From c022776a5704be758b90a56563d491861d29fa49 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@efficios.com>
Date: Mon, 11 Dec 2023 16:07:18 -0500
Subject: [PATCH] cpp-common: add `bt2s::optional`, alias of `nonstd::optional`

In order to avoid having all sorts of external namespaces, make
`bt2s::optional` an alias of `nonstd::optional`, and make sure
everything in the project uses `bt2s::optional`.

Also add aliases for other STL types and functions of `<optional>`.

This will make it possible to easily change the implementation without
changing the code using it indirectly (only
`cpp-common/bt2s/optional.hpp` will change).

Move `cpp-common/optional.hpp` to
`cpp-common/vendor/optional-lite/optional.hpp` to make it clear it's an
external project.

Making everything under `cpp-common/vendor` an exception in
`tools/format-cpp.sh`.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I2a1ea52c484c85fbf8d68631d40369efd969818a
Reviewed-on: https://review.lttng.org/c/babeltrace/+/11391
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>
CI-Build: Simon Marchi <simon.marchi@efficios.com>
---
 src/Makefile.am                               |  5 +-
 src/cpp-common/bt2/clock-class.hpp            |  6 +-
 src/cpp-common/bt2/field-class.hpp            | 30 ++++----
 src/cpp-common/bt2/field.hpp                  | 12 ++--
 src/cpp-common/bt2/message-iterator.hpp       |  6 +-
 src/cpp-common/bt2/message.hpp                | 18 ++---
 src/cpp-common/bt2/shared-object.hpp          |  4 +-
 src/cpp-common/bt2/trace-ir.hpp               | 71 +++++++++----------
 src/cpp-common/bt2/value.hpp                  | 10 +--
 src/cpp-common/bt2s/optional.hpp              | 61 ++++++++++++++++
 .../{ => vendor/optional-lite}/optional.hpp   |  0
 tools/format-cpp.sh                           |  2 +-
 12 files changed, 143 insertions(+), 82 deletions(-)
 create mode 100644 src/cpp-common/bt2s/optional.hpp
 rename src/cpp-common/{ => vendor/optional-lite}/optional.hpp (100%)

diff --git a/src/Makefile.am b/src/Makefile.am
index 9f4796e4..23acb9e1 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -54,9 +54,10 @@ noinst_HEADERS = \
 	cpp-common/bt2c/uuid.hpp \
 	cpp-common/bt2c/vector.hpp \
 	cpp-common/bt2s/make-unique.hpp \
+	cpp-common/bt2s/optional.hpp \
 	cpp-common/nlohmann/json.hpp \
-	cpp-common/optional.hpp \
-	cpp-common/string_view.hpp
+	cpp-common/string_view.hpp \
+	cpp-common/vendor/optional-lite/optional.hpp
 
 ## This target generates an include file that contains the git version
 ## string of the current branch, it must be continuously updated when
diff --git a/src/cpp-common/bt2/clock-class.hpp b/src/cpp-common/bt2/clock-class.hpp
index 64e093f4..6d99ed1f 100644
--- a/src/cpp-common/bt2/clock-class.hpp
+++ b/src/cpp-common/bt2/clock-class.hpp
@@ -14,7 +14,7 @@
 #include <babeltrace2/babeltrace.h>
 
 #include "cpp-common/bt2c/uuid-view.hpp"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "borrowed-object.hpp"
 #include "exc.hpp"
@@ -219,7 +219,7 @@ public:
         bt_clock_class_set_uuid(this->libObjPtr(), uuid);
     }
 
-    nonstd::optional<bt2c::UuidView> uuid() const noexcept
+    bt2s::optional<bt2c::UuidView> uuid() const noexcept
     {
         const auto uuid = bt_clock_class_get_uuid(this->libObjPtr());
 
@@ -227,7 +227,7 @@ public:
             return bt2c::UuidView {uuid};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     template <typename LibValT>
diff --git a/src/cpp-common/bt2/field-class.hpp b/src/cpp-common/bt2/field-class.hpp
index f299690e..94cdb8e6 100644
--- a/src/cpp-common/bt2/field-class.hpp
+++ b/src/cpp-common/bt2/field-class.hpp
@@ -13,7 +13,7 @@
 #include <babeltrace2/babeltrace.h>
 
