force enum DISCR_* to const u64 to allow for inspection via LLDB's SBTypeStaticField::GetConstantValue()

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -73,6 +73,9 @@ const DW_ATE_unsigned: c_uint = 0x07;
 #[allow(non_upper_case_globals)]
 const DW_ATE_UTF: c_uint = 0x10;
 
+#[allow(non_upper_case_globals)]
+const DW_TAG_const_type: c_uint = 0x26;
+
 pub(super) const UNKNOWN_LINE_NUMBER: c_uint = 0;
 pub(super) const UNKNOWN_COLUMN_NUMBER: c_uint = 0;
 

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

@@ -15,9 +15,9 @@ use crate::common::{AsCCharPtr, CodegenCx};
 use crate::debuginfo::metadata::enums::DiscrResult;
 use crate::debuginfo::metadata::type_map::{self, Stub, UniqueTypeId};
 use crate::debuginfo::metadata::{
-    DINodeCreationResult, NO_GENERICS, NO_SCOPE_METADATA, SmallVec, UNKNOWN_LINE_NUMBER,
+    DINodeCreationResult, DW_TAG_const_type, NO_GENERICS, NO_SCOPE_METADATA, SmallVec,
-    build_field_di_node, file_metadata, file_metadata_from_def_id, size_and_align_of, type_di_node,
+    UNKNOWN_LINE_NUMBER, build_field_di_node, file_metadata, file_metadata_from_def_id,
-    unknown_file_metadata, visibility_di_flags,
+    size_and_align_of, type_di_node, unknown_file_metadata, visibility_di_flags,
 };
 use crate::debuginfo::utils::DIB;
 use crate::llvm::debuginfo::{DIFile, DIFlags, DIType};
@@ -566,8 +566,25 @@ fn build_variant_struct_wrapper_type_di_node<'ll, 'tcx>(
                 None,
             ));
 
-            let build_assoc_const =
+            let build_assoc_const = |name: &str,
-                |name: &str, type_di_node: &'ll DIType, value: u64, align: Align| unsafe {
+                                     type_di_node_: &'ll DIType,
+                                     value: u64,
+                                     align: Align| unsafe {
+                // FIXME: Currently we force all DISCR_* values to be u64's as LLDB seems to have
+                // problems inspecting other value types. Since DISCR_* is typically only going to be
+                // directly inspected via the debugger visualizer - which compares it to the `tag` value
+                // (whose type is not modified at all) it shouldn't cause any real problems.
+                let (t_di, align) = if name == ASSOC_CONST_DISCR_NAME {
+                    (type_di_node_, align.bits() as u32)
+                } else {
+                    let ty_u64 = Ty::new_uint(cx.tcx, ty::UintTy::U64);
+                    (type_di_node(cx, ty_u64), Align::EIGHT.bits() as u32)
+                };
+
+                // must wrap type in a `const` modifier for LLDB to be able to inspect the value of the member
+                let field_type =
+                    llvm::LLVMRustDIBuilderCreateQualifiedType(DIB(cx), DW_TAG_const_type, t_di);
+
                 llvm::LLVMRustDIBuilderCreateStaticMemberType(
                     DIB(cx),
                     wrapper_struct_type_di_node,
@@ -575,10 +592,10 @@ fn build_variant_struct_wrapper_type_di_node<'ll, 'tcx>(
                     name.len(),
                     unknown_file_metadata(cx),
                     UNKNOWN_LINE_NUMBER,
-                        type_di_node,
+                    field_type,
                     DIFlags::FlagZero,
                     Some(cx.const_u64(value)),
-                        align.bits() as u32,
+                    align,
                 )
             };
 

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1143,8 +1143,8 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateStaticMemberType(
 extern "C" LLVMMetadataRef
 LLVMRustDIBuilderCreateQualifiedType(LLVMDIBuilderRef Builder, unsigned Tag,
                                      LLVMMetadataRef Type) {
-  return wrap(unwrap(Builder)->createQualifiedType(Tag,
+  return wrap(
-                                                   unwrapDI<DIType>(Type)));
+      unwrap(Builder)->createQualifiedType(Tag, unwrapDI<DIType>(Type)));
 }
 
 extern "C" LLVMMetadataRef