Tolerate missing debug info in the shared_ptr pretty printer.

Certain fields of shared ptr have virtual functions and therefore have their debug info homed in libc++. But if libc++ wasn't built with debug info, the pretty printer would fail. This patch makes the pretty printer tolerate such conditions and updates the test harness. This patch significantly reworks a previous attempt. This addresses https://bugs.llvm.org/show_bug.cgi?id=48937 Differential Revision: https://reviews.llvm.org/D100610 (cherry picked from commit 55b7061)

Author: Sterling-Augustine

libcxx/test/libcxx/gdb/gdb_pretty_printer_test.py

@@ -45,7 +45,6 @@ def invoke(self, arg, from_tty):
  # Ignore the convenience variable name and newline
  value = value_str[value_str.find("= ") + 2:-1]
  gdb.newest_frame().select()
-
  expectation_val = compare_frame.read_var("expectation")
  check_literal = expectation_val.string(encoding="utf-8")
  if "PrettyPrintToRegex" in compare_frame.name():

libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp

@@ -608,25 +608,27 @@ void shared_ptr_test() {
  // due to which there is one more count for the pointer. Hence, all the
  // following tests are testing with expected count plus 1.
  std::shared_ptr<const int> test0 = std::make_shared<const int>(5);
+ // The python regular expression matcher treats newlines as significant, so
+ // these regular expressions should be on one line.
  ComparePrettyPrintToRegex(
  test0,
- R"(std::shared_ptr<int> count 2, weak 0 containing = {__ptr_ = 0x[a-f0-9]+})");
+ R"(std::shared_ptr<int> count [2\?], weak [0\?]( \(libc\+\+ missing debug info\))? containing = {__ptr_ = 0x[a-f0-9]+})");
 
  std::shared_ptr<const int> test1(test0);
  ComparePrettyPrintToRegex(
  test1,
- R"(std::shared_ptr<int> count 3, weak 0 containing = {__ptr_ = 0x[a-f0-9]+})");
+ R"(std::shared_ptr<int> count [3\?], weak [0\?]( \(libc\+\+ missing debug info\))? containing = {__ptr_ = 0x[a-f0-9]+})");
 
  {
  std::weak_ptr<const int> test2 = test1;
  ComparePrettyPrintToRegex(
  test0,
- R"(std::shared_ptr<int> count 3, weak 1 containing = {__ptr_ = 0x[a-f0-9]+})");
+ R"(std::shared_ptr<int> count [3\?], weak [1\?]( \(libc\+\+ missing debug info\))? containing = {__ptr_ = 0x[a-f0-9]+})");
  }
 
  ComparePrettyPrintToRegex(
  test0,
- R"(std::shared_ptr<int> count 3, weak 0 containing = {__ptr_ = 0x[a-f0-9]+})");
+ R"(std::shared_ptr<int> count [3\?], weak [0\?]( \(libc\+\+ missing debug info\))? containing = {__ptr_ = 0x[a-f0-9]+})");
 
  std::shared_ptr<const int> test3;
  ComparePrettyPrintToChars(test3, "std::shared_ptr is nullptr");

libcxx/utils/gdb/libcxx/printers.py

@@ -312,12 +312,21 @@ def to_string(self):
  return "%s is nullptr" % typename
  refcount = self.val["__cntrl_"]
  if refcount != 0:
- usecount = refcount["__shared_owners_"] + 1
- weakcount = refcount["__shared_weak_owners_"]
- if usecount == 0:
- state = "expired, weak %d" % weakcount
- else:
- state = "count %d, weak %d" % (usecount, weakcount)
+ try:
+ usecount = refcount["__shared_owners_"] + 1
+ weakcount = refcount["__shared_weak_owners_"]
+ if usecount == 0:
+ state = "expired, weak %d" % weakcount
+ else:
+ state = "count %d, weak %d" % (usecount, weakcount)
+ except:
+ # Debug info for a class with virtual functions is emitted
+ # in the same place as its key function. That means that
+ # for std::shared_ptr, __shared_owners_ is emitted into
+ # into libcxx.[so|a] itself, rather than into the shared_ptr
+ # instantiation point. So if libcxx.so was built without
+ # debug info, these fields will be missing.
+ state = "count ?, weak ? (libc++ missing debug info)"
  return "%s<%s> %s containing" % (typename, pointee_type, state)
 
  def __iter__(self):