 #include "common/assert.h"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "borrowed-object-iterator.hpp"
 #include "borrowed-object.hpp"
@@ -850,7 +850,7 @@ public:
             this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Mapping> operator[](const char * const label) const noexcept
+    bt2s::optional<Mapping> operator[](const char * const label) const noexcept
     {
         const auto libObjPtr = internal::CommonEnumerationFieldClassSpec<MappingT>::mappingByLabel(
             this->libObjPtr(), label);
@@ -859,10 +859,10 @@ public:
             return Mapping {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Mapping> operator[](const std::string& label) const noexcept
+    bt2s::optional<Mapping> operator[](const std::string& label) const noexcept
     {
         return (*this)[label.data()];
     }
@@ -1188,7 +1188,7 @@ public:
             this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Member> operator[](const char * const name) const noexcept
+    bt2s::optional<Member> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr =
             internal::CommonStructureFieldClassSpec<LibObjT>::memberByName(this->libObjPtr(), name);
@@ -1197,10 +1197,10 @@ public:
             return Member {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Member> operator[](const std::string& name) const noexcept
+    bt2s::optional<Member> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -2186,7 +2186,7 @@ public:
             this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Option> operator[](const char * const name) const noexcept
+    bt2s::optional<Option> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr =
             internal::CommonVariantFieldClassSpec<LibObjT>::optionByName(this->libObjPtr(), name);
@@ -2195,10 +2195,10 @@ public:
             return Option {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Option> operator[](const std::string& name) const noexcept
+    bt2s::optional<Option> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -2282,7 +2282,7 @@ public:
         }
     }
 
-    void appendOption(const nonstd::optional<std::string>& name, const FieldClass fc) const
+    void appendOption(const bt2s::optional<std::string>& name, const FieldClass fc) const
     {
         this->appendOption(name ? name->data() : nullptr, fc);
     }
@@ -2482,7 +2482,7 @@ public:
         return Option {_Spec::optionByIndex(this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Option> operator[](const char * const name) const noexcept
+    bt2s::optional<Option> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr = _Spec::optionByName(this->libObjPtr(), name);
 
@@ -2490,10 +2490,10 @@ public:
             return Option {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Option> operator[](const std::string& name) const noexcept
+    bt2s::optional<Option> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -2514,7 +2514,7 @@ public:
         }
     }
 
-    void appendOption(const nonstd::optional<std::string>& name, const FieldClass fc,
+    void appendOption(const bt2s::optional<std::string>& name, const FieldClass fc,
                       const typename Option::RangeSet ranges) const
     {
         this->appendOption(name ? name->data() : nullptr, fc, ranges);
diff --git a/src/cpp-common/bt2/field.hpp b/src/cpp-common/bt2/field.hpp
index 32ea17c7..69bf4ab6 100644
--- a/src/cpp-common/bt2/field.hpp
+++ b/src/cpp-common/bt2/field.hpp
@@ -13,7 +13,7 @@
 #include <babeltrace2/babeltrace.h>
 
 #include "common/assert.h"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "borrowed-object.hpp"
 #include "field-class.hpp"
@@ -1116,7 +1116,7 @@ public:
         return CommonField<LibObjT> {_Spec::memberFieldByIndex(this->libObjPtr(), index)};
     }
 
-    nonstd::optional<CommonField<LibObjT>> operator[](const char * const name) const noexcept
+    bt2s::optional<CommonField<LibObjT>> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr = _Spec::memberFieldByName(this->libObjPtr(), name);
 
@@ -1124,10 +1124,10 @@ public:
             return CommonField<LibObjT> {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<CommonField<LibObjT>> operator[](const std::string& name) const noexcept
+    bt2s::optional<CommonField<LibObjT>> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -1404,7 +1404,7 @@ public:
         return this->field().has_value();
     }
 
-    nonstd::optional<CommonField<LibObjT>> field() const noexcept
+    bt2s::optional<CommonField<LibObjT>> field() const noexcept
     {
         const auto libObjPtr = _Spec::field(this->libObjPtr());
 
@@ -1412,7 +1412,7 @@ public:
             return CommonField<LibObjT> {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 };
 
diff --git a/src/cpp-common/bt2/message-iterator.hpp b/src/cpp-common/bt2/message-iterator.hpp
index 9ba7ed96..9f3084b1 100644
--- a/src/cpp-common/bt2/message-iterator.hpp
+++ b/src/cpp-common/bt2/message-iterator.hpp
@@ -10,7 +10,7 @@
 #include <babeltrace2/babeltrace.h>
 
