Add generator-debug test for MSVC

..which doesn't use variant types.

Author: tmandry

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -1652,23 +1652,25 @@ impl VariantMemberDescriptionFactory<'ll, 'tcx> {
             .iter()
             .enumerate()
             .map(|(i, &(ref name, ty))| {
+                // Discriminant is always the first field of our variant
+                // when using the enum fallback.
+                let is_artificial_discr = use_enum_fallback(cx) && i == 0;
                 let (size, align) = cx.size_and_align_of(ty);
                 MemberDescription {
                     name: name.to_string(),
-                    type_metadata: if use_enum_fallback(cx) {
-                        match self.tag_type_metadata {
-                            // Discriminant is always the first field of our variant
-                            // when using the enum fallback.
-                            Some(metadata) if i == 0 => metadata,
-                            _ => type_metadata(cx, ty, self.span),
-                        }
+                    type_metadata: if is_artificial_discr {
+                        self.tag_type_metadata.unwrap_or_else(|| type_metadata(cx, ty, self.span))
                     } else {
                         type_metadata(cx, ty, self.span)
                     },
                     offset: self.offsets[i],
                     size,
                     align,
-                    flags: DIFlags::FlagZero,
+                    flags: if is_artificial_discr {
+                        DIFlags::FlagArtificial
+                    } else {
+                        DIFlags::FlagZero
+                    },
                     discriminant: None,
                     source_info: None,
                 }

src/test/codegen/generator-debug-msvc.rs

@@ -0,0 +1,88 @@
+// Verify debuginfo for generators:
+//  - Each variant points to the file and line of its yield point
+//  - The generator types and variants are marked artificial
+//  - Captured vars from the source are not marked artificial
+//
+// ignore-tidy-linelength
+// compile-flags: -C debuginfo=2 --edition=2018
+// only-msvc
+
+#![feature(generators, generator_trait)]
+use std::ops::Generator;
+
+fn generator_test() -> impl Generator<Yield = i32, Return = ()> {
+    || {
+        yield 0;
+        let s = String::from("foo");
+        yield 1;
+    }
+}
+
+async fn foo() {}
+async fn async_fn_test() {
+    foo().await;
+    let s = String::from("foo");
+    foo().await;
+}
+
+// FIXME: We need "checksum" to prevent matching with the wrong (duplicate) file
+//        metadata, even when -C codegen-units=1.
+// CHECK-DAG:  [[FILE:!.*]] = !DIFile(filename: "{{.*}}generator-debug-msvc.rs", {{.*}}, checksum:
+
+// CHECK-DAG:  [[GEN_FN:!.*]] = !DINamespace(name: "generator_test"
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "generator-0", scope: [[GEN_FN]],
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// For brevity, we just check the struct name and members of the last variant.
+// CHECK-SAME: file: [[FILE]], line: 14,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 18,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 18,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 15,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 17,
+// CHECK-SAME: baseType: [[VARIANT:![0-9]*]]
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[GEN_FN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "RUST$ENUM$DISR", scope: [[S1]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "s", scope: [[S1]]
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
+
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "generator-0", scope: [[ASYNC_FN:![0-9]*]], {{.*}}flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// For brevity, we just check the struct name and members of the last variant.
+// CHECK-SAME: file: [[FILE]], line: 22,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 26,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 26,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 23,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 25,
+// CHECK-SAME: baseType: [[VARIANT:![0-9]*]]
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[ASYNC_FN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "RUST$ENUM$DISR", scope: [[S1]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "s", scope: [[S1]]
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
+
+fn main() {
+    let _dummy = generator_test();
+    let _dummy = async_fn_test();
+}