Describe the Bug

On Debian Bookworm (12), building GRASS GIS from source fails at the LAPACKE check stage.
Although liblapacke-dev and libopenblas-dev are installed, CMake reports:

Could NOT find LAPACKE (missing: HAVE_LAPACKE_DGESV) (found version "0.3.21")

The reason is that CMake’s FindLAPACKE.cmake uses check_symbol_exists() which only checks headers, but does not link against liblapacke.so.
Since Bookworm ships LAPACK via OpenBLAS and keeps LAPACKE in a separate library, the detection always fails unless manually overridden.

So even with correct headers and libraries present, you have to “hand-hold” CMake by explicitly pointing it to the LAPACKE library and include path.

To Reproduce

First install all the required dependencies before re-producing this issue. Follow INSTALL.md

1. sudo apt update
2. sudo apt install build-essential cmake liblapacke-dev libopenblas-dev \ libblas-dev liblapack-dev gfortran
3. git clone <your forked repository url>
4. cd grass
5. mkdir build && cd build
6. cmake ..

Result: CMake configuration fails with the LAPACKE error shown above.

Expected Behaviour

CMake should detect LAPACKE automatically when liblapacke-dev is installed, without requiring manual overrides.

Screenshot

The following error is displayed when running cmake ..

Logs

Excerpt from CMakeError.log

undefined reference to LAPACKE_dgesv'`

To prove that liblapacke-dev is actually installed and exists on the system, I have tried the following:

#include <lapacke.h>
#include <stdio.h>

int main() {
    printf("LAPACKE_dgesv is here: %p\n", LAPACKE_dgesv);
    return 0;
}

compile using

gcc test_lapacke.c -o test_lapacke -llapacke -llapack -lblas
./test_lapacke

Output: LAPACKE_dgesv is here: 0x7fe4658c1320

System Description

• OS: Debian Bookworm (12), amd64
• GRASS version: current main branch (as of Sept 2025)
• CMake: 3.25
• BLAS/LAPACK: OpenBLAS + LAPACKE (Debian packaged versions)