Addresses #948

Fixes an issue where we would rewrite structs and their fields
even though they appear in extern blocks.

Author: aneksteind

c2rust-analyze/src/context.rs

@@ -25,7 +25,7 @@ use rustc_middle::ty::{
     tls, AdtDef, FieldDef, GenericArgKind, GenericParamDefKind, Ty, TyCtxt, TyKind,
 };
 use rustc_type_ir::RegionKind::{ReEarlyBound, ReStatic};
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::fmt::Debug;
 use std::ops::Index;
 
@@ -287,6 +287,8 @@ pub struct GlobalAnalysisCtxt<'tcx> {
     pub addr_of_static: HashMap<DefId, PointerId>,
 
     pub adt_metadata: AdtMetadataTable<'tcx>,
+
+    pub foreign_mentioned_tys: HashSet<Ty<'tcx>>,
 }
 
 pub struct AnalysisCtxt<'a, 'tcx> {
@@ -536,6 +538,7 @@ impl<'tcx> GlobalAnalysisCtxt<'tcx> {
             static_tys: HashMap::new(),
             addr_of_static: HashMap::new(),
             adt_metadata: construct_adt_metadata(tcx),
+            foreign_mentioned_tys: HashSet::new(),
         }
     }
 
@@ -582,6 +585,7 @@ impl<'tcx> GlobalAnalysisCtxt<'tcx> {
             ref mut static_tys,
             ref mut addr_of_static,
             adt_metadata: _,
+            foreign_mentioned_tys: _,
         } = *self;
 
         *ptr_info = remap_global_ptr_info(ptr_info, map, counter.num_pointers());

c2rust-analyze/src/main.rs

@@ -474,6 +474,24 @@ fn run(tcx: TyCtxt) {
                 || info.contains(PointerInfo::NOT_TEMPORARY_REF))
     }
 
+    // track all types mentioned in extern blocks, we
+    // don't want to rewrite those
+    let mut foreign_mentioned_tys = HashSet::new();
+    for item in tcx.hir_crate_items(()).foreign_items() {
+        let ldid = item.def_id.to_def_id();
+        match tcx.def_kind(ldid) {
+            DefKind::Fn | DefKind::AssocFn => {
+                let sig = tcx.fn_sig(ldid);
+                let sig = tcx.erase_late_bound_regions(sig);
+                for ty in sig.inputs_and_output {
+                    foreign_mentioned_tys.insert(ty);
+                }
+            }
+            _ => continue,
+        }
+    }
+    gacx.foreign_mentioned_tys = foreign_mentioned_tys;
+
     let mut gasn =
         GlobalAssignment::new(gacx.num_pointers(), PermissionSet::UNIQUE, FlagSet::empty());
     for (ptr, &info) in gacx.ptr_info().iter() {
@@ -482,6 +500,24 @@ fn run(tcx: TyCtxt) {
         }
     }
 
+    // FIX the fields of structs mentioned in extern blocks
+    for adt_did in &gacx.adt_metadata.struct_dids {
+        let ty = &tcx.type_of(adt_did);
+        if gacx.foreign_mentioned_tys.contains(ty) {
+            if let TyKind::Adt(adt_def, _) = tcx.type_of(adt_did).kind() {
+                let fields = &adt_def.non_enum_variant().fields;
+                for field in fields {
+                    let field_lty = gacx.field_ltys[&field.did];
+                    eprintln!(
+                        "adding FIX permission for {adt_did:?} field {:?}",
+                        field.did
+                    );
+                    make_ty_fixed(&mut gasn, field_lty);
+                }
+            }
+        }
+    }
+
     for info in func_info.values_mut() {
         let num_pointers = info.acx_data.num_pointers();
         let mut lasn = LocalAssignment::new(num_pointers, PermissionSet::UNIQUE, FlagSet::empty());

c2rust-analyze/src/rewrite/ty.rs

@@ -473,6 +473,15 @@ impl<'a, 'tcx> intravisit::Visitor<'tcx> for HirTyVisitor<'a, 'tcx> {
         #[allow(clippy::single_match)]
         match &item.kind {
             ItemKind::Struct(VariantData::Struct(field_defs, _), generics) => {
+                if self
+                    .acx
+                    .gacx
+                    .foreign_mentioned_tys
+                    .contains(&self.acx.tcx().type_of(did))
+                {
+                    eprintln!("Avoiding rewrite for foreign-mentioned type: {did:?}");
+                    return;
+                }
                 let adt_metadata = &self.acx.gacx.adt_metadata.table[&did];
                 let updated_lifetime_params = &adt_metadata.lifetime_params;
 
@@ -538,16 +547,14 @@ impl<'a, 'tcx> intravisit::Visitor<'tcx> for HirTyVisitor<'a, 'tcx> {
                         f_lty,
                         field_metadata.origin_args,
                         &mut |pointer_lty, lifetime_lty, args| {
-                            {
-                                create_rewrite_label(
-                                    pointer_lty,
-                                    args,
-                                    &self.asn.perms(),
-                                    &self.asn.flags(),
-                                    lifetime_lty.label,
-                                    &self.acx.gacx.adt_metadata,
-                                )
-                            }
+                            create_rewrite_label(
+                                pointer_lty,
+                                args,
+                                &self.asn.perms(),
+                                &self.asn.flags(),
+                                lifetime_lty.label,
+                                &self.acx.gacx.adt_metadata,
+                            )
                         },
                     );
 

c2rust-analyze/tests/filecheck.rs

@@ -48,6 +48,7 @@ define_tests! {
     fields,
     field_temp,
     fixed,
+    foreign,
     insertion_sort,
     insertion_sort_driver,
     insertion_sort_rewrites,

c2rust-analyze/tests/filecheck/foreign.rs

@@ -0,0 +1,25 @@
+extern "Rust" {
+    fn foo(bar: Alias) -> Baz;
+}
+
+type Alias = Bar;
+
+// CHECK-DAG: p: (g1) perms = UNIQUE, flags = FIXED
+// CHECK-DAG: p: (g2) perms = UNIQUE, flags = FIXED
+
+// CHECK-DAG: struct Bar
+struct Bar {
+    // CHECK-DAG: p: *mut i32
+    p: *mut i32
+}
+
+// CHECK-DAG: struct Baz
+struct Baz {
+    // CHECK-DAG: p: *mut i32
+    p: *mut i32
+}
+
+// we need something to get rewritten in order
+// to check that `Bar` and `Baz` get output
+// in the rewrite string
+fn fizz(i: *const i32) {}