Add JSON_DELETE_DEPRECATED_FUNCTIONS to delete the deprecated functions (#5755)

* Add JSON_DELETE_DEPRECATED_FUNCTIONS to delete the deprecated functions

Defining JSON_DELETE_DEPRECATED_FUNCTIONS to 1 (or the CMake option
JSON_DeleteDeprecatedFunctions) declares every deprecated function as
deleted instead of deprecated, so that code that is not ready for 4.0.0
no longer compiles. A deleted function still takes part in overload
resolution, so from_*(ptr, len) cannot silently bind len to the strict
parameter of from_*(InputType&&, bool); the roadmap now plans to keep
these overloads deleted in 4.0.0 instead of removing them.

The legacy discarded-value comparison is left to its own macro.

Also update the 4.0 roadmap: add JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
and JSON_DELETE_DEPRECATED_FUNCTIONS to the macro table, add the
from_bjdata/from_bon8 (ptr, len) overloads to the deprecated functions,
document the macro in the migration guide, and fix the docs style check
findings (example titles, missing docset entry for JSON_STRICT_BINARY_UTF8).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Declare each deprecated function once and guard only its body

Instead of repeating every deprecated declaration in an
#if JSON_DELETE_DEPRECATED_FUNCTIONS branch, keep one declaration
(with its deprecation attribute) and switch only between "= delete;"
and the function body. Suggested by @gregmarr in the review.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-10-04 22:11:34 +02:00
committed by GitHub
parent c5a7a4b46d
commit 23d3b373e1
30 changed files with 755 additions and 15 deletions
+15 -1
View File
@@ -249,6 +249,20 @@ add_custom_target(ci_test_strict_nul_handling
COMMENT "Compile and test with strict NUL-byte handling enabled"
)
###############################################################################
# Delete the deprecated functions.
###############################################################################
add_custom_target(ci_test_delete_deprecated_functions
COMMAND ${CMAKE_COMMAND}
-DCMAKE_BUILD_TYPE=Debug -GNinja
-DJSON_BuildTests=ON -DJSON_FastTests=ON -DJSON_DeleteDeprecatedFunctions=ON
-S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_delete_deprecated_functions
COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_delete_deprecated_functions
COMMAND cd ${PROJECT_BINARY_DIR}/build_delete_deprecated_functions && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
COMMENT "Compile and test with the deprecated functions deleted"
)
###############################################################################
# Disable global UDLs.
###############################################################################
@@ -705,7 +719,7 @@ ci_get_cmake(4.0.0 CMAKE_4_0_0_BINARY)
# the tests require CMake 3.13 or later, so they are excluded for CMake 3.5.0
set(JSON_CMAKE_FLAGS_3_5_0 JSON_Diagnostics JSON_Diagnostic_Positions JSON_GlobalUDLs JSON_ImplicitConversions JSON_DisableEnumSerialization
JSON_LegacyDiscardedValueComparison JSON_Install JSON_MultipleHeaders JSON_SystemInclude JSON_Valgrind
JSON_StrictNulHandling JSON_StrictBinaryUTF8)
JSON_StrictNulHandling JSON_StrictBinaryUTF8 JSON_DeleteDeprecatedFunctions)
set(JSON_CMAKE_FLAGS_3_31_6 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_5_0})
set(JSON_CMAKE_FLAGS_4_0_0 JSON_BuildTests ${JSON_CMAKE_FLAGS_3_5_0})