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.