[lldb] Fix and test completion for ambiguous long options

The refactoring patch for the option completion broke the completion
for ambiguous long options. As this feature was also untested (as
testing ambiguous options with the current test methods is impossible),
I just noticed now. This patch restores the old behavior and adds a
test for this feature.

llvm-svn: 370185

lldb/packages/Python/lldbsuite/test/functionalities/completion/TestCompletion.py

@@ -90,6 +90,13 @@ def test_process_launch_arch(self):
                               ['mips',
                                'arm64'])
 
+    @skipIfFreeBSD  # timing out on the FreeBSD buildbot
+    def test_ambiguous_long_opt(self):
+        self.completions_match('breakpoint modify --th',
+                               ['--thread-id',
+                                '--thread-index',
+                                '--thread-name'])
+
     @skipIfFreeBSD  # timing out on the FreeBSD buildbot
     def test_plugin_load(self):
         self.complete_from_to('plugin load ', [])

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -2194,6 +2194,16 @@ def complete_from_to(self, str_input, patterns, turn_off_re_match=False):
                     compare_string, msg=COMPLETION_MSG(
                         str_input, p, match_strings), exe=False, patterns=[p])
 
+    def completions_match(self, command, completions):
+        """Checks that the completions for the given command are equal to the
+        given list of completions"""
+        interp = self.dbg.GetCommandInterpreter()
+        match_strings = lldb.SBStringList()
+        interp.HandleCompletion(command, len(command), 0, -1, match_strings)
+        # match_strings is a 1-indexed list, so we have to slice...
+        self.assertItemsEqual(completions, list(match_strings)[1:],
+                              "List of returned completion is wrong")
+
     def filecheck(
             self,
             command,

lldb/source/Interpreter/Options.cpp

@@ -706,17 +706,11 @@ bool Options::HandleOptionCompletion(CompletionRequest &request,
         // elements
         // that are not unique up to this point.  getopt_long_only does
         // shortest unique match for long options already.
-
-        if (cur_opt_str.startswith("--")) {
+        if (cur_opt_str.consume_front("--")) {
           for (auto &def : opt_defs) {
-            if (!def.long_option)
-              continue;
-
-            if (cur_opt_str.startswith(def.long_option)) {
-              std::string full_name("--");
-              full_name.append(def.long_option);
-              request.AddCompletion(full_name);
-            }
+            llvm::StringRef long_option(def.long_option);
+            if (long_option.startswith(cur_opt_str))
+              request.AddCompletion("--" + long_option.str());
           }
         }
         return true;