add documentation category to the symbol graph

Author: QuietMisdreavus

docs/ReferenceGuides/UnderscoredAttributes.md

@@ -119,7 +119,8 @@ extension Text {
 
 ## `@_documentation(...)`
 
-Adds a "documentation category" to the given symbol.
+Adds a "documentation category" to the given symbol. The identifier in the
+attribute is added to the symbol graph in the `"category"` field of the symbol.
 
 There are two special-case categories: `underscored` will treat the given symbol
 as having an underscored name regardless of its actual name, effectively marking

lib/SymbolGraphGen/Symbol.cpp

@@ -19,6 +19,7 @@
 #include "swift/Basic/PrimitiveParsing.h"
 #include "swift/Basic/SourceManager.h"
 #include "swift/Basic/Unicode.h"
+#include "swift/SymbolGraphGen/DocumentationCategory.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/SourceManager.h"
@@ -452,6 +453,12 @@ void Symbol::serializeAccessLevelMixin(llvm::json::OStream &OS) const {
   OS.attribute("accessLevel", getAccessLevelSpelling(VD->getFormalAccess()));
 }
 
+void Symbol::serializeCategoryMixin(llvm::json::OStream &OS) const {
+  StringRef Category = documentationCategoryForDecl(VD);
+  if (!Category.empty())
+    OS.attribute("category", Category);
+}
+
 void Symbol::serializeLocationMixin(llvm::json::OStream &OS) const {
   if (ClangNode ClangN = VD->getClangNode()) {
     if (!Graph->Walker.Options.IncludeClangDocs)
@@ -592,6 +599,7 @@ void Symbol::serialize(llvm::json::OStream &OS) const {
     serializeDeclarationFragmentMixin(OS);
     serializeAccessLevelMixin(OS);
     serializeAvailabilityMixin(OS);
+    serializeCategoryMixin(OS);
     serializeLocationMixin(OS);
     serializeSPIMixin(OS);
   });

lib/SymbolGraphGen/Symbol.h

@@ -72,6 +72,8 @@ class Symbol {
 
   void serializeAccessLevelMixin(llvm::json::OStream &OS) const;
 
+  void serializeCategoryMixin(llvm::json::OStream &OS) const;
+
   void serializeLocationMixin(llvm::json::OStream &OS) const;
 
   void serializeAvailabilityMixin(llvm::json::OStream &OS) const;

test/SymbolGraph/Symbols/DocumentationCategories.swift

@@ -0,0 +1,8 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift %s -module-name DocumentationCategories -emit-module -emit-module-path %t/
+// RUN: %target-swift-symbolgraph-extract -module-name DocumentationCategories -I %t -pretty-print -output-dir %t
+// RUN: %FileCheck %s --input-file %t/DocumentationCategories.symbols.json
+
+// CHECK: "category": "cool_stuff"
+@_documentation(cool_stuff) public class SomeClass {}
+