debuginfo: Use is unsigned flag when emitting enumerators

Author: tmiasko

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -1780,14 +1780,19 @@ fn prepare_enum_metadata(
                 .zip(&def.variants)
                 .map(|((_, discr), v)| {
                     let name = v.ident.as_str();
+                    let is_unsigned = match discr.ty.kind {
+                        ty::Int(_) => false,
+                        ty::Uint(_) => true,
+                        _ => bug!("non integer discriminant"),
+                    };
                     unsafe {
                         Some(llvm::LLVMRustDIBuilderCreateEnumerator(
                             DIB(cx),
                             name.as_ptr().cast(),
                             name.len(),
                             // FIXME: what if enumeration has i128 discriminant?
                             discr.val as i64,
-                            false, // FIXME: IsUnsigned.
+                            is_unsigned,
                         ))
                     }
                 })

src/test/codegen/enum-discriminant-value.rs

@@ -0,0 +1,27 @@
+// Verify that DIEnumerator uses isUnsigned flag when appropriate.
+//
+// compile-flags: -g -C no-prepopulate-passes
+
+#[repr(i64)]
+pub enum I64 {
+    I64Min = std::i64::MIN,
+    I64Max = std::i64::MAX,
+}
+
+#[repr(u64)]
+pub enum U64 {
+    U64Min = std::u64::MIN,
+    U64Max = std::u64::MAX,
+}
+
+fn main() {
+    let _a = I64::I64Min;
+    let _b = I64::I64Max;
+    let _c = U64::U64Min;
+    let _d = U64::U64Max;
+}
+
+// CHECK: !DIEnumerator(name: "I64Min", value: -9223372036854775808)
+// CHECK: !DIEnumerator(name: "I64Max", value: 9223372036854775807)
+// CHECK: !DIEnumerator(name: "U64Min", value: 0, isUnsigned: true)
+// CHECK: !DIEnumerator(name: "U64Max", value: 18446744073709551615, isUnsigned: true)