macOS llvm can't find stdio.h anymore

Question

I come to you with a weird problem I've been facing. So last week, I installed llvm and libomp for a C project, and it compiled just fine with this at the start of my makefile:

CC=clang
CFLAGS = -O2 -fopenmp
CFLAGS += -I/usr/local/opt/libomp/include
LDFLAGS = -fopenmp
LDFLAGS += -L /usr/local/opt/libomp/lib

Today I meant to finish that project, I opened vs code (I don't know if that's relevant), added some code left and right, and when I wanted to compile the code again to test if everything was fine, it gave me

me@macbookPro% make
clang -c  -O2 -fopenmp -I/usr/local/opt/libomp/include bubble.c -o bubble.o
bubble.c:1:10: fatal error: 'stdio.h' file not found
#include <stdio.h>
         ^~~~~~~~~
1 error generated.
make: *** [bubble.o] Error 1

which has left me dumbfounded since it worked just fine a few days ago. I tried to do an export CPATH with

export CPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include

but I got a bunch of warning and it didn't work either. Any help is greatly appreciated !

Info: I'm running the latest version of BigSur and VSCode.

Answer 1

Apparently a macOS update had uninstalled the XCode developer tools.

I ended up uninstalling llvm and libomp, and when reinstalling it told me brew didn't have CLT (use brew config to check that).

Then I ran the classic xcode-select --install then brew install llvm and brew install libomp, edited my path to include the llvm's bin and it works again.

Answer 2

My solution:

• masOS12.3.1 monterey

"software update" --> "update commandLineTool" if push --> you can compile correctly without 'stdio.h' file not found.