[lldb] Allow aliases to aliases of raw input commands

[kastiglione]

Summary

Allow users to create aliases for aliases to raw input commands. That probably
sounds convoluted, so here's an example:

command alias some-setup env SOMEVAR=SOMEVALUE

This an alias based on env, which itself is an alias for _regex-env.
_regex-env is a command regex command, which takes raw input.

The above some-setup alias fails with:

error: Unable to create requested alias.

This change allows such aliases to be created. lldb already supports aliases to
aliases for parsed commands.

[jingham]

Should this have a test?

[kastiglione]

add a test

[jingham]

That tests that we made the alias, but not that it actually works. If you did something like:

command alias start_with_two expr -- 2
command alias add_two start_with_two +

then

add_two 3

should produce 5, which would be easy to test for.

[kastiglione]

use Jim's testing improvement

[jingham]

What an excellent test!

LGTM

lldb/source/Commands/CommandObjectCommands.cpp

bool HandleAliasingRawCommand(llvm::StringRef alias_command,
                                 llvm::StringRef raw_command_string,
                                 CommandObject &cmd_obj,
                                 CommandReturnObject &result) {
     // Verify & handle any options/arguments passed to the alias command
 
     OptionArgVectorSP option_arg_vector_sp =
         OptionArgVectorSP(new OptionArgVector);
 
-    if (CommandObjectSP cmd_obj_sp =
-            m_interpreter.GetCommandSPExact(cmd_obj.GetCommandName())) {
+    const bool include_aliases = true;
+    if (CommandObjectSP cmd_obj_sp = m_interpreter.GetCommandSPExact(
+            cmd_obj.GetCommandName(), include_aliases)) {
       if (m_interpreter.AliasExists(alias_command) ||
           m_interpreter.UserCommandExists(alias_command)) {
         result.AppendWarningWithFormat(
             "Overwriting existing definition for '%s'.\n",
             alias_command.str().c_str());
       }
       if (CommandAlias *alias = m_interpreter.AddAlias(
               alias_command, cmd_obj_sp, raw_command_string)) {

lldb/test/API/commands/command/nested_alias/TestNestedAlias.py

def test_nested_alias(self):
 
         # This is the function to remove the custom aliases in order to have a
         # clean slate for the next test case.
         def cleanup():
             self.runCmd('command unalias read', check=False)
             self.runCmd('command unalias rd', check=False)
             self.runCmd('command unalias fo', check=False)
             self.runCmd('command unalias foself', check=False)
+            self.runCmd('command unalias add_two', check=False)
+            self.runCmd('command unalias two', check=False)
 
         # Execute the cleanup function during test case tear down.
         self.addTearDownHook(cleanup)
 
         self.runCmd('command alias read memory read -f A')
         self.runCmd('command alias rd read -c 3')
 
         self.expect(
def test_nested_alias(self):
         # Check that foself was resolved and is now independent of 'fo'.
         self.runCmd('command unalias fo')
         self.expect(
             'help foself',
             substrs=[
                 'Show variables for the current',
                 'stack frame.'],
             matching=True)
+
+        # Check that aliases can be created for raw input commands.
+        self.expect('command alias two expr -- 2')
+        self.expect('command alias add_two two +')
+        self.expect('add_two 3', patterns=[' = 5$'])