common: support win-iconv's const iconv() prototype - #9
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iconv()'s second argument is 'char **' on glibc and GNU libiconv, but 'const char **' on win-iconv (the POSIX/SysV signature) - which is what Fedora's mingw stack ships. charset.c hard-coded 'char *', so it failed to compile (-Wincompatible-pointer-types) against win-iconv even though it built fine against the GNU libiconv used by the MSYS2 CI leg. Detect the prototype at configure time (a -Werror cc.compiles() probe, the autotools ICONV_CONST idiom) and type charset.c's input pointer through the resulting SEER_ICONV_CONST macro - 'const' for win-iconv, empty for glibc/GNU libiconv - so it is warning-clean under either. This makes the protocol core cross-compile cleanly with the Fedora mingw-w64 toolchain (relevant both for local Windows-port iteration and for any future Fedora mingw package of SeerODBC), with no change on the existing Linux/macOS/MSYS2 builds. Verified: full mingw cross-build links; native Linux unchanged (offline 9/0/4, live 11g integration OK). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
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A small, self-contained portability fix that unblocks cross-compiling the protocol core with Fedora's mingw-w64 toolchain. Split out ahead of the ODBC-shim Windows port (Phase 2) since it's independent.
The problem
iconv()'s second argument ischar **on glibc and GNU libiconv, butconst char **on win-iconv (the POSIX/SysV signature) — which is what Fedora's mingw stack (mingw64-win-iconv) ships.charset.chard-codedchar *inbuf, so it compiled fine against the GNU libiconv used by the MSYS2 CI leg but failed (-Wincompatible-pointer-types) against win-iconv.This matters beyond local tooling: any future Fedora mingw package of SeerODBC would link win-iconv and hit the same wall.
The fix
Detect the prototype at configure time — a
-Werrorcc.compiles()probe (the autotoolsICONV_CONSTidiom) — and typecharset.c's input pointer through the resultingSEER_ICONV_CONSTmacro:constfor win-iconv, empty for glibc/GNU libiconv. Warning-clean under either, no runtime change.Verification
charset.c).🤖 Generated with Claude Code