Hi Thomas, On Thu, Aug 11, 2022 at 10:02:29PM +1200, Thomas Munro wrote: > Remove configure probe for sys/uio.h.
Removing the configure probe is fine, but the patch also changes behavior in the sense that IOV_MAX is now considered defined everywhere but on Windows. However, in the good-old GNU "we have no arbitrary limits" fashion, this breaks on GNU Hurd: |gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wcast-function-type -Wshado |w=compatible-local -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation -g -O2 -DFRONTEND -I. -I../../src/common - |I../../src/include -D_GNU_SOURCE -I/usr/include/libxml2 -DVAL_CC="\"gcc\"" -DVAL_CPPFLAGS="\"-D_GNU_SOURCE -I/usr/include/libxml2\"" -DVAL_CFLAGS="\"-Wall -Wmissing-prototypes -Wpoin |ter-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wcast-function-type -Wshadow=compatible-local -Wformat-security |-fno-strict-aliasing -fwrapv -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation -g -O2\"" -DVAL_CFLAGS_SL="\"-fPIC\"" -DVAL_LDFLAGS="\"-Wl,--as-needed -Wl,-rpa |th,'/home/demo/build-farm-19.1/buildroot/REL_16_STABLE/inst/lib',--enable-new-dtags\"" -DVAL_LDFLAGS_EX="\"\"" -DVAL_LDFLAGS_SL="\"\"" -DVAL_LIBS="\"-lpgcommon -lpgport -lxslt -lxml2 - |lssl -lcrypto -lgssapi_krb5 -lz -lreadline -lpthread -lm \"" -c -o file_utils.o file_utils.c |In file included from ../../src/include/postgres_fe.h:25, | from file_utils.c:19: |file_utils.c: In function 'pg_pwritev_with_retry': |../../src/include/port/pg_iovec.h:36:24: error: 'IOV_MAX' undeclared (first use in this function); did you mean 'INT_MAX'? | 36 | #define PG_IOV_MAX Min(IOV_MAX, 32) | | ^~~~~~~ |../../src/include/c.h:988:35: note: in definition of macro 'Min' | 988 | #define Min(x, y) ((x) < (y) ? (x) : (y)) | | ^ |file_utils.c:474:31: note: in expansion of macro 'PG_IOV_MAX' | 474 | struct iovec iov_copy[PG_IOV_MAX]; | | ^~~~~~~~~~ |../../src/include/port/pg_iovec.h:36:24: note: each undeclared identifier is reported only once for each function it appears in |$ grep IOV_MAX /usr/include/i386-gnu/bits/uio_lim.h |#undef __IOV_MAX Postgres built fine up and until v15 on the Hurd, so this is a build regression, and the fact that we define #PG_IOV_MAX to at most 32 anyway suggest we could just #definde IOV_MAX to 16 if undefined as on Windows. Christoph fixed this up for Debian's hurd-i386 builds in https://salsa.debian.org/postgresql/postgresql/-/commit/641713a4585e4b040266a1fa567b7ec90469a1bb but I have not seen a discussion about this (but might have missed it), so bringing it up here for upstream consideration in v16 and newer. Michael
