Re: pg_preadv() and pg_pwritev()

On 14.01.2021 18:42, Tom Lane wrote:
>> I noticed that "cc" invoked from command line uses:
>> -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
> 
> Hm, how did you determine that exactly?
> 

% echo 'int main(void){}' >tmp.c
% cc -v tmp.c
Apple clang version 12.0.0 (clang-1200.0.32.28)
Target: x86_64-apple-darwin19.6.0
Thread model: posix
InstalledDir: 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 
"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" 
-cc1 -triple x86_64-apple-macosx10.15.0 -Wdeprecated-objc-isa-usage 
-Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration 
-emit-obj -mrelax-all -disable-free -disable-llvm-verifier 
-discard-value-names -main-file-name tmp.c -mrelocation-model pic 
-pic-level 2 -mthread-model posix -mframe-pointer=all -fno-strict-return 
-masm-verbose -munwind-tables -target-sdk-version=10.15.6 
-fcompatibility-qualified-id-block-type-checking -target-cpu penryn 
-dwarf-column-info -debugger-tuning=lldb -target-linker-version 609.8 -v 
-resource-dir 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/12.0.0 
-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk 
-I/usr/local/include -internal-isystem 
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/local/include 
-internal-isystem 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/12.0.0/include 
-internal-externc-isystem 
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include 
-internal-externc-isystem 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include 
-Wno-reorder-init-list -Wno-implicit-int-float-conversion 
-Wno-c99-designator -Wno-final-dtor-non-final-class -Wno-extra-semi-stmt 
-Wno-misleading-indentation -Wno-quoted-include-in-framework-header 
-Wno-implicit-fallthrough -Wno-enum-enum-conversion 
-Wno-enum-float-conversion -fdebug-compilation-dir /Users/shinderuk 
-ferror-limit 19 -fmessage-length 238 -stack-protector 1 -fstack-check 
-mdarwin-stkchk-strong-link -fblocks -fencode-extended-block-signature 
-fregister-global-dtors-with-atexit -fgnuc-version=4.2.1 
-fobjc-runtime=macosx-10.15.0 -fmax-type-align=16 
-fdiagnostics-show-option -fcolor-diagnostics -o 
/var/folders/8x/jvqv7hyd5h98m7tz2zm9r0yc0000gn/T/tmp-91fb5e.o -x c tmp.c
clang -cc1 version 12.0.0 (clang-1200.0.32.28) default target 
x86_64-apple-darwin19.6.0
ignoring nonexistent directory 
"/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/local/include"
ignoring nonexistent directory 
"/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
  /usr/local/include
 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/12.0.0/include
  /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include
 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks 
(framework directory)
End of search list.
 
"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld" 
-demangle -lto_library 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/libLTO.dylib 
-no_deduplicate -dynamic -arch x86_64 -platform_version macos 10.15.0 
10.15.6 -syslibroot 
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -o a.out 
-L/usr/local/lib 
/var/folders/8x/jvqv7hyd5h98m7tz2zm9r0yc0000gn/T/tmp-91fb5e.o -lSystem 

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/12.0.0/lib/darwin/libclang_rt.osx.a