[clang][ExtractAPI]Fix Declaration fragments for instancetype in the type position degrade to id

[chaitanyav]

Summary

Fixes https://github.com/llvm/llvm-project/issues/61481

[dang]

LGTM, but you should also check in the test that id still renders as expected.

[chaitanyav]

Will update the test to also include a Id instance method.

[chaitanyav]

update test to check for id type

[chaitanyav]

@dang Please review the test/output.

[dang]

Yup looks fine to me!

clang/lib/ExtractAPI/DeclarationFragments.cpp

if (const ElaboratedType *ET = dyn_cast<ElaboratedType>(T)) {
     if (const NestedNameSpecifier *NNS = ET->getQualifier())
       Fragments.append(getFragmentsForNNS(NNS, Context, After));
 
     // After handling the elaborated keyword or qualified name, build
     // declaration fragments for the desugared underlying type.
     return Fragments.append(getFragmentsForType(ET->desugar(), Context, After));
   }
 
-  // Everything we care about has been handled now, reduce to the canonical
-  // unqualified base type.
-  QualType Base = T->getCanonicalTypeUnqualified();
-
-  // Render Objective-C `id`/`instancetype` as keywords.
-  if (T->isObjCIdType())
-    return Fragments.append(Base.getAsString(),
-                            DeclarationFragments::FragmentKind::Keyword);
-
   // If the type is a typedefed type, get the underlying TypedefNameDecl for a
   // direct reference to the typedef instead of the wrapped type.
+
+  // 'id' type is a typedef for an ObjCObjectPointerType
+  //  we treat it as a typedef
   if (const TypedefType *TypedefTy = dyn_cast<TypedefType>(T)) {
     const TypedefNameDecl *Decl = TypedefTy->getDecl();
     TypedefUnderlyingTypeResolver TypedefResolver(Context);
     std::string USR = TypedefResolver.getUSRForType(QualType(T, 0));
+
+    if (T->isObjCIdType()) {
+      return Fragments.append(Decl->getName(),
+                              DeclarationFragments::FragmentKind::Keyword);
+    }
+
     return Fragments.append(
         Decl->getName(), DeclarationFragments::FragmentKind::TypeIdentifier,
         USR, TypedefResolver.getUnderlyingTypeDecl(QualType(T, 0)));
   }
 
+  // Everything we care about has been handled now, reduce to the canonical
+  // unqualified base type.
+  QualType Base = T->getCanonicalTypeUnqualified();
+
   // If the base type is a TagType (struct/interface/union/class/enum), let's
   // get the underlying Decl for better names and USRs.
   if (const TagType *TagTy = dyn_cast<TagType>(Base)) {
     const TagDecl *Decl = TagTy->getDecl();
     // Anonymous decl, skip this fragment.
     if (Decl->getName().empty())
       return Fragments;
     SmallString<128> TagUSR;

