[lldb] Add description to option completions.

Summary:
Right now our argument completions are rather cryptic for command options as they only list the letters:

```
(lldb) breakpoint set -
Available completions:
	-G
	-C
	-c
	-d
	-i
	-o
	-q
	-t
	-x
[...]
```

With the new completion API we can easily extend this with the flag description so that it looks like this now:

```
(lldb) breakpoint set -
Available completions:
	-G -- The breakpoint will auto-continue after running its commands.
	-C -- A command to run when the breakpoint is hit, can be provided more than once, the commands will get run in order left to right.
	-c -- The breakpoint stops only if this condition expression evaluates to true.
	-d -- Disable the breakpoint.
	-i -- Set the number of times this breakpoint is skipped before stopping.
	-o -- The breakpoint is deleted the first time it stop causes a stop.
	-q -- The breakpoint stops only for threads in the queue whose name is given by this argument.
	-t -- The breakpoint stops only for the thread whose TID matches this argument.
	-x -- The breakpoint stops only for the thread whose index matches this argument.
```

The same happens with --long-options now.

Reviewers: #lldb, labath

Reviewed By: labath

Subscribers: labath, JDevlieghere, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D67063

llvm-svn: 370628

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

@@ -375,6 +375,30 @@ class CommandLineCompletionTestCase(TestBase):
         self.check_completion_with_desc("comman", [])
         self.check_completion_with_desc("non-existent-command", [])
 
+    def test_completion_description_command_options(self):
+        """Test descriptions of command options"""
+        # Short options
+        self.check_completion_with_desc("breakpoint set -", [
+            ["-h", "Set the breakpoint on exception catcH."],
+            ["-w", "Set the breakpoint on exception throW."]
+        ])
+
+        # Long options.
+        self.check_completion_with_desc("breakpoint set --", [
+            ["--on-catch", "Set the breakpoint on exception catcH."],
+            ["--on-throw", "Set the breakpoint on exception throW."]
+        ])
+
+        # Ambiguous long options.
+        self.check_completion_with_desc("breakpoint set --on-", [
+            ["--on-catch", "Set the breakpoint on exception catcH."],
+            ["--on-throw", "Set the breakpoint on exception throW."]
+        ])
+
+        # Unknown long option.
+        self.check_completion_with_desc("breakpoint set --Z", [
+        ])
+
     @expectedFailureAll(oslist=["windows"], bugnumber="llvm.org/pr24489")
     def test_symbol_name(self):
         self.build()

lldb/source/Interpreter/Options.cpp

@@ -672,7 +672,7 @@ bool Options::HandleOptionCompletion(CompletionRequest &request,
           if (!def.short_option)
             continue;
           opt_str[1] = def.short_option;
-          request.AddCompletion(opt_str);
+          request.AddCompletion(opt_str, def.usage_text);
         }
 
         return true;
@@ -684,7 +684,7 @@ bool Options::HandleOptionCompletion(CompletionRequest &request,
 
           full_name.erase(full_name.begin() + 2, full_name.end());
           full_name.append(def.long_option);
-          request.AddCompletion(full_name);
+          request.AddCompletion(full_name, def.usage_text);
         }
         return true;
       } else if (opt_defs_index != OptionArgElement::eUnrecognizedArg) {
@@ -692,9 +692,10 @@ bool Options::HandleOptionCompletion(CompletionRequest &request,
         // anyway (getopt_long_only is happy with shortest unique string, but
         // it's still a nice thing to do.)  Otherwise return The string so the
         // upper level code will know this is a full match and add the " ".
-        llvm::StringRef long_option = opt_defs[opt_defs_index].long_option;
+        const OptionDefinition &opt = opt_defs[opt_defs_index];
+        llvm::StringRef long_option = opt.long_option;
         if (cur_opt_str.startswith("--") && cur_opt_str != long_option) {
-          request.AddCompletion("--" + long_option.str());
+          request.AddCompletion("--" + long_option.str(), opt.usage_text);
           return true;
         } else
           request.AddCompletion(request.GetCursorArgument());
@@ -710,7 +711,7 @@ bool Options::HandleOptionCompletion(CompletionRequest &request,
           for (auto &def : opt_defs) {
             llvm::StringRef long_option(def.long_option);
             if (long_option.startswith(cur_opt_str))
-              request.AddCompletion("--" + long_option.str());
+              request.AddCompletion("--" + long_option.str(), def.usage_text);
           }
         }
         return true;