 #include "common/common.h"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "component-port.hpp"
 #include "exc.hpp"
@@ -50,7 +50,7 @@ public:
         return ConstComponent {bt_message_iterator_borrow_component(this->libObjPtr())};
     }
 
-    nonstd::optional<ConstMessageArray> next() const
+    bt2s::optional<ConstMessageArray> next() const
     {
         bt_message_array_const libMsgsPtr;
         std::uint64_t count;
@@ -61,7 +61,7 @@ public:
             /* Caller becomes the owner of the contained messages */
             return ConstMessageArray::wrapExisting(libMsgsPtr, count);
         case BT_MESSAGE_ITERATOR_NEXT_STATUS_END:
-            return nonstd::nullopt;
+            return bt2s::nullopt;
         case BT_MESSAGE_ITERATOR_NEXT_STATUS_AGAIN:
             throw TryAgain {};
         case BT_MESSAGE_ITERATOR_NEXT_STATUS_MEMORY_ERROR:
diff --git a/src/cpp-common/bt2/message.hpp b/src/cpp-common/bt2/message.hpp
index ff0240d2..afc751c5 100644
--- a/src/cpp-common/bt2/message.hpp
+++ b/src/cpp-common/bt2/message.hpp
@@ -15,7 +15,7 @@
 #include "common/assert.h"
 #include "cpp-common/bt2/clock-snapshot.hpp"
 #include "cpp-common/bt2/trace-ir.hpp"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "borrowed-object.hpp"
 #include "internal/utils.hpp"
@@ -274,7 +274,7 @@ public:
         bt_message_stream_beginning_set_default_clock_snapshot(this->libObjPtr(), val);
     }
 
-    nonstd::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
+    bt2s::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
     {
         const bt_clock_snapshot *libObjPtr;
         const auto state = bt_message_stream_beginning_borrow_default_clock_snapshot_const(
@@ -284,7 +284,7 @@ public:
             return ConstClockSnapshot {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
@@ -388,7 +388,7 @@ public:
         bt_message_stream_end_set_default_clock_snapshot(this->libObjPtr(), val);
     }
 
-    nonstd::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
+    bt2s::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
     {
         const bt_clock_snapshot *libObjPtr;
         const auto state = bt_message_stream_end_borrow_default_clock_snapshot_const(
@@ -398,7 +398,7 @@ public:
             return ConstClockSnapshot {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
@@ -839,7 +839,7 @@ public:
         bt_message_discarded_events_set_count(this->libObjPtr(), count);
     }
 
-    nonstd::optional<std::uint64_t> count() const noexcept
+    bt2s::optional<std::uint64_t> count() const noexcept
     {
         std::uint64_t count;
         const auto avail = bt_message_discarded_events_get_count(this->libObjPtr(), &count);
@@ -848,7 +848,7 @@ public:
             return count;
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
@@ -970,7 +970,7 @@ public:
         bt_message_discarded_packets_set_count(this->libObjPtr(), count);
     }
 
-    nonstd::optional<std::uint64_t> count() const noexcept
+    bt2s::optional<std::uint64_t> count() const noexcept
     {
         std::uint64_t count;
         const auto avail = bt_message_discarded_packets_get_count(this->libObjPtr(), &count);
@@ -979,7 +979,7 @@ public:
             return count;
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
diff --git a/src/cpp-common/bt2/shared-object.hpp b/src/cpp-common/bt2/shared-object.hpp
index 5361f6db..8eb15652 100644
--- a/src/cpp-common/bt2/shared-object.hpp
+++ b/src/cpp-common/bt2/shared-object.hpp
@@ -8,7 +8,7 @@
 #define BABELTRACE_CPP_COMMON_BT2_SHARED_OBJECT_HPP
 
 #include "common/assert.h"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 namespace bt2 {
 
@@ -292,7 +292,7 @@ private:
         }
     }
 
-    nonstd::optional<ObjT> _mObj;
+    bt2s::optional<ObjT> _mObj;
 };
 
 } /* namespace bt2 */
diff --git a/src/cpp-common/bt2/trace-ir.hpp b/src/cpp-common/bt2/trace-ir.hpp
index 9df6abbf..51e53732 100644
--- a/src/cpp-common/bt2/trace-ir.hpp
+++ b/src/cpp-common/bt2/trace-ir.hpp
@@ -12,7 +12,7 @@
 
