Fix C++11 ABI breakage when compiled with C++17 #1668 (#1675)
* ci: suppress Node 20 deprecation and missing python-version warnings
- 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.
* Fix C++11 ABI breakage when compiled with C++17 (#1668)
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.
* ci: add ABI compatibility matrix workflow
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.
* fix: inline std::string_view methods to prevent ABI breaks
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.
* run clang format
* finish clang format
diff --git a/.github/workflows/abi-compatibility.yml b/.github/workflows/abi-compatibility.yml
new file mode 100644
index 0000000..881c4e8
--- /dev/null
+++ b/.github/workflows/abi-compatibility.yml
@@ -0,0 +1,79 @@
+name: ABI Compatibility
+
+on: [check_run, push, pull_request]
+
+env:
+ FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
+
+jobs:
+ abi-compatibility:
+ runs-on: ${{ matrix.os }}
+
+ strategy:
+ fail-fast: false
+ matrix:
+ os: [ubuntu-latest, windows-latest, macos-latest]
+ shared_libs: [ON, OFF]
+ include:
+ - jsoncpp_std: 11
+ app_std: 23
+ - jsoncpp_std: 23
+ app_std: 11
+
+ steps:
+ - name: checkout project
+ uses: actions/checkout@v4
+
+ - name: build and install JsonCpp (C++${{ matrix.jsoncpp_std }})
+ shell: bash
+ run: |
+ mkdir build-jsoncpp
+ cd build-jsoncpp
+ cmake .. -DCMAKE_CXX_STANDARD=${{ matrix.jsoncpp_std }} \
+ -DCMAKE_CXX_STANDARD_REQUIRED=ON \
+ -DCMAKE_INSTALL_PREFIX=$GITHUB_WORKSPACE/install-jsoncpp \
+ -DBUILD_SHARED_LIBS=${{ matrix.shared_libs }} \
+ -DJSONCPP_WITH_TESTS=OFF
+ cmake --build . --config Release
+ cmake --install . --config Release
+
+ - name: create example app
+ shell: bash
+ run: |
+ mkdir example-app
+ cat << 'EOF' > example-app/CMakeLists.txt
+ cmake_minimum_required(VERSION 3.10)
+ project(abi_test)
+
+ find_package(jsoncpp REQUIRED CONFIG)
+
+ add_executable(abi_test stringView.cpp)
+ target_link_libraries(abi_test PRIVATE JsonCpp::JsonCpp)
+ EOF
+
+ cp $GITHUB_WORKSPACE/example/stringView/stringView.cpp example-app/stringView.cpp
+
+ - name: build example app (C++${{ matrix.app_std }})
+ shell: bash
+ run: |
+ cd example-app
+ mkdir build
+ cd build
+ cmake .. -DCMAKE_CXX_STANDARD=${{ matrix.app_std }} \
+ -DCMAKE_CXX_STANDARD_REQUIRED=ON \
+ -DCMAKE_PREFIX_PATH=$GITHUB_WORKSPACE/install-jsoncpp
+ cmake --build . --config Release
+
+ - name: run example app
+ shell: bash
+ run: |
+ if [ "$RUNNER_OS" == "Windows" ]; then
+ export PATH=$GITHUB_WORKSPACE/install-jsoncpp/bin:$PATH
+ ./example-app/build/Release/abi_test.exe
+ elif [ "$RUNNER_OS" == "macOS" ]; then
+ export DYLD_LIBRARY_PATH=$GITHUB_WORKSPACE/install-jsoncpp/lib:$DYLD_LIBRARY_PATH
+ ./example-app/build/abi_test
+ else
+ export LD_LIBRARY_PATH=$GITHUB_WORKSPACE/install-jsoncpp/lib:$LD_LIBRARY_PATH
+ ./example-app/build/abi_test
+ fi
diff --git a/example/BUILD.bazel b/example/BUILD.bazel
index ebbd0b5..3581308 100644
--- a/example/BUILD.bazel
+++ b/example/BUILD.bazel
@@ -33,3 +33,9 @@
srcs = ["stringWrite/stringWrite.cpp"],
deps = ["//:jsoncpp"],
)
+
+cc_binary(
+ name = "stringView",
+ srcs = ["stringView/stringView.cpp"],
+ deps = ["//:jsoncpp"],
+)
diff --git a/example/CMakeLists.txt b/example/CMakeLists.txt
index 230d1bd..0666db7 100644
--- a/example/CMakeLists.txt
+++ b/example/CMakeLists.txt
@@ -4,6 +4,7 @@
readFromStream
stringWrite
streamWrite
+ stringView
)
add_definitions(-D_GLIBCXX_USE_CXX11_ABI)
diff --git a/example/stringView/stringView.cpp b/example/stringView/stringView.cpp
new file mode 100644
index 0000000..b5e33e9
--- /dev/null
+++ b/example/stringView/stringView.cpp
@@ -0,0 +1,29 @@
+#include "json/json.h"
+#include <cstdlib>
+#include <iostream>
+
+#if defined(JSONCPP_HAS_STRING_VIEW)
+#include <string_view>
+#endif
+
+/**
+ * \brief Example using std::string_view with JsonCpp.
