cmake: Teach -E capabilities to report supported fileapi requests

Fixes: #19339

3 files changed, 36 insertions, 0 deletions

diff --git a/Source/cmFileAPI.cxx b/Source/cmFileAPI.cxx
index 9cb484c..ed45398 100644
--- a/Source/cmFileAPI.cxx
+++ b/Source/cmFileAPI.cxx
@@ -801,3 +801,35 @@ Json::Value cmFileAPI::BuildInternalTest(Object const& object)
   }
   return test;
 }
+
+Json::Value cmFileAPI::ReportCapabilities()
+{
+  Json::Value capabilities = Json::objectValue;
+  Json::Value& requests = capabilities["requests"] = Json::arrayValue;
+
+  {
+    Json::Value request = Json::objectValue;
+    request["kind"] = ObjectKindName(ObjectKind::CodeModel);
+    Json::Value& versions = request["version"] = Json::arrayValue;
+    versions.append(BuildVersion(2, CodeModelV2Minor));
+    requests.append(std::move(request));
+  }
+
+  {
+    Json::Value request = Json::objectValue;
+    request["kind"] = ObjectKindName(ObjectKind::Cache);
+    Json::Value& versions = request["version"] = Json::arrayValue;
+    versions.append(BuildVersion(2, CacheV2Minor));
+    requests.append(std::move(request));
+  }
+
+  {
+    Json::Value request = Json::objectValue;
+    request["kind"] = ObjectKindName(ObjectKind::CMakeFiles);
+    Json::Value& versions = request["version"] = Json::arrayValue;
+    versions.append(BuildVersion(1, CMakeFilesV1Minor));
+    requests.append(std::move(request));
+  }
+
+  return capabilities;
+}
diff --git a/Source/cmFileAPI.h b/Source/cmFileAPI.h
index 1315532..602efa8 100644
--- a/Source/cmFileAPI.h
+++ b/Source/cmFileAPI.h
@@ -36,6 +36,9 @@ public:
       and holding the original object.  Other JSON types are unchanged.  */
   Json::Value MaybeJsonFile(Json::Value in, std::string const& prefix);
 
+  /** Report file-api capabilities for cmake -E capabilities.  */
+  static Json::Value ReportCapabilities();
+
 private:
   cmake* CMakeInstance;
 
diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 0dca578..3772f09 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -284,6 +284,7 @@ Json::Value cmake::ReportCapabilitiesJson() const
     generators.append(i.second);
   }
   obj["generators"] = generators;
+  obj["fileApi"] = cmFileAPI::ReportCapabilities();
   obj["serverMode"] = true;
 
   return obj;