlyDepthTest {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ConservativeDepth {
     /// Shader may rewrite depth only with a value greater than calculated;
     GreaterEqual,
@@ -279,6 +283,7 @@ pub enum ConservativeDepth {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 #[allow(missing_docs)] // The names are self evident
 pub enum ShaderStage {
     Vertex,
@@ -290,6 +295,7 @@ pub enum ShaderStage {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum StorageClass {
     /// Function locals.
     Function,
@@ -311,6 +317,7 @@ pub enum StorageClass {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum BuiltIn {
     Position,
     ViewIndex,
@@ -345,6 +352,7 @@ pub type Bytes = u8;
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum VectorSize {
     /// 2D vector
     Bi = 2,
@@ -359,6 +367,7 @@ pub enum VectorSize {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ScalarKind {
     /// Signed integer type.
     Sint,
@@ -375,6 +384,7 @@ pub enum ScalarKind {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ArraySize {
     /// The array size is constant.
     Constant(Handle<Constant>),
@@ -386,6 +396,7 @@ pub enum ArraySize {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum Interpolation {
     /// The value will be interpolated in a perspective-correct fashion.
     /// Also known as "smooth" in glsl.
@@ -402,6 +413,7 @@ pub enum Interpolation {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum Sampling {
     /// Interpolate the value at the center of the pixel.
     Center,
@@ -421,6 +433,7 @@ pub enum Sampling {
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct StructMember {
     pub name: Option<String>,
     /// Type of the field.
@@ -435,6 +448,7 @@ pub struct StructMember {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ImageDimension {
     /// 1D image
     D1,
@@ -450,6 +464,7 @@ bitflags::bitflags! {
     /// Flags describing an image.
     #[cfg_attr(feature = "serialize", derive(Serialize))]
     #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+    #[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
     #[derive(Default)]
     pub struct StorageAccess: u32 {
         /// Storage can be used as a source for load ops.
@@ -463,6 +478,7 @@ bitflags::bitflags! {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum StorageFormat {
     // 8-bit formats
     R8Unorm,
@@ -513,6 +529,7 @@ pub enum StorageFormat {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ImageClass {
     /// Regular sampled image.
     Sampled {
@@ -540,6 +557,7 @@ pub enum ImageClass {
 #[derive(Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct Type {
     /// The name of the type, if any.
     pub name: Option<String>,
@@ -551,6 +569,7 @@ pub struct Type {
 #[derive(Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum TypeInner {
     /// Number of integral or floating-point kind.
     Scalar { kind: ScalarKind, width: Bytes },
@@ -680,6 +699,7 @@ pub enum TypeInner {
 #[derive(Debug, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct Constant {
     pub name: Option<String>,
     pub specialization: Option<u32>,
@@ -690,6 +710,7 @@ pub struct Constant {
 #[derive(Debug, Clone, Copy, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ScalarValue {
     Sint(i64),
     Uint(u64),
@@ -701,6 +722,7 @@ pub enum ScalarValue {
 #[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ConstantInner {
     Scalar {
         width: Bytes,
@@ -716,6 +738,7 @@ pub enum ConstantInner {
 #[derive(Clone, Debug, Eq, PartialEq, Hash)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum Binding {
     /// Built-in shader variable.
     BuiltIn(BuiltIn),
@@ -747,6 +770,7 @@ pub enum Binding {
 #[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct ResourceBinding {
     /// The bind group index.
     pub group: u32,
@@ -758,6 +782,7 @@ pub struct ResourceBinding {
 #[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct GlobalVariable {
     /// Name of the variable, if any.
     pub name: Option<String>,
@@ -775,6 +800,7 @@ pub struct GlobalVariable {
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct LocalVariable {
     /// Name of the variable, if any.
     pub name: Option<String>,
@@ -788,6 +814,7 @@ pub struct LocalVariable {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum UnaryOperator {
     Negate,
     Not,
@@ -797,6 +824,7 @@ pub enum UnaryOperator {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum BinaryOperator {
     Add,
     Subtract,
@@ -827,6 +855,7 @@ pub enum BinaryOperator {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum AtomicFunction {
     Add,
     Subtract,
@@ -842,6 +871,7 @@ pub enum AtomicFunction {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum DerivativeAxis {
     X,
     Y,
@@ -852,6 +882,7 @@ pub enum DerivativeAxis {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum RelationalFunction {
     All,
     Any,
@@ -865,6 +896,7 @@ pub enum RelationalFunction {
 #[derive(Clone, Copy, Debug, Hash, Eq, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum MathFunction {
     // comparison
     Abs,
@@ -948,6 +980,7 @@ pub enum MathFunction {
 #[derive(Clone, Copy, Debug, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum SampleLevel {
     Auto,
     Zero,
@@ -963,6 +996,7 @@ pub enum SampleLevel {
 #[derive(Clone, Copy, Debug, PartialEq)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum ImageQuery {
     /// Get the size at the specified level.
     Size {
@@ -982,6 +1016,7 @@ pub enum ImageQuery {
 #[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum SwizzleComponent {
     ///
     X = 0,
@@ -997,6 +1032,7 @@ bitflags::bitflags! {
     /// Memory barrier flags.
     #[cfg_attr(feature = "serialize", derive(Serialize))]
     #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+    #[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
     #[derive(Default)]
     pub struct Barrier: u32 {
         /// Barrier affects all `StorageClass::Storage` accesses.
@@ -1013,6 +1049,7 @@ bitflags::bitflags! {
 #[cfg_attr(test, derive(PartialEq))]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum Expression {
     /// Array access with a computed index.
     ///
@@ -1301,6 +1338,7 @@ pub use block::Block;
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum SwitchValue {
     Integer(i32),
     Default,
@@ -1311,6 +1349,7 @@ pub enum SwitchValue {
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct SwitchCase {
     /// Value, upon which the case is considered true.
     pub value: SwitchValue,
@@ -1327,6 +1366,7 @@ pub struct SwitchCase {
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum Statement {
     /// Emit a range of expressions, visible to all statements that follow in this block.
     ///
@@ -1470,6 +1510,7 @@ pub enum Statement {
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct FunctionArgument {
     /// Name of the argument, if any.
     pub name: Option<String>,
@@ -1483,6 +1524,7 @@ pub struct FunctionArgument {
 #[derive(Clone, Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct FunctionResult {
     /// Type of the result.
     pub ty: Handle<Type>,
@@ -1495,6 +1537,7 @@ pub struct FunctionResult {
 #[derive(Debug, Default)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct Function {
     /// Name of the function, if any.
     pub name: Option<String>,
@@ -1558,6 +1601,7 @@ pub struct Function {
 #[derive(Debug)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct EntryPoint {
     /// Name of this entry point, visible externally.
     ///
@@ -1587,6 +1631,7 @@ pub struct EntryPoint {
 #[derive(Debug, Default)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub struct Module {
     /// Storage for the types defined in this module.
     pub types: UniqueArena<Type>,

src/span.rs

@@ -3,6 +3,7 @@ use std::{error::Error, fmt, ops::Range};
 
 /// A source code span, used for error reporting.
 #[derive(Clone, Copy, Debug, PartialEq, Default)]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Span {
     start: u32,
     end: u32,