codegen_llvm: set DW_AT_accessibility

Sets the accessibility of types and fields in DWARF using
`DW_AT_accessibility` attribute.

`DW_AT_accessibility` (public/protected/private) isn't exactly right for
Rust,  but neither is `DW_AT_visibility` (local/exported/qualified), and
there's no way to set `DW_AT_visbility` in LLVM's API.

Signed-off-by: David Wood <david@davidtw.co>

Author: davidtwco

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -922,6 +922,27 @@ fn build_field_di_node<'ll, 'tcx>(
     }
 }
 
+/// Returns the `DIFlags` corresponding to the visibility of the item identified by `did`.
+///
+/// `DIFlags::Flag{Public,Protected,Private}` correspond to `DW_AT_accessibility`
+/// (public/protected/private) aren't exactly right for Rust, but neither is `DW_AT_visibility`
+/// (local/exported/qualified), and there's no way to set `DW_AT_visibility` in LLVM's API.
+fn visibility_di_flags<'ll, 'tcx>(
+    cx: &CodegenCx<'ll, 'tcx>,
+    did: DefId,
+    type_did: DefId,
+) -> DIFlags {
+    let parent_did = cx.tcx.parent(type_did);
+    let visibility = cx.tcx.visibility(did);
+    match visibility {
+        Visibility::Public => DIFlags::FlagPublic,
+        // Private fields have a restricted visibility of the module containing the type.
+        Visibility::Restricted(did) if did == parent_did => DIFlags::FlagPrivate,
+        // `pub(crate)`/`pub(super)` visibilities are any other restricted visibility.
+        Visibility::Restricted(..) => DIFlags::FlagProtected,
+    }
+}
+
 /// Creates the debuginfo node for a Rust struct type. Maybe be a regular struct or a tuple-struct.
 fn build_struct_type_di_node<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
@@ -945,7 +966,7 @@ fn build_struct_type_di_node<'ll, 'tcx>(
             &compute_debuginfo_type_name(cx.tcx, struct_type, false),
             size_and_align_of(struct_type_and_layout),
             Some(containing_scope),
-            DIFlags::FlagZero,
+            visibility_di_flags(cx, adt_def.did(), adt_def.did()),
         ),
         // Fields:
         |cx, owner| {
@@ -968,7 +989,7 @@ fn build_struct_type_di_node<'ll, 'tcx>(
                         &field_name[..],
                         (field_layout.size, field_layout.align.abi),
                         struct_type_and_layout.fields.offset(i),
-                        DIFlags::FlagZero,
+                        visibility_di_flags(cx, f.did, adt_def.did()),
                         type_di_node(cx, field_layout.ty),
                     )
                 })

compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs

@@ -26,8 +26,8 @@ use crate::{
             enums::{tag_base_type, DiscrResult},
             file_metadata, size_and_align_of, type_di_node,
             type_map::{self, Stub, UniqueTypeId},
-            unknown_file_metadata, DINodeCreationResult, SmallVec, NO_GENERICS, NO_SCOPE_METADATA,
-            UNKNOWN_LINE_NUMBER,
+            unknown_file_metadata, visibility_di_flags, DINodeCreationResult, SmallVec,
+            NO_GENERICS, NO_SCOPE_METADATA, UNKNOWN_LINE_NUMBER,
         },
         utils::DIB,
     },
@@ -215,7 +215,7 @@ pub(super) fn build_enum_type_di_node<'ll, 'tcx>(
             &enum_type_name,
             cx.size_and_align_of(enum_type),
             NO_SCOPE_METADATA,
-            DIFlags::FlagZero,
+            visibility_di_flags(cx, enum_adt_def.did(), enum_adt_def.did()),
         ),
         |cx, enum_type_di_node| {
             match enum_type_and_layout.variants {
@@ -320,13 +320,15 @@ fn build_single_variant_union_fields<'ll, 'tcx>(
     variant_index: VariantIdx,
 ) -> SmallVec<&'ll DIType> {
     let variant_layout = enum_type_and_layout.for_variant(cx, variant_index);
+    let visibility_flags = visibility_di_flags(cx, enum_adt_def.did(), enum_adt_def.did());
     let variant_struct_type_di_node = super::build_enum_variant_struct_type_di_node(
         cx,
         enum_type_and_layout,
         enum_type_di_node,
         variant_index,
         enum_adt_def.variant(variant_index),
         variant_layout,
+        visibility_flags,
     );
 