+ */
+int main() {
+ Json::Value root;
+ root["key"] = "value";
+
+#if defined(JSONCPP_HAS_STRING_VIEW)
+ std::cout << "Has string_view support" << std::endl;
+ std::string_view sv("key");
+ if (root.isMember(sv)) {
+ std::cout << root[sv].asString() << std::endl;
+ }
+#else
+ std::cout << "No string_view support" << std::endl;
+ if (root.isMember("key")) {
+ std::cout << root["key"].asString() << std::endl;
+ }
+#endif
+ return EXIT_SUCCESS;
+}
diff --git a/include/json/value.h b/include/json/value.h
index f32f456..2007e6b 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -357,7 +357,8 @@
Value(const StaticString& value);
Value(const String& value);
#ifdef JSONCPP_HAS_STRING_VIEW
- Value(std::string_view value);
+ inline Value(std::string_view value)
+ : Value(value.data(), value.data() + value.length()) {}
#endif
Value(bool value);
Value(std::nullptr_t ptr) = delete;
@@ -405,7 +406,14 @@
/** Get string_view of string-value.
* \return false if !string. (Seg-fault if str is NULL.)
*/
- bool getString(std::string_view* str) const;
+ inline bool getString(std::string_view* str) const {
+ char const* begin;
+ char const* end;
+ if (!getString(&begin, &end))
+ return false;
+ *str = std::string_view(begin, static_cast<size_t>(end - begin));
+ return true;
+ }
#endif
Int asInt() const;
UInt asUInt() const;
@@ -496,12 +504,19 @@
#ifdef JSONCPP_HAS_STRING_VIEW
/// Access an object value by name, create a null member if it does not exist.
/// \param key may contain embedded nulls.
- Value& operator[](std::string_view key);
+ inline Value& operator[](std::string_view key) {
+ return resolveReference(key.data(), key.data() + key.length());
+ }
/// Access an object value by name, returns null if there is no member with
/// that name.
/// \param key may contain embedded nulls.
- const Value& operator[](std::string_view key) const;
-#else
+ inline const Value& operator[](std::string_view key) const {
+ Value const* found = find(key.data(), key.data() + key.length());
+ if (!found)
+ return nullSingleton();
+ return *found;
+ }
+#endif
/// Access an object value by name, create a null member if it does not exist.
/// \note Because of our implementation, keys are limited to 2^30 -1 chars.
/// Exceeding that will cause an exception.
@@ -516,7 +531,6 @@
/// that name.
/// \param key may contain embedded nulls.
const Value& operator[](const String& key) const;
-#endif
/** \brief Access an object value by name, create a null member if it does not
* exist.
*
@@ -533,8 +547,10 @@
#ifdef JSONCPP_HAS_STRING_VIEW
/// Return the member named key if it exist, defaultValue otherwise.
/// \note deep copy
- Value get(std::string_view key, const Value& defaultValue) const;
-#else
+ inline Value get(std::string_view key, const Value& defaultValue) const {
+ return get(key.data(), key.data() + key.length(), defaultValue);
+ }
+#endif
/// Return the member named key if it exist, defaultValue otherwise.
/// \note deep copy
Value get(const char* key, const Value& defaultValue) const;
@@ -542,7 +558,6 @@
/// \note deep copy
/// \param key may contain embedded nulls.
