C++20 standard library compile error for module on macOS - c++

Question

Here are my test code and build scripts.
testmodule.cpp
#include <iostream>
export module testmodule;
export int add(int a, int b)
{
return a + b;
}
main.cpp
#include <iostream>
import testmodule;
using namespace std;
int main() {
cout << "Test Modules" << endl;
cout << "add 1 and 2 is " << add(1,2) << endl;
}
build.sh
rm *.o
rm *.pcm
clang++ -fmodules-ts -Wall -v -c -ferror-limit=1 -Xclang -emit-module-interface testmodule.cpp -o testmodule.pcm
clang++ -fmodules-ts -Wall -v -c -ferror-limit=1 -fprebuilt-module-path=. main.cpp -o main.o
clang++ -fmodules-ts -o main main.o *.pcm
When I run the build.sh, I got the following compile errors:
Apple clang version 14.0.0 (clang-1400.0.29.102)
Target: x86_64-apple-darwin21.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
"/Library/Developer/CommandLineTools/usr/bin/clang" -cc1 -triple x86_64-apple-macosx12.0.0 -Wundef-prefix=TARGET_OS_ -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model pic -pic-level 2 -mframe-pointer=all -fno-strict-return -fno-rounding-math -funwind-tables=2 -target-sdk-version=12.3 -fvisibility-inlines-hidden-static-local-var -target-cpu penryn -tune-cpu generic -debugger-tuning=lldb -target-linker-version 819.6 -v -resource-dir /Library/Developer/CommandLineTools/usr/lib/clang/14.0.0 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -I/usr/local/include -stdlib=libc++ -internal-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1 -internal-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include -internal-isystem /Library/Developer/CommandLineTools/usr/lib/clang/14.0.0/include -internal-externc-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include -internal-externc-isystem /Library/Developer/CommandLineTools/usr/include -Wall -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 -Wno-elaborated-enum-base -Wno-reserved-identifier -Wno-gnu-folding-constant -Wno-cast-function-type -Wno-bitwise-instead-of-logical -fdeprecated-macro -fdebug-compilation-dir=/Users/bf/Workspaces/C-plus-plus-Playground/validateC++20 -ferror-limit 1 -stack-protector 1 -fstack-check -mdarwin-stkchk-strong-link -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fgnuc-version=4.2.1 -fno-cxx-modules -fmodules-ts -fno-implicit-modules -fprebuilt-module-path=. -fcxx-exceptions -fexceptions -fmax-type-align=16 -fcommon -fcolor-diagnostics -clang-vendor-feature=+messageToSelfInClassMethodIdReturnType -clang-vendor-feature=+disableInferNewAvailabilityFromInit -clang-vendor-feature=+disableNonDependentMemberExprInCurrentInstantiation -fno-odr-hash-protocols -clang-vendor-feature=+enableAggressiveVLAFolding -clang-vendor-feature=+revert09abecef7bbf -clang-vendor-feature=+thisNoAlignAttr -clang-vendor-feature=+thisNoNullAttr -mllvm -disable-aligned-alloc-awareness=1 -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o main.o -x c++ main.cpp
clang -cc1 version 14.0.0 (clang-1400.0.29.102) default target x86_64-apple-darwin21.6.0
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include"
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1
/Library/Developer/CommandLineTools/usr/lib/clang/14.0.0/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include
/Library/Developer/CommandLineTools/usr/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks (framework directory)
End of search list.
In module 'testmodule' imported from main.cpp:3:
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1/ostream:216:20: error: 'std::basic_ostream<char>::operator<<' from module 'testmodule.<global>' is not present in definition of 'std::ostream' provided earlier
basic_ostream& operator<<(nullptr_t)
^
If I comment out the line #1 in testmodule.cpp and run build.sh, I'll get a main binary as expected.
% ./main
Test Modules
add 1 and 2 is 3
It seems that I cannot include std libraries in both main.cpp and testmodule.cpp.
Any idea where I can start to look into this?
[Update 2022-10-18]
With Remy's suggestion, I tried import <iostream>; in testmodule.cpp, and got the following errors,
Apple clang version 14.0.0 (clang-1400.0.29.102)
Target: x86_64-apple-darwin21.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
"/Library/Developer/CommandLineTools/usr/bin/clang" -cc1 -triple x86_64-apple-macosx12.0.0 -Wundef-prefix=TARGET_OS_ -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name testmodule.cpp -mrelocation-model pic -pic-level 2 -mframe-pointer=all -fno-strict-return -fno-rounding-math -funwind-tables=2 -target-sdk-version=12.3 -fvisibility-inlines-hidden-static-local-var -target-cpu penryn -tune-cpu generic -debugger-tuning=lldb -target-linker-version 819.6 -v -resource-dir /Library/Developer/CommandLineTools/usr/lib/clang/14.0.0 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -I/usr/local/include -stdlib=libc++ -internal-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1 -internal-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include -internal-isystem /Library/Developer/CommandLineTools/usr/lib/clang/14.0.0/include -internal-externc-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include -internal-externc-isystem /Library/Developer/CommandLineTools/usr/include -Wall -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 -Wno-elaborated-enum-base -Wno-reserved-identifier -Wno-gnu-folding-constant -Wno-cast-function-type -Wno-bitwise-instead-of-logical -fdeprecated-macro -fdebug-compilation-dir=/Users/bf/Workspaces/C-plus-plus-Playground/validateC++20 -ferror-limit 1 -stack-protector 1 -fstack-check -mdarwin-stkchk-strong-link -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fgnuc-version=4.2.1 -fno-cxx-modules -fmodules-ts -fno-implicit-modules -fcxx-exceptions -fexceptions -fmax-type-align=16 -fcommon -fcolor-diagnostics -emit-module-interface -clang-vendor-feature=+messageToSelfInClassMethodIdReturnType -clang-vendor-feature=+disableInferNewAvailabilityFromInit -clang-vendor-feature=+disableNonDependentMemberExprInCurrentInstantiation -fno-odr-hash-protocols -clang-vendor-feature=+enableAggressiveVLAFolding -clang-vendor-feature=+revert09abecef7bbf -clang-vendor-feature=+thisNoAlignAttr -clang-vendor-feature=+thisNoNullAttr -mllvm -disable-aligned-alloc-awareness=1 -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o testmodule.pcm -x c++ testmodule.cpp
clang -cc1 version 14.0.0 (clang-1400.0.29.102) default target x86_64-apple-darwin21.6.0
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include"
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1
/Library/Developer/CommandLineTools/usr/lib/clang/14.0.0/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include
/Library/Developer/CommandLineTools/usr/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks (framework directory)
End of search list.
