Update snapshot command to fallback to the .documentation field

lsif-java/src/main/scala/com/sourcegraph/lsif_java/SemanticdbPrinters.scala

@@ -3,6 +3,7 @@ package com.sourcegraph.lsif_java
 import scala.jdk.CollectionConverters._
 
 import com.sourcegraph.lsif_java.commands.CommentSyntax
+import com.sourcegraph.lsif_java.commands.SnapshotLsifCommand
 import com.sourcegraph.lsif_semanticdb.LsifTextDocument
 import com.sourcegraph.lsif_semanticdb.SignatureFormatter
 import com.sourcegraph.lsif_semanticdb.Symtab
@@ -88,11 +89,23 @@ object SemanticdbPrinters {
       .append(
         symtab.symbols.asScala.get(occ.getSymbol) match {
           case Some(info) if occ.getRole == Role.DEFINITION =>
-            val sig = new SignatureFormatter(info, symtab).formatSymbol()
-            if (sig.isEmpty)
+            val signature: String =
+              if (info.hasSignature) {
+                new SignatureFormatter(info, symtab)
+                  .formatSymbol()
+                  .trim
+                  .replace('\n', ' ')
+              } else if (info.hasDocumentation) {
+                SnapshotLsifCommand
+                  .signatureLines(info.getDocumentation.getMessage)
+                  .mkString(" ")
+              } else {
+                ""
+              }
+            if (signature.isEmpty)
               " " + info.getDisplayName
             else
-              " " + sig.trim.replace('\n', ' ')
+              " " + signature
           case _ =>
             ""
         }

lsif-java/src/main/scala/com/sourcegraph/lsif_java/commands/SnapshotLsifCommand.scala

@@ -143,13 +143,7 @@ object SnapshotLsifCommand {
                 resultSetId <- lsif.next.get(o.getId).toList
                 hoverId <- lsif.hoverEdges.get(resultSetId).toList
                 hover <- lsif.hoverVertexes.get(hoverId).toList
-                line <- hover
-                  .getContents
-                  .getValue
-                  .linesIterator
-                  .dropWhile(!_.startsWith("```"))
-                  .drop(1)
-                  .takeWhile(_ != "```")
+                line <- signatureLines(hover.getContents.getValue)
               } yield line
             ).mkString("\n")
           val symInfo = SymbolInformation
@@ -164,6 +158,14 @@ object SnapshotLsifCommand {
     lsif.documents.values.map(_.build()).toList
   }
 
+  def signatureLines(documentation: String): Iterator[String] = {
+    documentation
+      .linesIterator
+      .dropWhile(!_.startsWith("```"))
+      .drop(1)
+      .takeWhile(_ != "```")
+  }
+
   class IndexedLsif(
       val path: Path,
       val objects: mutable.Buffer[LsifObject],

tests/unit/src/test/scala/tests/SemanticdbPrintersSuite.scala

@@ -1,7 +1,9 @@
 package tests
 
 import com.sourcegraph.lsif_java.SemanticdbPrinters
+import com.sourcegraph.semanticdb_javac.Semanticdb.Documentation
 import com.sourcegraph.semanticdb_javac.Semanticdb.Range
+import com.sourcegraph.semanticdb_javac.Semanticdb.SymbolInformation
 import com.sourcegraph.semanticdb_javac.Semanticdb.SymbolOccurrence
 import com.sourcegraph.semanticdb_javac.Semanticdb.SymbolOccurrence.Role
 import com.sourcegraph.semanticdb_javac.Semanticdb.TextDocument
@@ -84,4 +86,42 @@ class SemanticdbPrintersSuite extends FunSuite {
     )
   }
 
+  test("documentation") {
+    val doc = TextDocument
+      .newBuilder()
+      .setText("fun main() {}\n")
+      .addOccurrences(
+        SymbolOccurrence
+          .newBuilder()
+          .setSymbol("main().")
+          .setRange(
+            Range
+              .newBuilder()
+              .setStartLine(0)
+              .setStartCharacter(4)
+              .setEndLine(0)
+              .setEndCharacter(8)
+          )
+          .setRole(Role.DEFINITION)
+      )
+      .addSymbols(
+        SymbolInformation
+          .newBuilder()
+          .setSymbol("main().")
+          .setDocumentation(
+            Documentation
+              .newBuilder()
+              .setMessage("```kt\nfun main(): kotlin.Unit\n```")
+          )
+      )
+      .build()
+
+    assertNoDiff(
+      SemanticdbPrinters.printTextDocument(doc),
+      """|fun main() {}
+         |//  ^^^^ definition main(). fun main(): kotlin.Unit
+         |""".stripMargin
+    )
+  }
+
 }