 #include <babeltrace2/babeltrace.h>
 
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "borrowed-object.hpp"
 #include "clock-class.hpp"
@@ -163,9 +163,9 @@ public:
 
     Class cls() const noexcept;
     _Stream stream() const noexcept;
-    nonstd::optional<_Packet> packet() const noexcept;
+    bt2s::optional<_Packet> packet() const noexcept;
 
-    nonstd::optional<_StructureField> payloadField() const noexcept
+    bt2s::optional<_StructureField> payloadField() const noexcept
     {
         const auto libObjPtr = _Spec::payloadField(this->libObjPtr());
 
@@ -173,10 +173,10 @@ public:
             return _StructureField {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<_StructureField> specificContextField() const noexcept
+    bt2s::optional<_StructureField> specificContextField() const noexcept
     {
         const auto libObjPtr = _Spec::specificContextField(this->libObjPtr());
 
@@ -184,10 +184,10 @@ public:
             return _StructureField {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<_StructureField> commonContextField() const noexcept
+    bt2s::optional<_StructureField> commonContextField() const noexcept
     {
         const auto libObjPtr = _Spec::commonContextField(this->libObjPtr());
 
@@ -195,7 +195,7 @@ public:
             return _StructureField {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 };
 
@@ -304,7 +304,7 @@ public:
 
     _Stream stream() const noexcept;
 
-    nonstd::optional<_StructureField> contextField() const noexcept
+    bt2s::optional<_StructureField> contextField() const noexcept
     {
         const auto libObjPtr = _Spec::contextField(this->libObjPtr());
 
@@ -312,7 +312,7 @@ public:
             return _StructureField {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
@@ -345,8 +345,7 @@ struct TypeDescr<ConstPacket> : public PacketTypeDescr
 } /* namespace internal */
 
 template <typename LibObjT>
-nonstd::optional<typename CommonEvent<LibObjT>::_Packet>
-CommonEvent<LibObjT>::packet() const noexcept
+bt2s::optional<typename CommonEvent<LibObjT>::_Packet> CommonEvent<LibObjT>::packet() const noexcept
 {
     const auto libObjPtr = _Spec::packet(this->libObjPtr());
 
@@ -354,7 +353,7 @@ CommonEvent<LibObjT>::packet() const noexcept
         return _Packet {libObjPtr};
     }
 
-    return nonstd::nullopt;
+    return bt2s::nullopt;
 }
 
 namespace internal {
@@ -690,7 +689,7 @@ public:
         bt_trace_set_uuid(this->libObjPtr(), uuid.begin());
     }
 
-    nonstd::optional<bt2c::UuidView> uuid() const noexcept
+    bt2s::optional<bt2c::UuidView> uuid() const noexcept
     {
         const auto uuid = bt_trace_get_uuid(this->libObjPtr());
 
@@ -698,7 +697,7 @@ public:
             return bt2c::UuidView {uuid};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     std::uint64_t length() const noexcept
@@ -711,7 +710,7 @@ public:
         return _Stream {_Spec::streamByIndex(this->libObjPtr(), index)};
     }
 
-    nonstd::optional<_Stream> streamById(const std::uint64_t id) const noexcept
+    bt2s::optional<_Stream> streamById(const std::uint64_t id) const noexcept
     {
         const auto libObjPtr = _Spec::streamById(this->libObjPtr(), id);
 
@@ -719,7 +718,7 @@ public:
             return _Stream {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     void environmentEntry(const char * const name, const std::int64_t val) const
@@ -779,7 +778,7 @@ public:
         return ConstEnvironmentEntry {name, ConstValue {libObjPtr}};
     }
 
-    nonstd::optional<ConstValue> environmentEntry(const char * const name) const noexcept
+    bt2s::optional<ConstValue> environmentEntry(const char * const name) const noexcept
     {
         const auto libObjPtr =
             bt_trace_borrow_environment_entry_value_by_name_const(this->libObjPtr(), name);
@@ -788,10 +787,10 @@ public:
             return ConstValue {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<ConstValue> environmentEntry(const std::string& name) const noexcept
+    bt2s::optional<ConstValue> environmentEntry(const std::string& name) const noexcept
     {
         return this->environmentEntry(name.data());
     }
@@ -1011,7 +1010,7 @@ public:
                                      static_cast<bt_event_class_log_level>(logLevel));
     }
 
