Enable defining custom namespace for spdlog by hel-ableton · Pull Request #3611 · gabime/spdlog

hel-ableton · 2026-05-26T11:04:45Z

Enable defining custom namespace for spdlog

When spdlog is used by multiple components in the same process,
each bundling their own copy, the linker or dynamic loader may resolve
all spdlog:: symbols to whichever definition it finds first. This is an ODR
(One Definition Rule) violation and can cause subtle misbehavior:
loggers silently share state across components, or the program crashes
when internal data structures disagree on their layout.

The SPDLOG_NAMESPACE macro lets a consumer place their copy of
spdlog in a dedicated namespace, making its symbols distinct from any
other copy in the process and avoiding ODR conflicts entirely.

For more sophisticated use cases, SPDLOG_NAMESPACE_BEGIN and
SPDLOG_NAMESPACE_END can be overridden directly. One example is
defining the namespace as inline, which keeps existing source code that
refers to spdlog::logger or spdlog::info(…) compiling without
changes, while the mangled symbol names still include the namespace
and remain ABI-distinct from other copies.

Copilot

Pull request overview

This PR introduces a configurable namespace mechanism for spdlog (via SPDLOG_NAMESPACE, SPDLOG_NAMESPACE_BEGIN, SPDLOG_NAMESPACE_END) to help consumers avoid ODR/linker collisions when multiple spdlog copies are present in the same process, and updates many headers to use these namespace macros.

Changes:

Adds namespace customization macros in include/spdlog/common.h.
Replaces namespace spdlog { ... } blocks across many public headers with SPDLOG_NAMESPACE_BEGIN/END.
Adjusts one C++17 nested-namespace usage (namespace spdlog::details) to a C++11-compatible form using the new macros.

Reviewed changes

Copilot reviewed 51 out of 51 changed files in this pull request and generated 20 comments.

Show a summary per file

File	Description
include/spdlog/common.h	Defines namespace customization macros and wraps common declarations in `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/spdlog.h	Wraps API functions in `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/source_loc.h	Switches source_loc namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/stopwatch.h	Switches stopwatch namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/bin_to_hex.h	Switches hex-dump utilities namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/pattern_formatter.h	Switches pattern_formatter namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/logger.h	Switches logger namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/fwd.h	Switches forward declarations namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/formatter.h	Switches formatter namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/filename_t.h	Switches filename_t namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/file_event_handlers.h	Switches file event handlers namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/async_log_msg.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/circular_q.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/err_helper.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/file_helper.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/fmt_helper.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/log_msg.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/mpmc_blocking_q.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/null_mutex.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/os.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/tcp_client_unix.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/tcp_client_windows.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/udp_client_unix.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/details/udp_client_windows.h	Switches details namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/ansicolor_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/android_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/async_sink.h	Switches sinks/details forward-decl namespaces to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/base_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/basic_file_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/callback_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/daily_file_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/dist_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/dup_filter_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/hourly_file_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/kafka_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/mongo_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/msvc_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/null_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/ostream_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/qt_sinks.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/ringbuffer_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/rotating_file_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/stdout_color_sinks.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/stdout_sinks.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/syslog_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/systemd_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/tcp_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/udp_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/win_eventlog_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.
include/spdlog/sinks/wincolor_sink.h	Switches sinks namespace to `SPDLOG_NAMESPACE_BEGIN/END`.

Comments suppressed due to low confidence (4)

include/spdlog/common.h:60

Inside SPDLOG_NAMESPACE_BEGIN this header still hard-codes spdlog:: in declarations (e.g. to_string_view(spdlog::level), level_from_str), which will fail to compile when SPDLOG_NAMESPACE is set to a non-spdlog namespace. Prefer unqualified level (since you’re already inside the namespace) or qualify via the configurable namespace macro consistently.

SPDLOG_NAMESPACE_BEGIN

class formatter;

namespace sinks {
class sink;
}

include/spdlog/bin_to_hex.h:93

After switching to SPDLOG_NAMESPACE_BEGIN/END, this header’s fmt::formatter specialization and helper functions still hard-code spdlog::details::dump_info and spdlog::fmt_lib::format_to. When SPDLOG_NAMESPACE is customized, those names won’t resolve. Use the active namespace macro (or another consistent qualifier) for these references.

SPDLOG_NAMESPACE_END

template <typename T>
struct fmt::formatter<spdlog::details::dump_info<T>, char> {
    char delimiter = ' ';

include/spdlog/details/fmt_helper.h:18

Within SPDLOG_NAMESPACE_BEGIN, append_string_view still takes a spdlog::string_view_t. With a custom namespace, spdlog::string_view_t won’t exist. Use string_view_t (unqualified) or qualify via the configurable namespace.

SPDLOG_NAMESPACE_BEGIN
namespace details {
namespace fmt_helper {

inline void append_string_view(spdlog::string_view_t view, memory_buf_t &dest) {
    const auto *buf_ptr = view.data();
    dest.append(buf_ptr, buf_ptr + view.size());

include/spdlog/details/os.h:18

details/os.h is inside SPDLOG_NAMESPACE_BEGIN, but now() is declared as returning spdlog::log_clock::time_point. That hard-codes the original namespace and will fail with SPDLOG_NAMESPACE customization. Use log_clock::time_point (unqualified) or qualify via the configurable namespace consistently.

