From a0c2276ee7bd71a619f0f66c7a875cb8c54409ac Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Mon, 8 Feb 2021 11:48:54 +0100
Subject: [PATCH] Add a version marker

This prevents deserializing a function with a different Cranelift version
---
 cranelift/codegen/src/ir/function.rs | 47 +++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/cranelift/codegen/src/ir/function.rs b/cranelift/codegen/src/ir/function.rs
index f5dc7f916f..1b579e18a1 100644
--- a/cranelift/codegen/src/ir/function.rs
+++ b/cranelift/codegen/src/ir/function.rs
@@ -18,19 +18,63 @@ use crate::isa::{CallConv, EncInfo, Encoding, Legalize, TargetIsa};
 use crate::regalloc::{EntryRegDiversions, RegDiversions};
 use crate::value_label::ValueLabelsRanges;
 use crate::write::write_function;
+#[cfg(feature = "enable-serde")]
+use alloc::string::String;
 use alloc::vec::Vec;
 use core::fmt;
 
+#[cfg(feature = "enable-serde")]
+use serde::de::{Deserializer, Error};
+#[cfg(feature = "enable-serde")]
+use serde::ser::Serializer;
 #[cfg(feature = "enable-serde")]
 use serde::{Deserialize, Serialize};
 
-/// A function.
+/// A version marker used to ensure that serialized clif ir is never deserialized with a
+/// different version of Cranelift.
+#[derive(Copy, Clone, Debug)]
+pub struct VersionMarker;
+
+#[cfg(feature = "enable-serde")]
+impl Serialize for VersionMarker {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        crate::VERSION.serialize(serializer)
+    }
+}
+
+#[cfg(feature = "enable-serde")]
+impl<'de> Deserialize<'de> for VersionMarker {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let version = String::deserialize(deserializer)?;
+        if version != crate::VERSION {
+            return Err(D::Error::custom(&format!(
+                "Expected a clif ir function for version {}, found one for version {}",
+                crate::VERSION,
+                version,
+            )));
+        }
+        Ok(VersionMarker)
+    }
+}
+
 ///
 /// Functions can be cloned, but it is not a very fast operation.
 /// The clone will have all the same entity numbers as the original.
 #[derive(Clone)]
 #[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub struct Function {
+    /// A version marker used to ensure that serialized clif ir is never deserialized with a
+    /// different version of Cranelift.
+    // Note: This must be the first field to ensure that Serde will deserialize it before
+    // attempting to deserialize other fields that are potentially changed between versions.
+    pub version_marker: VersionMarker,
+
     /// Name of this function. Mostly used by `.clif` files.
     pub name: ExternalName,
 
@@ -113,6 +157,7 @@ impl Function {
     /// Create a function with the given name and signature.
     pub fn with_name_signature(name: ExternalName, sig: Signature) -> Self {
         Self {
+            version_marker: VersionMarker,
             name,
             signature: sig,
             old_signature: None,