-    nonstd::optional<LogLevel> logLevel() const noexcept
+    bt2s::optional<LogLevel> logLevel() const noexcept
     {
         bt_event_class_log_level libLogLevel;
         const auto avail = bt_event_class_get_log_level(this->libObjPtr(), &libLogLevel);
@@ -1020,7 +1019,7 @@ public:
             return static_cast<LogLevel>(libLogLevel);
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     void emfUri(const char * const emfUri) const
@@ -1056,7 +1055,7 @@ public:
         }
     }
 
-    nonstd::optional<_StructureFieldClass> payloadFieldClass() const noexcept
+    bt2s::optional<_StructureFieldClass> payloadFieldClass() const noexcept
     {
         const auto libObjPtr = _Spec::payloadFieldClass(this->libObjPtr());
 
@@ -1064,7 +1063,7 @@ public:
             return _StructureFieldClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     void specificContextFieldClass(const StructureFieldClass fc) const
@@ -1079,7 +1078,7 @@ public:
         }
     }
 
-    nonstd::optional<_StructureFieldClass> specificContextFieldClass() const noexcept
+    bt2s::optional<_StructureFieldClass> specificContextFieldClass() const noexcept
     {
         const auto libObjPtr = _Spec::specificContextFieldClass(this->libObjPtr());
 
@@ -1087,7 +1086,7 @@ public:
             return _StructureFieldClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     template <typename LibValT>
@@ -1474,7 +1473,7 @@ public:
         BT_ASSERT(status == BT_STREAM_CLASS_SET_DEFAULT_CLOCK_CLASS_STATUS_OK);
     }
 
-    nonstd::optional<_ClockClass> defaultClockClass() const noexcept
+    bt2s::optional<_ClockClass> defaultClockClass() const noexcept
     {
         const auto libObjPtr = _Spec::defaultClockClass(this->libObjPtr());
 
@@ -1482,7 +1481,7 @@ public:
             return _ClockClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     std::uint64_t length() const noexcept
@@ -1495,7 +1494,7 @@ public:
         return _EventClass {_Spec::eventClassByIndex(this->libObjPtr(), index)};
     }
 
-    nonstd::optional<_EventClass> eventClassById(const std::uint64_t id) const noexcept
+    bt2s::optional<_EventClass> eventClassById(const std::uint64_t id) const noexcept
     {
         const auto libObjPtr = _Spec::eventClassById(this->libObjPtr(), id);
 
@@ -1503,7 +1502,7 @@ public:
             return _EventClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     void packetContextFieldClass(const StructureFieldClass fc) const
@@ -1519,7 +1518,7 @@ public:
         }
     }
 
-    nonstd::optional<_StructureFieldClass> packetContextFieldClass() const noexcept
+    bt2s::optional<_StructureFieldClass> packetContextFieldClass() const noexcept
     {
         const auto libObjPtr = _Spec::packetContextFieldClass(this->libObjPtr());
 
@@ -1527,7 +1526,7 @@ public:
             return _StructureFieldClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     void eventCommonContextFieldClass(const StructureFieldClass fc) const
@@ -1543,7 +1542,7 @@ public:
         }
     }
 
-    nonstd::optional<_StructureFieldClass> eventCommonContextFieldClass() const noexcept
+    bt2s::optional<_StructureFieldClass> eventCommonContextFieldClass() const noexcept
     {
         const auto libObjPtr = _Spec::eventCommonContextFieldClass(this->libObjPtr());
 
@@ -1551,7 +1550,7 @@ public:
             return _StructureFieldClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     template <typename LibValT>
@@ -1981,7 +1980,7 @@ public:
         return _StreamClass {_Spec::streamClassByIndex(this->libObjPtr(), index)};
     }
 
-    nonstd::optional<_StreamClass> streamClassById(const std::uint64_t id) const noexcept
+    bt2s::optional<_StreamClass> streamClassById(const std::uint64_t id) const noexcept
     {
         const auto libObjPtr = _Spec::streamClassById(this->libObjPtr(), id);
 
@@ -1989,7 +1988,7 @@ public:
             return _StreamClass {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     template <typename LibValT>
diff --git a/src/cpp-common/bt2/value.hpp b/src/cpp-common/bt2/value.hpp
index 54d33bcc..19919ed2 100644
--- a/src/cpp-common/bt2/value.hpp
+++ b/src/cpp-common/bt2/value.hpp
@@ -15,7 +15,7 @@
 
