Attaching LLDB to a Debug build of Swift

gistfile1.txt

 $ lldb -- ../build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swiftc -dump-parse ~/GitHub/tmp/hello.swift
(lldb) target create "../build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swiftc"
Current executable set to '../build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swiftc' (x86_64).
(lldb) settings set -- target.run-args  "-dump-parse" "/Users/bgesiak/GitHub/tmp/hello.swift"
(lldb) process launch --stop-at-entry
Process 91478 stopped
* thread #1: tid = 0x1bd329, 0x00007fff5fc01000 dyld`_dyld_start, stop reason = signal SIGSTOP
    frame #0: 0x00007fff5fc01000 dyld`_dyld_start
dyld`_dyld_start:
->  0x7fff5fc01000 <+0>: popq   %rdi
    0x7fff5fc01001 <+1>: pushq  $0x0
    0x7fff5fc01003 <+3>: movq   %rsp, %rbp
    0x7fff5fc01006 <+6>: andq   $-0x10, %rsp
Process 91478 launched: '../build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swiftc' (x86_64)
(lldb) b Driver::buildCompilation
Breakpoint 1: where = swiftc`swift::driver::Driver::buildCompilation(llvm::ArrayRef<char const*>) + 79 at Driver.cpp:343, address = 0x00000001000fd83f
(lldb) c
Process 91478 resuming
Process 91478 stopped
* thread #1: tid = 0x1bd329, 0x00000001000fd83f swiftc`swift::driver::Driver::buildCompilation(this=0x00007fff5fbfdc98, Args=ArrayRef<const char *> @ 0x00007fff5fbfc2b8) + 79 at Driver.cpp:343, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x00000001000fd83f swiftc`swift::driver::Driver::buildCompilation(this=0x00007fff5fbfdc98, Args=ArrayRef<const char *> @ 0x00007fff5fbfc2b8) + 79 at Driver.cpp:343
   340
   341 	std::unique_ptr<Compilation> Driver::buildCompilation(
   342 	    ArrayRef<const char *> Args) {
-> 343 	  llvm::PrettyStackTraceString CrashInfo("Compilation construction");
   344
   345 	  llvm::sys::TimeValue StartTime = llvm::sys::TimeValue::now();
   346
(lldb) b Driver::parseArgStrings
Breakpoint 2: where = swiftc`swift::driver::Driver::parseArgStrings(llvm::ArrayRef<char const*>) + 77 at Driver.cpp:634, address = 0x00000001001012cd
(lldb) c
Process 91478 resuming
Process 91478 stopped
* thread #1: tid = 0x1bd329, 0x00000001001012cd swiftc`swift::driver::Driver::parseArgStrings(this=0x00007fff5fbfdc98, Args=ArrayRef<const char *> @ 0x00007fff5fbfb370) + 77 at Driver.cpp:634, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1
    frame #0: 0x00000001001012cd swiftc`swift::driver::Driver::parseArgStrings(this=0x00007fff5fbfdc98, Args=ArrayRef<const char *> @ 0x00007fff5fbfb370) + 77 at Driver.cpp:634
   631
   632 	std::unique_ptr<InputArgList>
   633 	Driver::parseArgStrings(ArrayRef<const char *> Args) {
-> 634 	  unsigned IncludedFlagsBitmask = 0;
   635 	  unsigned ExcludedFlagsBitmask = options::NoDriverOption;
   636 	  unsigned MissingArgIndex, MissingArgCount;
   637 	  std::unique_ptr<InputArgList> ArgList;
(lldb) s
Process 91478 stopped
* thread #1: tid = 0x1bd329, 0x00000001001012d7 swiftc`swift::driver::Driver::parseArgStrings(this=0x00007fff5fbfdc98, Args=ArrayRef<const char *> @ 0x00007fff5fbfb370) + 87 at Driver.cpp:635, queue = 'com.apple.main-thread', stop reason = step in
    frame #0: 0x00000001001012d7 swiftc`swift::driver::Driver::parseArgStrings(this=0x00007fff5fbfdc98, Args=ArrayRef<const char *> @ 0x00007fff5fbfb370) + 87 at Driver.cpp:635
   632 	std::unique_ptr<InputArgList>
   633 	Driver::parseArgStrings(ArrayRef<const char *> Args) {
   634 	  unsigned IncludedFlagsBitmask = 0;
-> 635 	  unsigned ExcludedFlagsBitmask = options::NoDriverOption;
   636 	  unsigned MissingArgIndex, MissingArgCount;
   637 	  std::unique_ptr<InputArgList> ArgList;
   638
(lldb) p Args
(llvm::ArrayRef<const char *>) $0 = {
  Data = 0x00007fff5fbff070
  Length = 2
}
(lldb) exit
Quitting LLDB will kill one or more processes. Do you really want to proceed: [Y/n] Y