Add hypothetical lifetime to structure rewrites with empty generic type parameter lists

c2rust-analyze/src/rewrite/ty.rs

@@ -120,7 +120,9 @@ where
     })
 }
 
-fn hir_generic_ty_args<'tcx>(ty: &hir::Ty<'tcx>) -> Option<Vec<&'tcx hir::Ty<'tcx>>> {
+// Gets the generic type arguments of an HIR type. If the type has no generic
+// arguments, an empty vector is returned
+fn hir_generic_ty_args<'tcx>(ty: &hir::Ty<'tcx>) -> Vec<&'tcx hir::Ty<'tcx>> {
     let args = match ty.kind {
         hir::TyKind::Path(hir::QPath::Resolved(
             _,
@@ -140,6 +142,7 @@ fn hir_generic_ty_args<'tcx>(ty: &hir::Ty<'tcx>) -> Option<Vec<&'tcx hir::Ty<'tc
             })
             .collect()
     })
+    .unwrap_or_default()
 }
 
 /// Extract arguments from `hir_ty` if it corresponds to the tcx type `ty`.  If the two types
@@ -205,19 +208,18 @@ fn deconstruct_hir_ty<'a, 'tcx>(
         }
 
         (&ty::TyKind::Adt(adt_def, substs), &hir::TyKind::Path(..)) => {
-            hir_generic_ty_args(hir_ty).map(|type_args| {
-                if type_args.len() < substs.types().count() {
-                    // this situation occurs when there are hidden type arguments
-                    // such as the allocator `std::alloc::Global` type argument in `Vec`
-                    eprintln!("warning: extra MIR type argument for {adt_def:?}:");
-                    for mir_arg in substs.types().into_iter().skip(type_args.len()) {
-                        eprintln!("\t{:?}", mir_arg)
-                    }
-                } else if type_args.len() != substs.types().count() {
-                    panic!("mismatched number of type arguments for {adt_def:?} and {hir_ty:?}")
+            let type_args = hir_generic_ty_args(hir_ty);
+            if type_args.len() < substs.types().count() {
+                // this situation occurs when there are hidden type arguments
+                // such as the allocator `std::alloc::Global` type argument in `Vec`
+                eprintln!("warning: extra MIR type argument for {adt_def:?}:");
+                for mir_arg in substs.types().into_iter().skip(type_args.len()) {
+                    eprintln!("\t{:?}", mir_arg)
                 }
-                type_args
-            })
+            } else if type_args.len() != substs.types().count() {
+                panic!("mismatched number of type arguments for {adt_def:?} and {hir_ty:?}")
+            }
+            Some(type_args)
         }
         (tk, hir_tk) => {
             eprintln!("deconstruct_hir_ty: {tk:?} -- {hir_tk:?} not supported");

c2rust-analyze/tests/filecheck/fields.rs

@@ -35,6 +35,14 @@ struct VecTup<'a> {
     bar: *mut Vec<(VecTup<'a>, *mut A<'a>)>,
 }
 
+struct Hypo {
+    h: *mut i32
+}
+
+struct HypoWrapper {
+    hw: *const Hypo
+}
+
 // let rd = (*(**ppd).a.pra).rd
 // CHECK-DAG: Label { origin: Some(Origin([[REF_D_ORIGIN:[0-9]+]])), origin_params: []{{.*}}}#&'a Data
 // CHECK-DAG: Label { origin: None, origin_params: [('d, Origin([[REF_D_ORIGIN]]){{.*}}}#Data
@@ -79,3 +87,6 @@ unsafe fn _field_access<'d>(ra: &'d mut A<'d>, ppd: *mut *mut Data<'d>) {
 // CHECK-DAG: pub rd: &'a Data<'a,'h0,'h1,'h2>,
 // CHECK-DAG: pub pra: &'h2 core::cell::Cell<(&'a mut A<'a,'h0,'h1,'h2>)>,
 // CHECK-DAG: bar: &'h3 (Vec<(VecTup<'a,'h3,'h4,'h0,'h1,'h2>, &'h4 (A<'a,'h0,'h1,'h2>))>),
+
+// CHECK-DAG: struct HypoWrapper<'h6,'h5>
+// CHECK-DAG: hw: &'h6 (Hypo<'h5>)