 #include "common/assert.h"
 #include "common/common.h"
-#include "cpp-common/optional.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
 #include "borrowed-object-iterator.hpp"
 #include "borrowed-object.hpp"
@@ -241,7 +241,7 @@ public:
     }
 
     template <typename KeyT>
-    nonstd::optional<CommonValue<LibObjT>> operator[](KeyT&& key) const noexcept
+    bt2s::optional<CommonValue<LibObjT>> operator[](KeyT&& key) const noexcept
     {
         return this->asMap()[std::forward<KeyT>(key)];
     }
@@ -1285,19 +1285,19 @@ public:
         return this->length() == 0;
     }
 
-    nonstd::optional<CommonValue<LibObjT>> operator[](const char * const key) const noexcept
+    bt2s::optional<CommonValue<LibObjT>> operator[](const char * const key) const noexcept
     {
         const auto libObjPtr =
             internal::CommonMapValueSpec<LibObjT>::entryByKey(this->libObjPtr(), key);
 
         if (!libObjPtr) {
-            return nonstd::nullopt;
+            return bt2s::nullopt;
         }
 
         return CommonValue<LibObjT> {libObjPtr};
     }
 
-    nonstd::optional<CommonValue<LibObjT>> operator[](const std::string& key) const noexcept
+    bt2s::optional<CommonValue<LibObjT>> operator[](const std::string& key) const noexcept
     {
         return (*this)[key.data()];
     }
diff --git a/src/cpp-common/bt2s/optional.hpp b/src/cpp-common/bt2s/optional.hpp
new file mode 100644
index 00000000..96d003df
--- /dev/null
+++ b/src/cpp-common/bt2s/optional.hpp
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2023 Philippe Proulx <pproulx@efficios.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#ifndef BABELTRACE_CPP_COMMON_BT2S_OPTIONAL_HPP
+#define BABELTRACE_CPP_COMMON_BT2S_OPTIONAL_HPP
+
+#include "cpp-common/vendor/optional-lite/optional.hpp"
+
+namespace bt2s {
+
+template <typename T>
+using optional = nonstd::optional<T>;
+
+using nullopt_t = nonstd::nullopt_t;
+using bad_optional_access = nonstd::bad_optional_access;
+constexpr nullopt_t nullopt {nonstd::nullopt};
+
+template <typename T>
+constexpr optional<typename std::decay<T>::type> make_optional(T&& value)
+{
+    return nonstd::make_optional(std::forward<T>(value));
+}
+
+template <typename T, typename... ArgTs>
+constexpr optional<T> make_optional(ArgTs&&...args)
+{
+    return nonstd::make_optional<T>(std::forward<ArgTs>(args)...);
+}
+
+using in_place_t = nonstd::in_place_t;
+
+template <typename T>
+inline in_place_t in_place()
+{
+    return nonstd::in_place<T>();
+}
+
+template <std::size_t K>
+inline in_place_t in_place()
+{
+    return nonstd::in_place<K>();
+}
+
+template <typename T>
+inline in_place_t in_place_type()
+{
+    return nonstd::in_place_type<T>();
+}
+
+template <std::size_t K>
+inline in_place_t in_place_index()
+{
+    return nonstd::in_place_index<K>();
+}
+
+} /* namespace bt2s */
+
+#endif /* BABELTRACE_CPP_COMMON_BT2S_OPTIONAL_HPP */
diff --git a/src/cpp-common/optional.hpp b/src/cpp-common/vendor/optional-lite/optional.hpp
similarity index 100%
rename from src/cpp-common/optional.hpp
rename to src/cpp-common/vendor/optional-lite/optional.hpp
diff --git a/tools/format-cpp.sh b/tools/format-cpp.sh
index 364dafe1..04444ddc 100755
--- a/tools/format-cpp.sh
+++ b/tools/format-cpp.sh
@@ -44,7 +44,7 @@ format_cpp() {
 	# We want an absolute starting directory because find(1) excludes
 	# files in specific subdirectories.
 	find "$(realpath "$root_dir")" \( -name '*.cpp' -o -name '*.hpp' \) \
-		! -path '*/src/cpp-common/optional.hpp' \
+		! -path '*/src/cpp-common/vendor/*' \
 		! -path '*/src/cpp-common/string_view.hpp' \
 		! -path '*/src/cpp-common/nlohmann/json.hpp' \
 		! -path '*/src/plugins/ctf/common/metadata/parser.*' \
-- 
2.34.1