Value get(const String& key, const Value& defaultValue) const;
-#endif
/// Return the member named key if it exist, defaultValue otherwise.
/// \note deep copy
/// \note key may contain embedded nulls.
@@ -588,13 +603,14 @@
/// \pre type() is objectValue or nullValue
/// \post type() is unchanged
#if JSONCPP_HAS_STRING_VIEW
- void removeMember(std::string_view key);
-#else
+ inline void removeMember(std::string_view key) {
+ removeMember(key.data(), key.data() + key.length(), nullptr);
+ }
+#endif
void removeMember(const char* key);
/// Same as removeMember(const char*)
/// \param key may contain embedded nulls.
void removeMember(const String& key);
-#endif
/** \brief Remove the named map member.
*
* Update 'removed' iff removed.
@@ -602,13 +618,14 @@
* \return true iff removed (no exceptions)
*/
#if JSONCPP_HAS_STRING_VIEW
- bool removeMember(std::string_view key, Value* removed);
-#else
+ inline bool removeMember(std::string_view key, Value* removed) {
+ return removeMember(key.data(), key.data() + key.length(), removed);
+ }
+#endif
bool removeMember(String const& key, Value* removed);
/// Same as removeMember(const char* begin, const char* end, Value* removed),
/// but 'key' is null-terminated.
bool removeMember(const char* key, Value* removed);
-#endif
/// Same as removeMember(String const& key, Value* removed)
bool removeMember(const char* begin, const char* end, Value* removed);
/** \brief Remove the indexed array element.
@@ -622,15 +639,16 @@
#ifdef JSONCPP_HAS_STRING_VIEW
/// Return true if the object has a member named key.
/// \param key may contain embedded nulls.
- bool isMember(std::string_view key) const;
-#else
+ inline bool isMember(std::string_view key) const {
+ return isMember(key.data(), key.data() + key.length());
+ }
+#endif
/// Return true if the object has a member named key.
/// \note 'key' must be null-terminated.
bool isMember(const char* key) const;
/// Return true if the object has a member named key.
/// \param key may contain embedded nulls.
bool isMember(const String& key) const;
-#endif
/// Same as isMember(String const& key)const
bool isMember(const char* begin, const char* end) const;
diff --git a/src/lib_json/CMakeLists.txt b/src/lib_json/CMakeLists.txt
index 03e9335..a0695e9 100644
--- a/src/lib_json/CMakeLists.txt
+++ b/src/lib_json/CMakeLists.txt
@@ -131,9 +131,6 @@
target_compile_features(${SHARED_LIB} PUBLIC ${REQUIRED_FEATURES})
- if(JSONCPP_HAS_STRING_VIEW)
- target_compile_definitions(${SHARED_LIB} PUBLIC JSONCPP_HAS_STRING_VIEW=1)
- endif()
target_include_directories(${SHARED_LIB} PUBLIC
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
@@ -168,9 +165,6 @@
target_compile_features(${STATIC_LIB} PUBLIC ${REQUIRED_FEATURES})
- if(JSONCPP_HAS_STRING_VIEW)
- target_compile_definitions(${STATIC_LIB} PUBLIC JSONCPP_HAS_STRING_VIEW=1)
- endif()
target_include_directories(${STATIC_LIB} PUBLIC
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
@@ -198,9 +192,6 @@
target_compile_features(${OBJECT_LIB} PUBLIC ${REQUIRED_FEATURES})
- if(JSONCPP_HAS_STRING_VIEW)
- target_compile_definitions(${OBJECT_LIB} PUBLIC JSONCPP_HAS_STRING_VIEW=1)
- endif()
target_include_directories(${OBJECT_LIB} PUBLIC
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 74f7789..a8eb72d 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -441,14 +441,6 @@
value.data(), static_cast<unsigned>(value.length()));
}
-#ifdef JSONCPP_HAS_STRING_VIEW
-Value::Value(std::string_view value) {
- initBasic(stringValue, true);
- value_.string_ = duplicateAndPrefixStringValue(
- value.data(), static_cast<unsigned>(value.length()));
-}
-#endif
-
Value::Value(const StaticString& value) {
initBasic(stringValue);
value_.string_ = const_cast<char*>(value.c_str());