testmodule.cpp:2:8: error: expected a module name after 'import'
import <iostream>;
^
[update Tue Oct 18 2:38PM]
Thanks for sigma's comments. I moved [export] section to the beginning of the code. I added cout statement in testmodule.cpp to make iostream required in testmodule.cpp. After the modification I still see compile errors when compile main.cpp
1 // testmodule.cpp
2 export module testmodule;
3 #include <iostream>
4 export int add(int a, int b)
5 {
6 std::cout << "in add()\n";
7 return a + b;
8 }
1 // main.cpp
2 #include <iostream>
3
4 import testmodule;
5
6 using namespace std;
7
8 int main() {
9 cout << "Test Modules" << endl;
10 cout << "add 1 and 2 is " << add(1,2) << endl;
11 }
% clang++ -fmodules-ts -Wall -c -ferror-limit=1 -Xclang -emit-module-interface testmodule.cpp -o testmodule.pcm
% clang++ -fmodules-ts -Wall -v -c -ferror-limit=1 -fprebuilt-module-path=. main.cpp -o main.o
Apple clang version 14.0.0 (clang-1400.0.29.102)
Target: x86_64-apple-darwin21.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
"/Library/Developer/CommandLineTools/usr/bin/clang" -cc1 -triple x86_64-apple-macosx12.0.0 -Wundef-prefix=TARGET_OS_ -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model pic -pic-level 2 -mframe-pointer=all -fno-strict-return -fno-rounding-math -funwind-tables=2 -target-sdk-version=12.3 -fvisibility-inlines-hidden-static-local-var -target-cpu penryn -tune-cpu generic -debugger-tuning=lldb -target-linker-version 819.6 -v -resource-dir /Library/Developer/CommandLineTools/usr/lib/clang/14.0.0 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -I/usr/local/include -stdlib=libc++ -internal-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1 -internal-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include -internal-isystem /Library/Developer/CommandLineTools/usr/lib/clang/14.0.0/include -internal-externc-isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include -internal-externc-isystem /Library/Developer/CommandLineTools/usr/include -Wall -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 -Wno-elaborated-enum-base -Wno-reserved-identifier -Wno-gnu-folding-constant -Wno-cast-function-type -Wno-bitwise-instead-of-logical -fdeprecated-macro -fdebug-compilation-dir=/Users/bf/Workspaces/C-plus-plus-Playground/validateC++20/try001 -ferror-limit 1 -stack-protector 1 -fstack-check -mdarwin-stkchk-strong-link -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fgnuc-version=4.2.1 -fno-cxx-modules -fmodules-ts -fno-implicit-modules -fprebuilt-module-path=. -fcxx-exceptions -fexceptions -fmax-type-align=16 -fcommon -fcolor-diagnostics -clang-vendor-feature=+messageToSelfInClassMethodIdReturnType -clang-vendor-feature=+disableInferNewAvailabilityFromInit -clang-vendor-feature=+disableNonDependentMemberExprInCurrentInstantiation -fno-odr-hash-protocols -clang-vendor-feature=+enableAggressiveVLAFolding -clang-vendor-feature=+revert09abecef7bbf -clang-vendor-feature=+thisNoAlignAttr -clang-vendor-feature=+thisNoNullAttr -mllvm -disable-aligned-alloc-awareness=1 -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o main.o -x c++ main.cpp
clang -cc1 version 14.0.0 (clang-1400.0.29.102) default target x86_64-apple-darwin21.6.0
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include"
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1
/Library/Developer/CommandLineTools/usr/lib/clang/14.0.0/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include
/Library/Developer/CommandLineTools/usr/include
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks (framework directory)
End of search list.
In module 'testmodule' imported from main.cpp:3:
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1/type_traits:436:43: error: 'std::integral_constant<bool, false>::value' from module 'testmodule' is not present in definition of 'std::integral_constant<bool, false>' provided earlier
static _LIBCPP_CONSTEXPR const _Tp value = __v;
^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1/type_traits:436:43: note: declaration of 'value' does not match
static _LIBCPP_CONSTEXPR const _Tp value = __v;
^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
2 errors generated.
[update 2022-10-19]
Thanks sigma. I did some further tests on module fragment test. It seems the clang++ on macOS does not fully support c++ module.
Code,
// interface_part.cppm
export module M:interface_part;
export void World();
Compile command and output,
% clang++ -std=c++20 -fmodules-ts interface_part.cppm --precompile -o M-interface_part.pcm
interface_part.cppm:2:16: error: sorry, module partitions are not yet supported
export module M:interface_part;
^~~~~~~~~~~~~~~
1 error generated.