Skip to content

feat: make the public headers consumable as C++20 #936

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
PingLiuPing wants to merge 11 commits into
base: main
Choose a base branch
from
+3,469 −55
Open

feat: make the public headers consumable as C++20 #936

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
11 commits
Select commit Hold shift + click to select a range
4b8ac81
restore the vendored iceberg::expected backport
PingLiuPing Sep 10, 2026
812c881
let iceberg::expected hold a value type with no default constructor
PingLiuPing Sep 10, 2026
b3256fb
make Result portable by aliasing it to iceberg::expected
PingLiuPing Sep 16, 2026
995e31f
replace the remaining C++23 library features in public headers
PingLiuPing Sep 10, 2026
8718bb0
drop deducing this from TaskGroup
PingLiuPing Sep 10, 2026
10680bb
give ErrorCollector::AddError a C++20 form
PingLiuPing Sep 16, 2026
adb5956
give SnapshotUpdate's chaining setters a C++20 form
PingLiuPing Sep 16, 2026
4a66df4
build the example as C++20
PingLiuPing Sep 10, 2026
734369a
Fix pre-commit
PingLiuPing Sep 17, 2026
0cfe9b4
Removed invalid e1.error() access on a successful expected<void, int>
PingLiuPing Sep 17, 2026
c5ce092
prevents MSVC from trying to construct private or non default constru…
PingLiuPing Sep 17, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions .github/.licenserc.yaml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ header:
- 'LICENSE'
- 'NOTICE'
- 'requirements.txt'
- 'src/iceberg/expected.h'
- 'src/iceberg/util/murmurhash3_internal.*'
- 'src/iceberg/test/resources/**'
- 'src/iceberg/catalog/hive/gen-cpp/**'
Expand Down
28 changes: 28 additions & 0 deletions LICENSE
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -230,6 +230,34 @@ License: https://www.apache.org/licenses/LICENSE-2.0

--------------------------------------------------------------------------------

This product includes code from zeus-cpp/expected.

* src/iceberg/expected.h is adapted from zeus-cpp/expected.

Copyright: 2024 zeus-cpp.
Home page: https://github.com/zeus-cpp/expected
License: MIT

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

--------------------------------------------------------------------------------

This product bundles utf8proc, which is available under the MIT License:

utf8proc is a software package originally developed by Jan Behrens and the rest
Expand Down
64 changes: 59 additions & 5 deletions example/CMakeLists.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,13 +20,67 @@ cmake_minimum_required(VERSION 3.25)

project(example)

set(CMAKE_CXX_STANDARD 23)

@zhjwpku zhjwpku Sep 17, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can we make C++23 still as default and let it accept user supplied option so that C++20 can be test manually locally.

@PingLiuPing PingLiuPing Sep 17, 2026

Copy link
Copy Markdown
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@zhjwpku Thank you for the comments.

Making it configurable is a good idea. Have different thoughts on making C++23 as default though.

With this patch, it changes the minimum supported C++ standard from C++23 to C++20 for downstream consumers. And C++20 is the interface contract between the consumer and iceberg-cpp library, and the contract should be tested continuously.

Setting the default to C++20 ensures the minimum supported standard (contract) is continuously exercised. Defaulting it to C++23 would let C++20 only breakages slip through.

One refinement is that C++23 compatibility should still be tested separately. C++23 should accepts C++20 code, but we can enhance this by provide an optional example configuration for C++23, for example, expose an ICEBERG_EXAMPLE_CXX_STANDARD cache setting that defaults to 20 and accepts 23; then update CI to build both.
And also refine the document to state clearly that the minimum C++ standard is C++20 for public headers. What do you think?

Happy to make changes either way.

@zhjwpku zhjwpku Sep 17, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Make sense to me, I think we should build both for compatibility purpose.

set(CMAKE_CXX_STANDARD 20)

find_package(iceberg CONFIG REQUIRED COMPONENTS bundle rest)

if(TARGET iceberg::iceberg_bundle_shared)
set(ICEBERG_BUNDLE_TARGET iceberg::iceberg_bundle_shared)
else()
set(ICEBERG_BUNDLE_TARGET iceberg::iceberg_bundle_static)
endif()

if(TARGET iceberg::iceberg_rest_shared)
set(ICEBERG_REST_TARGET iceberg::iceberg_rest_shared)
else()
set(ICEBERG_REST_TARGET iceberg::iceberg_rest_static)
endif()

add_executable(demo_example demo_example.cc)

target_link_libraries(demo_example
PRIVATE "$<IF:$<TARGET_EXISTS:iceberg::iceberg_bundle_shared>,iceberg::iceberg_bundle_shared,iceberg::iceberg_bundle_static>"
"$<IF:$<TARGET_EXISTS:iceberg::iceberg_rest_shared>,iceberg::iceberg_rest_shared,iceberg::iceberg_rest_static>"
)
target_link_libraries(demo_example PRIVATE ${ICEBERG_BUNDLE_TARGET}
${ICEBERG_REST_TARGET})

# Compile every installed public header as a C++20 consumer. The installed include
# tree is the public API contract: iceberg_install_all_headers excludes internal
# headers before packaging them.
get_target_property(ICEBERG_BUNDLE_INCLUDE_DIRS ${ICEBERG_BUNDLE_TARGET}
INTERFACE_INCLUDE_DIRECTORIES)
foreach(ICEBERG_INCLUDE_DIR IN LISTS ICEBERG_BUNDLE_INCLUDE_DIRS)
if(EXISTS "${ICEBERG_INCLUDE_DIR}/iceberg")
set(ICEBERG_PUBLIC_INCLUDE_DIR "${ICEBERG_INCLUDE_DIR}")
break()
endif()
endforeach()

if(NOT ICEBERG_PUBLIC_INCLUDE_DIR)
message(FATAL_ERROR "Could not locate iceberg's installed public headers")
endif()

file(GLOB_RECURSE
ICEBERG_PUBLIC_HEADERS
CONFIGURE_DEPENDS
"${ICEBERG_PUBLIC_INCLUDE_DIR}/iceberg/*.h"
"${ICEBERG_PUBLIC_INCLUDE_DIR}/iceberg/*.hpp")
list(SORT ICEBERG_PUBLIC_HEADERS)

set(ICEBERG_PUBLIC_HEADER_CHECK_SOURCE
"// Generated from iceberg's installed public headers.\n")
foreach(ICEBERG_PUBLIC_HEADER IN LISTS ICEBERG_PUBLIC_HEADERS)
file(RELATIVE_PATH ICEBERG_PUBLIC_HEADER_RELATIVE_PATH "${ICEBERG_PUBLIC_INCLUDE_DIR}"
"${ICEBERG_PUBLIC_HEADER}")
string(APPEND ICEBERG_PUBLIC_HEADER_CHECK_SOURCE
"#include <${ICEBERG_PUBLIC_HEADER_RELATIVE_PATH}>\n")
endforeach()
string(APPEND ICEBERG_PUBLIC_HEADER_CHECK_SOURCE "\nint main() { return 0; }\n")

file(GENERATE
OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/public_headers_cxx20.cc"
CONTENT "${ICEBERG_PUBLIC_HEADER_CHECK_SOURCE}")

add_executable(public_headers_cxx20 "${CMAKE_CURRENT_BINARY_DIR}/public_headers_cxx20.cc")
set_target_properties(public_headers_cxx20
PROPERTIES CXX_STANDARD 20 CXX_STANDARD_REQUIRED ON CXX_EXTENSIONS
OFF)
target_link_libraries(public_headers_cxx20 PRIVATE ${ICEBERG_BUNDLE_TARGET}
${ICEBERG_REST_TARGET})
Loading
Loading