     let tag_base_type = cx.tcx.types.u32;
@@ -364,7 +366,7 @@ fn build_single_variant_union_fields<'ll, 'tcx>(
             //       since the later is sometimes smaller (if it has fewer fields).
             size_and_align_of(enum_type_and_layout),
             Size::ZERO,
-            DIFlags::FlagZero,
+            visibility_flags,
             variant_struct_type_wrapper_di_node,
         ),
         unsafe {
@@ -376,7 +378,7 @@ fn build_single_variant_union_fields<'ll, 'tcx>(
                 unknown_file_metadata(cx),
                 UNKNOWN_LINE_NUMBER,
                 variant_names_type_di_node,
-                DIFlags::FlagZero,
+                visibility_flags,
                 Some(cx.const_u64(SINGLE_VARIANT_VIRTUAL_DISR)),
                 tag_base_type_align.bits() as u32,
             )
@@ -403,6 +405,7 @@ fn build_union_fields_for_enum<'ll, 'tcx>(
             (variant_index, variant_name)
         }),
     );
+    let visibility_flags = visibility_di_flags(cx, enum_adt_def.did(), enum_adt_def.did());
 
     let variant_field_infos: SmallVec<VariantFieldInfo<'ll>> = variant_indices
         .map(|variant_index| {
@@ -417,6 +420,7 @@ fn build_union_fields_for_enum<'ll, 'tcx>(
                 variant_index,
                 variant_def,
                 variant_layout,
+                visibility_flags,
             );
 
             VariantFieldInfo {
@@ -437,6 +441,7 @@ fn build_union_fields_for_enum<'ll, 'tcx>(
         tag_base_type,
         tag_field,
         untagged_variant_index,
+        visibility_flags,
     )
 }
 
@@ -744,6 +749,7 @@ fn build_union_fields_for_direct_tag_generator<'ll, 'tcx>(
         tag_base_type,
         tag_field,
         None,
+        DIFlags::FlagZero,
     )
 }
 
@@ -758,6 +764,7 @@ fn build_union_fields_for_direct_tag_enum_or_generator<'ll, 'tcx>(
     tag_base_type: Ty<'tcx>,
     tag_field: usize,
     untagged_variant_index: Option<VariantIdx>,
+    di_flags: DIFlags,
 ) -> SmallVec<&'ll DIType> {
     let tag_base_type_di_node = type_di_node(cx, tag_base_type);
     let mut unions_fields = SmallVec::with_capacity(variant_field_infos.len() + 1);
@@ -801,7 +808,7 @@ fn build_union_fields_for_direct_tag_enum_or_generator<'ll, 'tcx>(
                 align.bits() as u32,
                 // Union fields are always at offset zero
                 Size::ZERO.bits(),
-                DIFlags::FlagZero,
+                di_flags,
                 variant_struct_type_wrapper,
             )
         }
@@ -835,7 +842,7 @@ fn build_union_fields_for_direct_tag_enum_or_generator<'ll, 'tcx>(
             TAG_FIELD_NAME_128_LO,
             size_and_align,
             lo_offset,
-            DIFlags::FlagZero,
+            di_flags,
             type_di_node,
         ));
 
@@ -855,7 +862,7 @@ fn build_union_fields_for_direct_tag_enum_or_generator<'ll, 'tcx>(
             TAG_FIELD_NAME,
             cx.size_and_align_of(enum_type_and_layout.field(cx, tag_field).ty),
             enum_type_and_layout.fields.offset(tag_field),
-            DIFlags::FlagZero,
+            di_flags,
             tag_base_type_di_node,
         ));
     }

compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/mod.rs

@@ -250,6 +250,7 @@ fn build_enum_variant_struct_type_di_node<'ll, 'tcx>(
     variant_index: VariantIdx,
     variant_def: &VariantDef,
     variant_layout: TyAndLayout<'tcx>,
+    di_flags: DIFlags,
 ) -> &'ll DIType {
     debug_assert_eq!(variant_layout.ty, enum_type_and_layout.ty);
 
@@ -267,7 +268,7 @@ fn build_enum_variant_struct_type_di_node<'ll, 'tcx>(
             // NOTE: We use size and align of enum_type, not from variant_layout:
             size_and_align_of(enum_type_and_layout),
             Some(enum_type_di_node),
-            DIFlags::FlagZero,
+            di_flags,
         ),
         |cx, struct_type_di_node| {
             (0..variant_layout.fields.count())
@@ -289,7 +290,7 @@ fn build_enum_variant_struct_type_di_node<'ll, 'tcx>(
                         &field_name,
                         (field_layout.size, field_layout.align.abi),
                         variant_layout.fields.offset(field_index),
-                        DIFlags::FlagZero,
+                        di_flags,
                         type_di_node(cx, field_layout.ty),
                     )
                 })

compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/native.rs

@@ -7,8 +7,8 @@ use crate::{
             enums::tag_base_type,
             file_metadata, size_and_align_of, type_di_node,
             type_map::{self, Stub, StubInfo, UniqueTypeId},
-            unknown_file_metadata, DINodeCreationResult, SmallVec, NO_GENERICS,
-            UNKNOWN_LINE_NUMBER,
+            unknown_file_metadata, visibility_di_flags, DINodeCreationResult, SmallVec,
+            NO_GENERICS, UNKNOWN_LINE_NUMBER,
         },
         utils::{create_DIArray, get_namespace_for_item, DIB},
     },
@@ -63,6 +63,8 @@ pub(super) fn build_enum_type_di_node<'ll, 'tcx>(
     let enum_type_and_layout = cx.layout_of(enum_type);
     let enum_type_name = compute_debuginfo_type_name(cx.tcx, enum_type, false);
 
