Change logic to ensure compatibility

Author: kastiglione

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -1019,23 +1019,25 @@ CommandInterpreter::VerifyUserMultiwordCmdPath(Args &path, bool leaf_is_command,
 }
 
 CommandObjectSP CommandInterpreter::GetFrameLanguageCommand() const {
-  if (auto frame_sp = GetExecutionContext().GetFrameSP()) {
-    auto frame_language = Language::GetPrimaryLanguage(
-        frame_sp->GuessLanguage().AsLanguageType());
-
-    auto it = m_command_dict.find("language");
-    if (it != m_command_dict.end()) {
-      // The root "language" command.
-      CommandObjectSP language_cmd_sp = it->second;
-
-      if (auto *plugin = Language::FindPlugin(frame_language)) {
-        // "cplusplus", "objc", etc.
-        auto lang_name = plugin->GetPluginName();
-        return language_cmd_sp->GetSubcommandSPExact(lang_name);
-      }
-    }
-  }
-  return {};
+  auto frame_sp = GetExecutionContext().GetFrameSP();
+  if (!frame_sp)
+    return {};
+  auto frame_language =
+      Language::GetPrimaryLanguage(frame_sp->GuessLanguage().AsLanguageType());
+
+  auto it = m_command_dict.find("language");
+  if (it == m_command_dict.end())
+    return {};
+  // The root "language" command.
+  CommandObjectSP language_cmd_sp = it->second;
+
+  auto *plugin = Language::FindPlugin(frame_language);
+  if (!plugin)
+    return {};
+  // "cplusplus", "objc", etc.
+  auto lang_name = plugin->GetPluginName();
+
+  return language_cmd_sp->GetSubcommandSPExact(lang_name);
 }
 
 CommandObjectSP
@@ -1070,20 +1072,11 @@ CommandInterpreter::GetCommandSP(llvm::StringRef cmd_str, bool include_aliases,
       command_sp = pos->second;
   }
 
-  // The `language` subcommand ("language objc", "language cplusplus", etc).
-  CommandObjectMultiword *lang_subcmd = nullptr;
-  if (!command_sp) {
-    if (auto subcmd_sp = GetFrameLanguageCommand()) {
-      lang_subcmd = subcmd_sp->GetAsMultiwordCommand();
-      command_sp = subcmd_sp->GetSubcommandSPExact(cmd_str);
-    }
-  }
-
   if (!exact && !command_sp) {
     // We will only get into here if we didn't find any exact matches.
 
     CommandObjectSP user_match_sp, user_mw_match_sp, alias_match_sp,
-        real_match_sp, lang_match_sp;
+        real_match_sp;
 
     StringList local_matches;
     if (matches == nullptr)
@@ -1093,7 +1086,6 @@ CommandInterpreter::GetCommandSP(llvm::StringRef cmd_str, bool include_aliases,
     unsigned int num_alias_matches = 0;
     unsigned int num_user_matches = 0;
     unsigned int num_user_mw_matches = 0;
-    unsigned int num_lang_matches = 0;
 
     // Look through the command dictionaries one by one, and if we get only one
     // match from any of them in toto, then return that, otherwise return an
@@ -1151,41 +1143,49 @@ CommandInterpreter::GetCommandSP(llvm::StringRef cmd_str, bool include_aliases,
         user_mw_match_sp = pos->second;
     }
 
-    if (lang_subcmd) {
-      num_lang_matches =
-          AddNamesMatchingPartialString(lang_subcmd->GetSubcommandDictionary(),
-                                        cmd_str, *matches, descriptions);
-    }
-
-    if (num_lang_matches == 1) {
-      cmd.assign(matches->GetStringAtIndex(num_cmd_matches + num_alias_matches +
-                                           num_user_matches +
-                                           num_user_mw_matches));
-
-      auto &lang_dict = lang_subcmd->GetSubcommandDictionary();
-      auto pos = lang_dict.find(cmd);
-      if (pos != lang_dict.end())
-        lang_match_sp = pos->second;
-    }
-
     // If we got exactly one match, return that, otherwise return the match
     // list.
 
     if (num_user_matches + num_user_mw_matches + num_cmd_matches +
-            num_alias_matches + num_lang_matches ==
+            num_alias_matches ==
         1) {
       if (num_cmd_matches)
         return real_match_sp;
       else if (num_alias_matches)
         return alias_match_sp;
       else if (num_user_mw_matches)
         return user_mw_match_sp;
-      else if (num_user_matches)
-        return user_match_sp;
       else
-        return lang_match_sp;
+        return user_match_sp;
+    }
+  }
+
+  // When no single match is found, attempt to resolve the command as a language
+  // plugin subcommand.
+  if (!command_sp) {
+    // The `language` subcommand ("language objc", "language cplusplus", etc).
+    CommandObjectMultiword *lang_subcmd = nullptr;
+    if (auto lang_subcmd_sp = GetFrameLanguageCommand()) {
+      lang_subcmd = lang_subcmd_sp->GetAsMultiwordCommand();
+      command_sp = lang_subcmd_sp->GetSubcommandSPExact(cmd_str);
+    }
+
+    if (!command_sp && !exact && lang_subcmd) {
+      StringList lang_matches;
+      AddNamesMatchingPartialString(lang_subcmd->GetSubcommandDictionary(),
+                                    cmd_str, lang_matches, descriptions);
+      if (matches)
+        matches->AppendList(lang_matches);
+      if (lang_matches.GetSize() == 1) {
+        const auto &lang_dict = lang_subcmd->GetSubcommandDictionary();
+        auto pos = lang_dict.find(lang_matches[0]);
+        if (pos != lang_dict.end())
+          return pos->second;
+      }
     }
-  } else if (matches && command_sp) {
+  }
+
+  if (matches && command_sp) {
     matches->AppendString(cmd_str);
     if (descriptions)
       descriptions->AppendString(command_sp->GetHelp());

lldb/test/API/commands/command/language/TestFrameLanguageCommands.py

@@ -3,7 +3,6 @@
 from lldbsuite.test.decorators import *
 import lldbsuite.test.lldbutil as lldbutil
 
-
 class TestCase(TestBase):
     def test(self):
         self.build()
@@ -48,3 +47,14 @@ def test(self):
                 "info -- Dump information on a tagged pointer.",
             ],
         )
+
+        # To ensure compatability with existing scripts, a language specific
+        # command must not be invoked if another command (such as a python
+        # command) has the language specific command name as its prefix.
+        #
+        # For example, this test loads a `tagged-pointer-collision` command. A
+        # script could exist that invokes this command using its prefix
+        # `tagged-pointer`, under the assumption that "tagged-pointer" uniquely
+        # identifies the python command `tagged-pointer-collision`.
+        self.runCmd("command script import commands.py")
+        self.expect("tagged-pointer", startstr="ran tagged-pointer-collision")

lldb/test/API/commands/command/language/commands.py

@@ -0,0 +1,5 @@
+import lldb
+
+@lldb.command("tagged-pointer-collision")
+def noop(dbg, cmdstr, ctx, result, _):
+    print("ran tagged-pointer-collision", file=result)