Fix overcapturing, unsafe extern blocks, and new unsafe ops

compiler/rustc/src/main.rs

@@ -65,7 +65,7 @@ fn main() {
         // linking, so we need to explicitly depend on the function.
         #[cfg(target_os = "macos")]
         {
-            extern "C" {
+            unsafe extern "C" {
                 fn _rjem_je_zone_register();
             }
 

compiler/rustc_borrowck/src/universal_regions.rs

@@ -308,7 +308,7 @@ impl<'tcx> UniversalRegions<'tcx> {
 
     /// Returns an iterator over all the RegionVids corresponding to
     /// universally quantified free regions.
-    pub(crate) fn universal_regions_iter(&self) -> impl Iterator<Item = RegionVid> {
+    pub(crate) fn universal_regions_iter(&self) -> impl Iterator<Item = RegionVid> + use<> {
         (FIRST_GLOBAL_INDEX..self.num_universals).map(RegionVid::from_usize)
     }
 

compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs

@@ -7,7 +7,7 @@ use super::ffi::{BasicBlock, Metadata, Module, Type, Value};
 use crate::llvm::Bool;
 
 #[link(name = "llvm-wrapper", kind = "static")]
-extern "C" {
+unsafe extern "C" {
     // Enzyme
     pub(crate) fn LLVMRustHasMetadata(I: &Value, KindID: c_uint) -> bool;
     pub(crate) fn LLVMRustEraseInstUntilInclusive(BB: &BasicBlock, I: &Value);
@@ -18,7 +18,7 @@ extern "C" {
     pub(crate) fn LLVMRustVerifyFunction(V: &Value, action: LLVMRustVerifierFailureAction) -> Bool;
 }
 
-extern "C" {
+unsafe extern "C" {
     // Enzyme
     pub(crate) fn LLVMDumpModule(M: &Module);
     pub(crate) fn LLVMDumpValue(V: &Value);

compiler/rustc_data_structures/src/graph/scc/mod.rs

@@ -133,7 +133,7 @@ impl<N: Idx, S: Idx + Ord, A: Annotation> Sccs<N, S, A> {
     /// meaning that if `S1 -> S2`, we will visit `S2` first and `S1` after.
     /// This is convenient when the edges represent dependencies: when you visit
     /// `S1`, the value for `S2` will already have been computed.
-    pub fn all_sccs(&self) -> impl Iterator<Item = S> {
+    pub fn all_sccs(&self) -> impl Iterator<Item = S> + use<N, S, A> {
         (0..self.scc_data.len()).map(S::new)
     }
 

compiler/rustc_expand/src/proc_macro.rs

@@ -31,7 +31,7 @@ impl<T> pm::bridge::server::MessagePipe<T> for MessagePipe<T> {
     }
 }
 
-fn exec_strategy(ecx: &ExtCtxt<'_>) -> impl pm::bridge::server::ExecutionStrategy {
+fn exec_strategy(ecx: &ExtCtxt<'_>) -> impl pm::bridge::server::ExecutionStrategy + use<> {
     pm::bridge::server::MaybeCrossThread::<MessagePipe<_>>::new(
         ecx.sess.opts.unstable_opts.proc_macro_execution_strategy
             == ProcMacroExecutionStrategy::CrossThread,

compiler/rustc_interface/src/passes.rs

@@ -171,6 +171,7 @@ fn configure_and_expand(
                     new_path.push(path);
                 }
             }
+            unsafe {
                 env::set_var(
                     "PATH",
                     &env::join_paths(
@@ -179,6 +180,7 @@ fn configure_and_expand(
                     .unwrap(),
                 );
             }
+        }
 
         // Create the config for macro expansion
         let recursion_limit = get_recursion_limit(pre_configured_attrs, sess);
@@ -216,8 +218,10 @@ fn configure_and_expand(
         }
 
         if cfg!(windows) {
+            unsafe {
                 env::set_var("PATH", &old_path);
             }
+        }
 
         krate
     });

compiler/rustc_llvm/build.rs

@@ -51,10 +51,14 @@ fn detect_llvm_link() -> (&'static str, &'static str) {
 fn restore_library_path() {
     let key = tracked_env_var_os("REAL_LIBRARY_PATH_VAR").expect("REAL_LIBRARY_PATH_VAR");
     if let Some(env) = tracked_env_var_os("REAL_LIBRARY_PATH") {
+        unsafe {
             env::set_var(&key, env);
+        }
     } else {
+        unsafe {
             env::remove_var(&key);
         }
+    }
 }
 
 /// Reads an environment variable and adds it to dependencies.