Add support for `--env` on `tracked_env::var`

3 files changed, 7 insertions, 1 deletions

diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 5308e338d7f..523e0eda40e 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -426,6 +426,10 @@ impl server::Types for Rustc<'_, '_> {
 }
 
 impl server::FreeFunctions for Rustc<'_, '_> {
+    fn injected_env_var(&mut self, var: &str) -> Option<String> {
+        self.ecx.sess.opts.logical_env.get(var).cloned()
+    }
+
     fn track_env_var(&mut self, var: &str, value: Option<&str>) {
         self.sess()
             .env_depinfo
diff --git a/library/proc_macro/src/bridge/mod.rs b/library/proc_macro/src/bridge/mod.rs
index 86ce5d9c6d5..75bf3329786 100644
--- a/library/proc_macro/src/bridge/mod.rs
+++ b/library/proc_macro/src/bridge/mod.rs
@@ -55,6 +55,7 @@ macro_rules! with_api {
         $m! {
             FreeFunctions {
                 fn drop($self: $S::FreeFunctions);
+                fn injected_env_var(var: &str) -> Option<String>;
                 fn track_env_var(var: &str, value: Option<&str>);
                 fn track_path(path: &str);
                 fn literal_from_str(s: &str) -> Result<Literal<$S::Span, $S::Symbol>, ()>;
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index 7ebb6810b3e..6e664a162df 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -1503,7 +1503,8 @@ pub mod tracked_env {
     #[unstable(feature = "proc_macro_tracked_env", issue = "99515")]
     pub fn var<K: AsRef<OsStr> + AsRef<str>>(key: K) -> Result<String, VarError> {
         let key: &str = key.as_ref();
-        let value = env::var(key);
+        let value = crate::bridge::client::FreeFunctions::injected_env_var(key)
+            .map_or_else(|| env::var(key), Ok);
         crate::bridge::client::FreeFunctions::track_env_var(key, value.as_deref().ok());
         value
     }