Re: pg_preadv() and pg_pwritev()

Tom Lane wrote:
> The symptoms sound consistent with using bleeding-edge Xcode on a
> Catalina machine ... please report exact OS and Xcode versions.

macOS 10.15.7 (19H2)
Xcode 12.3 (12C33)
macOS SDK 11.1 (20C63)

> Attached is an untested quick hack to make that happen --- Sergey,
> can you verify that this fixes configure's results on your setup?

"-no_weak_imports" doesn't help.

configure:15161: checking for pwritev
configure:15161: gcc -o conftest -Wall -Wmissing-prototypes
-Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels
-Wmissing-format-attribute -Wformat-security -fno-strict-aliasing
-fwrapv -Wno-unused-command-line-argument -O2 -isysroot
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk
-Wl,-no_weak_imports -isysroot
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk
conftest.c -lz -lm >&5
configure:15161: $? = 0
configure:15161: result: yes

Then I get the same compiler warnings about pwritev and an unrelated
link error:

ld: weak import of symbol '___darwin_check_fd_set_overflow' not
supported because of option: -no_weak_imports for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
make[2]: *** [postgres] Error 1
make[1]: *** [all-backend-recurse] Error 2
make: *** [all-src-recurse] Error 2

Please see the logs attached.