@@ -656,21 +648,6 @@
return true;
}
-#ifdef JSONCPP_HAS_STRING_VIEW
-bool Value::getString(std::string_view* str) const {
- if (type() != stringValue)
- return false;
- if (value_.string_ == nullptr)
- return false;
- const char* begin;
- unsigned length;
- decodePrefixedString(this->isAllocated(), this->value_.string_, &length,
- &begin);
- *str = std::string_view(begin, length);
- return true;
-}
-#endif
-
String Value::asString() const {
switch (type()) {
case nullValue:
@@ -1190,17 +1167,6 @@
"objectValue or nullValue");
return &resolveReference(begin, end);
}
-#ifdef JSONCPP_HAS_STRING_VIEW
-const Value& Value::operator[](std::string_view key) const {
- Value const* found = find(key.data(), key.data() + key.length());
- if (!found)
- return nullSingleton();
- return *found;
-}
-Value& Value::operator[](std::string_view key) {
- return resolveReference(key.data(), key.data() + key.length());
-}
-#else
const Value& Value::operator[](const char* key) const {
Value const* found = find(key, key + strlen(key));
if (!found)
@@ -1221,7 +1187,6 @@
Value& Value::operator[](const String& key) {
return resolveReference(key.data(), key.data() + key.length());
}
-#endif
Value& Value::operator[](const StaticString& key) {
return resolveReference(key.c_str());
@@ -1261,18 +1226,12 @@
Value const* found = find(begin, end);
return !found ? defaultValue : *found;
}
-#ifdef JSONCPP_HAS_STRING_VIEW
-Value Value::get(std::string_view key, const Value& defaultValue) const {
- return get(key.data(), key.data() + key.length(), defaultValue);
-}
-#else
Value Value::get(char const* key, Value const& defaultValue) const {
return get(key, key + strlen(key), defaultValue);
}
Value Value::get(String const& key, Value const& defaultValue) const {
return get(key.data(), key.data() + key.length(), defaultValue);
}
-#endif
bool Value::removeMember(const char* begin, const char* end, Value* removed) {
if (type() != objectValue) {
@@ -1288,31 +1247,13 @@
value_.map_->erase(it);
return true;
}
-#ifdef JSONCPP_HAS_STRING_VIEW
-bool Value::removeMember(std::string_view key, Value* removed) {
- return removeMember(key.data(), key.data() + key.length(), removed);
-}
-#else
bool Value::removeMember(const char* key, Value* removed) {
return removeMember(key, key + strlen(key), removed);
}
bool Value::removeMember(String const& key, Value* removed) {
return removeMember(key.data(), key.data() + key.length(), removed);
}
-#endif
-#ifdef JSONCPP_HAS_STRING_VIEW
-void Value::removeMember(std::string_view key) {
- JSON_ASSERT_MESSAGE(type() == nullValue || type() == objectValue,
- "in Json::Value::removeMember(): requires objectValue");
- if (type() == nullValue)
- return;
-
- CZString actualKey(key.data(), unsigned(key.length()),
- CZString::noDuplication);
- value_.map_->erase(actualKey);
-}
-#else
void Value::removeMember(const char* key) {
JSON_ASSERT_MESSAGE(type() == nullValue || type() == objectValue,
"in Json::Value::removeMember(): requires objectValue");
@@ -1323,7 +1264,6 @@
value_.map_->erase(actualKey);
}
void Value::removeMember(const String& key) { removeMember(key.c_str()); }
-#endif
bool Value::removeIndex(ArrayIndex index, Value* removed) {
if (type() != arrayValue) {
@@ -1353,18 +1293,12 @@
Value const* value = find(begin, end);
return nullptr != value;
}
-#ifdef JSONCPP_HAS_STRING_VIEW
-bool Value::isMember(std::string_view key) const {
- return isMember(key.data(), key.data() + key.length());
-}
-#else
bool Value::isMember(char const* key) const {
return isMember(key, key + strlen(key));
}
bool Value::isMember(String const& key) const {
return isMember(key.data(), key.data() + key.length());
}
-#endif
Value::Members Value::getMemberNames() const {
JSON_ASSERT_MESSAGE(
