Fix the lldb-dap error when empty source map is specified

Author: Jeffrey Tan

lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py

@@ -851,7 +851,7 @@ def request_launch(
             args_dict["debuggerRoot"] = debuggerRoot
         if launchCommands:
             args_dict["launchCommands"] = launchCommands
-        if sourceMap:
+        if sourceMap is not None: # sourceMap can be empty array.
             args_dict["sourceMap"] = sourceMap
         if runInTerminal:
             args_dict["runInTerminal"] = runInTerminal

lldb/test/API/tools/lldb-dap/launch/TestDAP_launch.py

@@ -99,6 +99,24 @@ def test_stopOnEntry(self):
                         reason, "breakpoint", 'verify stop isn\'t "main" breakpoint'
                     )
 
+    @skipIfWindows
+    def test_empty_sourceMap(self):
+        """
+        Tests the launch with empty source map should not issue source map command.
+        """
+        program = self.getBuildArtifact("a.out")
+        self.build_and_create_debug_adapter()
+        empty_source_map = []
+        self.launch(program, sourceMap=empty_source_map)
+        self.continue_to_exit()
+
+        # Now get the console output and verify no source map command was issued for empty source map.
+        console_output = self.get_console()
+        self.assertTrue(
+            console_output and len(console_output) > 0, "expect some console output"
+        )
+        self.assertNotIn("Setting source map:", console_output)
+
     @skipIfWindows
     def test_cwd(self):
         """

lldb/tools/lldb-dap/Handler/RequestHandler.cpp

@@ -57,9 +57,8 @@ void BaseRequestHandler::SetSourceMapFromArguments(
       "source must be be an array of two-element arrays, "
       "each containing a source and replacement path string.\n";
 
-  std::string sourceMapCommand;
-  llvm::raw_string_ostream strm(sourceMapCommand);
-  strm << "settings set target.source-map ";
+  std::string sourceMapCommandMappings;
+  llvm::raw_string_ostream strm(sourceMapCommandMappings);
   const auto sourcePath = GetString(arguments, "sourcePath").value_or("");
 
   // sourceMap is the new, more general form of sourcePath and overrides it.
@@ -94,7 +93,9 @@ void BaseRequestHandler::SetSourceMapFromArguments(
     // Do any source remapping needed before we create our targets
     strm << "\".\" \"" << sourcePath << "\"";
   }
-  if (!sourceMapCommand.empty()) {
+  if (!sourceMapCommandMappings.empty()) {
+    std::string sourceMapCommand = "settings set target.source-map ";
+    sourceMapCommand += sourceMapCommandMappings;
     dap.RunLLDBCommands("Setting source map:", {sourceMapCommand});
   }
 }