在 mac 上，g++ (clang) 默认搜索 /usr/local/include 和 /usr/local/lib 失败

Question

I'm on a mac and I used homebrew to install gmp .

Kyumins-iMac:gcjlib math4tots$ g++ main.cpp -lgmp -lgmpxx
In file included from main.cpp:2:
./gcjlib.hpp:4:10: fatal error: 'gmpxx.h' file not found
#include <gmpxx.h>
         ^
1 error generated.

So then I explicitly told g++ to use /usr/local/include

Kyumins-iMac:gcjlib math4tots$ g++ main.cpp -lgmp -lgmpxx -I/usr/local/include
ld: library not found for -lgmp
clang: error: linker command failed with exit code 1 (use -v to see invocation)

So then I explicitly told g++ to use /usr/local/lib

Kyumins-iMac:gcjlib math4tots$ g++ main.cpp -lgmp -lgmpxx -I/usr/local/include -L/usr/local/lib
Kyumins-iMac:gcjlib math4tots$ ./a.out 
sum is -4444
absolute value is 4444

So the only issue seems to be that g++ fails to acknowledge /usr/local .

But it is tedious to type all this out all the time, especially when I'm just writing small single file programs.

Is there a way for me to get g++ to acknowledge the stuff in /usr/local by default? Is there a standard way homebrew users do this?

---

I'm on OS X 10.9.3 with Xcode 5.1.1 in case it is relevant.

Answer 1

I also use Homebrew and had a similar problem on Mac OSX Maverick 10.9.5 and Xcode 6.0.1, but it was solved by running:

xcode-select --install

Note that it doesn't work without the double hyphens given by the previous answer. This installs the command-line tools that also create /usr/lib/ and /usr/include/ . I don't know why Homebrew doesn't automatically check this upon installation, since it does check for Xcode...

If you want to check exactly what folders your compiler is looking through for header files you can write:

cpp -v

Answer 2

A workaround would be to:

export C_INCLUDE_PATH=/usr/local/include
export CPLUS_INCLUDE_PATH=/usr/local/include

At least this tricked the pre-processor to behave here :)

Answer 3

Try running xcode-select --install

At least on Mavericks, I've found that if I install the Xcode application without installing the command-line tools, then the tools are sort of available, but normal unix-ey builds don't work correctly. One symptom is that /usr/local/include is not on the include search path. The command-line tools seem to resolve this issue.

Answer 4

I have Yosemite 10.10.5 and running xcode-select --install didn't fix the problem for me. The command returned with xcode-select: error: command line tools are already installed, use "Software Update" to install updates .

When I ran xcode-select -p , it showed /Applications/Xcode.app/Contents/Developer . I ended up deleting Xcode from the Applications directory, which resulted in xcode-select -p returning /Library/Developer/CommandLineTools . This fixed compiler error for me.

Answer 5

That was helpful for me:

Use the latest version. 1.0.2o_1 just a current build.

brew install openssl
ln -s /usr/local/Cellar/openssl/1.0.2o_1/include/openssl /usr/local/include/openssl
ln -s /usr/local/Cellar/openssl/1.0.2o_1/lib /usr/local/lib/openssl

Answer 6

CMake always adds -isysroot explicitly to get the macosx SDK. This behavior that was once required to get anything to compile on the command line. One can see that the flag affects whether /usr/local/include is considered an implicit include directory by the compiler. The above command-line examples show that macOS command-line compilers no longer require an explicit -isysroot. However, since commit 1f085e11 CMake resolves /usr/bin/cc, /usr/bin/c++, and other macOS compiler wrappers that find a real compiler through xcrun to the path to that real compiler. In our case, AudioConverterLib is an external dependency. The convention in CMake projects is to not rely on system include directories for anything outside the standard library. Therefore it should use find_package(AudioConverterLib) with a FindAudioConverterLibConfic.cmake find module. Short of a full find module, I ask CMake to find the external header file and add the appropriate include directory using this patch:

find_path(MYLIB_INCLUDE_DIR NAMES MyLib_global.h)
 
target_include_directories(MyClientApp PRIVATE
  "${PROJECT_SOURCE_DIR}/include" ${MYLIB_INC

You can find the whole post here: https://michae9.wordpress.com/2022/09/01/shared-lib-to-be-used-by-client-programs-with-cmake/

Answer 7

There are a few questions around this topic with answers that suggest putting a symlink in /usr/local/include . However I'm running macOS Monterey 12.3 (on an M1 MacBook) and that directory doesn't exist.

I had installed the Xcode command line tools by downloading the package from Apple, so xcode-select --install just tells me it's already installed and doesn't create any directories.

I ran cpp -v to see which directories are searched for #include <...> :

 /Library/Developer/CommandLineTools/usr/lib/clang/13.1.6/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)

I picked /Library/Developer/CommandLineTools/usr/include for the symlink. In that directory, I ran the following command (note the new location for Homebrew installations, under /opt/homebrew - some old answers are also out of date on this point):

sudo ln -s /opt/homebrew/opt/openssl@3/include/openssl .

clang was then able to find the OpenSSL files.

Answer 8

If you want a solution just for compiling and running like I needed, you can use

gcc file.c \
-I /usr/local/opt/openssl/include \
-L /usr/local/opt/openssl/lib -lcrypto

-I is to perform an incremental link

-L is to search the library given when linking

Answer 9

apk add --no-cache build-base it works fine ！！！！ go build -tags musl -o main main.go