feat: export Postgres parser version

build.rs

@@ -135,6 +135,8 @@ fn main() {
         .allowlist_item("newNode")
         .allowlist_item("pg_query_normalize")
         .allowlist_item("pg_query_free_normalize_result")
+        .allowlist_var("PG_VERSION")
+        .allowlist_var("PG_VERSION_NUM")
         .wrap_static_fns(true)
         .wrap_static_fns_path(out_dir.join("wrap_static_fns"));
     for struct_name in &node_structs {

src/lib.rs

@@ -1,5 +1,5 @@
 #![cfg_attr(feature = "field_offset_assertions", feature(offset_of_enum))]
-use std::{fmt, ops};
+use std::{ffi::CStr, fmt, ops};
 
 pub mod const_val;
 mod deparse;
@@ -24,6 +24,17 @@ pub use crate::error::{Error, Result};
 pub use crate::node_enum::{Node, NodeMut};
 pub use crate::owned::Owned;
 
+/// PostgreSQL version number whose parser sources are used by this crate.
+pub const POSTGRES_VERSION_NUM: u32 = raw::PG_VERSION_NUM;
+
+/// Returns the PostgreSQL version whose parser sources are used by this crate.
+pub fn postgres_version() -> &'static str {
+    CStr::from_bytes_with_nul(raw::PG_VERSION)
+        .expect("generated PG_VERSION without a trailing NUL")
+        .to_str()
+        .expect("generated a non-UTF-8 PG_VERSION")
+}
+
 pub(crate) use node_ptr::{
     AsNodePtr, AsNodeRef, ConstructableNode, FromNodeMut, FromNodePtr, List,
 };
@@ -63,3 +74,20 @@ impl fmt::Debug for ParseResult {
             .finish_non_exhaustive()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{POSTGRES_VERSION_NUM, postgres_version};
+
+    #[test]
+    fn postgres_version_constants_are_consistent() {
+        let mut components = postgres_version()
+            .split('.')
+            .map(|component| component.parse::<u32>().unwrap());
+        let major = components.next().unwrap();
+        let minor = components.next().unwrap();
+
+        assert_eq!(POSTGRES_VERSION_NUM, major * 10_000 + minor);
+        assert!(components.next().is_none());
+    }
+}