+    let visibility_flags = visibility_di_flags(cx, enum_adt_def.did(), enum_adt_def.did());
+
     debug_assert!(!wants_c_like_enum_debuginfo(enum_type_and_layout));
 
     type_map::build_type_with_children(
@@ -74,7 +76,7 @@ pub(super) fn build_enum_type_di_node<'ll, 'tcx>(
             &enum_type_name,
             size_and_align_of(enum_type_and_layout),
             Some(containing_scope),
-            DIFlags::FlagZero,
+            visibility_flags,
         ),
         |cx, enum_type_di_node| {
             // Build the struct type for each variant. These will be referenced by the
@@ -92,6 +94,7 @@ pub(super) fn build_enum_type_di_node<'ll, 'tcx>(
                         variant_index,
                         enum_adt_def.variant(variant_index),
                         enum_type_and_layout.for_variant(cx, variant_index),
+                        visibility_flags,
                     ),
                     source_info: None,
                 })

tests/codegen/debug-accessibility.rs

@@ -0,0 +1,121 @@
+// compile-flags: -C debuginfo=2
+
+#![allow(dead_code)]
+
+// Checks that visibility information is present in the debuginfo for types and their fields.
+
+use std::hint::black_box;
+
+mod fields {
+    use super::black_box;
+
+    struct StructFields {
+        a: u32,
+        pub(crate) b: u32,
+        pub(super) c: u32,
+        pub d: u32,
+    }
+
+    // CHECK: [[StructFields:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "StructFields"{{.*}}flags: DIFlagPrivate{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: [[StructFields]]{{.*}}flags: DIFlagPrivate{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: [[StructFields]]{{.*}}flags: DIFlagProtected{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "c", scope: [[StructFields]]{{.*}}flags: DIFlagProtected{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "d", scope: [[StructFields]]{{.*}}flags: DIFlagPublic{{.*}})
+
+    struct TupleFields(u32, pub(crate) u32, pub(super) u32, pub u32);
+
+    // CHECK: [[TupleFields:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "TupleFields"{{.*}}flags: DIFlagPrivate{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: [[TupleFields]]{{.*}}flags: DIFlagPrivate{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "__1", scope: [[TupleFields]]{{.*}}flags: DIFlagProtected{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "__2", scope: [[TupleFields]]{{.*}}flags: DIFlagProtected{{.*}})
+    // CHECK: {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "__3", scope: [[TupleFields]]{{.*}}flags: DIFlagPublic{{.*}})
+
+    pub fn use_everything() {
+        black_box(StructFields { a: 1, b: 2, c: 3, d: 4 });
+        black_box(TupleFields(1, 2, 3, 4));
+    }
+}
+
+mod structs {
+    use super::black_box;
+
+    struct PrivateFooStruct {
+        x: u32,
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "PrivateFooStruct"{{.*}}flags: DIFlagPrivate{{.*}})
+
+    pub(crate) struct CrateFooStruct {
+        x: u32,
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "CrateFooStruct"{{.*}}flags: DIFlagProtected{{.*}})
+
+    pub(super) struct SuperFooStruct {
+        x: u32,
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "SuperFooStruct"{{.*}}flags: DIFlagProtected{{.*}})
+
+    pub struct PublicFooStruct {
+        x: u32,
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "PublicFooStruct"{{.*}}flags: DIFlagPublic{{.*}})
+
+    pub fn use_everything() {
+        black_box(PrivateFooStruct { x: 1 });
+        black_box(CrateFooStruct { x: 2 });
+        black_box(SuperFooStruct { x: 3 });
+        black_box(PublicFooStruct { x: 4 });
+    }
+}
+
+mod enums {
+    use super::black_box;
+
+    enum PrivateFooEnum {
+        A,
+        B(u32),
+        C { x: u32 },
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "PrivateFooEnum"{{.*}}flags: DIFlagPrivate{{.*}})
+
+    pub(crate) enum CrateFooEnum {
+        A,
+        B(u32),
+        C { x: u32 },
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "CrateFooEnum"{{.*}}flags: DIFlagProtected{{.*}})
+
+    pub(super) enum SuperFooEnum {
+        A,
+        B(u32),
+        C { x: u32 },
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "SuperFooEnum"{{.*}}flags: DIFlagProtected{{.*}})
+
+    pub enum PublicFooEnum {
+        A,
+        B(u32),
+        C { x: u32 },
+    }
+
+    // CHECK: {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "PublicFooEnum"{{.*}}flags: DIFlagPublic{{.*}})
+
+    pub fn use_everything() {
+        black_box(PrivateFooEnum::A);
+        black_box(CrateFooEnum::A);
+        black_box(SuperFooEnum::A);
+        black_box(PublicFooEnum::A);
+    }
+}
+
+fn main() {
+    fields::use_everything();
+    structs::use_everything();
+    enums::use_everything();
+}