[lldb] Fix thread backtrace --count (#83602)

The help output for `thread backtrace` specifies that you can pass -1 to
`--count` to display all the frames.

```
-c <count> ( --count <count> )
            How many frames to display (-1 for all)
```

However, that doesn't work:

```
(lldb) thread backtrace --count -1
error: invalid integer value for option 'c'
```

The problem is that we store the option value as an unsigned and the
code to parse the string correctly rejects it. There's two ways to fix
this:

1. Make `m_count` a signed value so that it accepts negative values and
appease the parser. The function that prints the frames takes an
unsigned so a negative value will just become a really large positive
value, which is what the current implementation relies on.
2. Keep `m_count` unsigned and instead use 0 the magic value to show all
frames. I don't really see a point in not showing any frames at all,
plus that's already broken (`error: error displaying backtrace for
thread: "0x0001"`).

This patch implements (2) and at the same time improve the error
reporting so that we print the invalid value when we cannot parse it.

rdar://123881767

Author: JDevlieghere

lldb/source/Commands/CommandObjectThread.cpp

@@ -67,21 +67,27 @@ class CommandObjectThreadBacktrace : public CommandObjectIterateOverThreads {
         if (option_arg.getAsInteger(0, m_count)) {
           m_count = UINT32_MAX;
           error.SetErrorStringWithFormat(
-              "invalid integer value for option '%c'", short_option);
+              "invalid integer value for option '%c': %s", short_option,
+              option_arg.data());
         }
+        // A count of 0 means all frames.
+        if (m_count == 0)
+          m_count = UINT32_MAX;
         break;
       case 's':
         if (option_arg.getAsInteger(0, m_start))
           error.SetErrorStringWithFormat(
-              "invalid integer value for option '%c'", short_option);
+              "invalid integer value for option '%c': %s", short_option,
+              option_arg.data());
         break;
       case 'e': {
         bool success;
         m_extended_backtrace =
             OptionArgParser::ToBoolean(option_arg, false, &success);
         if (!success)
           error.SetErrorStringWithFormat(
-              "invalid boolean value for option '%c'", short_option);
+              "invalid boolean value for option '%c': %s", short_option,
+              option_arg.data());
       } break;
       default:
         llvm_unreachable("Unimplemented option");
@@ -228,9 +234,9 @@ class CommandObjectThreadBacktrace : public CommandObjectIterateOverThreads {
           thread->GetIndexID());
       return false;
     }
-    if (m_options.m_extended_backtrace) { 
-      if (!INTERRUPT_REQUESTED(GetDebugger(), 
-                              "Interrupt skipped extended backtrace")) {
+    if (m_options.m_extended_backtrace) {
+      if (!INTERRUPT_REQUESTED(GetDebugger(),
+                               "Interrupt skipped extended backtrace")) {
         DoExtendedBacktrace(thread, result);
       }
     }
@@ -272,8 +278,9 @@ class ThreadStepScopeOptionGroup : public OptionGroup {
       bool avoid_no_debug =
           OptionArgParser::ToBoolean(option_arg, true, &success);
       if (!success)
-        error.SetErrorStringWithFormat("invalid boolean value for option '%c'",
-                                       short_option);
+        error.SetErrorStringWithFormat(
+            "invalid boolean value for option '%c': %s", short_option,
+            option_arg);
       else {
         m_step_in_avoid_no_debug = avoid_no_debug ? eLazyBoolYes : eLazyBoolNo;
       }
@@ -284,17 +291,19 @@ class ThreadStepScopeOptionGroup : public OptionGroup {
       bool avoid_no_debug =
           OptionArgParser::ToBoolean(option_arg, true, &success);
       if (!success)
-        error.SetErrorStringWithFormat("invalid boolean value for option '%c'",
-                                       short_option);
+        error.SetErrorStringWithFormat(
+            "invalid boolean value for option '%c': %s", short_option,
+            option_arg);
       else {
         m_step_out_avoid_no_debug = avoid_no_debug ? eLazyBoolYes : eLazyBoolNo;
       }
     } break;
 
     case 'c':
       if (option_arg.getAsInteger(0, m_step_count))
-        error.SetErrorStringWithFormat("invalid step count '%s'",
-                                       option_arg.str().c_str());
+        error.SetErrorStringWithFormat(
+            "invalid integer value for option '%c': %s", short_option,
+            option_arg.data());
       break;
 
     case 'm': {

lldb/source/Commands/Options.td

@@ -805,7 +805,7 @@ let Command = "script add" in {
   def script_add_function : Option<"function", "f">, Group<1>,
     Arg<"PythonFunction">,
     Desc<"Name of the Python function to bind to this command name.">;
-  def script_add_class : Option<"class", "c">, Groups<[2,3]>, 
+  def script_add_class : Option<"class", "c">, Groups<[2,3]>,
     Arg<"PythonClass">,
     Desc<"Name of the Python class to bind to this command name.">;
   def script_add_help : Option<"help", "h">, Group<1>, Arg<"HelpText">,
@@ -816,7 +816,7 @@ let Command = "script add" in {
     EnumArg<"ScriptedCommandSynchronicity">,
     Desc<"Set the synchronicity of this command's executions with regard to "
     "LLDB event system.">;
-  def script_add_completion_type : Option<"completion-type", "C">, 
+  def script_add_completion_type : Option<"completion-type", "C">,
     Groups<[1,2]>, EnumArg<"CompletionType">,
     Desc<"Specify which completion type the command should use - if none is "
     "specified, the command won't use auto-completion.">;
@@ -1037,7 +1037,7 @@ let Command = "target stop hook add" in {
 
 let Command = "thread backtrace" in {
   def thread_backtrace_count : Option<"count", "c">, Group<1>, Arg<"Count">,
-  Desc<"How many frames to display (-1 for all)">;
+  Desc<"How many frames to display (0 for all)">;
   def thread_backtrace_start : Option<"start", "s">, Group<1>,
   Arg<"FrameIndex">, Desc<"Frame in which to start the backtrace">;
   def thread_backtrace_extended : Option<"extended", "e">, Group<1>,

lldb/test/Shell/Commands/command-thread-backtrace.test

@@ -0,0 +1,14 @@
+# RUN: %clang_host -g %S/Inputs/main.c -o %t
+
+# RUN: not %lldb %t -b -o 'b foo' -o 'r' -o 'thread backtrace --count -1' 2>&1 | FileCheck %s --check-prefix COUNT
+# COUNT: error: invalid integer value for option 'c': -1
+
+# RUN: not %lldb %t -b -o 'b foo' -o 'r' -o 'thread backtrace --extended nah' 2>&1 | FileCheck %s --check-prefix EXTENDED
+# EXTENDED: error: invalid boolean value for option 'e': nah
+
+# RUN: not %lldb %t -b -o 'b foo' -o 'r' -o 'thread backtrace --start -1' 2>&1 | FileCheck %s --check-prefix START
+# START: error: invalid integer value for option 's': -1
+
+# RUN: %lldb %t -b -o 'b foo' -o 'r' -o 'thread backtrace --count 0' | FileCheck %s
+# CHECK: frame #0:
+# CHECK: frame #1: