Fix C++11 ABI breakage when compiled with C++17 #1668#1675
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- Injects `FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true` in all workflows to opt-in to Node.js 24 and suppress the deprecation warnings from multiple GitHub Actions. - Specifies `python-version: '3.x'` for `actions/setup-python@v5` in `meson.yml` to fix the missing input warning.
When JSONCPP_HAS_STRING_VIEW was defined, the library dropped the `const char*` and `const String&` overloads for `operator[]`, `get`, `removeMember`, and `isMember`, breaking ABI compatibility for projects consuming the library with C++11. This change unconditionally declares and defines the legacy overloads so they are always exported, restoring compatibility.
baylesj
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Coverage Report for CI Build 24204236720Coverage remained the same at 90.093%Details
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This adds a new GitHub Actions workflow to verify ABI compatibility across C++ standard boundaries. It explicitly tests the scenario where JsonCpp is built with one standard (e.g., C++11) and consumed by an application built with a newer one (e.g., C++23), and vice versa. To facilitate testing the specific `std::string_view` boundary that is conditionally compiled, a new `stringView` demo application has been added to the `example/` directory and is consumed directly by the CI matrix to ensure standard library symbols link correctly across standard versions, build types (shared/static), and operating systems.
This commit completely eliminates the ABI breakage that occurs across C++ standard boundaries when using `std::string_view`. Previously, when the library was built with C++17+, CMake would leak `JSONCPP_HAS_STRING_VIEW=1` as a PUBLIC definition. A C++11 consumer would receive this definition, attempt to parse the header, and fail with compiler errors because `std::string_view` is not available in their environment. Conversely, if the library was built in C++11 (without `string_view` symbols), a C++17 consumer would naturally define `JSONCPP_HAS_STRING_VIEW` based on `__cplusplus` inside `value.h`. The consumer would then call the declared `string_view` methods, resulting in linker errors because the methods weren't compiled into the library. By moving all `std::string_view` overloads directly into `value.h` as `inline` methods that delegate to the fundamental `const char*, const char*` methods: 1. The consumer's compiler dictates whether the overloads are visible (via `__cplusplus >= 201703L`). 2. The consumer compiles the inline wrappers locally, removing any reliance on the library's exported symbols for `std::string_view`. 3. CMake no longer needs to pollute the consumer's environment with PUBLIC compile definitions.
baylesj
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When
JSONCPP_HAS_STRING_VIEWis defined while JsonCpp is built, but not in a consuming library, theconst char*andconst String&overloads foroperator[],get,removeMember, andisMemberare defined in the header but do not have an implementation, breaking ABI compatibility for projects consuming the library with C++11.This patchset includes the following changes:
Unconditionally declares and defines the legacy overloads so they are always exported, restoring compatibility
Adds new ABI GitHub Actions targets to ensure that JsonCpp properly links when installed at C++23 and used in a C++11 project, and vice versa
Moves all of the string view methods to be inline and thus header only, which hopefully will make versioning and maintenance slightly easier and usage a little more clear
Fixed #1668