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Fixed the WASM (emscripten) build, which broke starting with emscripten 6.0.2. The failure is not in magic itself but in the TCL dependency build: emscripten 6.0.2 began shipping a <sys/epoll.h> stub in its sysroot (6.0.1 did not), so TCL's configure now detects epoll on the Linux CI host via AC_CHECK_HEADERS([sys/epoll.h]), defines NOTIFIER_EPOLL, and compiles tclEpollNotfy.c. That file also requires <sys/queue.h>, which emscripten does not provide, so the build died with "fatal error: 'sys/queue.h' file not found". Fixed by passing ac_cv_header_sys_epoll_h=no to TCL's configure in toolchains/emscripten/build-tcl-wasm.sh, which forces the select()-based notifier. That notifier is the correct choice for single-threaded WASM anyway (emscripten's epoll is only a stub), and overriding the autoconf cache variable avoids patching the read-only TCL source tree and keeps the build working across future emscripten versions.

This commit is contained in:
Intubun 2026-07-07 14:14:21 +02:00
parent 443045b331
commit ac059f0918
1 changed files with 14 additions and 1 deletions
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15
toolchains/emscripten/build-tcl-wasm.sh
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@ -93,6 +93,18 @@ cd "$OUT"
# --disable-shared we statically link libtcl into magic.wasm.
# --disable-load no dynamic loading inside wasm.
# --enable-symbols=no release (-O2). Override CFLAGS to add -g for debug.
#
# ac_cv_header_sys_epoll_h=no forces TCL onto its select()-based notifier.
# On a Linux host, TCL's configure runs `AC_CHECK_HEADERS([sys/epoll.h])` and,
# if found, defines NOTIFIER_EPOLL and compiles tclEpollNotfy.c. Emscripten
# 6.0.2 started shipping a <sys/epoll.h> stub in its sysroot (6.0.1 did not),
# so that probe now passes — but tclEpollNotfy.c also needs <sys/queue.h>,
# which emscripten does NOT provide, so the build dies with
# tclEpollNotfy.c: fatal error: 'sys/queue.h' file not found
# The select() notifier is the correct choice for single-threaded WASM anyway
# (emscripten's epoll is a stub), so we pin it here rather than track the
# emscripten sysroot. Overriding the autoconf cache var is cleaner than
# patching the read-only TCL source tree.
if [ ! -f Makefile ]; then
echo "=== emconfigure ==="
CFLAGS="-O2 -sUSE_ZLIB=1" \
@ -101,7 +113,8 @@ if [ ! -f Makefile ]; then
--disable-load \
--enable-symbols=no \
--host=wasm32-unknown-emscripten \
--prefix="$OUT/install"
--prefix="$OUT/install" \
ac_cv_header_sys_epoll_h=no
fi
# emconfigure writes tclConfig.sh into the build dir. If it is missing, the