feat: Use semver crate for -model version, and include in docs

hugr-model/Cargo.toml

@@ -27,6 +27,7 @@ ordered-float = { workspace = true }
 pest = { workspace = true }
 pest_derive = { workspace = true }
 pretty = { workspace = true }
+semver = { workspace = true }
 smol_str = { workspace = true, features = ["serde"] }
 thiserror.workspace = true
 pyo3 = { workspace = true, optional = true, features = ["extension-module"] }

hugr-model/FORMAT_VERSION

@@ -0,0 +1 @@
+1.0.0

hugr-model/src/lib.rs

@@ -1,12 +1,29 @@
 //! The data model of the HUGR intermediate representation.
+//!
 //! This crate defines data structures that capture the structure of a HUGR graph and
 //! all its associated information in a form that can be stored on disk. The data structures
 //! are not designed for efficient traversal or modification, but for simplicity and serialization.
+//!
+//! This crate supports version `
+#![doc = include_str!("../FORMAT_VERSION")]
+//! ` of the HUGR model format.
 mod capnp;
 
 pub mod v0;
-mod version;
-pub use version::*;
+
+use std::sync::LazyLock;
 
 // This is required here since the generated code assumes it's in the package root.
 use capnp::hugr_v0_capnp;
+
+/// The current version of the HUGR model format.
+pub static CURRENT_VERSION: LazyLock<semver::Version> = LazyLock::new(|| {
+    // We allow non-zero patch versions, but ignore them for compatibility checks.
+    let v = semver::Version::parse(include_str!("../FORMAT_VERSION").trim())
+        .expect("`FORMAT_VERSION` in `hugr-model` contains version that fails to parse");
+    assert!(
+        v.pre.is_empty(),
+        "`FORMAT_VERSION` in `hugr-model` should not have a pre-release version"
+    );
+    v
+});

hugr-model/src/v0/binary/read.rs

@@ -1,6 +1,6 @@
 use crate::capnp::hugr_v0_capnp as hugr_capnp;
 use crate::v0::table;
-use crate::{Version, v0 as model};
+use crate::{CURRENT_VERSION, v0 as model};
 use bumpalo::Bump;
 use bumpalo::collections::Vec as BumpVec;
 use std::io::BufRead;
@@ -18,9 +18,9 @@ pub enum ReadError {
     #[display("Can not read file with version {actual} (tooling version {current}).")]
     VersionError {
         /// The current version of the hugr-model format.
-        current: Version,
+        current: semver::Version,
         /// The version of the hugr-model format in the file.
-        actual: Version,
+        actual: semver::Version,
     },
 }
 
@@ -68,11 +68,10 @@ fn read_package<'a>(
     reader: hugr_capnp::package::Reader,
 ) -> ReadResult<table::Package<'a>> {
     let version = read_version(reader.get_version()?)?;
-    let current_version = Version::current();
 
-    if version.major != current_version.major || version.minor > current_version.minor {
+    if version.major != CURRENT_VERSION.major || version.minor > CURRENT_VERSION.minor {
         return Err(ReadError::VersionError {
-            current: current_version,
+            current: CURRENT_VERSION.clone(),
             actual: version,
         });
     }
@@ -86,10 +85,10 @@ fn read_package<'a>(
     Ok(table::Package { modules })
 }
 
-fn read_version(reader: hugr_capnp::version::Reader) -> ReadResult<Version> {
+fn read_version(reader: hugr_capnp::version::Reader) -> ReadResult<semver::Version> {
     let major = reader.get_major();
     let minor = reader.get_minor();
-    Ok(Version { minor, major })
+    Ok(semver::Version::new(major as u64, minor as u64, 0))
 }
 
 fn read_module<'a>(

hugr-model/src/v0/binary/write.rs

@@ -1,6 +1,6 @@
 use std::io::Write;
 
-use crate::Version;
+use crate::CURRENT_VERSION;
 use crate::capnp::hugr_v0_capnp as hugr_capnp;
 use crate::v0::{self as model, table};
 
@@ -47,12 +47,12 @@ pub fn write_to_vec(package: &table::Package) -> Vec<u8> {
 
 fn write_package(mut builder: hugr_capnp::package::Builder, package: &table::Package) {
     write_list!(builder, init_modules, write_module, package.modules);
-    write_version(builder.init_version(), Version::current());
+    write_version(builder.init_version(), &CURRENT_VERSION);
 }
 
-fn write_version(mut builder: hugr_capnp::version::Builder, version: Version) {
-    builder.set_major(version.major);
-    builder.set_minor(version.minor);
+fn write_version(mut builder: hugr_capnp::version::Builder, version: &semver::Version) {
+    builder.set_major(version.major as u32);
+    builder.set_minor(version.minor as u32);
 }
 
 fn write_module(mut builder: hugr_capnp::module::Builder, module: &table::Module) {