With this change locations that don't have a source file look like this:
18# __libc_start_call_main at [0x7fd6568f6574]
19# __libc_start_main@GLIBC_2.2.5 at [0x7fd6568f6627]
20# _start at [0x4006a4]
Instead of:
18# __libc_start_call_main at :0
19# __libc_start_main@GLIBC_2.2.5 at :0
20# _start at :0
For a non-empty stacktrace_entry, if the function name returned by
description() is an empty string we now print "<unknown>" for the
function name. For an empty (e.g. default constructed) stacktrace_entry
the entire string representation is now "<unknown>" instead of an empty
string.
Instead of printing "<unknown>" for the function name, we could set that
string in the stacktrace_entry::_Info object, so that description()
returns "<unknown>" and then operator<< wouldn't need to handle an empty
description() string. However, returning an empty string from that
function seems simpler for users to detect, rather than having to parse
"<unknown>".
We could also choose a different string for an empty stacktrace_entry,
maybe "<none>" or "<invalid>", but "<unknown>" seems OK for now.
libstdc++-v3/ChangeLog:
* include/std/stacktrace
(operator<<(ostream&, const stacktrace_entry&)): Improve output
when description() or source_file() returns an empty string,
or the stacktrace_entry is invalid.
(operator<<(ostream&, const basic_stacktrace<A>&)): Use
size_type of the correct specialization.
---
v2: Restore fmtflags as pointed out by Nathan. Adjust control flow in
operator<< as suggested by Tomasz.
Tested x86_64-linux.
libstdc++-v3/include/std/stacktrace | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)
diff --git a/libstdc++-v3/include/std/stacktrace
b/libstdc++-v3/include/std/stacktrace
index b9e260e19f89..28ffda76328f 100644
--- a/libstdc++-v3/include/std/stacktrace
+++ b/libstdc++-v3/include/std/stacktrace
@@ -685,11 +685,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
string __desc, __file;
int __line;
- if (__f._M_get_info(&__desc, &__file, &__line))
+ if (__f._M_get_info(&__desc, &__file, &__line)) [[likely]]
{
- __os.width(4);
- __os << __desc << " at " << __file << ':' << __line;
+ if (__desc.empty()) [[unlikely]]
+ __os << "<unknown>";
+ else
+ __os << __desc;
+ __os << string_view(" at ");
+ if (!__file.empty()) [[likely]]
+ return __os << __file << ':' << __line;
+ // else fall through and write native_handle() as the location.
}
+
+ if (__f) [[likely]]
+ {
+ struct _Flag_guard
+ {
+ ios_base& _M_ios;
+ ios_base::fmtflags _M_f;
+ ~_Flag_guard() { _M_ios.setf(_M_f); }
+ };
+ _Flag_guard _ = { __os, __os.setf(ios::hex, ios::basefield) };
+ __os << "[0x" << __f.native_handle() << ']';
+ }
+ else
+ __os << "<unknown>";
return __os;
}
@@ -697,7 +717,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline ostream&
operator<<(ostream& __os, const basic_stacktrace<_Allocator>& __st)
{
- for (stacktrace::size_type __i = 0; __i < __st.size(); ++__i)
+ using size_type = typename basic_stacktrace<_Allocator>::size_type;
+ for (size_type __i = 0, __size = __st.size(); __i < __size; ++__i)
{
__os.width(4);
__os << __i << "# " << __st[__i] << '\n';
--
2.51.0
