[lldb-dap] Add a CMake variable for defining a welcome message

[walter-erquinigo]

lldb-dap instances managed by other extensions benefit from having a welcome message with, for example, a basic user guide or a troubleshooting message.
This PR adds a cmake variable for defining such message in a simple way. This message appears upon initialization but before initCommands are executed, as they might cause a failure and prevent the message from being displayed.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Walter Erquinigo (walter-erquinigo)

Changes

lldb-dap instances managed by other extensions benefit from having a welcome message with, for example, a basic user guide or a troubleshooting message.
This PR adds a cmake variable for defining such message in a simple way. This message appears upon initialization but before initCommands are executed, as they might cause a failure and prevent the message from being displayed.

---

Full diff: https://github.com/llvm/llvm-project/pull/78811.diff

2 Files Affected:

• (modified) lldb/tools/lldb-dap/CMakeLists.txt (+6)
• (modified) lldb/tools/lldb-dap/lldb-dap.cpp (+16-4)

diff --git a/lldb/tools/lldb-dap/CMakeLists.txt b/lldb/tools/lldb-dap/CMakeLists.txt
index c71c80981890bd5..554567eb3b0e236 100644
--- a/lldb/tools/lldb-dap/CMakeLists.txt
+++ b/lldb/tools/lldb-dap/CMakeLists.txt
@@ -46,6 +46,12 @@ add_lldb_tool(lldb-dap
     Support
   )
 
+if(LLDB_DAP_WELCOME_MESSAGE)
+  target_compile_definitions(lldb-dap
+    PRIVATE
+    -DLLDB_DAP_WELCOME_MESSAGE=\"${LLDB_DAP_WELCOME_MESSAGE}\")
+endif()
+
 if(LLDB_BUILD_FRAMEWORK)
   # In the build-tree, we know the exact path to the framework directory.
   # The installed framework can be in different locations.
diff --git a/lldb/tools/lldb-dap/lldb-dap.cpp b/lldb/tools/lldb-dap/lldb-dap.cpp
index 0d45b0379c85261..1e1af990cca0b41 100644
--- a/lldb/tools/lldb-dap/lldb-dap.cpp
+++ b/lldb/tools/lldb-dap/lldb-dap.cpp
@@ -106,6 +106,14 @@ typedef void (*RequestCallback)(const llvm::json::Object &command);
 
 enum LaunchMethod { Launch, Attach, AttachForSuspendedLaunch };
 
+/// Prints a welcome message on the editor if the preprocessor variable
+/// LLDB_DAP_WELCOME_MESSAGE is defined.
+static void PrintWelcomeMessage() {
+#ifdef LLDB_DAP_WELCOME_MESSAGE
+  g_dap.SendOutput(OutputType::Console, LLDB_DAP_WELCOME_MESSAGE);
+#endif
+}
+
 lldb::SBValueList *GetTopLevelScope(int64_t variablesReference) {
   switch (variablesReference) {
   case VARREF_LOCALS:
@@ -655,6 +663,8 @@ void request_attach(const llvm::json::Object &request) {
   g_dap.SetFrameFormat(GetString(arguments, "customFrameFormat"));
   g_dap.SetThreadFormat(GetString(arguments, "customThreadFormat"));
 
+  PrintWelcomeMessage();
+
   // This is a hack for loading DWARF in .o files on Mac where the .o files
   // in the debug map of the main executable have relative paths which require
   // the lldb-dap binary to have its working directory set to that relative
@@ -664,7 +674,7 @@ void request_attach(const llvm::json::Object &request) {
 
   // Run any initialize LLDB commands the user specified in the launch.json
   if (llvm::Error err = g_dap.RunInitCommands()) {
-    response["success"] = false;
+    kkkk response["success"] = false;
     EmplaceSafeString(response, "message", llvm::toString(std::move(err)));
     g_dap.SendJSON(llvm::json::Value(std::move(response)));
     return;
@@ -1824,10 +1834,12 @@ void request_launch(const llvm::json::Object &request) {
   g_dap.SetFrameFormat(GetString(arguments, "customFrameFormat"));
   g_dap.SetThreadFormat(GetString(arguments, "customThreadFormat"));
 
+  PrintWelcomeMessage();
+
   // This is a hack for loading DWARF in .o files on Mac where the .o files
-  // in the debug map of the main executable have relative paths which require
-  // the lldb-dap binary to have its working directory set to that relative
-  // root for the .o files in order to be able to load debug info.
+  // in the debug map of the main executable have relative paths which
+  // require the lldb-dap binary to have its working directory set to that
+  // relative root for the .o files in order to be able to load debug info.
   if (!debuggerRoot.empty())
     llvm::sys::fs::set_current_path(debuggerRoot);
 

[walter-erquinigo]

Merging this innocuous PR very quickly due to time constraints, but very happy to apply any feedback in a subsequent PR.

[clayborg]

Looks like the typo will break the buildbots and we want the welcome message to be printed for launches too right?

[clayborg]

We want this in request_launch(...) as well as request_attach(...) right?

[walter-erquinigo]

Yes, it's defined in both places