[Lldb-commits] [lldb] [lldb-dap] Emit declarations along with variables (PR #74865)

[Walter Erquinigo via lldb-commits]

https://github.com/walter-erquinigo created https://github.com/llvm/llvm-project/pull/74865

This is an extension to the protocol that emits the declaration information along with the metadata of each variable. This can be used by vscode extensions to implement, for example, a "goToDefinition" action in the debug tab, or for showing the value of a variable right next to where it's declared during a debug session.
As this is cheap, I'm not gating this information under any setting.


>From 534d019a744a4421f5ddef01635b62dfa39fe968 Mon Sep 17 00:00:00 2001
From: walter erquinigo <walter at modular.com>
Date: Fri, 8 Dec 2023 11:53:15 -0500
Subject: [PATCH] [lldb-dap] Emit declarations along with variables

This is an extension to the protocol that emits the declaration information along with the metadata of each variable. This can be used by vscode extensions to implement, for example, a "goToDefinition" action in the debug tab, or for showing the value of a variable right next to where it's declared during a debug session.
As this is cheap, I'm not gating this information under any setting.
---
 .../lldb-dap/variables/TestDAP_variables.py   | 10 ++++-
 lldb/tools/lldb-dap/JSONUtils.cpp             | 41 +++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py b/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py
index d2a21ad3cd1d4..9b0755eea7d3e 100644
--- a/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py
+++ b/lldb/test/API/tools/lldb-dap/variables/TestDAP_variables.py
@@ -4,8 +4,8 @@
 
 import os
 
-import lldbdap_testcase
 import dap_server
+import lldbdap_testcase
 from lldbsuite.test import lldbutil
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
@@ -152,7 +152,13 @@ def do_test_scopes_variables_setVariable_evaluate(
         globals = self.dap_server.get_global_variables()
         buffer_children = make_buffer_verify_dict(0, 32)
         verify_locals = {
-            "argc": {"equals": {"type": "int", "value": "1"}},
+            "argc": {
+                "equals": {"type": "int", "value": "1"},
+                "declaration": {
+                    "equals": {"line": 12, "column": 14},
+                    "contains": {"path": ["lldb-dap", "variables", "main.cpp"]},
+                },
+            },
             "argv": {
                 "equals": {"type": "const char **"},
                 "startswith": {"value": "0x"},
diff --git a/lldb/tools/lldb-dap/JSONUtils.cpp b/lldb/tools/lldb-dap/JSONUtils.cpp
index 03a43f9da87f2..d8b5636fd03a9 100644
--- a/lldb/tools/lldb-dap/JSONUtils.cpp
+++ b/lldb/tools/lldb-dap/JSONUtils.cpp
@@ -1101,6 +1101,29 @@ std::string CreateUniqueVariableNameForDisplay(lldb::SBValue v,
 //                       can use this optional information to present the
 //                       children in a paged UI and fetch them in chunks."
 //     }
+//     "declaration": {
+//       "type": "object | undefined",
+//       "description": "Extension to the protocol that indicates the source
+//                       location where the variable was declared. This value
+//                       might not be present if no declaration is available.",
+//       "properties": {
+//         "path": {
+//           "type": "string | undefined",
+//           "description": "The source file path where the variable was
+//                           declared."
+//         },
+//         "line": {
+//           "type": "number | undefined",
+//           "description": "The 1-indexed source line where the variable was
+//                          declared."
+//         },
+//         "column": {
+//           "type": "number | undefined",
+//           "description": "The 1-indexed source column where the variable was
+//                          declared."
+//         }
+//       }
+//     }
 //   },
 //   "required": [ "name", "value", "variablesReference" ]
 // }
@@ -1165,6 +1188,24 @@ llvm::json::Value CreateVariable(lldb::SBValue v, int64_t variablesReference,
   const char *evaluateName = evaluateStream.GetData();
   if (evaluateName && evaluateName[0])
     EmplaceSafeString(object, "evaluateName", std::string(evaluateName));
+
+  if (lldb::SBDeclaration decl = v.GetDeclaration(); decl.IsValid()) {
+    llvm::json::Object decl_obj;
+    if (lldb::SBFileSpec file = decl.GetFileSpec(); file.IsValid()) {
+      char path[PATH_MAX] = "";
+      if (file.GetPath(path, sizeof(path)) &&
+          lldb::SBFileSpec::ResolvePath(path, path, PATH_MAX)) {
+        decl_obj.try_emplace("path", std::string(path));
+      }
+    }
+
+    if (int line = decl.GetLine())
+      decl_obj.try_emplace("line", line);
+    if (int column = decl.GetColumn())
+      decl_obj.try_emplace("column", column);
+
+    object.try_emplace("declaration", std::move(decl_obj));
+  }
   return llvm::json::Value(std::move(object));
 }