SPDLOG_NAMESPACE_BEGIN
namespace details {
namespace os {

SPDLOG_API spdlog::log_clock::time_point now() noexcept;

SPDLOG_API std::tm localtime(const std::time_t &time_tt) noexcept;

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

hel-ableton · 2026-05-27T08:00:41Z

+SPDLOG_NAMESPACE_BEGIN  // source location
 struct source_loc {
    constexpr source_loc() = default;


Should be fixed by 1d52715

hel-ableton · 2026-05-27T08:01:12Z

 #pragma once

-namespace spdlog {
+SPDLOG_NAMESPACE_BEGIN
 class logger;


See 1d52715

hel-ableton · 2026-05-27T08:01:35Z

 #endif

-namespace spdlog {
+SPDLOG_NAMESPACE_BEGIN
 using filename_t = std::filesystem::path;
-}  // namespace spdlog
+SPDLOG_NAMESPACE_END


See 1d52715

hel-ableton · 2026-05-27T08:01:55Z

 #include "./filename_t.h"

-namespace spdlog {
+SPDLOG_NAMESPACE_BEGIN
 struct file_event_handlers {
    file_event_handlers()


See 1d52715

hel-ableton · 2026-05-27T08:02:41Z

 inline void critical(std::string_view msg) { log(level::critical, msg); }

-}  // namespace spdlog
+SPDLOG_NAMESPACE_END


Fixed by 4072679

hel-ableton · 2026-05-27T08:10:09Z

 }  // namespace sinks
-}  // namespace spdlog
+SPDLOG_NAMESPACE_END


hel-ableton · 2026-05-27T08:10:32Z

 }  // namespace sinks
-}  // namespace spdlog
+SPDLOG_NAMESPACE_END


hel-ableton · 2026-05-27T08:10:54Z

 }  // namespace sinks
-}  // namespace spdlog
+SPDLOG_NAMESPACE_END


hel-ableton · 2026-05-27T08:11:14Z

 // clang-format on

-namespace spdlog {
+SPDLOG_NAMESPACE_BEGIN


hel-ableton · 2026-05-27T08:11:31Z

 // qt_sink class
 //
-namespace spdlog {
+SPDLOG_NAMESPACE_BEGIN


gabime · 2026-05-26T21:57:38Z

SPDLOG_NAMESPACE_BEGIN is enough. no need for the SPDLOG_NAMESPACE.
Also see the copilot findings. seems more involved than appears. I am not sure it worth it .

Move namespace macros to a dedicated namespace.h header and include it in headers that don't pull in common.h, making each self-contained.

Inside SPDLOG_NAMESPACE_BEGIN blocks, names are already in scope unqualified. The explicit spdlog:: prefix was harmless with the default namespace but would silently break with any customization.

Fix logging macros in spdlog.h to use SPDLOG_NS__ instead of hardcoded spdlog::, so they resolve correctly when SPDLOG_NAMESPACE_BEGIN is customized.

hel-ableton · 2026-05-27T08:27:00Z

Thank you for the review!

SPDLOG_NAMESPACE_BEGIN is enough. no need for the SPDLOG_NAMESPACE

See here for a suggestion to handle SPDLOG_NAMESPACE more like an implementation detail.

Also see the copilot findings.

I'm sorry for the oversight! ca6be4e fixes the namespaces which fell besides the customization. I'm afraid you would have to make it a rule not to introduce new redundant namespace qualifiers in headers. 😬

With the v2.x-based changes, I'm tapping in the dark a bit, as I can't easily use v2.x in our project. I've applied the necessary changes from this review to #3610 too, though.

Enable defining custom namespace for spdlog

b4747e8

gabime requested a review from Copilot May 26, 2026 21:44

Copilot started reviewing on behalf of gabime May 26, 2026 21:44 View session

Copilot AI reviewed May 26, 2026

View reviewed changes

hel-ableton added 4 commits May 27, 2026 09:46

fixup! Enable defining custom namespace for spdlog

1d52715

Move namespace macros to a dedicated namespace.h header and include it in headers that don't pull in common.h, making each self-contained.

Remove redundant spdlog:: qualification inside namespace blocks

ca6be4e

Inside SPDLOG_NAMESPACE_BEGIN blocks, names are already in scope unqualified. The explicit spdlog:: prefix was harmless with the default namespace but would silently break with any customization.

fixup! Enable defining custom namespace for spdlog

4072679

Fix logging macros in spdlog.h to use SPDLOG_NS__ instead of hardcoded spdlog::, so they resolve correctly when SPDLOG_NAMESPACE_BEGIN is customized.

fixup! fixup! Enable defining custom namespace for spdlog

6aeba71

Conversation

hel-ableton commented May 26, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

gabime commented May 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

hel-ableton commented May 27, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

gabime commented May 26, 2026 •

edited

Loading