[lldb] Unify target checking in CommandObject

Summary:
We currently have several CommandObjects that manually reimplement the checking for a selected target
or a target in the execution context (which is the selected target when they are invoked). This patch removes
all these checks and replaces them by setting the eCommandRequiresTarget flag that Pavel suggested. With
this flag we are doing the same check but without having to duplicate this code in all these CommandObjects.

I also added a `GetSelectedTarget()` variant of the `GetSelectedOrDummyTarget()` function to the
CommandObject that checks that the flag is set and then returns a reference to the target. I didn't rewrite
all the `target` variables from `Target *` to `Target &` in this patch as last time this change caused a lot of merge
conflicts in Swift and I would prefer having that in a separate NFC commit.

Reviewers: labath, clayborg

Reviewed By: labath, clayborg

Subscribers: clayborg, JDevlieghere, jingham, amccarth, abidh, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D66863

llvm-svn: 370571

1 files changed, 5 insertions, 12 deletions

diff --git a/lldb/source/Commands/CommandObjectBreakpointCommand.cpp b/lldb/source/Commands/CommandObjectBreakpointCommand.cpp
index 5988b1c5302..11fdb85e844 100644
--- a/lldb/source/Commands/CommandObjectBreakpointCommand.cpp
+++ b/lldb/source/Commands/CommandObjectBreakpointCommand.cpp
@@ -589,10 +589,10 @@ private:
 class CommandObjectBreakpointCommandList : public CommandObjectParsed {
 public:
   CommandObjectBreakpointCommandList(CommandInterpreter &interpreter)
-      : CommandObjectParsed(interpreter, "list", "List the script or set of "
-                                                 "commands to be executed when "
-                                                 "the breakpoint is hit.",
-                            nullptr) {
+      : CommandObjectParsed(interpreter, "list",
+                            "List the script or set of commands to be "
+                            "executed when the breakpoint is hit.",
+                            nullptr, eCommandRequiresTarget) {
     CommandArgumentEntry arg;
     CommandArgumentData bp_id_arg;
 
@@ -612,14 +612,7 @@ public:
 
 protected:
   bool DoExecute(Args &command, CommandReturnObject &result) override {
-    Target *target = GetDebugger().GetSelectedTarget().get();
-
-    if (target == nullptr) {
-      result.AppendError("There is not a current executable; there are no "
-                         "breakpoints for which to list commands");
-      result.SetStatus(eReturnStatusFailed);
-      return false;
-    }
+    Target *target = &GetSelectedTarget();
 
     const BreakpointList &breakpoints = target->GetBreakpointList();
     size_t num_breakpoints = breakpoints.GetSize();