clang/test/ExtractAPI/objc_instancetype.m

+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s@INPUT_DIR@%{/t:regex_replacement}@g" \
+             // RUN: %t/reference.output.json.in >> %t/reference.output.json
+// RUN: %clang_cc1 -extract-api -triple arm64-apple-macosx -x objective-c-header %t/input.h -o %t/output.json -verify
+
+// Generator version is not consistent across test runs, normalize it.
+// RUN: sed -e "s@\"generator\": \".*\"@\"generator\": \"?\"@g" \
+             // RUN: %t/output.json >> %t/output-normalized.json
+// RUN: diff %t/reference.output.json %t/output-normalized.json
+
+
+//--- input.h
+@interface Foo
+- (instancetype) init;
+- (id) reset;
+@end
+// expected-no-diagnostics
+
+
+//--- reference.output.json.in
+{
+  "metadata": {
+    "formatVersion": {
+      "major": 0,
+      "minor": 5,
+      "patch": 3
+    },
+    "generator": "?"
+  },
+  "module": {
+    "name": "",
+    "platform": {
+      "architecture": "arm64",
+      "operatingSystem": {
+        "minimumVersion": {
+          "major": 11,
+          "minor": 0,
+          "patch": 0
+        },
+        "name": "macosx"
+      },
+      "vendor": "apple"
+    }
+  },
+  "relationships": [
+    {
+      "kind": "memberOf",
+      "source": "c:objc(cs)Foo(im)init",
+      "target": "c:objc(cs)Foo",
+      "targetFallback": "Foo"
+    },
+    {
+      "kind": "memberOf",
+      "source": "c:objc(cs)Foo(im)reset",
+      "target": "c:objc(cs)Foo",
+      "targetFallback": "Foo"
+    }
+  ],
+  "symbols": [
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "keyword",
+          "spelling": "@interface"
+        },
+        {
+          "kind": "text",
+          "spelling": " "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "Foo"
+        }
+      ],
+      "identifier": {
+        "interfaceLanguage": "objective-c",
+        "precise": "c:objc(cs)Foo"
+      },
+      "kind": {
+        "displayName": "Class",
+        "identifier": "objective-c.class"
+      },
+      "location": {
+        "position": {
+          "character": 12,
+          "line": 1
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "Foo"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "identifier",
+            "spelling": "Foo"
+          }
+        ],
+        "title": "Foo"
+      },
+      "pathComponents": [
+        "Foo"
+      ]
+    },
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "text",
+          "spelling": "- ("
+        },
+        {
+          "kind": "keyword",
+          "spelling": "instancetype"
+        },
+        {
+          "kind": "text",
+          "spelling": ") "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "init"
+        },
+        {
+          "kind": "text",
+          "spelling": ";"
+        }
+      ],
+      "functionSignature": {
+        "returns": [
+          {
+            "kind": "keyword",
+            "spelling": "instancetype"
+          }
+        ]
+      },
+      "identifier": {
+        "interfaceLanguage": "objective-c",
+        "precise": "c:objc(cs)Foo(im)init"
+      },
+      "kind": {
+        "displayName": "Instance Method",
+        "identifier": "objective-c.method"
+      },
+      "location": {
+        "position": {
+          "character": 1,
+          "line": 2
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "init"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "text",
+            "spelling": "- "
+          },
+          {
+            "kind": "identifier",
+            "spelling": "init"
+          }
+        ],
+        "title": "init"
+      },
+      "pathComponents": [
+        "Foo",
+        "init"
+      ]
+    },
+    {
+      "accessLevel": "public",
+      "declarationFragments": [
+        {
+          "kind": "text",
+          "spelling": "- ("
+        },
+        {
+          "kind": "keyword",
+          "spelling": "id"
+        },
+        {
+          "kind": "text",
+          "spelling": ") "
+        },
+        {
+          "kind": "identifier",
+          "spelling": "reset"
+        },
+        {
+          "kind": "text",
+          "spelling": ";"
+        }
+      ],
+      "functionSignature": {
+        "returns": [
+          {
+            "kind": "keyword",
+            "spelling": "id"
+          }
+        ]
+      },
+      "identifier": {
+        "interfaceLanguage": "objective-c",
+        "precise": "c:objc(cs)Foo(im)reset"
+      },
+      "kind": {
+        "displayName": "Instance Method",
+        "identifier": "objective-c.method"
+      },
+      "location": {
+        "position": {
+          "character": 1,
+          "line": 3
+        },
+        "uri": "file://INPUT_DIR/input.h"
+      },
+      "names": {
+        "navigator": [
+          {
+            "kind": "identifier",
+            "spelling": "reset"
+          }
+        ],
+        "subHeading": [
+          {
+            "kind": "text",
+            "spelling": "- "
+          },
+          {
+            "kind": "identifier",
+            "spelling": "reset"
+          }
+        ],
+        "title": "reset"
+      },
+      "pathComponents": [
+        "Foo",
+        "reset"
+      ]
+    }
+  ]
+}