Make RapidJSON Stack::Bottom pointer cast explicit via void*#173
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SergioRZMasson merged 1 commit intoJul 14, 2026
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Stack::Bottom<T>() returns the internal raw byte buffer (char* stack_) reinterpret_cast directly to T*. When T is a wider element type (e.g. a wide-character type) this is a narrow-to-wide pointer conversion that some compilers and static analysis tools diagnose as a potentially misaligned/narrowing cast. Apply a small CMake patch during the RapidJSON ExternalProject_Add download step (matching the existing fix-null-allocator-deref.cmake mechanism) that routes the cast through void*: reinterpret_cast<T*>(stack_) -> reinterpret_cast<T*>(static_cast<void*>(stack_)) This makes the raw-storage intent explicit. It is address-identical and preserves the exact behavior of the generic memory stack, covering both the const and non-const Bottom() overloads, and is idempotent. Validated by applying the patch to RapidJSON at the pinned commit (232389d4) and compiling a translation unit that includes rapidjson and exercises Stack::Bottom<char>/<wchar_t> (const and non-const overloads) plus Document parse + Writer, with -Wall -Wextra -Werror. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Background
Stack::Bottom<T>()returns the internal raw byte buffer (char* stack_)reinterpret_castdirectly toT*. WhenTis a wider element type (e.g. awide-character type), this is a narrow-to-wide pointer conversion that some
compilers and static analysis tools diagnose as a potentially
misaligned/narrowing cast.
Change
Following the same mechanism as the existing
fix-null-allocator-deref.cmakepatch (#167), a small CMake
string(REPLACE)patch is applied during theRapidJSON
ExternalProject_Adddownload step, routing the cast throughvoid*:reinterpret_cast<T*>(stack_)→reinterpret_cast<T*>(static_cast<void*>(stack_))This makes the "treat this buffer as raw storage" intent explicit. It is
address-identical and preserves the exact behavior of the generic memory stack,
covers both the
constand non-constBottom()overloads, and is idempotent.Changes
External/RapidJSON/patches/fix-string-type-conversion.cmakeExternal/RapidJSON/CMakeRapidJSONDownload.txt.in— chain the newpatch after the existing one in
PATCH_COMMANDValidation
Applied the patch to RapidJSON at the pinned commit (
232389d4) and compiled atranslation unit that includes rapidjson and exercises
Stack::Bottom<char>/<wchar_t>(const+ non-const) plusDocumentparse +Writer, withclang++ -std=c++14 -Wall -Wextra -Werror. Re-running the patchis a no-op.