internal: Ensure proc-macro-api version check works with postcard across protocol versions

crates/hir-def/src/lang_item.rs

@@ -161,11 +161,12 @@ pub enum GenericRequirement {
 
 macro_rules! language_item_table {
     (
+        $LangItems:ident =>
         $( $(#[$attr:meta])* $lang_item:ident, $module:ident :: $name:ident, $method:ident, $target:ident, $generics:expr; )*
     ) => {
         #[allow(non_snake_case)] // FIXME: Should we remove this?
         #[derive(Debug, Default, Clone, PartialEq, Eq, Hash)]
-        pub struct LangItems {
+        pub struct $LangItems {
             $(
                 $(#[$attr])*
                 pub $lang_item: Option<$target>,
@@ -219,7 +220,7 @@ macro_rules! language_item_table {
     }
 }
 
-language_item_table! {
+language_item_table! { LangItems =>
 //  Variant name,            Name,                     Getter method name,         Target                  Generic requirements;
     Sized,                   sym::sized,               sized_trait,                TraitId,                GenericRequirement::Exact(0);
     MetaSized,               sym::meta_sized,          sized_trait,                TraitId,                GenericRequirement::Exact(0);

crates/proc-macro-api/src/legacy_protocol/msg.rs

@@ -13,6 +13,13 @@ use crate::{ProcMacroKind, codec::Codec};
 /// Represents requests sent from the client to the proc-macro-srv.
 #[derive(Debug, Serialize, Deserialize)]
 pub enum Request {
+    // IMPORTANT: Keep his first, otherwise postcard will break as its not a self describing format
+    // As such, this is the only request that needs to be supported across all protocol versions
+    // and by keeping it first, we ensure it always has the same discriminant encoding in postcard
+    /// Performs an API version check between the client and the server.
+    /// Since [`VERSION_CHECK_VERSION`]
+    ApiVersionCheck {},
+
     /// Retrieves a list of macros from a given dynamic library.
     /// Since [`NO_VERSION_CHECK_VERSION`]
     ListMacros { dylib_path: Utf8PathBuf },
@@ -21,10 +28,6 @@ pub enum Request {
     /// Since [`NO_VERSION_CHECK_VERSION`]
     ExpandMacro(Box<ExpandMacro>),
 
-    /// Performs an API version check between the client and the server.
-    /// Since [`VERSION_CHECK_VERSION`]
-    ApiVersionCheck {},
-
     /// Sets server-specific configurations.
     /// Since [`RUST_ANALYZER_SPAN_SUPPORT`]
     SetConfig(ServerConfig),
@@ -44,6 +47,13 @@ pub enum SpanMode {
 /// Represents responses sent from the proc-macro-srv to the client.
 #[derive(Debug, Serialize, Deserialize)]
 pub enum Response {
+    // IMPORTANT: Keep his first, otherwise postcard will break as its not a self describing format
+    // As such, this is the only request that needs to be supported across all protocol versions
+    // and by keeping it first, we ensure it always has the same discriminant encoding in postcard
+    /// Returns the API version supported by the server.
+    /// Since [`NO_VERSION_CHECK_VERSION`]
+    ApiVersionCheck(u32),
+
     /// Returns a list of available macros in a dynamic library.
     /// Since [`NO_VERSION_CHECK_VERSION`]
     ListMacros(Result<Vec<(String, ProcMacroKind)>, String>),
@@ -52,10 +62,6 @@ pub enum Response {
     /// Since [`NO_VERSION_CHECK_VERSION`]
     ExpandMacro(Result<FlatTree, PanicMessage>),
 
-    /// Returns the API version supported by the server.
-    /// Since [`NO_VERSION_CHECK_VERSION`]
-    ApiVersionCheck(u32),
-
     /// Confirms the application of a configuration update.
     /// Since [`RUST_ANALYZER_SPAN_SUPPORT`]
     SetConfig(ServerConfig),

crates/proc-macro-srv/src/lib.rs

@@ -198,7 +198,13 @@ impl ProcMacroSrvSpan for SpanId {
     type Server = server_impl::token_id::SpanIdServer;
 
     fn make_server(call_site: Self, def_site: Self, mixed_site: Self) -> Self::Server {
-        Self::Server { call_site, def_site, mixed_site }
+        Self::Server {
+            call_site,
+            def_site,
+            mixed_site,
+            tracked_env_vars: Default::default(),
+            tracked_paths: Default::default(),
+        }
     }
 }
 impl ProcMacroSrvSpan for Span {

crates/proc-macro-srv/src/server_impl/token_id.rs

@@ -1,6 +1,9 @@
 //! proc-macro server backend based on [`proc_macro_api::msg::SpanId`] as the backing span.
 //! This backend is rather inflexible, used by RustRover and older rust-analyzer versions.
-use std::ops::{Bound, Range};
+use std::{
+    collections::{HashMap, HashSet},
+    ops::{Bound, Range},
+};
 
 use intern::Symbol;
 use proc_macro::bridge::server;
@@ -24,6 +27,10 @@ type Span = SpanId;
 pub struct FreeFunctions;
 
 pub struct SpanIdServer {
+    // FIXME: Report this back to the caller to track as dependencies
+    pub tracked_env_vars: HashMap<Box<str>, Option<Box<str>>>,
+    // FIXME: Report this back to the caller to track as dependencies
+    pub tracked_paths: HashSet<Box<str>>,
     pub call_site: Span,
     pub def_site: Span,
     pub mixed_site: Span,
@@ -40,8 +47,13 @@ impl server::FreeFunctions for SpanIdServer {
     fn injected_env_var(&mut self, _: &str) -> Option<std::string::String> {
         None
     }
-    fn track_env_var(&mut self, _var: &str, _value: Option<&str>) {}
-    fn track_path(&mut self, _path: &str) {}
+    fn track_env_var(&mut self, var: &str, value: Option<&str>) {
+        self.tracked_env_vars.insert(var.into(), value.map(Into::into));
+    }
+    fn track_path(&mut self, path: &str) {
+        self.tracked_paths.insert(path.into());
+    }
+
     fn literal_from_str(&mut self, s: &str) -> Result<Literal<Self::Span>, ()> {
         literal_from_str(s, self.call_site)
     }